Search

Tannic acid (TA) film covered magnetic microspheres (Fe 3 O 4 @TA–Fe 3+ ) was synthesized and applied for removal of Pb 2+ and Hg 2+ from aqueous solution. The resulted Fe 3 O 4 @TA–Fe 3+ was characterized with thermo-gravimetric analysis, vibrating sample magnetometer, transmission electron microscope, and Fourier transform infrared spectra. The adsorption of pollutants was pH dependent because the complexation of TA with Fe 3+ was disassembled at low pH. The composites showed high maximum adsorption capacity for Pb 2+ up to 1115.3 mg/g and Hg 2+ to 279.4 mg/g. Furthermore, the Fe 3 O 4 @TA–Fe 3+ composites could be easily separated from the solution by a magnet after adsorption because of the excellent superparamagnetic property. Thermodynamics study indicated that the adsorption of Pb 2+ and Hg 2+ on Fe 3 O 4 @TA–Fe 3+ sorbents was spontaneous, chaotic degree decreasing and endothermic process. The present results warrant the promising application of magnetic Fe 3 O 4 @TA–Fe 3+ composites for removal of Pb 2+ and Hg 2+ from contaminated water, and this study is the first application of TA film in environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • HNTs@MoS 2 /goethite with high catalysis and adsorption performance was synthesized. • Adjustment of acid sites of material ensures the efficient adsorption of Cd2+. • AAF by-products could improve adsorption of Cd2+ via bridging effect. • S-Scheme e- transfer, fast Fe3+/Fe2+ cycle enhance the photo-Fenton process. • Adsorption energy and molecular frontier orbit were calculated to reveal mechanism. Aniline aerofloat (AAF) and Cd2+ have caused severe pollution near the mine site, simultaneous remediation technologies are facing enormous challenges due to different reaction conditions of these two pollutants. Herein, a surface optimized Halloysite@MoS 2 /goethite was established to simultaneously remove AAF-Cd2+ pollution in a photo-Fenton reaction system. The spatial confinement of halloysite nanotube, special surface modulated particle size, acid-base property, and Zeta potential efficiently enhanced photo-Fenton degradation activity and adsorption for cations. 94.2 % of AAF and 94.1 % of Cd2+ were eliminated within 60 min and the adsorption capacity for Cd2+ reached 68.14 mg g−1. The built-in electric field between MoS 2 and goethite promoted separation of photogenerated carrier via an S-Scheme separation strategy, which maintained high potential electrons in CB and holes in VB for generating reactive oxidation species (ROS). The photocatalysis of MoS 2 facilitate to regulate valence of iron species for sustainable activation of H 2 O 2. Combined with HPLC-MS analysis, theoretical calculation of frontier molecular orbital and adsorption energy, the removal mechanism of AAF-Cd2+ was proposed. This study provides novel insights into simultaneous removal of beneficiation reagents-heavy metals combined pollutants and may contribute to remediation of water pollution near the mine sites. [ABSTRACT FROM AUTHOR]

• Four spatially contiguous regions were adaptively detected by spatial clustering. • The input combinations of WQPs were found to be diverse in different clusters. • The locally optimal prediction models were constructed for Cluster 1 to Cluster 4. • Fewer parameters have been verified to achieve acceptable prediction results. Water quality prediction in the spatially heterogeneous environment is challenging as the importance of water quality parameters (WQPs) and the performance of prediction models may vary across space. Thus, this study proposed spatially adaptive machine learning models to predict water quality status in Hong Kong. First, spatial clusters with relatively homogeneous water quality were adaptively detected using dynamically constrained agglomerative clustering and partitioning. Then, the optimal prediction models were constructed for each cluster by locally evaluating the prediction performance of six standalone machine learning models, including multi-layer perceptron neural network (MLPNN), support vector machine (SVM), random forest (RF), extremely randomized tree (ET), eXtreme gradient boosting (XGBoost) and categorical gradient boosting (CatBoost), as well as four novel hybrid models (MLPNN-SVM, ET-CatBoost, MLPNN-CatBoost and XGBoost-CatBoost). Finally, a sensitivity analysis was conducted to explore the minimum sets of indicative WQPs to achieve more cost-efficient water quality prediction based on locally optimal prediction models. The results revealed that the water quality in the study area was spatially heterogeneous and four spatially contiguous clusters were identified. MLPNN-SVM, ET-CatBoost, MLPNN-CatBoost and CaBboost performed best in Cluster 1 to Cluster 4, with R2 values of 0.917, 0.906, 0.901 and 0.937 and RMSE values of 1.978, 0.843, 2.020 and 1.572, respectively. The results of the sensitivity analysis indicated that acceptable local prediction results can be obtained using fewer WQPs. It is conducive to issuing timely water quality warnings and striving for more time for water pollution remediation. [ABSTRACT FROM AUTHOR]

The structural design and morphology control of materials is a very attractive topic because the structure and morphology of materials usually play a key role for their performance and application. In this work, we report a facile two-step hydrothermal process for construction of the binary composite oxide system (i.e., 1D/2D Co 3 O 4 /NiMnO 3 core-shell heterostructure) based on Ostwald ripening effect. Interestingly, Co 3 O 4 nanowire will expand only when it is fully covered with NiMnO 3 nanosheets to form a core-shell structure in sequential hydrothermal process. In binary composite oxide system, the formation of continuous and uniform interface between core (Co 3 O 4) and shell (NiMnO 3) based on Ostwald ripening effect is the key factor in the heterogeneous nucleation process, which can be proved by the homogeneous diffusion of Co element in the Ti/Co 3 O 4 -NiMnO 3 sample. As a result, the optimized Ti/Co 3 O 4 -NiMnO 3 -1.5 exhibited superior PEC performance (degradation rates are ∼ 91.2% for 120 min and 80.5% after 5 cycles) for degrading reactive brilliant blue KN-R solution, which can be attributed to the construction of the hollow Co 3 O 4 /NiMnO 3 core-shell heterostructure. Furthermore, the identification experiments of active species showed that the h+ and •O 2 - radicals are the dominant reactive species, indicating the induced charge transfer is based on the type II semiconductor heterostructure. • A special hollow Co 3 O 4 /NiMnO 3 core-shell heterogeneous structure was constructed. • The homogeneous diffusion of Co element verifies the heterogeneous nucleation process. • The optimized coupling of Co 3 O 4 with NiMnO 3 exhibits good photocatalytic activity. • The special core-shell structure provides efficient surface adsorption and ample active sites. [ABSTRACT FROM AUTHOR]

This study demonstrated the formation of N-enriched mixed metal oxides (Ta 2 O 5 -Nb 2 O 5 -N and Ta 2 O 5 -Nb 2 O 5) thin film composites used as photocatalysts to degrade P-Rosaniline Hydrochloride (PRH-Dye) dye under solar radiation. By controlling the N gas flow rate during the sputtering process, the N concentration in the Ta 2 O 5 -Nb 2 O 5 -N composite is significantly included, and demonstrated by XPS and HRTEM analysis. With the help of XPS and HRTEM investigations, it was determined that the addition of N to Ta 2 O 5 -Nb 2 O 5 -N significantly enhances the active sites. The Ta-O-N bond (N 1 s and Ta 4p 3/2 spectra) was verified by the XPS spectra. Ta 2 O 5 -Nb 2 O 5 was found to have a lattice interplanar distance (d -spacing) of 2.52, whereas Ta 2 O 5 -Nb 2 O 5 -N showed the 2.5 (620 planes). A sputter-coated Ta 2 O 5 -Nb 2 O 5 and Ta 2 O 5 -Nb 2 O 5 -N photocatalysts were prepared, and their photocatalytic activity was evaluated using PRH-Dye as a model pollutant under solar radiation by adding H 2 O 2 (0.01 mol). The photocatalytic activity of the Ta 2 O 5 -Nb 2 O 5 -N composite was compared with TiO 2 (P-25) and Ta 2 O 5 -Nb 2 O 5. Ta 2 O 5 -Nb 2 O 5 -N showed very high photocatalytic activity compared to Degussa P-25 TiO 2 and Ta 2 O 5 -Nb 2 O 5 under solar radiation and confirmed the presence of N in Ta 2 O 5 -Nb 2 O 5 -N significantly increased the generation of ˙OH radicals (in pH 3, 7 and 9). With the use of LC/MS, the stable intermediates or metabolite created during the photooxidation of PRH-Dye were assessed. The results of this study will provide useful insights on how Ta 2 O 5 -Nb 2 O 5 -N influences the efficiency of water pollution remediation. [Display omitted] • Using sputter techniques, a highly N-enriched Ta 2 O 5 -Nb 2 O 5 -N photocatalyst was created. • The Ta 2 O 5 -Nb 2 O 5 -N photocatalyst displayed a remarkable bandgap (2.55 eV) narrowing. • Ta 2 O 5 -Nb 2 O 5 -N was estimated to generate 411 µmol of ˙OH radicals at pH 3 under sunlight. • Complete mineralization of PRT-Dye was achieved in all three pH (3, 7, and 9). • Reusability of Ta 2 O 5 -Nb 2 O 5 -N thin film photocatalyst kinetics showed not much deviation. [ABSTRACT FROM AUTHOR]

The development of carbon-based mesoporous semiconductor composites with superior photocatalytic performance is of great importance for water remediation of organic pollution caused by antibiotics or dyes. In this work, series of novel peanut shell biochar anchored NiCr-LDH(NiCr-LDH/PSB) photocatalysts were constructed via one-pot hydrothermal method for photodegradation of ofloxacin and tetracycline antibiotics. The comprehensive characterization indicated that NiCr-LDH uniformly dispersed on biochar matrix and formed a three-dimensional flower-like mesoporous structure. Appropriate doping of PSB can remarkably improve the photodegradation performance of NiCr-LDH for ofloxacin and tetracycline removal under UV-light irradiation. The photodegradation efficiency is better than that of pristine NiCr-LDH and biochar alone. More importantly, the optimal NiCr-LDH/PSB (18 %) composite exhibited the superior photodegradation and mineralization performance for ofloxacin and tetracycline. The photocatalytic degradation activities of NiCr-LDH/PSB for OFX and TC were about 3.5 and 2.3 times than that of NiCr-LDH, respectively. After four successive operations, the removal efficiency decreased by less than 20 %, suggesting that the as-synthesized NiCr-LDH/PSB has a good application prospect. Furthermore, a possible photocatalytic mechanism with •OH and •O 2 − as the main active species was proposed on the basis of photoelectrical properties, active species trapping and ESR tests. The study offers a novel idea for the fabrication of biochar anchored LDH system with excellent synergic adsorption and photocatalytic performance for the removal of antibiotic wastewater. [Display omitted] • One-pot hydrothermal fabrication of mesoporous flower-like NiCr-LDH/PSB photocatalyst. • Synergistic photocatalysis of NiCr-LDH and PSB for enhanced antibiotics removal. • High antibiotic mineralization efficiency and stability of NiCr-LDH/PSB. • Proposed a plausible photocatalytic degradation mechanism of antibiotics. [ABSTRACT FROM AUTHOR]

Photocatalysis technology is considered as an important strategy to solve the environmental and energy crisis, but the powdered photocatalyst is difficult to recover from water environment and may lead secondary pollution, restricts its practical applications. In this work, a novel AgInS 2 /CN/PAN photocatalytic film with recyclable and high-performance was successfully prepared for RhB and phenol degradation. The microstructure of this photocatalytic film was evaluated by XRD, FTIR, XPS, SEM, TEM, UV–vis, Photoluminescence spectra, Transient photocurrent, etc. The as-prepared AgInS 2 /CN/PAN photocatalytic film exhibited the excellent photocatalytic activity, about 94.48% of RhB and about 77.71% of phenol can be degraded after 60 min visible light irradiation, respectively. The enhanced photocatalytic activity of the photocatalytic film was believed to be related to the improved light-harvest ability and the facilitated carrier transport ability between AgInS 2 and CN. The AgInS 2 /CN/PAN photocatalytic film could be easily separate from water after photocatalytic process only through a sample filtering method, which can be reused via a simple washing and drying process. Meanwhile, biology and environment toxicities of the as-prepared samples towards Mung bean seeds were performed. This study may develop a novel strategy to rationally design the novel recyclable and high-performance photocatalysts for water pollution remediation. [Display omitted] • A highly efficient and easily recyclable photocatalytic thin film is prepared. • Photocatalytic activity is evaluated by photodegradation of RhB and phenol. • AgInS 2 /CN/PAN exhibits the highest photocatalytic activity. • Enhanced photocatalytic activity is believe to faster spatial charge transfer. • Biology and environment toxicities of the as-prepared samples are performed. [ABSTRACT FROM AUTHOR]

• Aqueous and surface reactions rule FeS oxygenation at acidic and basic pH severally. • γ-FeOOH replaces α-FeOOH and amarantite as the main product besides S0 as pH rises. • H+ can regulate FeS transformation and further affect its ability to reduce Cr(VI). • Increasing oxygenation time of FeS impedes Cr(VI) reduction and removal at pH 5.0. • Pyrite from brief oxygenation of FeS improves Cr(VI) reduction and removal at pH 9.0. Iron sulfide (FeS) has been widely used to reduce toxic Cr(VI) into Cr(III) in anoxic aquatic environments, where pH could strongly influence Cr(VI) removal. However, it remains unclear how pH regulates the fate and transformation of FeS under oxic conditions and the immobilization of Cr(VI). The results of this study showed that typical pH conditions of natural aquatic environment significantly affected the mineral transformation of FeS. Under acidic conditions, FeS was principally transformed to goethite, amarantite, and elemental sulfur with minor lepidocrocite through proton-promoted dissolution and oxidation. Instead, under basic conditions, the main products were lepidocrocite and elemental sulfur via surface-mediated oxidation. In typical acidic or basic aquatic environment, the pronounced pathway for the oxygenation of FeS solids may alter their ability to remove Cr(VI). Longer oxygenation impeded Cr(VI) removal at acidic pH, and a decreasing ability to reduce Cr(VI) caused a drop in Cr(VI) removal performance. Cr(VI) removal decreased from 733.16 to 36.82 mg g−1 with the duration of FeS oxygenation increasing to 5760 min at pH 5.0. In contrast, newly generated pyrite from brief oxygenation of FeS improved Cr(VI) reduction at basic pH, followed by a drop in Cr(VI) removal performance due to the impaired reduction capacity with increasing to the complete oxygenation. Cr(VI) removal increased from 669.58 to 804.83 mg g−1 with increasing oxygenation time to 5 min and then decreased to 26.27 mg g−1 after the full oxygenation for 5760 min at pH 9.0. These findings provide insight into the dynamic transformation of FeS in oxic aquatic environments with various pHs and the impact on Cr(VI) immobilization. [Display omitted] [ABSTRACT FROM AUTHOR]

• A simple method for successfully preparing GT-PAC-nZVI/S was developed. • The removal rate of nitrate by GT-PAC-nZVI/S at optimal conditions can reach 93%. • GT-PAC-nZVI/S has good anti-oxidation and anti-agglomeration properties. • The nitrate removal mechanism was complexation, redox, adsorption coprecipitation. In this study, A green reducing agent green tea extract is used instead of traditional sodium borohydride and porous activated carbon was supported to prepare nano-zero valent iron (nZVI) combined with sulfate (GT-PAC-nZVI/S) to remove Nitrate Nitrogen (NO 3 –-N) in wastewater. SEM-EDS, BET, XRD and FTIR characterization results confirmed that effective preparation of porous and high specific surface area and successful loading of sulfide nZVI on PAC. Batch experiments were conducted to measure the effects on the removal of nitrate nitrogen of different parameters including pH, temperature, dosage, interfering agents, carbon-iron ratio and iron-sulfur ratio. The experimental results demonstrate that GT-PAC-nZVI/S has a high nitrate nitrogen removal rate and reduction product gaseous nitrogen can reach 93.00% and 22.10%, respectively, at pH = 7, the dosage of GT-PAC-nZVI/S = 4 g/L, temperature of 60 ℃, iron-sulfur ratio = 1:0.3 and time of 95 min. And interfering ion HPO 4 2- have the strong inhibition for NO 3 –-N degradation. The adsorption isotherm and kinetic data for GT-PAC-nZVI/S was fitted well with the Langmuir and pseudo-second order model, respectively, indicating that the adsorption process for nitrate was chemisorption. Furthermore, GT-PAC-nZVI/S enhanced the removal of nitrate nitrogen through complexation, redox, and adsorption co-precipitation. This work highlights the efficient remediation of nitrate-nitrogen water pollution by porous activated carbon loaded with sulfide nZVI. [ABSTRACT FROM AUTHOR]

Heavy metals prevent the growing amount of sewage sludge from being disposed as fertilizeron land. The electrokinetic remediation and bioleaching technology are the promising methods to remove heavy metals. In recent years, some innovation has been made to achieve better efficiency, including the innovation of processes and agents. This paper reviews the development of the electrokinetic remediation and bioleaching technology and analyses their advantages and limitation, pointing out the need of the future research for the heavy metals-contaminated sewage sludge. [ABSTRACT FROM AUTHOR]

The indigenous microalgae-activated sludge (MAAS) process during remediation of municipal wastewater was investigated by studying the influence of iron flocculation step and light intensity. In addition, availability of total phosphorous (P) and photosynthetic activity was examined in fed-batch and batch mode under northern climatic conditions and limited lighting. This was followed by a semi-continuous operation with 4 d of hydraulic retention time and mean cell residence time of 6.75 d in a photo-bioreactor (PBR) with varying P availability. The fed-batch condition showed that P concentrations of 3–4 mg L −1 were effective for photosynthetic chl. a development in iron flocculated conditions. In the PBR, the oxygen evolution rate increased with increase in the concentration of MAAS (from 258 to 573 mg TSS L −1 ) at higher surface photosynthetic active radiation (250 and 500 μmol m −2 s −1 ). Additionally, the rate approached a saturation phase at low MAAS (110 mg L −1 ) with higher light intensities. Semi-continuous operation with luxury P uptake and effective P condition showed stable average total nitrogen removal of 88 and 92% respectively, with residual concentrations of 3.77 and 2.21 mg L −1 . The corresponding average P removal was 68 and 59% with residual concentrations of 2.32 and 1.75 mg L −1 . The semi-continuous operation produced a rapidly settleable MAAS under iron flocculated condition with a settling velocity of 92–106 m h −1 and sludge volume index of 31–43 ml g −1 in the studied cases. [ABSTRACT FROM AUTHOR]

A rough-interval-based multicriteria decision analysis method (RI-MCDA) is developed for supporting the selection of remediation strategies for 1,1-dichloroethane contaminated sites. The concept of ‘‘rough interval’’ is introduced in the design framework to represent dual-uncertain parameters. Three rough-interval scenarios generated through pair-wise combining the values under three confidence levels (i.e. 68.3%, 95.4% and 99.7%) and one deterministic scenario adopted crisp numbers for parameters are introduced into the framework. The proposed method is then applied to a contaminated site in the Pudong district of Shanghai, China. Fifty remediation alternatives under four duration options (i.e. 5, 10, 15, and 20 years) and ten criteria, including daily total pumping rate, total cost and rough-interval risk information in light of uncertainty parameter (e.g. slope factor), are taken into consideration to compare different alternatives through RI-MCDA. Results indicated that the most desirable remediation strategy lied in A25 for the 5-year, A10 for the 10-year, A15 for the 15-year, and A11 for the 20-year remediation. Compared to the traditional MCDA, the proposed RI-MCDA shows the uniqueness in addressing the interaction between dual intervals of highly uncertain parameters, as well as their joint impact on the decision results, which reduces the subjectivity as much as possible. [ABSTRACT FROM AUTHOR]

The continuous release of emerging contaminants (ECs) in the aquatic environment, as a result of the inadequate removal by conventional treatment methods, has prompted research to explore viable solutions to this rising global problem. One promising alternative is the use of electrochemical processes since they represent a simple and highly efficient technology with less footprint. In this paper, the feasibility of treating ECs (i.e., pharmaceuticals) using an intermittent electrocoagulation process, a known electrochemical technology, has been investigated. Diclofenac (DCF), carbamazepine (CBZ) and amoxicillin (AMX) were chosen as being representative of highly consumed drugs that are frequently detected in our water resources and were added in synthetic municipal wastewater. The removal efficiencies of both individual and combined pharmaceuticals were determined under different experimental conditions: hydraulic retention time (HRT) (6, 19 and 38 h), initial concentration (0.01, 4 and 10 mg/L) and intermittent application (5 min ON/20 min OFF) of current density (0.5, 1.15 and 1.8 mA/cm2). Results have shown that these parameters have significant effects on pharmaceutical degradation. Maximum removals (DCF = 90%, CBZ = 70% and AMX = 77%) were obtained at a current density of 0.5 mA/cm2, an initial concentration of 10 mg/L and HRT of 38 h. [ABSTRACT FROM AUTHOR]

Boron (B) contamination of wastewater is a serious environmental and health problem, which has proved difficult to remediate. One potential approach is phytoremediation, i.e., the use of plants to extract B into the shoot systems, which can then be harvested and removed. The purpose of this study was to investigate the ability of seven hybrid poplar clones to accumulate and tolerate B at different levels of B and salinity. The clones were grown in quarter strength Hoagland's nutrient solution and exposed to four B treatments: 0.25, 25, 75 and 125 mg B L −1 in factorial combination with three salinity treatments: 0, 0.5 and 5 g L −1 . Measurements were made of biomass (dry weight) and B concentrations (analyzed by inductively coupled plasma-optical emission spectroscopy) of plant tissues. The results showed that, with increasing level of B supply, the B concentrations in the shoot tissue of the poplar clones increased, while shoot biomass decreased. Comparison of the seven different poplar clones revealed that the clone designated 195–529 exhibited the greatest ability for B accumulation and tolerance. Generally, the 0.5 g L −1 level of salinity was beneficial for poplar growth and B removal, while the high salinity level of 5 g L −1 significantly inhibited poplar growth and B translocation from roots to shoots. Based on the results obtained with this hydroponic system, the clone 195–529 ( P. trichocarpa × P. deltoides ) is likely to be the most useful for the removal of B from B contaminated wastewater. [ABSTRACT FROM AUTHOR]

In the present study, the concentrations and proportions of perfluoroalkyl substances (PFASs) in water and sediments (in different seasons) from the Qing River were investigated. The highest concentration of PFASs in water (207.59 ng L −1 ) was found in summer. The composition of PFASs in water changed with time, perfluorobutane sulfonate (PFBS) was the predominant compound in spring and summer, while long-chain PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), started to increase in autumn and winter. The PFASs concentration in sediments ranged from 0.96 to 4.05 ng g −1 dw. The proportion of long-chain PFASs was higher than that of short-chain PFASs in sediments, the dominant component in sediments was PFOA with a contribution of 24.6–75.4% to total PFASs in sediments, followed by PFOS. The concentrations of PFASs in roots of emergent plants were relatively higher than those in submerged plants. However, the translocation effect of PFASs was not remarkable. Bioaccumulation factors (BAFs) of the aquatic plants indicated the absorption of PFASs were effective. BAFs in submerged plants basically increased with increasing chain length accordingly. In general, aquatic plants had the absorption preference for long-chain PFASs, especially PFOS, which was the predominant compounds in both submerged and emergent plants. Based on the results above, hornworts were selected to be cultivated indoor in the nutrient solution spiked gradient concentrations of PFOS to assess the general ecological risk. The results revealed that hornworts were resistant to PFOS and might be used as remediation flora to eliminate PFOS contamination. [ABSTRACT FROM AUTHOR]

The ability of the use of dried activated sludge for removing methylene blue (MB) was investigated. The dye binding capacity of biosorbent was shown as a function of initial dye concentration, initial pH, and temperature at agitation rate 700 rpm. The experimental results indicated that the equilibrium between the dye and the adsorbent in the solution was established within 30 min and the maximum % removal value was found as 96.54% at pH 7.5. The uptake biosorption increased with increasing initial MB concentration. The maximum MB adsorption capacities were obtained at the temperature of 30°C. The equilibrium data fitted very well to the both Freundlich and Redlich–Peterson adsorption models with high correlation coefficient (R2 > 0.99). The pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data, consequently; the results showed that the dyes uptake processes followed the pseudo-second-order rate expression. So, it can be concluded that dried activated sludge could be a potential low-cost biosorbent for the MB removal from aqueous solutions. [ABSTRACT FROM PUBLISHER]

Suspensions of zero valent iron nanoparticles (nZVI) are commonly used for the in situ remediation of groundwater contaminated with chlorinated solvents. Stable aqueous suspensions of zero-valent nano-particles (nZVI) are prepared by wet chemistry techniques and stabilized with a carboxyl-methyl-cellulose (CMC) coating. To enhance their penetration length along with their capacity to attach on oil/water interfaces, nanocomposites are prepared where the CMC-coated nZVI suspension is encapsulated in liposomes. The liposomes might be regarded as vehicles for the safe delivery of nZVI to hydrophobic pollutant targets. The integrity of synthesized liposomes membranes is evaluated with batch tests and flow-through tests in a pre-saturated with oil glass-etched pore network. For assessing the mobility and longevity of nZVI suspensions under flow-through conditions, visualization flow tests are performed on the glass-etched pore network for three types of suspensions: (i) CMC-coated nZVI; (ii) CMC-coated nZVI encapsulated in liposomes; (iii) mixture of CMC-coated nZVI and empty liposomes. The measured iron and lipid concentration breakthrough curves for all cases are interpreted by accounting for the transient changes caused on the particle size distribution in the suspension collected from the outlet. Albeit the CMC-coated nZVI are always very mobile, stable, and detectable in the effluent, a fraction of the liposomes or no liposomes are detected in the effluent, when injecting CMC-coated nZVI encapsulated in liposomes or mixed with empty liposomes, respectively. The flushing of the pore network with water, remobilizes the liposomes and withdraws them completely from the pore system. [ABSTRACT FROM AUTHOR]

Mesoporous magnesium oxide modified diatomite (MgO-D) was developed through a simple precipitation method, and applied for simultaneous removal of nutrients from contaminated waters. Different adsorption conditions including adsorbent dosage, solution pH, contact time and coexisting substances were investigated. MgO-D exhibited a high removal capacity in a wide pH range of 3–9 with the maximum removal capacity of 160.94 mg g −1 for phosphate and 77.05 mg g −1 for ammonium at initial pH of 7, adsorbent dosage of 0.3 g −1 . The adsorption kinetics followed the pseudo-second-order kinetic model corresponding to a chemisorption process. Characterization of adsorbents by X-ray diffraction (XRD), field-emssion scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) before and after adsorption revealed that struvite crystallization, physical adsorption, and electrostatic attraction contributed to the removal process. The results illustrated that MgO-D could be used as an efficient and environmental adsorbent for simultaneous nutrients removal. [ABSTRACT FROM AUTHOR]

The cleaning of water contaminated with organic dyes is a crucial problem nowadays. The search for good catalysts is intense, and bismuth tungstates have attracted a lot of attention because of their catalytic properties which are related to their crystal structure and morphology. In this study, we show that Bi 2 WO 6 (BWO) crystals synthesized by the surfactant-assisted hydrothermal method create a different morphology than non-assisted crystals. With the assistance of the PVP surfactant, even the BWO crystalline structure could change, crystallizing into a high-symmetry metastable phase. These changes in morphology imply a decrease in BWO catalytic activity, which shows that insightful control of BWO synthesis is necessary to improve the BWO properties. [ABSTRACT FROM AUTHOR]

A novel electrolysis-integrated biofilter system was developed in this study to evaluate the intensified removal of nitrogen and phosphorus from contaminated water. Two laboratory-scale biofilter systems were established, one with electrolysis (E-BF) and one without electrolysis (BF) as control. The dynamics of intensified nitrogen and phosphorus removal and the changes of inflow and outflow water qualities were also evaluated. The total nitrogen (TN) removal rate was 94.4% in our newly developed E-BF, but only 74.7% in the control BF. Ammonium removal rate was up to 95% in biofilters with or without electrolysis integration with an influent ammonium concentration of 40 mg/L, and the accumulation of nitrate and nitrite was much lower in the effluent of E-BF than that of BF. Thus electrolysis plays an important role in TN removal especially the nitrate and nitrite removal. Phosphorus removal was significantly enhanced, exceeding 90% in E-BF by chemical precipitation, physical adsorption, and flocculation of phosphorus because of the in situ formation of ferric ions by the anodizing of sacrificial iron anodes. Results from this study indicate that the electrolysis integrated biofilter is a promising solution for intensified nitrogen and phosphorus removal. [ABSTRACT FROM AUTHOR]

The current study aimed to remediate membrane fouling by latex effluent by altering membrane surface charge or ionic strength of the effluent. Hydrophilic polysulfone and Ultrafilic flat membranes, with molecular weight cutoff (MWCO) of 60,000 and 100,000, respectively, and hydrophobic polyvinylidene difluoride membrane (PVDF; MWCO 100,000) were used under a constant flow rate and in cross-flow mode for ultrafiltration of latex effluent. The effect of linear alkyl benzene sulfonate (LAS) on the ionic strength of the effluent and the zeta potential of latex particles was investigated. LAS was also used to improve the anti-fouling properties of the membrane surface. The ionic strength of latex effluent was increased by raising its pH from 7 to 12, resulting in an increase of the zeta potential negativity of the latex particles from -26.61 to -42.66 mV. LAS was found to be an ineffective pretreatment for limiting the fouling propensity of latex effluent using hydrophilic membranes even at high concentration and long treatment times. It was concluded that LAS-treated membrane surface is much more favorable than pH changed feed pretreatment. The total mass of fouling decreased by 44.00 and 29.60%, when PVDF membrane surface was treated with LAS at a concentration of 1 × 10-4 g/L, and latex effluent at pH 11 was used, respectively. [ABSTRACT FROM AUTHOR]

The National Project RITMARE (la Ricerca ITaliana per il MARE-Italian Research for the sea) started from 1 January 2012. It is one of the national research programs funded by the Italian Ministry of University and Research. RITMARE is coordinated by the National Research Council (CNR) and involves an integrated effort of most of the scientific community working on marine and maritime issues. Within the project, different marine study areas of strategic importance for the Mediterranean have been identified: Among these, the coastal area of Taranto (Ionian Sea, Southern Italy) was chosen for its different industry settlements and the relative impact on the marine environment. In particular, the research has been concentrated on the Mar Piccolo of Taranto, a complex marine ecosystem model important in terms of ecological, social, and economic activities for the presence also of extensive mussel farms. The site has been selected also because the Mar Piccolo area is a characteristic 'on field' laboratory suitable to investigate release and diffusion mechanisms of contaminants, evaluate chemical-ecological risks towards the marine ecosystem and human health, and suggest and test potential remediation strategies for contaminated sediments. In this context, within the project RITMARE, a task force of researchers has contributed to elaboration a functioning conceptual model with a multidisciplinary approach useful to identify anthropogenic forcings, its impacts, and solutions of environmental remediation. This paper describes in brief some of the environmental issues related to the Mar Piccolo basin. [ABSTRACT FROM AUTHOR]

Granular hydrated ferric oxides (HFO) have been proven to be a reliable material for As adsorption. However, it is difficult to directly apply it to the remediation of As contaminated rivers or lakes due to the small size and low hydraulic conductivity. Considering the demands for application in sudden water pollution remediation, a newly designed iron doped amino-functionalized sawdust (Fe-AFSD) presents effective As adsorptive performance from water. The maximum grafted amino group density was 0.96 mmol/g and the corresponding iron loading amount reached 17%. Fe-AFSD exhibited a much stronger affinity towards As(V) with a maximum adsorption capacity of 43.7 mg/g, while affinity towards As (III) was 10.1 mg/g at pH 7.0 ± 0.2. The kinetic curve can be well described by the pseudo-second-order model, indicating the chemical adsorption nature. The mass transfer model revealed that the internal diffusion is the rate-determining step for As adsorption on Fe-AFSD. The incorporated HFO played a key role for As(III) adsorption through surface complexing reaction, while grafted amino groups were mainly responsible for As(V) adsorption by electrostatic attraction. Furthermore, testing Fe-AFSD adsorbent with As contaminated Songhua river water showed suspended solids (SS) and total organic carbon (TOC) can be effectively eliminated after filtration process. The suspended Fe-AFSD can be effectively intercepted by UF membrane with no obvious permeate flux decline observed during three-day test using As contaminated Songhua river water sample. [ABSTRACT FROM AUTHOR]

Treated sullage water could be the answer to urban water scarcity. In this study, urban sullage water was subjected to various tests to determine a number of physiochemical parameters, heavy metal content and coliform count. Obtained results were compared with the Dhaka Water and Sewerage Authority (DWASA) water samples. The sullage water was then treated using a proposed filtration system with indigenous gravel-coal-sand filter. The pH, chlorine (Cl) and phosphate (PO) of the sullage water, DWASA water and treated sullage water were found to be within the allowed limit set by Bangladesh Drinking Water Quality Standard. The nitrate (NO), BOD, DO, coliform and phosphate (PO) of the sullage water exceeded both the Bangladesh and WHO standard. The amount of toxic heavy metals, lead, cadmium, chromium, mercury and arsenic, were determined to be below the standards. The results indicated that sullage water is not safe and the treated one is safe from toxic heavy metals for household use. The significant portion of treated water can be reutilized which is equivalent of 29 % savings from the annual DWASA water bill. The quality of the treated sullage water revealed that it can be reused for cleaning, washing, bathing in household activities along with other agricultural and industrial purposes. [ABSTRACT FROM AUTHOR]

Investigating the mechanisms that influence the concentration of heavy metals (Cu, Cr, Ni, Zn, Pb, and Cd) and possible sources of these elements is vital in developing lake management strategies and conserving lake ecosystems. This is the first systematic research focusing on the content, distribution, and origin of heavy metals in Poyang Lake area, the largest freshwater lake in China. Samples were collected, and the concentration of trace elements was measured. The distribution, sources, and potential ecological risk, which has undergone rapid economic development and intensive anthropogenic activity, was evaluated. Multivariate statistical analyses were carried out to determine the relationship between these trace elements and to identify the possible pollution sources. Assessment methods were carried out by applying the geoaccumulation index ( I) along with potential ecological risk indices (PERI) and USEPA guidelines. The results show that: (1) in comparison to Chinese Soil Standard I, the study area was polluted with Cd and Cr, which had an average concentration that was higher than the Class I criteria. However, the results showed that the heavy metal concentration of Cd was lower than that in other areas. (2) The correlation analysis indicates that Pb and Cd may potentially have the same pollution source. (3) The geoaccumulation (Igeo) and potential ecological risk index (PERI) of these metals were evaluated. The average pollution degree of Igeo decreased in the following order: Cd > Cr > Ni > Cu > Zn > Pb > As, which is similar to that observed from the EF values. PERI varied between 48.64 and 453.45 for all metals, and the general average was calculated as 113.71. Both Igeo and ER indicate that the study area was polluted by Cd. The results of FA show that 87.90 % of the variance could be explained by three factors and an independent variable. The research results obtained from this study can provide the scientific impetus to create policies for the economic development and environmental protection in Poyang Lake and other areas of the world. [ABSTRACT FROM AUTHOR]

The article discusses the possible removal of polychlorinated biphenyls through commercial fishery from Chesapeake Bay in the U.S. Topics discussed include an overview of the polychlorinated biphenyl deposits at the bay, the calculation of polychlorinated biphenyl mass balance, and the use of contaminant data in the system.

The present study applied nontargeted screening techniques as a novel approach to evaluate the tap water samples collected during the "4.11" tap water pollution incident occurred on April 11, 2014 in Lanzhou in west China. Multivariate analysis (PCA and OPLS-DA) of about 3000 chemical features obtained in extracts of tap water samples by ultrahigh-pressure liquid chromatography quadrupole time-of flight mass spectrometry (UPLC-QTOF-MS) analysis showed significantly different chemical profiles in tap water from pollution regions versus reference regions during the event. These different chemical profiles in samples from different regions were not observed in samples collected during the nonpollution period. The compounds responsible for the differences in profiles between regions were identified as naphthenic acids (NAs) and oxidized NAs (oxy-NAs) after the sample extracts underwent bromination to explore saturations, daiisylation to identify hydroxylations and corresponding MS/MS mode analysis. A consistent finding was further observed in the targeted analysis of NA mixtures, demonstrating that the Lanzhou "4.11" tap water pollution incident could be attributed to oil spill pollution, and NA mixtures would be a marker for oil contamination. Such evaluations can help to rapidly discriminate pollution sources in accidental pollution events and contribute to regular water monitoring management of water safety issues. [ABSTRACT FROM AUTHOR]

Suspended particles in water are a major concern in global pollution management. They affect the appreciation of water due to clarity, photosynthesis, and poor oxygen environment rendering water unsuitable for aquatic animals. Some suspended materials contain functional groups capable of forming complex compounds with metals making them available for poisoning. Such material promotes the growth of bacteria and fouling that give rise to unpleasant taste and odor of the water and thus requires removal. Removal of suspended solids is normally achieved through sedimentation or filtration. However, some suspended colloidal particles are very stable in water and cannot settle while others are able to pass through the filter due to small size, hence difficult to remove. This study investigated the use of triethanolamine-modified maize tassels to form a flocculent for their removal. The modified maize tassels were characterized using Fourier transform infrared (FTIR), and it was found that the triethanolamine was anchored within the cellulose structure of the maize tassels. Clarification parameters such as settling time, reagent dosage, and pH were investigated. The best clarification was at a pH of 6.0 with clearance being less than in 30 min. The optimal flocculent dosage was found to be 3.5 ml of the material, showing that the material has a potential of enhancing clarity in polluted water. [ABSTRACT FROM AUTHOR]

• Intramolecular D-A structure and n-π* transition copromote CN photodegradation. • Photodegradation rate reached 92.1% for TC and 100% for RhB. • LC-MS, on-line FTIR and TEST prediction reveal intermediates, routes and toxicity. • A low-cost, easy-made, robust CN photocatalyst was supplies for water remediation. The weak visible-light harvest, limited active-site exposure and sluggish charge separation/migration are three bottlenecks faced by carbon nitride (CN) photocatalyst, which seriously hinder CN for environmental water remediation utilizing solar energy. Herein, focusing on the above defects, an ultrathin CN nanosheet with intramolecular D-A structure and awaken n-π* transition was fabricated via a fully ground reaction followed one-pot thermal-induce copolymerization of urea and 2,5-thiophenedicarboxylic acid. Series characterization tests verify that the optimized 2,5-thiophenedicarboxylic acid doped CN (0.02-TACN) sample possesses absorption edge of 670 nm, superior specific surface area of 98.3 m2 g−1 and evidently improved charge behaviors in contrast to single CN. The three merits endow 0.02-TACN boosted activity with photodegradation efficiency of 92.1 % for tetracycline (100 % for rhodamine B), and significant TOC removal efficiency of 77.5 % for TC, which is significantly higher than that of CN (4.8 %). Quench tests and ESR affirm that h+, ·O 2 – and 1O 2 dedicate to photodegradation, which benefit by upshifted conduction band and the existence of midgap state. The LC-MS, toxicity prediction and online FTIR investigated intermediate, route and toxicity, as well as in-situ monitor the variation of functional groups during photodegradation. Finally, DFT theoretical calculation further affirm the generation of intramolecular D-A structure and clarify conceivable propel mechanism of photodegradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The flexible superhydrophobic N-TiO 2 silicone composite aerogels with photocatalytic properties. • KH570 grafted N-TiO 2 (K-N-TiO 2) was co-polymerized with the hydrolysates of siloxane. • The flexible composite aerogels with good mechanical properties and formability. • The air-layer between superhydrophobic surface and liquid surface forms a triphase photocatalytic interface. • The oxygen introduced by air phase can remove photogenerated electrons and improve photocatalytic efficiency. • Under the wave impact of 360 h, the aquatic grass-like aerogels in the water channel maintain the stability of structure and photocatalytic performance. TiO 2 nanoparticles are promising photocatalysts for the remediation of water pollution. However, the difficulty in recycling and low light absorption of powder TiO 2 hinder their application in photocatalysis. Although some studies have attempted to address these problems by immobilizing TiO 2 , the application of traditional immobilized TiO 2 in water environment is limited because of their unstable immobilization, poor mechanical strength, low light utilization, high electron-hole recombination,and unsatisfactory photocatalytic performance. In this study, flexible superhydrophobic Nitrogen-doped TiO 2 (N-TiO 2) silicone composite aerogels were achieved by copolymerization of γ-methacryloxypropyl trimethoxy silane (KH570)-grafted N-TiO 2 with methyltrimethoxysilane and dimethoxydimethylsilane. These flexible composite aerogels possess improved mechanical strength and stable immobilization of N-TiO 2. Moreover, an air–liquid–solid triphase photocatalytic interface was formed by the superhydrophobic surface of composite aerogel, solution and the air layer existed between them. This triphase photocatalytic interface enabled oxygen at the reaction interface to be directly and rapidly supplied from the air layer, thus photogenerated electrons from the photocatalyst surface can be effectively removed and the recombination of electron holes can be reduced. Besides, the flexible photocatalyst was molded into water grass shape and placed in a water channel to verify its photodegradation efficiency and durability under hydrodynamic conditions. Experimental results confirmed that the proposed flexible photocatalyst with a triphase catalytic interface has application prospects for the degradation of pollutants in water environment. [ABSTRACT FROM AUTHOR]

High-efficiency adsorbents made from clay minerals have a wide application in remediation of soil and water pollution, especially in the treatment of refractory and highly toxic heavy metals. Montmorillonite itself has a good adsorption capacity and a large modification space for its layered structure. Therefore, carboxylate polymer grafted montmorillonite was developed to improve the adsorption capacity of heavy metals in this paper. Two kinds of modified preparation routes were compared, and a series of batch adsorption tests were conducted to evaluate the influence degree of parameters (contact time, pH, temperature, and cadmium concentration). The structural changes of montmorillonite samples before and after modification were characterized by a series of microscopic analyses and measurement techniques. The results show that the silicon hydroxyl produced by the hydrolysis of silane coupling agent can indeed be grafted by dehydration condensation with Si/Al-OH on clay surface. The grafting chain can be greatly increased by C=C double bond breaking polymerization. The polycarboxylate group can effectively improve the adsorption performance of modified montmorillonite for cadmium ions. The maximum adsorption capacity of modified montmorillonite increased by about 224.75%, reaching 63.49 mg/g. The adsorption model of montmorillonite conforms to Langmuir monolayer adsorption model, while modified montmorillonite samples exhibit Freundlich adsorption model and S-type isothermal adsorption curve characteristics of resin. The preparation method of neutralizing after polymerization of acrylic acid was proposed to be better, which provides technical guidance for scientific and efficient application. [Display omitted] • A new method for modification of montmorillonite by grafting polymerization was proposed. • The maximum adsorption capacity for Cd(II) increased from 19.55 mg/g to 63.49 mg/g. • The effect of different preparation routes on the adsorption capacity of Cd(II) was studied. • The adsorption priority of polycarboxylate is higher than that of montmorillonite. • The adsorption mechanism of carboxylate polymer-grafted montmorillonite was studied. [ABSTRACT FROM AUTHOR]

Transient absorption studies have contributed to our current understanding of heterogeneous photocatalytic systems. Insights have been gained into the nature of the photogenerated charge carriers and their trapping, their subsequent transfer to the reaction medium, the transformations and kinetics that ensue from transient species to the final reaction products, and equally important the time scales at which these events occur. In this review, the focus is on learnings relevant to heterogeneous photocatalytic systems for water pollution remediation. It is subdivided into sections on TAS studies of heterogeneous photocatalysis for: Dye degradation (Section 2.0); Organic pollutant degradation (Section 3.0); and Inorganic pollutants removal (Section 4.0). The majority of the studies has been on heterogenous TiO 2 photocatalysis, but more recently novel photocatalytic materials such as doped and heterostructured materials have also been studied. Those latter systems have great potential for the development of solar driven heterogeneous photocatalysis for environmental remediation. [Display omitted] • TAS studies give insights into reaction time scales, elementary steps and reaction mechanisms. • Significant for design of improved photocatalytic materials. • Significant for identifying key reaction parameters. • Significant for photoreactor design. [ABSTRACT FROM AUTHOR]

Microalgae, the primary producers in water ecosystems, are the main food of fish and shrimp. Microalgae have a great capacity to absorb heavy metals, and low concentrations of heavy metals can promote the growth of them. But high concentrations have a strong influence on the physiological and biochemical processes in algae, such as growth, photosynthesis, cell ultrastructure, protein content and fatty acid composition. Heavy metals may also induce the formation of reactive oxygen species (ROS), which causes the oxidation damage of protein, lipid and thiol peptides, and activates the antioxidant system. Heavy metals can be removed or converted into another state by biosorption of cell surface, accumulation in cells, combining with antioxidant enzymes and so on. This review summarized the responses of microalgae to heavy metals and comprehensively described the removal and tolerance mechanisms by extracellular adsorption and intracellular accumulation, which are helpful to treat pollution and improve the culture of microalgae. • Responses of microalgae to heavy metal stress. • Mechanisms of heavy metal tolerance in microalgae. • Accumulation of heavy metals in the microalgae cells. • The technology for researching algae and treating wastewater. [ABSTRACT FROM AUTHOR]

In this paper, two mathematical models for simulating water pollutant level and pollution control in a connected reservoir system are proposed. The reservoir system is consisted of two ponds connected by a narrow channel. One pond allows water in from a canal through an entrance gate while the other pond lets the water flow out through an exit gate. The pond water is contaminated with wastewater released from several industrial plants located near the pond. One of the proposed models is a steady-state dispersion model simulating the pollutant level in the connected ponds. The other model is a pollution control model that determines the maximum pollutant level allowed in the wastewater released from each plant in order to achieve a specified pollution level in the ponds as well as to incur a minimum water pre-treatment cost to each plant. The simulation results of these models show that the maximum pollutant level in the two ponds could be effectively controlled at a minimum cost to each plant by optimally limiting the pollutant level in the wastewater it releases. [ABSTRACT FROM AUTHOR]

Today's ecology is erected with miscellaneous framework. However, numerous sources deteriorate it, such as urban rivers that directly cause the environmental pollution. For chemical pollution abatement from urban water bodies, many techniques were introduced to rehabilitate the water quality of these water bodies. In this research, Bacterial Technology (BT) was applied to urban rivers escalating the necessity to control the water pollution in different places (Xuxi River (XXU); Gankeng River (GKS); Xia Zhang River (XZY); Fenghu and Song Yang Rivers (FSR); Jiu Haogang River (JHH)) in China. For data analysis, the physiochemical parameters such as temperature, chemical oxygen demand (COD), dissolved oxygen (DO), total phosphorus (TP), and ammonia nitrogen (NH3N) were determined before and after the treatment. Multicriteria Decision Making (MCDM) method was used for relative significance of different water quality on each station, based on fuzzy analytical hierarchy process (FAHP). The overall results revealed that the pollution is exceeding at "JHH" due to the limit of "COD" as critical water quality parameter and after treatment, an abrupt recovery of the rivers compared with the average improved efficiency of nutrients was 79%, 74%, 68%, and 70% of COD, DO, TP, and NH3N, respectively. The color of the river's water changed to its original form and aquatic living organism appeared with clear effluents from them. [ABSTRACT FROM AUTHOR]

To protect against the environmental pollution, the present research was undertaken to enumerate the Bacterial Technologies (BTs) on the restoration of polluted urban rivers, that is, Fenghu-Song Yang River (FSR) and Xuxi River (XXR). Experimental research accounted for the physiochemical parameters (pH; temperature; dissolved oxygen (DO); chemical oxygen demand (COD); total phosphorus (TP); total nitrogen (TN); and ammonia nitrogen (NH3N)) before and after the BT operation. The results declared that the BT is efficient to restore the polluted rivers up to reliable condition. These results were analyzed by using multivariate statistical techniques (principal component analysis (PCA) and cluster analysis (CA)). These techniques interpreted the complex data sets and expressed the point source information about the water quality of these rivers at SA5, SA6, and SB3 under highly polluted regions. For better understanding, water quality index (WQI) was applied to compute the single numeric value. WQI results are evidence of the above results which prove the water quality of both rivers faced under outrageous condition (below 50 WQI scores) before the BT treatment, but, after the treatment, the rivers were restored from fair to good level (above 50 WQI scores) and overall output of these scores was quite similar to detect the point source of pollution. These results described an abrupt recovery of the urban rivers up to reliable condition for aquatic organism and clear effluents from the rivers. [ABSTRACT FROM AUTHOR]

In this study, by coupling long-term ecological data with empirical proxies of societal demand for benefits, we measured the capacity of forest watersheds to provide ecosystem services over variable time periods, to different beneficiaries, and in response to discrete perturbations and drivers of change. We revisited one of the earliest ecosystem experiments in North America: the 1963 de-vegetation of a forested catchment at Hubbard Brook Experimental Forest in New Hampshire, USA. Potential benefits of the regulation of water flow, water quality, greenhouse gases, and forest growth were compared between experimental (WS 2) and reference (WS 6) watersheds over a 30-year period. Both watersheds exhibited similarly high capacity for flow regulation, in part because functional loads remained low (i.e., few major storm events) during the de-vegetation period. Drought mitigation capacity, or the maintenance of flows sufficient to satisfy municipal water consumption, was higher in WS 2 due to reduced evapotranspiration associated with loss of plant cover. We also assessed watershed capacity to regulate flows to satisfy different beneficiaries, including hypothetical flood averse and drought averse types. Capacity to regulate water quality was severely degraded during de-vegetation, as nitrate concentrations exceeded drinking water standards on 40% of measurement days. Once forest regeneration began, WS 2 rapidly recovered the capacity to provide safe drinking water, and subsequently mitigated the eutrophication potential of rainwater at a marginally higher level than WS 6. We estimated this additional pollution removal benefit would have to accrue for approximately 65-70 years to offset the net eutrophication cost incurred during forest removal. Overall, our results affirmed the critical role of forest vegetation in water regulation, but also indicated trade-offs associated with forest removal and recovery that partially depend on larger-scale exogenous changes in climate forcing and pollution inputs. We also provide a starting point for integrating long-term ecological research and modeling data into ecosystem services science. [ABSTRACT FROM AUTHOR]

Summary The most important parameter controlling the water quality is the dissolved oxygen Y ( x , t ) because it is very essential for aquatic life. An analytic solution is presented for unsteady equation representing the concentration of the dissolved oxygen Y ( x , t ) along a river at any time t . The solution is obtained by using Laplace transformation technique. Adjoin solution techniques are used as boundary conditions to solve the equations. The variations of Y ( x , t ) with time t from t = 0 up to t → ∞ (the steady state case) and with the parameters of the flow are taken into account in our study. It is shown that Y ( x , t ) increases as t increases, keeping the other parameters constant, but Y ( x , t ) decreases as the added pollutant rate along the river q increases. The adjoin solution techniques used in this work are effective and accurate for solving the equations representing the concentration of the dissolved oxygen Y ( x , t ) when arbitrary initial and boundary conditions are given. The details are demonstrated in graphs. [ABSTRACT FROM AUTHOR]

Development of novel nanocatalysts for the highly efficient in situ synthesis of H2O2 from H2 and O2 in the electro-Fenton (EF) process has potential for the remediation of water pollution. In this work, AuPd/carbon nanotube (CNT) nanocatalysts were successfully synthesized by the facile aggregation of AuPd bimetals on CNTs. Characterization by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy indicated that pure AuPd bimetallic heterogeneous nanospheres (≈20 nm) were well dispersed outside the CNTs, which resulted in better catalytic performance than Pd/CNTs alone: 0.36 M H2O2 was synthesized; 0.05 M Fe2+ optimally initiated the EF process due to the superior in situ Fe2+ regeneration; and the organic pollutant removal reached 100 % at 37 min, with a pseudo-first-order kinetic constant k1=0.051 min−1. Moreover, structural insights before/after catalysis revealed that Au strengthened the construction of the nanocrystals, avoided negative deactivation caused by AuPd agglomeration, and immobilized the active Pd(111). The catalytic stability of AuPd/CNTs over ten cycles implied long durability and promising applications of this material. [ABSTRACT FROM AUTHOR]

Underwater sinkholes in Quintana Roo, Mexican Caribbean, are affected by the run-off of nearby highways promoting the presence of aromatic and polyaromatic hydrocarbons. Phenanthrene, naphthalene, and benzene derivatives were found as the most common hydrocarbon contaminants present in underwater sinkholes located in Cancún and Playa del Carmen, two well-developed tourism poles. This confirms the impact of urban activities related with the increased transportation of locals and tourists around these areas, in comparison with Holbox which is a recent touristic development where transportation of tourists and locals is scarce; there is no hydrocarbon detectable pollution. Additionally, the development of a new water cleaning approach by airlift bioreactors, using indigenous microbial consortium, shows promising results and may be used in futureex-situremediation technique in tourism poles. [ABSTRACT FROM PUBLISHER]

In this approach, a method utilizing data series from multivariate parameters to detect contaminant events is discussed and evaluated. Eight water quality sensors (pH, turbidity, conductivity, temperature, oxidation reduction potential, UV-254, nitrate and phosphate) are used in this study and the most commonly used herbicide, glyphosate, is selected as the test contaminant. Variations of all parameters are recorded in real time at different concentrations. The results from the experiment and analysis show that the proposed method with suitable optimization can detect a glyphosate contamination less than 5 min after the introduction of the contaminant using responses from online water quality sensors. The average true positive rate is 95.5%. The study also discusses the impact of the number of sensors on detection performance. The results show that if the number of sensors is reduced from 8 to 5, the true positive rate performance is still good. This indicates that the method is flexible and can be applied using a smaller number of sensors to reduce monitoring costs. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-nZVI@Kaol was synthesized by combining kaolinite-supported and surface-sulfidation. • The two-step prepared S-nZVI had core–shell structure with Fe0 core and FeS x shell. • The maximum adsorption capacity of Cd2+ by S-nZVI@Kaol reached 104.7 mg/g. • Cd2+ was removed synergistically by chemical precipitation and surface complexation. Nano zero-valent iron (nZVI) had great potential in water pollution remediation, but the instability and easy agglomeration limited its application. To improve the dispersion and antioxidant properties of the nZVI, kaolinite-supported sulfide-modified nZVI (S-nZVI@Kaol) was synthesized for the removal of cadmium (II) (Cd(II)) in aqueous solution. The structure and morphology of the samples were characterized by field emission scanning electronic microscopy (FE-SEM) and X-ray diffraction (XRD), the elemental distribution and microstructure of the S-nZVI@Kaol were accomplished by transmission electron microcopy (TEM) and energy dispersive X-Ray spectroscopy (EDX), Fourier transform infrared (FTIR) and X-ray photoelectron spectrum (XPS). The results showed that S-nZVI was successfully loaded on kaolinite with a "core–shell" structure. The S-nZVI had higher specific surface area and lower magnetism compared with nZVI. The adsorption process of S-nZVI@Kaol for Cd(II) conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm model better, and the maximum adsorption capacity was 104.7 mg·g−1. When the S/Fe molar ratio (M S/Fe) was 0.3, and the Fe/Kaol mass ratio (m Fe/Kaol) was 50:50, S-nZVI@Kaol had the best removal efficiency for Cd(II). A higher solution pH (3.0–9.0) was beneficial for the removal of Cd(II). Adsorption thermodynamics studies showed that removing Cd(II) by composites was a spontaneous endothermic process. The mechanisms of the removal of Cd(II) involved electrostatic gravitation, chemical precipitation of CdS, and surface complexation. [ABSTRACT FROM AUTHOR]

In nature, the hydroxyl radical (•OH) is produced during the anaerobic-aerobic transition when groundwater level fluctuates. In addition, the •OH is also detected in iron-bearing clay minerals and iron oxides during the redox process. Goethite is one of the most stable iron oxides involved in biogeochemical cycles. In this study, the coexisting humic acid (HA) enhanced the generation of Fe(II) during the iron reduction process and accelerated the generation of •OH in the redox process of goethite. The organic contaminants in black and odorous water were decomposed by constructing an iron-reducing bacteria-HA-Fe(II)/Fe(III) reaction system under anaerobic-aerobic alternation. The results demonstrated that in the anaerobic stage, HA could promote the reduction and dissolution of goethite through the complexation effect and electron shuttle mechanism, as well as significantly strengthening the iron reduction process in water. Under aerobic conditions, Fe(II) in the reaction system would activate O 2 to generate •O 2 −. The •OH, formed by Fe (II) and •O 2 − via Fenton reaction and Haber-Weiss mechanism, oxidized dissolved organic matter (DOM) in water. The characterization of DOM by three-dimensional fluorescence spectroscopy (3DEEM) indicated that after four redox fluctuations, the organic contaminants in water samples were effectively degraded. Generally, this study provides new approaches and insights into the biogeochemical cycling of Fe and C elements and water pollution remediation at the anoxic-anoxic interface. • He humic substance enhanced the generation of Fe(II) in the iron reduction. • He humic acid accelerated the generation of.•OH in the redox process of goethite. • The.•OH was formed by Fenton reaction and Haber-Weiss mechanism. • DOM in black and odorous water could be effectively degraded by.•OH. [ABSTRACT FROM AUTHOR]

Zeolite imidazolate framework-8 (ZIF-8) is a nanomaterial of metal-organic frameworks (MOFs), which have various applications in drug delivery and water pollution remediation. However, little is known about its developmental neurotoxicity in aquatic organisms, especially on the low-level exposure. In the present study, we investigated the toxic effects of ZIF-8 NPs on the neuron development, behavioral traits, oxidative stress and gene expression in zebrafish embryos. Firstly, our results showed that ZIF-8 induced significantly embryonic malformations and abnormal development of nervous system in zebrafish embryos with a concentration-dependent manner. Meanwhile, the locomotor behavior was obviously inhibited while the anxiety behavior was greatly increased after ZIF-8 exposure. Secondly, the levels of ROS and antioxidant enzyme activities (CAT, SOD and MDA) together with AChE and ATPase were substantially increased in the ZIF-8 exposed groups. At the molecular level, ZIF-8 NPs could down-regulate the expression profiles of neural development-related genes (gap43, synapsin 2a and neurogenin 1) and PD-like related genes (dj-1, dynactin and parkin), but up-regulate the expression levels of neuro-inflammatory genes (nox-1, glip1a and glip1b) in larval zebrafish. In addition, we further explored the molecular mechanism of neurotoxicity induced by ZIF-8 with pharmacological experiments. The results showed that specific inhibition of ROS-mediated oxidative stress by the astaxanthin could reverse the expression patterns of ATPase, AChE and neurodevelopmental genes. Moreover, astaxanthin can partially rescue the ZIF-8-modulated locomotor behavior. Taken together, our results demonstrated that ZIF-8 had the potential to cause neurotoxicity in zebrafish embryos. These informations presented in this study will help to elucidate the molecular mechanisms of ZIF-8 nanoparticles exposure in zebrafish, which providing a scientific evaluation of its safety to aquatic ecosystems. [Display omitted] • ZIF-8 nanoparticles induced developmental neurotoxicity in zebrafish. • ZIF-8 NPs could increase the levels of oxidative stress and neuro-inflammatory genes. • ZIF-8 exposure could markedly decrease the locomotor behavior and increase the anxiety behavior. • Inhibition of ROS by astaxanthin can partially rescue the ZIF-8 induced neurobehavioral disorders. [ABSTRACT FROM AUTHOR]

[Display omitted] • La-doped activated carbon adsorbents were prepared by one-pot hydrothermal method. • The La-AC had excellent adsorption properties within pH = 2–7. • The doping structure enhanced the robustness of the adsorbents. • The molecular configurations of adsorption structures were calculated by DFT. • The main mechanisms were electrostatic attraction and complexation. Phosphorus removal and recovery are important because phosphorus is both a water contaminant and present in chemicals used in agriculture and various industries. As an extremely effective approach to achieve this objective, chemisorption has been identified as a suitable technology. Herein, the adsorption materials La-doped powdered activated carbon and granular activated carbon (La-PAC (D), La-GAC (D)) were prepared by a one-pot hydrothermal process. The strategy behind the adsorbents was based on the ability of La to compensate for the electronegativity and poor selectivity of the activated carbon matrix. Furthermore, the mass transfer rate was enhanced through the formation of vacancies in the structure of the doped material resulting in larger pore sizes, more adsorption sites, and contributions to the diffusion of phosphate molecules to the interior. The phosphate adsorption capacities of La-PAC (D) and La-GAC (D) were 202.43 mg g−1 and 181.82 mg g−1, respectively, which were superior to most adsorbents. The excellent properties could be maintained at low phosphorus concentrations in actual wastewater. The employed characterization methods combined with density functional theory calculations revealed that AC, La, and the doping structure improved the adsorption performance, and the main adsorption pathways of phosphate were electrostatic attraction and complexation. La-AC (D) could accelerate the development of adsorption materials for water pollution remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel TiO 2-x /BiOBr/AgBr nanocomposites as efficient visible-light photocatalysts are reported. • BiOBr and AgBr nanoparticles were integrated with TiO 2-x via a facile one-pot reflux method. • TiO 2-x /BiOBr/AgBr (20%) illustrated the highest activity in degradation of five pollutants. • Activity of the photocatalyst was 45.6-folds premier than TiO 2 in degradation of tetracycline. The utilization of visible-light-responsive photocatalysts has received wide attention for the remediation of water pollution. Herein, BiOBr and AgBr nanoparticles were anchored on brown TiO 2 to fabricate ternary TiO 2-x /BiOBr/AgBr (named as TO x /BiOBr/AgBr) nanocomposites via a facile one-pot refluxing approach. The visible-light photocatalytic efficiencies were determined by elimination of tetracycline, methyl orange, fuchsine, and Rhodamine B. Ternary TO x /BiOBr/AgBr photocatalysts showed remarkable capability in the removal of aforesaid pollutants. The highest photocatalytic capability was related to the TO x /BiOBr/AgBr (20%) nanocomposite, which was 21.4, 211, 45.6, and 16.2 times as much as the TiO 2 and 4.9, 22, 2.8, and 8.7-folds higher than the TiO 2-x in photodegradation of methyl orange, Rhodamine B, tetracycline, and fuchsine pollutants, respectively. The enhanced photocatalytic performance for the ternary nanocomposite comes from the generation of oxygen vacancies on TiO 2 and effective transfer of charge carriers through formation of p-n-n heterojunctions. Also, the TO x /BiOBr/AgBr (20%) sample manifested good photostability. This work offers that the ternary TO x /BiOBr/AgBr (20%) photocatalyst could be a fascinating photocatalyst for the remediation of water pollution. [ABSTRACT FROM AUTHOR]

Nanosilver, widely employed in consumer products as biocide, has been recently proposed as sensor, adsorbent and photocatalyst for water pollution monitoring and remediation. Since nanosilver ecotoxicity still pose limitations to its environmental application, a more ecological exposure testing strategy should be coupled to the development of safer formulations. Here, we tested the environmental safety of novel bifunctionalized nanosilver capped with citrate and L -cysteine (AgNPcitLcys) as sensor/sorbent of Hg2+ in terms of behaviour and ecotoxicity on microalgae (1–1000 µg/L) and microcrustaceans (0.001–100 mg/L), from the freshwater and marine environment, in acute and chronic scenarios. Acute toxicity resulted poorly descriptive of nanosilver safety while chronic exposure revealed stronger effects up to lethality. Low dissolution of silver ions from AgNPcitLcys was observed, however a nano-related ecotoxicity is hypothesized. Double coating of AgNPcitLcys succeeded in mitigating ecotoxicity to tested organisms, hence encouraging further research on safer nanosilver formulations. Environmentally safe applications of nanosilver should focus on ecologically relevant exposure scenarios rather than relying only on acute exposure data. [Display omitted] • Environmental safety of novel citrate and L -cysteine AgNP for Hg detection in water. • Chronic toxicity rather than acute as predictor of nanosilver environmental safety. • Nanosilver capping and behaviour in water media as predictors of ecotoxicity. • Nano-size rather than dissolution as driver of ecotoxicity. • Ecologically based methods for safer nanosilver for environmental applications. [ABSTRACT FROM AUTHOR]