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As the application of biodegradable polymers has grown, so has the interest in exploring the environmental behaviors of biodegradable microplastics (MPs). In this study, we investigated the interaction of oxytetracycline (OTC) with poly(butylene adipate-co-terephthalate) (PBAT) MPs after biodegradation, and explored the effect of the coexisting Cu(II) on OTC adsorption and desorption processes. The maximum adsorption amounts of virgin PBAT, biofilm PBAT, and degraded PBAT reached 692.05 μg·g

Few studies have mentioned the enrichment of heavy metal pollutants on microplastics derived from degradable plastics. This study investigated the adsorption behavior of Pb(II) onto biodegradable poly(butylene succinate) (PBS) microplastics during its biodegradation. The results indicated that Pb(II) adsorbed by biofilm-colonized biodegraded-PBS microplastics (B-PBS) was about 10-folds higher than that of virgin PBS (647.09 μg·g

In this study, an environmentally friendly struvite-loaded zeolite (S-NZ), prepared by nutrient recovery from swine biogas slurry, was used in the simultaneous removal of Cu (II) and tetracycline (TC) in solution for the first time. The adsorption behavior was systematically studied by accessing solution pH, kinetics, equilibriums in sole and binary systems. The results showed that the adsorption of Cu(II) and TC was fast and remarkably affected by solution pH due to pH-dependent speciation of adsorbates and the zeta potential of the S-NZ. Adsorption isotherms of TC and Cu(II) in binary system were well fitted by the Langmuir model and competitive Langmuir model, with the maximum adsorption capacities of 197.53 mmol TC/kg and 379.42 mmol Cu(II)/kg, respectively. The removal of TC could be significantly enhanced when Cu(II) coexisted, but not vice versa. Besides, the Coulombic interaction in the binary system at different pH was further supported by calculating relative charge distribution over the entire Cu(II)-TC complex and postulating the orientation of Cu-TC complex on the surface of S-NZ. Moreover, dissolved organic matter (DOM) impeded the adsorption of TC and Cu (II) onto S-NZ because of its formation of complex with Cu(II) and TC. This study shows new guidelines and useful methods for nitrogen and phosphorus recovery from livestock and poultry biogas slurry as well as its application in heavy metals and antibiotic pollution control.

Harmful algae pollution in eutrophic waters represents one of the most serious problems in natural water environment. Adsorption assisted photocatalytic inactivation is often considered as a promising method to achieve the clean-up of harmful algae and the remediation of eutrophic water. Here, we synthesize the NP TiO2 (nitrogen and phosphorous doped TiO2)/C composites using a facile sol-gel method, and demonstrate successful achievement of efficient adsorption-photocatalytic performance via the in-situ formed carbides coated with NP TiO2 nanoparticles. We find that the composites have rough surfaces with porous structure, which can be tuned by the calcination temperature, and that such composites can be served to efficiently capture the algal cells. The N and P are successfully doped into the TiO2 crystal lattices, and the cooperation of carbides and NP TiO2 particles enhances significantly light absorption, while inhibiting the recombination of the photogenerated charge carriers. Among all the NP TiO2/C composites, the NP TiO2/C system calcinated at 550 °C shows the best photocatalytic performance for the algal inactivation, presenting a removal rate of 92.6% following 6 h visible light irradiation. The destruction of cell structures is clearly observed in the photocatalytic process. Interestingly, the metabolic activities are also disturbed by the photogenerated radicals, which accelerates the death of algal cells. Moreover, the NP TiO2/C composite can effectively remove the cytotoxins from water, rendering the composite and the doping strategy promising in the remediation practice for eutrophic waters.

In this study, MgO modified diatomite (MgO-D) was used for recovery of microalgae (Chlorella pyrenoidosa FACHB-9), NH4+-N and phosphate from wastewater. The effects of adsorbent dosage, solution pH, contact time, and coexisting substances were investigated. The results showed that MgO-D exhibited excellent recovery efficiency for microalgae, NH4+-N and phosphate in a wide pH range of 3.0–9.0. With initial pH = 8.0, MgO-D = 0.5 g/L and reaction time = 2 h, the recovery efficiencies of microalgae, NH4+-N and phosphate were 182.04 mg/g, 63.3 mg/g, 121.07 mg/g, respectively. Coexisting organic matters inhibited the recovery of microalgae, NH4+-N and phosphate in the order of alginate > humic acid > acetic acid. When in proper concentration range, NH4+-N and phosphate were preferentially recovered by MgO-D through struvite precipitation, and then the charge neutralization of hydroxylated Mg(OH)2 and sweeping of struvite precipitation played an important role in harvesting of microalgal cells. This study shows new guidelines and useful methods for the simultaneous recovery of microalgae, NH4+-N and phosphate from wastewater.

In this work, the superabsorbent polymer hydrogel (SPH) of Poly(potassium acrylate-co-acrylamide (PPAA)) incorporated with Fe-Mn binary oxides (FMBOs) was synthesized and used for the removal of Sb(III) from water. Characterization analysis proved that FMBO3 was successfully encapsulated into the SPH. The Fe/Mn oxide species in the composite SPH comprised FeO(OH), Fe2O3, MnO(OH), and MnO2. The functional groups including N–H, –OH, carboxy as well as Fe atoms were confirmed adsorption sites through ligand exchange and inner-sphere complexes formation. Mn oxides can partially oxidize Sb(III) to Sb(V). Compared with the pseudo-first-order model, the pseudo-second-order model could better describe the adsorption kinetics. And the swelling degree of the composite SPH had a positive impact on the removal rate. The Langmuir-Freundlich model was the most suitable isotherm model to analyze the experimental data. According to thermodynamic parameters, the adsorption process was a spontaneous exothermic reaction. The maximum adsorption capacity of the composite SPH for Sb(III) could be up to 105.59 mg/g at 288 K. In addition, a stable removal rate can be achieved over a wide pH range of 3–10, with little metal leaching even under acidic conditions. Furthermore, coexisting ions and DOM displayed an insignificant influence on the adsorption of Sb(III).

This work discussed the feasibility and stability of utilizing C–S–H phosphorus recovered products, HAP/C–S–H, to remove Zn(Ⅱ) from aqueous solution and in-situ immobilize Zn(Ⅱ) in contaminated soil. The removal mechanisms of Zn(Ⅱ) by HAP/C–S–H were relatively complex, combining multiple reactions including electrostatic attraction, ion exchange, surface complexation and (co-)precipitation. The removal rate of Zn(Ⅱ) by HAP/C–S–H raised with the increase of pH value, reaching 99.47% at pH of 8 in aqueous solution. The ion strength of background solution negatively affected the adsorption efficiency. The pseudo-second-order model and Langmuir model were more suitable to fit the Zn(Ⅱ) adsorption experimental data for the adsorbent. The adsorption process was endothermic and spontaneous naturally according to thermodynamic parameter. The maximum adsorption capacity of HAP/C–S–H can reach 114.0 mg/g at 308 K. After 28 days of immobilization, the release of Zn(Ⅱ) in soil with HAP/C–S–H remarkably decreased to 0.6 mg/L, compared with control group (2.9 mg/L). BCR sequential extraction results indicated that HAP/C–S–H could convert acid-soluble Zn(Ⅱ) into reducible and residual Zn(Ⅱ), reducing the bioavailability and ecotoxicity of Zn(Ⅱ) in contaminated soil. pH-dependent leaching tests revealed that the soil with HAP/C–S–H had stronger resistance to acid impact.

The present work provides the first attempt of using manganese dioxide loaded poly(sodium acrylate) hydrogel (MnO2@PSA) to address potential threats posed by oxytetracycline (OTC) antibiotics in aqueous environment. The MnO2@PSA was prepared via a facile approach and demonstrated enhanced removal performance even under extremely high concentrations of OTC. The outstanding performance exhibited by MnO2@PSA was attributed to synergetic effects of adsorption oxidative degradation. The synthesized composite was characterized evaluated under varying conditions. The adsorption pH was optimized at pH 5, at which the removal efficiency OTC was reached 91.46%. According to the kinetics study, the pseudo-second-order kinetic model was the best to explain the adsorption data, implying the interaction mechanisms were dominated by chemisorption. The Langmuir isotherm model was the best to explain the isotherm data, and the corresponding maximum adsorbed amount of OTC was 1150.4 mg g−1. The MnO2@PSA was highly selective for OTC adsorption and degradation under the presence of natural organic matter and common environmental metal ions. The oxidative degradation study indicated that OTC molecules were structurally degraded into 15 intermediate products via six reaction pathways. Both the theoretical models and spectroscopic methods demonstrated the removal mechanism of OTC onto MnO2@PSA was governed by ion exchange, cation-π bonding, hydrogen-bonding, and π-π electron donor-acceptor. Overall, MnO2@PSA is an excellent and environmentally sustainable material to remove OTC from water and wastewater via the combined effects of adsorption and oxidative degradation.

Metal sites (Ni, Bi or Ag) were introduced into carbon strengthened expanded graphite (CEG) based photocatalysts, and performed as a novel strategy to enhance the elimination of Microcystis aeruginosa and microcystin-LR from water. Results show that metal doping can efficiently improve the adsorption of harmful algae and enhance the photocatalytic activities in inactivation of harmful algae and degradation of MC-LR. Among the CEG catalysts, Ni-CEG can achieve the highest removal rate up to 90.6% for algal cells with 5 h visible light irradiation, while Bi-CEG catalyst provides the best performance for MC-LR degradation with the removal rate of 80.9% in 6 h visible light irradiation. In general, considering the coexistence of algal cells and microcystin-LR, Bi-CEG is proved to be an excellent candidate for the remediation of eutrophicated waters since it can achieve the efficient removal of both harmful algae and MC-LR. DFT calculations indicate that metal doping can transform the photocatalysts into n-type semiconductor, and provide the mid-gap state. In addition, the partial charge density distribution near Fermi level was mainly composed by the metal dopants, which can enhance the interaction with harmful algae and MC-LR.

Excessive copper (Cu) in contaminated soil and groundwater has attracted continuous attentions due to the bioaccumulation and durability. In this study, the feasibility of remediation of heavy metal pollution in soil and groundwater was investigated using hydroxyapatite/calcium silicate hydrate (HAP/C–S–H) recovered from phosphorus-rich wastewater in farmland. The results show that the pH has a strong effect on copper removal from Cu-contaminated groundwater but the impact of ion strength on the removal is weak. In general, high pH and low ion strength give better results in copper removal. Kinetic and isotherm data from the study fit well with Pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacity of HAP/C–S–H (138 mg/g) was higher than that of C–S–H (90.3 mg/g) when pH value, temperature, and ionic strength were 5, 308 K, and 0.01 M, respectively. Thermodynamics results indicate that Cu removal is a spontaneous and endothermic process. X-ray diffraction (XRD) results show that the mechanism of copper removal involves physical adsorption, chemical precipitation and ion exchange. For the remediation of Cu-contaminated soil, 76.3% of leachable copper was immobilized by HAP/C–S–H after 28 d. Acid soluble Cu, the main contributor to biotoxicity, decreased significantly while reducible and residual Cu increased. After immobilization, the acid neutralization capacity of the soil increased and the dissolution of copper was substantially reduced in near-neutral pH. It can be concluded that HAP/C–S–H is an effective, low-cost and eco-friendly reagent for in-situ remediation of heavy metal polluted soil and groundwater.

In this study, an industrial waste-blast furnace slag (BFS) supported sulfidized nanoscale zerovalent iron (S-nZVI@BFS) was prepared and used for synergistic reduction and adsorptive removal of Cr(VI) from aqueous solutions. The characterization analysis showed that Fe0 and FeS were well dispersed on the surface of BFS, and the specific surface area of S-nZVI@BFS was 141.986 m2 g−1. Batch experiments demonstrated that the removal capacity of Cr(VI) was as high as 184 mg/g for S-nZVI@BFS. The pseudo-second-order kinetic model fitted the Cr(VI) removal kinetics well. Cr(VI) removal on the S-nZVI@BFS relied highly on pH values. The reduced Cr(VI) precipitated on S-nZVI@BFS mainly as CrxFe(1-x)(OH)3, CrxFe(1-x) OOH and Cr2S3, and the alkaline capacity of the BFS could efficiently prevent the release of Cr(III) from the precipitations in acid condition. Thus, supporting S-nZVI on BFS was an effective and safe method for Cr(VI) removal from aqueous solutions.

Highly active TiO2 photocatalysts prepared at a low temperature are promising reagents to degrade organic pollutants. Moreover, the addition of macroporous resins should overcome the poor adsorption properties of TiO2. Here we prepared N-doped TiO2/macroporous resin composites at low temperatures using a hydrothermal-assisted sol–gel method. The results show that the composites have a spherical appearance, which is controlled by the macroporous resin. The composites exhibit high specific surface areas, and the microstructure can be tuned by the temperature. N can be doped into the TiO2 crystal by substitution of oxygen at a lower temperature. N-doped TiO2 particles are distributed on the surface with a dominant crystal form of anatase. The composite prepared at 200 °C gave the best performance for the photocatalytic degradation of rhodamine B, with removal efficiency of 74.8% following 240-min irradiation.

Harmful algal blooms (HABs) have increasingly occurred worldwide causing human and ecological health risks. In this study, we report on an effective alternative to inactivating Microcystis aeruginosa under visible light irradiation with the use of a floating heterojunction photocatalyst. The photocatalyst (CTAE for short) is made of graphitic carbon nitride (g-C3N4) and TiO2 that are loaded on Al2O3-modified expanded perlite via a facile sol-gel method. The N/C doping in TiO2 and the interaction between TiO2 and g-C3N4 enhanced the generation of h+ and OH independent of O2 activation, which could facilitate applications in oxygen-deficient waters. Consideration was given to the impacts of different mass ratios of g-C3N4 to TiO2. The photocatalysts were characterized by XRD, N2 adsorption/desorption isotherms, FESEM/EDS, TEM, XPS, UV–vis absorption and Photoluminescence spectroscopy. Results showed that different contents of g-C3N4 had an influence on the crystal structure, specific surface area and pore volumes of the photocatalysts. The use of 2 g/L of 0.03CTAE (i.e., the theoretical mass ratio of g-C3N4 to TiO2 = 0.03) photocatalyst could simultaneously remove 88.1% of M. aeruginosa at an initial concentration of 2.7 × 106 cells/mL and 54.4% of Microcystin-LR at an initial concentration of 50 μg/L following 6-h of visible light irradiation. Microcystin-LR was gradually degraded with oxidation of the Adda chain occurring. Following each treatment, the floating g-C3N4/TiO2 photocatalyst could be readily recovered from the solution, demonstrating a great potential for in situ remediation of eutrophic waters.

In this study, phosphate was recovered from wastewater by C-S-H, and its phosphate-rich product HAP/C-S-H was reused as a composite adsorbent to remove Pb(II) from aqueous solution. The samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), zeta potential and specific surface areas analysis. The adsorption of Pb(II) on C-S-H and HAP/C-S-H were investigated at different pH, ionic strength, contact time, initial concentration and temperature. The results showed that the adsorption capacities of Pb(II) were heavily dependent on pH and slightly dependent on ionic strength. The adsorption kinetics and adsorption isotherms were well described by pseudo-second-order model and Langmuir model, respectively, and the thermodynamic parameters indicated that the adsorption process was endothermic and spontaneous. The adsorption capacities of Pb(II) on C-S-H and HAP/C-S-H could reach 543.5 mg/g and 946.7 mg/g, respectively, when the pH was 5.0, the temperature was 298 K and the ionic strength was 0.01 M. All the results indicate that HAP/C-S-H, recovered from phosphate wastewater, is an effective material for Pb(II) removal from aqueous solution, providing double environmental benefits for resource recovery and pollution control.

In this study, efficient adsorption-photocatalysis functional expanded graphite covered carbon layer composites (shorted for AP-EGC) with graphitic carbon nitride (g-C3N4, shorted for C) and nitrogen-phosphorus codoped titanium dioxide (NP-TiO2, shorted for T) coating was successfully prepared, which has been named as AP-EGC-CT. It was used for in-situ remediation of harmful algae polluted water. It is shown that the AP-EGC-CT composites exhibit a worm-like structure which can be manipulated by the expanded graphite substrate, and g-C3N4 can tune their photoelectric property. Of all the composites, the AP-EGC-CT with 5 wt% g-C3N4 exhibits the best adsorption-photocatalytic inactivation performance under visible light irradiation, and presents a total removal efficiency of 98.5% after 2 h reaction. The photocatalytic inactivation behavior can be well described by the Modified Chick-Watson model and Hom model. It has been demonstrated that the photocatalytic oxidation can destroy cell structure, disturb cellular metabolism and realize inactivation of algal cells, and that the hole is the major reactive oxygen species. It has been found that these composites can simultaneously remove the algal cells and MC-LR with high efficiency, holding substantial promise in remediating algae pollution in eutrophic water.

A phosphorus-bearing product S-PAL obtained from nutrient-rich wastewater was reused as ameliorant for Cu, Pb and Cd immobilization in contaminated soil with three different rates (1%, 5% and 10% w/w). The 0.01 mol/L CaCl2 -extractability of metals significantly reduced with increasing rate of PAL and S-PAL in the first 7-day immobilization and insignificantly changed after 14-day immobilization. Compared with PAL, the lower metal extractability was observed after S-PAL addition. The BCR sequential extraction results showed that both of amendments were beneficial to transform acid soluble fraction to residual fraction. The XRD patterns of soil samples after immobilization evidenced that the formation of metal-bearing phosphate precipitates and the combination between functional groups such as Si-OH and metals played a key role for metal immobilization by S-PAL and PAL. Dominant phyla across all samples were Fusobacteria, Proteobacteria and Actinobacteria, and the relative abundance of Fusobacteria decreased under S-PAL treatment. The pH-dependent leaching test indicated that the metal release at a defined pH was not affected by the presence of PAL. Compared with S-PAL, the metals amended by PAL in soil were easier to release at acidic pH since the combination between functional groups and metals instead the formation of new metal-bearing precipitate.

The current trend towards the use of biodegradable polymers is considered as a sustainable solution to plastic pollution. However, microplastics (MPs) generation due to harsh degradation conditions may impose higher environmental risks on organisms in the aquatic environment, especially when coexisted with various complicated pollutants. This study aimed at investigating the significance of microbial colonization and degradation in the Cu(II) adsorption by poly(lactic acid) (PLA) MPs. The PLA MPs covered with biofilms showed higher monolayer Cu(II) adsorption capacity than the pristine PLA (151.802 ug·g−1 versus 1045.670 ug·g−1), which was attributed to the surface complexation between Cu(II) and functional groups contained in biofilms. The adsorption kinetics of the sewage-incubated PLA was limited by film diffusion and intraparticle diffusion, whereas film diffusion dominated the Cu(II) adsorption by the pristine PLA. Degradation of PLA MPs was detected by Fourier transform infrared spectroscopy (FTIR) with the breakdown of ester bonds, and the biofilm-mediated alterations were further enhanced with the extension of incubation. In addition, removal of biofilms increased the Cu(II) adsorption on PLA MPs by 32.36% due to the higher surface area with more adsorption sites and the pore-filling mechanism. Cu(II) adsorption capacity of PLA MPs was pH-dependent and the biofilm-removed PLA exhibited the lowest adsorption ability at the pH ranging from 4.5 to 6.0. Fulvic acid (FA) inhibited the Cu(II) adsorption due to the complexation of Cu(II) with FA. Our results filled the knowledge gap concerning the influence of microbial colonization and degradation on the adsorption behavior of biodegradable PLA MPs, which can further serve as the cornerstone to understand the environmental interaction between poly(α-hydroxy acid)-type polyesters and heavy metal pollutants.

In the conventional Fenton system, the relatively low efficiency of Fe (II) regeneration is a significant drawback. To address this shortcoming, a novel floating Z-scheme photo-Fenton catalyst FeMo3Ox/g-C3N4/EP was prepared by a facile dip-calcination method, in which iron and molybdenum oxides with mixed valence states (FeMo3Ox) and graphitic carbon nitride (g-C3N4) were loaded on the expanded perlite. The removal efficiencies reached the maximum at 98.0%, 93.1% and 97.1% for tetracycline, oxytetracycline and chlortetracycline, respectively, after 60 min dark adsorption and 60 min photo-Fenton process. The aid of dual ion (Fe and Mo) synergy system and photoreduction by Z-scheme photocatalyst enhanced the Fe (II) regeneration, resulting in the excellent performance. Radical scavenger experiment, electron spin resonance spectra (ESR) and X-ray photoelectron spectra (XPS) were used to confirm the mechanism of free radicals’ formation and Fe/Mo redox cycling. ·OH, ·O2- and 1O2 played important roles in the pollutant’s degradation, while the generation of ·O2- was enhanced due to the floatability in this system. The possible degradation pathways of TC were put forward according to the results of mass spectrum and Orbital-Weighted Fukui Function. Overall, this work provides new insights on the cooperation between iron-based mix oxides and semiconductor in the photo-Fenton system.

In this study, struvite-loaded zeolite (SZ) obtained by nutrient recovery from biogas slurry was prepared and used as a soil amendment to treat the combined pollution of Cu, tetracycline (TC) and antibiotic resistance genes (ARGs) in microplastic-contaminated soil. The adsorption of Cu and TC by SZ, environmental microplastics (EMs) and soil particles was investigated using batch experiments. Isothermal adsorption of Cu and TC onto SZ was well fitted by the Langmuir isotherm model, with maximum adsorption capacities of 103 mg g−1 and 158 mg g−1, respectively, which were much higher than the corresponding sorption capacities of EMs and soil particles. Three % SZ amendment reduced bioavailable Cu and TC by more than 73.0% and 71.3%, respectively, in 1% EMs contaminated soil. At the same time, the total relative abundance of ARGs was reduced by 76.2–80.3%. Redundancy analysis and network analysis showed that the relative abundance of most ARGs such as sul1, tetG, tetX and intl1 were significantly correlated to bio-available Cu and TC in soil. In presence of SZ, lower pollutant accumulation alleviated the selection pressure for ARGs on EMs. Structure equation models further indicated that SZ indirectly abated ARG proliferation in microplastic-contaminated soil by altering pollutant bioavailability, soil properties and soil microbe communities. These results demonstrate that SZ amendment could effectively alleviate the combined pollution of heavy metals, antibiotics and ARGs in microplastic-contaminated soil.

The coexistence of antibiotics, heavy metals and microplastics is becoming commonplace and may affect antibiotic resistance in manured soil. The current understanding of the role of microplastics in soil with combined pollution of antibiotics, heavy metals and antibiotic resistance genes (ARGs) is limited. Here, the effects of the coexistence of tetracycline (TC), Cu and environmental microplastics (EM) on the fate of nine ARGs and three heavy metal resistance genes in agricultural soil were investigated by batch and microcosm experiments. EM were obtained by exposing virgin microplastics to soil environments for 80 days, which exhibited higher adsorption affinity for Cu and TC than soil particles and virgin microplastics. 1% EM in soil increased bioavailable concentrations of TC and Cu by 79-138% and 88-135%, respectively, and decreased TC dissipation from 11.79 mg kg-1 to 3.08 mg kg-1. Correspondingly, the total relative abundances of target ARGs increased by 219-348%. The significant correlations of tetG, tetB, tetQ, sul2, sul1 and intl1 with bioavailable fractions of TC and Cu in soil environments were revealed by network analysis. Moreover, scanning electron micrographs showed the special plastisphere around EM. Attributed to the biofilm generation and higher pollutant accumulation in the plastisphere, EM could be the source of antibiotic-resistant bacteria and ARGs in soil environments. Structure equation models further identified that indirect effects of EM acted a major role in the propagation of ARGs by altering soil properties, soil microbial diversity and intl1 abundance. This study revealed that EM could increase the stimulative effects of Cu and TC on antibiotic resistance and magnify the environmental risk of manure application in soil environments.

Zinc is known as an essential element of human life. However, excessive zinc discharge into water and soil causes water pollution, leading to serious health issues such as septicemia, meningitis and iron-deficiency anemia. Here, a novel material made of struvite-supported diatomite was obtained from eutrophic water treated by mesoporous MgO-modified diatomite. This material was applied for zinc remediation in aqueous solutions and contaminated soils to test the reuse of P-containing products. Struvite-supported diatomite was characterized by field emission scanning electron microscopy and X-ray diffraction. Results show that the maximum removal efficiency of Zn(II) from wastewater streams reached 90.54% at an initial pH of 5 and struvite-supported diatomite dosage of 0.3 g/L. Moreover, the X-ray diffraction patterns of precipitates after Zn(II) sorption show that the combination between zinc and the phosphate group played a key role for zinc removal in solution. For Zn-contaminated soils amended with 10% struvite-supported diatomite, available Zn decreased by 65.38% and acid soluble Zn decreased by 56.9% after 56 days.

A series of efficient solar light-driven F-Ce-TiO2/expanded perlite (EP) floating photocatalysts were successfully synthesized using a facile sol-gel method and applied as algaecides in eutrophic waters. The as-synthesized photocatalysts were characterized by means of XRD, FESEM/EDX, TEM, N2 adsorption/desorption, XPS, UV–vis DRS and PL spectrum. The results show that F-Ce-TiO2/EP has a honeycomb-like structure with F-Ce co-doped TiO2 particles distributed on EP surface. Calcination temperature can greatly affect the doping status, specific surface area and photoelectric properties of F-Ce-TiO2/EP. Among the synthesized photocatalysts, those calcined at 450 °C (i.e., F-Ce-TiO2/EP450) exhibited the highest photocatalytic activity. The photocatalytic destruction process could be described by the modified Chick–Watson kinetic model and Hom kinetic model. F-Ce-TiO2/EP450 can achieve the algal cells removal rate of 98.1% within 9 h. The algal cell walls obviously damaged in this process. Following the damages, the electron transfer in water-water cycle was also inhibited, thereby accelerating the death of algal cells with the accumulation of the reactive oxygen species (ROS). In addition, microcystin-LR (MC-LR) and metabolic products proved to be effectively removed by photocatalytic oxidation during the algal destruction process. After three consecutive cycles, the removal rate of algal cells can still achieve 88.7% by F-Ce-TiO2/EP450, indicating the F-Ce-TiO2/EP photocatalyst has good reusability and stability.

In this study, raw attapulgite (APT) and a novel adsorbent, struvite/attapulgite (MAP/APT) obtained from nutrient-rich wastewater treated by MgO modified APT, were applied as the absorbent for Cd(II) ion removal from aqueous solution. The two adsorbents were characterized by BET, SEM-EDS, XRD, FT-IR. Raw APT and MAP/APT separately presented the maximum Cd(II) adsorption capacities of 10.38 mg/g and 121.14 mg/g at pH of 5.45. The Cd(II) adsorption on raw APT and MAP/APT could be well fitted by Freundlich isotherm and Langmuir isotherm, respectively. Pseudo-second order equation was able to properly describe the kinetics of Cd(II) adsorption by raw APT and MAP/APT. The calculated thermodynamic parameters indicated that Cd(II) adsorption onto raw APT and MAP/APT were spontaneous and endothermic. An economic evaluation revealed that the treatment costs of the adsorption process by raw APT and MPA/APT were 0.013 $ per 1000 mg Cd and 0.004 $ per 1000 mg Cd, respectively.

Biodegradable plastics have been evaluated as promising alternatives for conventional polymers in various fields. Although microplastics (MPs) have been reported as vectors for pollutants in the environment (e.g. antibiotics), knowledge about the chemicals carrying mechanisms of degradable MPs during the biodegradation process is limited. In this study, we investigated the adsorption behavior of oxytetracycline (OTC) on polylactic acid (PLA) MPs during its biodegradation process. Scanning electron microscopy (SEM) discovered the growth of scattered rod-shaped bacteria on the surface of PLA MPs. Two-dimensional correlation spectroscopy (2D-COS) combined with Fourier transform infrared spectroscopy (FTIR) identified the breakage of ester linkages and the generation of more oxygen-containing functional groups, indicating PLA biodegradation occurred. The presence of a biofilm coating increased the OTC adsorption capacity on MPs by 20.15%, mainly due to OTC complexing with chemical functional groups existing in biofilms (e.g. N–H functional group). More oxygen-containing functional groups were exposed on the surface of PLA MPs after removing biofilms, which further increased the adsorption quantity of OTC by 39.01% through enhanced hydrogen bonding compared with biofilm coating MPs. The adsorption quantity of OTC adsorbed onto MPs first increased and then decreased with the pH ranging from 3.0 to 9.0, which was dominated by electrostatic interaction and hydrophobic interaction. In addition, the adsorption capacity of MPs was suppressed by the presence of fulvic acid (FA) due to that the adsorbed FA blocked further OTC adsorption and OTC showed higher affinity to free FA compared with MPs. These results unravel the OTC adsorption behavior of PLA MPs undergoing microbial adhesion and degradation, which could be useful for understanding the environmental sorption behavior of degradable MPs.

In this study, hydrous manganese dioxide (HMO) modified poly(sodium acrylate) (PSA) hydrogel was produced for the first time to remove tetracycline(TC) and lead(Pb(II)) from water. The as-prepared composite was characterized using various techniques, such as SEM-EDS, FTIR, XRD, BET, and XPS, to elucidate the successful loading of HMO and analyze subsequent sorption mechanisms. Different influencing parameters such as adsorbent dose, initial concentration of adsorbates, reaction time, solution pH, and temperature were also investigated. The adsorption kinetic studies of both TC and Pb(II) removal indicated that equilibrium was achieved within 12 h, with respective removal rates of 91.9 and 99.5%, and the corresponding adsorption data were fitted to the second-order kinetics model. According to the adsorption isotherm studies, the sorption data of TC best fitted to the Langmuir isotherm model while the adsorption data of Pb(II) were explained by the Freundlich isotherm model. The maximum adsorption capacities of both TC and Pb(II) were found to be 475.8 and 288.7 mg/g, respectively, demonstrating excellent performances of the adsorbent. The uptake capacity of PSA-HMO was significantly influenced by the level of solution pH, in which optimum adsorption amount was realized at pH 4.0 in the TC and Pb(II) systems, respectively. Thermodynamic studies showed the process of TC and Pb(II) adsorptions were endothermic and spontaneous. Overall this study elucidated that PSA-HMO composite can be a promising candidate for antibiotics and heavy metal removal in water treatment applications.

With growing demand of oil, the increasing water oil pollution incidents have brought tremendous harm to the water and human health. Floating photocatalytic system under visible light was introduced as an effective remediation with low cost. Chitosan carbonized fly ash (FAC-CS) was used as a buoyant substrate to carry iron, nitrogen co-doped TiO2 through the sol-gel method. The Fe-N-TiO2/FAC-CS was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption–desorption isotherms, UV–vis diffuse reflectance spectroscopy (UV–vis-DRS), Photoluminescence (PL) spectra, X-ray photoelectron spectra (XPS) and thermal gravimetric analysis (TGA). Compared with N-TiO2/FAC and Fe-N-TiO2/FAC, the results showed that Fe-N-TiO2/FAC-CS exhibited a higher photocatalytic degradation remove rate (53.6%) for diesel under visible light. This is attributed to the synergistic adsorptive-photocatalytic effect: Modification by chitosan favors of improving specific surface area to increase adsorption capacity for diesel; Buoyant on the surface of water could fully use the sunlight especially in the visible light range. Through the study of kinetic reaction and remove rate, it could be found that adsorption is prerequisite for the improved diesel degradation during photocatalysis under visible light.

Nitrogen-doped titanium dioxide (TiO2) and Fe–N-codoped TiO2 layers on fly ash cenospheres (FAC) as floating photocatalyst were successfully prepared through sol–gel method. Photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet (UV)–Vis diffuse reflectance spectroscopy (DRS), and nitrogen adsorption analyses for Brunauer–Emmett–Teller (BET) specific surface area. Photocatalytic efficiency of the prepared catalyst was evaluated through using the decomposition of Rhodamine B (RhB) as a model compound under visible light irradiation. Photocatalytic activity and kinetics of catalyst under visible light were detected in details from different Fe/Ti mole ratios by detecting photodegradation of RhB. Experimental results show that when the calcination temperature was 550 °C, the dosage of FAC was 3.0 g, and the mole ratio of Fe/Ti was 0.71 %; the synthesized Fe–N-TiO2/FAC photocatalyst presented as anatase phase and that N and Fe ions were doped into TiO2 lattice. The material’s specific surface area was 34.027 m2/g, and UV–Vis diffuse reflectance spectroscopy shows that the edge of the photon absorption has been red shifted up to 400–500 nm. Fe–N-codoped titanium dioxide on FAC had excellent photocatalytic activity during the process of photodegradation of RhB under visible light irradiation.

TiO2-pearlstone (PS) floatable photocatalysts were synthesized using a facile sol-gel method and confirmed by XRD, N2 adsorption-desorption, SEM, EDX, TEM, FT-IR, XPS, and UV-vis DRS measurements. It has been found that the photocatalysts composed of anatase TiO2 deposited on the surface of PS and formed mesoporous structure. By N or B/N doping, the band gap of the photocatalyst has been narrowed. The obtained floatable photocatalysts can be applied to solar light-driven remediation of oil-contaminated water. Diesel oil was chosen as the model pollutant to evaluate the photocatalytic activity. The results showed B/N-TiO2-PS exhibited the highest photocatalytic activity for diesel oil under visible light irradiation, which is 48 % removal rate for 9 h. The reaction rate constant k of B/N-TiO2-PS is 0.08423 h(-1), which is four times larger than that of pure TiO2-PS. Moreover, the characteristic of floatable makes the photocatalysts easier to separate and reuse, which showed great potential for practical applications in the field of environmental cleanup and solar energy conversion.

The adsorption behaviors of Cu(II) and tetracycline (TC) on polyethylene microplastics that were exposed to air (A-PE-MPs), water (W-PE-MPs) and soil (S-PE-MPs) environments for a long time were investigated with batch experiments in this study. FT-IR and GC–MS analysis confirmed that phthalates (PAEs) were released from PE microplastics after exposure to UV light. When exposed to water and soil environments, PE microplastics were colonized by microorganisms and biofilms were formed on their surface. Compared with virgin microplastics (V-PE-MPs), the environment-exposed microplastics possessed higher adsorption and stabilization capacity for Cu(II) and TC. The adsorption isotherm data of V-PE-MPs and A-PE-MPs were well fitted by Freundlich model, whilst the adsorption by W-PE-MPs and S-PE-MPs were better described by Langmuir model. The Boyd equation used in kinetic experiments revealed that V-PE-MPs and A-PE-MPs were additionally affected by intra-particle diffusion compared with W-PE-MPs and S-PE-MPs. The glycosyl composition analysis suggested that the higher adsorption capacities of S-PE-MPs than W-PE-MPs could relate to the different components of extracellular polysaccharides in biofilms. Moreover, density functional theory further verified that Cu(II) and PAE adsorption on microplastics could be enhanced by the generation of Cu-PAE and Cu-PAE-TC complexes. In addition dissolved organic matter exerted opposite effects on the adsorption onto A-PE-MPs and S-PE-MPs due to their different affinity for Cu(II), TC and DOM. This study demonstrated that the contribution of microplastics to heavy metal and antibiotic migration could be affected by the way they exposed to environments.

The accumulation of heavy metals and the accelerated dissemination of antibiotic-resistance genes (ARGs) in soil receiving long-term manure application are causing worldwide concern. In this study, struvite-supported biochar composite (MAP/BC) obtained by N and P recovery from pig slurry with Mg(OH)2-modified biochar (Mg(OH)2/BC) was used as a novel amendment for the remediation of Cu- and ARG-contaminated agricultural soil. The effects of MAP/BC on Cu immobilization, ARG distribution, and the bacterial community in the soil were investigated simultaneously. The results showed that the mechanisms involved in the immobilization of Cu by MAP/BC included the formation of copper-phosphate precipitation and a surface complex. With a 10% MAP/BC modification, the acid-soluble Cu content in soil decreased by 0.47-fold at day 56 while the residual Cu content increased 1.41-fold. Meanwhile, the abundances of most of the target ARGs (tetX, tetT, tetW, tetG, ermB, sulI, sulII, and intlI) were reduced by 11.35-99.95%, and the abundance of total ARGs was reduced by 30.69%. The redundancy analysis indicated that the bio-available Cu content played a crucial role in the variations of both ARGs and bacterial communities. The network analysis further suggested that potential hosts of soil ARGs were mainly Firmicutes and Actinobacteria. The above results suggested that the application of MAP/BC can mitigate Cu and ARG pollution in manured soil.

In this study, the adsorption properties of Cu(II) and tetracycline (TC) onto virgin and biofilm-developed polyethylene (PE) microplastics were investigated in batch sorption experiments. PE microplastics were placed at sewage outlets (Shanghai, China) for 20 days to develop biofilm on their surface. The adsorption and desorption isotherms of Cu(II) and TC were well fitted by the Freundlich model, and revealed that biofilm could enhance the adsorption and stabilization of Cu(II) and TC on microplastics. The linearity test of the film diffusion model in kinetic experiments suggested that the adsorption on virgin and biofilm-developed microplastics was dominated by intra-particle diffusion and film diffusion, respectively. Compared with the virgin microplastics, the adsorption of Cu(II) and TC on biofilm-developed microplastics was additionally affected by pH-dependent complexation interactions in the biofilm and competition interactions. Cu(II) pre-adsorbed on the biofilm could be released into solution because of competition effects of TC. Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) further confirmed that the enhanced adsorption of TC on the biofilm could be attributed to the complexation of TC, Cu(II) and components in biofilm. This study illustrated that biofilms could enhance the role of microplastics in the Cu(II) and TC migration by changing their adsorption properties on microplastics.

A waste–struvite/diatomite compound (MAP@Dia) recovered from nutrient-rich wastewater treated by MgO-modified diatomite (MgO@Dia) was provided to immobilize lead in aqueous solution and contaminated soil. The mechanism and effectiveness of lead immobilization was investigated, and the pHstat leaching test and fixed-bed column experiments were carried out to assess the risk of MAP@Dia reuse for lead immobilization. The results showed that MAP@Dia were effective in immobilizing lead in aqueous solution with adsorption capacity of 832.47–946.50 mg/g. The main mechanism of Pb immobilization by MAP@Dia could be contributed by surface complexation and dissolution of struvite followed by precipitation of hydroxypyromorphite Pb10(PO4)6(OH)2. Lead(II) concentration reduced from 269.61 to 78.26 mg/kg, and residual lead(II) increased to 53.14% in contaminated soil when the MAP@Dia application rate was 5%. The increased neutralization capacity (ANC) and lower lead extraction yields in pHstat leaching test in amended soil suggested 5 times of buffering capacity against potential acidic stresses and delayed triggering of “chemical time bombs.” The results of column studies demonstrated that amendment with MAP@Dia could reduce the risk of lead and phosphorus (P) leaching. This study revealed that MAP@Dia could provide an effective solution for both P recycling and lead immobilization in contaminated soil.

Brevundimonas diminuta was isolated from the oil-contaminated seawater in Dalian, China. The effects of salinity and nutrients (nitrogen and external carbon) on diesel oil biodegradation were investigated. This strain could utilize diesel oil as the sole source of carbon and energy and gave a biodegradation rate of 45% over 6 d under the salinity of 3.38% (w/w). Under the saline condition, nutrient addition has been proved to be an effective strategy to enhance oil biodegradation in marine environment. The addition of soluble starch and methanol exhibited a significant stimulative effect on oil biodegradation. The optimum external carbon source was soluble starch. Based on this, the optimum carbon source to external carbon source (C/EC) ratio in the test range was 2:1. Under the optimum conditions, diesel oil biodegradation rate increased from 44 to 65%. The optimum nitrogen source and C/N ratio were found to be NaNO3 and 20:1, respectively. Under the optimum condition, the diesel oil biodegradati...

A simple, rapid and reliable amperometric mediated biosensor, which adopted activated sludge as biocomponent and p-benzoquinone as mediator, was developed successfully to determine the toxicity of heavy metal pollutants to the activated sludge environment. The obtained EC50 (30 min) for Cu(II) is 43.1 mg L−1, which had a good correlation to the EC50 values determined on the basis of COD (40.2 mg L−1) and NH4+-N (34.3 mg L−1) removal efficiencies of unacclimated activated sludge for 1.5 h incubation. The results showed that the activated sludge ToxTell biosensor, which was based on the reduction of the intra respiration activity of the whole system as a gross parameter for toxicity assessment, could be used as an effective tool for the protection of the activated sludge environment.

In this study, struvite-humic acid loaded biochar/bentonite composite (HMCC), a recovery product of humic acid, nitrogen and phosphorus from biogas slurry, was prepared and used for simultaneous control of Zn(II) and antibiotic resistance genes (ARGs) pollution in manure-soil. The adsorption performance and mechanism of Zn(II) on HMCC were first studied in aqueous solution. The adsorption data fitted well to the Freundlich isotherm model, and the primary mechanisms of Zn(II) absorbed by HMCC involved the formation of Zn3(PO4)2·4H2O and humic acid-metal complex. The changes of Zn(II) content, antibiotic resistance genes (ARGs) and bacterial communities during the remediation of Zn(II) contaminated manure-soil were analyzed simultaneously. With HMCC amendment, the content of bio-available Zn(II) (bio-Zn) efficiently reduced from 847.4 mg/g to 739.2 mg/g and the total relative abundance of ARGs accordingly decreased by 37.18%. RDA analysis indicated that soil pH and bio-Zn were the main contributors to the fluctuations of soil ARGs. Spearman correlation analysis revealed that the potential hosts for ARGs mainly belonged to the phylum Actinobacteria. In addition, HMCC addition increased the diversity of bacterial community but significantly reduced the abundance of an antibiotic resistant bacteria-Actinobacteria. It is the first study to demonstrate the feasibility of HMCC as an environmentally friendly amendment to immobilize Zn(II) and mitigate the dissemination of ARGs in manure-soil.

Battery separators have drawn considerable attention due to their vital roles for the safety and electrochemical performance of lithium-ion batteries. In this paper, the cellulose/polysulfonamide composite membrane was successfully fabricated from a mixture of microfibrillar cellulose and polysulfonamide via a facile papermaking process. And its potential application was explored as a high performance lithium-ion battery separator by characterizing their electrolyte wettability, heat tolerance, and electrochemical properties. Lithium cobalt oxide/graphite cells using the separator displayed better capacity retention ratios of 85% after 100 cycles and superior rate capability compared with those of a commercial polypropylene separator. Furthermore, the lithium iron phosphate/lithium half cell using cellulose/polysulfonamide separator exhibited stable charge–discharge capability even at 120 °C. It was demonstrated that the composite separator possessed an enhanced thermal dimensional stability. This researc...

ZnO coupled TiO2/bamboo charcoal (ZnO-TiO2/BC) was prepared using the sol-gel method combined with microwave irradiation. The ZnO-TiO2/BC and TiO2/BC were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption (BET), and UV-vis diffuse reflectance spectroscopy (UV-vis-DRS). The ZnO dopant promoted the transformation of anatase TiO2 to rutile phase, and a significant red shift of absorption edge was brought out due to the interfacial coupling effect between ZnO and TiO2 particles. The BET specific surface area and total pore volume decreased with ZnO doping, indicating that some micropores were blocked. SEM studies indicated that ZnO was almost uniformly deposited on the surface of the ZnO-TiO2/BC. The adsorption and photocatalytic degradation experiments showed that the photo-degrade efficiency for Zno-TiO2/BC was higher than that of TiO2/BC, and for both composites, the removal efficiency of HA increased as pH decreased from 10.0 to 2.0. The degradation of HA by ZnO-TiO2/BC and TiO2/BC fitted well with the Langmuir-Hinshelwood kinetics model, and HA degradation was achieved through a synergistic mechanism of adsorption and photocatalysis. ZnO-TiO2/BC could be used as an effective and alternative photocatalyst for the treatment of water contaminated by organic pollutants.

Bamboo charcoal (BC) was used as starting material to prepare Co-Fe binary oxideloaded adsorbent (Co-Fe-MBC) through its impregnation in Co(NO3)2, FeCl3 and HNO3 solutions simultaneously, followed by microwave heating. The low-cost composite was characterized and used as an adsorbent for Cr(VI) removal from water. The results showed that a cobalt and iron binary oxide (CoFe2O4) was uniformly formed on the BC through redox reactions. The composite exhibited higher surface area (331 m2/g) than that of BC or BC loaded with Fe alone (Fe-MBC). The adsorption of Cr(VI) strongly depended on solution pH, temperature and ionic strength. The adsorption isotherms followed the Langmuir isotherm model well, and the maximum adsorption capacities for Cr(VI) at 288 K and pH 5.0 were 35.7 and 51.7 mg/g for Fe-MBC and Co-Fe-MBC, respectively. The adsorption processes were well fitted by the pseudo second-order kinetic model. Thermodynamic parameters showed that the adsorption of Cr(VI) onto both adsorbents was feasible, spontaneous, and exothermic under the studied conditions. The spent Co-Fe-MBC could be readily regenerated for reuse.

Bamboo charcoal (BC) was used as starting material to prepare iron-modified bamboo charcoal (Fe-MBC) by its impregnation in FeCl3 and HNO3 solutions simultaneously, followed by microwave heating. The material can be used as an adsorbent for Pb(II) contaminants removal in water. The composites were prepared with Fe molar concentration of 0.5, 1.0 and 2.0 mol/L and characterized by means of N2 adsorption-desorption isotherms, X-ray diffraction spectroscopy (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS), Fourier transform infrared (FT-IR) and point of zero charge (pHpzc) measurements. Nitrogen adsorption analyses showed that the BET specific surface area and total pore volume increased with iron impregnation. The adsorbent with Fe molar concentration of 2 mol/L (2Fe-MBC) exhibited the highest surface area and produced the best pore structure. The Pb(II) adsorption process of 2Fe-MBC and BC were evaluated in batch experiments and 2Fe-MBC showed an excellent adsorption capability for removal Pb(II). The adsorption of Pb(II) strongly depended on solution pH, with maximum values at pH 5.0. The ionic strength had a significant effect on the adsorption at pH < 6.0. The adsorption isotherms followed the Langmuir isotherm model well, and the maximum adsorption capacity for Pb(II) was 200.38 mg/g for 2Fe-MBC. The adsorption processes were well fitted by a pseudo second-order kinetic model. Thermodynamic parameters showed that the adsorption of Pb(II) onto Fe-MBC was feasible, spontaneous, and exothermic under the studied conditions, and the ion exchange mechanism played an significant role. These results have important implications for the design of low-cost and effective adsorbents in the removal of Pb(II) from wastewater.

Bamboo charcoal-based, iron-containing adsorbent (Fe–BC) was developed by using bamboo charcoal (BC) as a supporting medium for ferric iron that was impregnated by Fe 2 (SO 4 ) 3 and H 2 SO 4 simultaneous treatment, followed by microwave heating. The low-cost composite was characterized and used as an adsorbent for Cr(VI) removal from water. The results showed that the BET specific surface area, total pore volume, and average mesoporous diameter of Fe–BC all decreased with iron impregnation. As an adsorbent, Fe–BC showed an excellent adsorption capability for Cr(VI), the adsorption process followed the Langmuir model, and the adsorption kinetic followed pseudo-second-order model. The adsorption of Cr(VI) onto Fe–BC was spontaneous and exothermic under the studied conditions. Column adsorption experiment with Fe–BC showed that Cr(VI) could be removed to below 0.05 mg/L within 360 bed volumes at empty bed contact time 2 min when the groundwater containing approximately 0.12 mg/L of Cr(VI) was treated. The spent Fe–BC adsorbent could be readily regenerated for reuse by dilute NaOH solution.

The materials with adsorbent properties were produced from urban sewage sludge by two different procedures via microwave irradiation: (1) by one single pyrolysis stage (SC); (2) by chemical activation with ZnCl 2 (SZ). The BET, SEM and FT-IR have been used to evaluate the pore structural parameters and surface chemistry of the adsorbents, respectively. Subsequently they were used for adsorption of Cu(II) from aqueous solutions. The effects of various experimental parameters, such as pH, temperature were investigated in a batch-adsorption technique. The results showed that the adsorption of Cu(II) was maximal at pH 5.0. The kinetic study demonstrated that the adsorption process was followed the second-order kinetic equation. The experimental adsorption isotherm data were well fitted with Langmuir model and the maximum adsorption capacity of Cu(II) were found to be 3.88 and 10.56 mg/g for SC and SZ, respectively, in the solution of pH 5.0. Thermodynamic parameters such as changes in the enthalpy (Δ H 0 ), entropy (Δ S 0 ) and free energy (Δ G 0 ) indicate that Cu(II) adsorption onto SC and SZ is an endothermic and spontaneous process in nature at 15–45 °C. These results indicate that the sewage sludge-derived material via microwave induced ZnCl 2 activation is an effective and alternative adsorbent for the removal of Cu(II) from aqueous solution.

This paper deals with the extracellular polymeric substance (EPS) of Proteus mirabilis TJ-1 used as a novel biosorbent to remove dye from aqueous solution in batch systems. As a widely used and hazardous dye, basic blue 54 (BB54) was chosen as the model dye to examine the adsorption performance of the EPS. The effects of pH, initial dye concentration, contact time and temperature on the sorption of BB54 to the EPS were examined. At various initial dye concentrations (50–400 mg/L), the batch sorption equilibrium can be obtained in only 5 min. Kinetic studies suggested that the sorption followed the internal transport mechanism. According to the Langmuir model, the maximum BB54 uptake of 2.005 g/g was obtained. Chemical analysis of the EPS indicated the presence of protein (30.9%, w/w) and acid polysaccharide (63.1%, w/w). Scanning electron microscopy (SEM) images showed that the EPS with a crystal-linear structure was whole enwrapped by adsorbed dye molecules. FTIR spectrum result revealed the presence of adsorbing groups such as carboxyl, hydroxyl and amino groups in the EPS. High-molecular weight of the EPS with more binding-sites and stronger van der Waals forces together with its specific construct leads to the excellent performance of dye adsorption. The EPS shows potential board application as a biosorbent for both environmental protection and dye recovery.

The flocculating activity of a novel bioflocculant MMF1 produced by multiple-microorganism consortia MM1 was investigated. MM1 was composed of strain BAFRT4 identified as Staphylococcus sp. and strain CYGS1 identified as Pseudomonas sp. The flocculating activity of MMF1 isolated from the screening medium was 82.9%, which is remarkably higher than that of the bioflocculant produced by either of the strains under the same condition. Brewery wastewater was also used as the carbon source for MM1, and the cost-effective production medium for MM1 mainly comprised 1.0 L brewery water (chemical oxygen demand (COD) 5000 mg/L), 0.5 g/L urea, 0.5 g/L yeast extract, and 0.2 g/L (NH4)2SO4. The optimal conditions for the production of MMF1 was inoculum size 2%, initial pH 6.0, cultivating temperature 30 degrees C, and shaking speed 160 r/min, under which the flocculating activity of the MMF1 reached 96.8%. Fifteen grams of purified bioflocculant could be recovered from 1.0 L of fermentation broth. MMF1 was identified as a macromolecular substance containing both protein and polysaccharide. It showed good flocculating performance in treating indigotin printing and dyeing wastewater, and the maximal removal efficiencies of COD and chroma were 79.2% and 86.5%, respectively.