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Microplastics are plastic particles less than 5 mm in diameter and are widely present in water environments. Their unique surface structures can adsorb coexisting pollutants in the surrounding environment, such as antibiotics and metal ions, leading to compound pollution. The adsorption of ciprofloxacin on polyethylene microplastics under different environmental conditions (pH and salinity) was investigated. The Freundlich model fitted well at 25 °C, indicating that the adsorption of ciprofloxacin by polyethylene microplastics was multilayered, and Fourier Transform infrared spectroscopy (FTIR) analysis indicated that the adsorption of ciprofloxacin by polyethylene microplastics was physical. The kinetic adsorption of ciprofloxacin on polyethylene microplastics followed a pseudo-second-order mode. Heavy metals (Cu2+, Cr3+, Cr6+, Cd2+, and Pb2+) affected the adsorption of ciprofloxacin by microplastics, which was related to the type and concentration of metal ions and the valence state of the ions. The acute toxicity of microplastics and the microplastic-ciprofloxacin-Cu2+ complex were evaluated using luminescent Photobacterium phosphoreum , demonstrating the polyethylene toxicity microplastic-ciprofloxacin-Cu2+ complex was mainly caused by Cu2+ and ciprofloxacin rather than microplastics. This study provides theoretical support for the environmental behavior and ecological effects of microplastics in aqueous environments. [Display omitted] • Ciprofloxacin adsorption on polyethylene microplastics is multilayered. • Adsorption kinetic shows a pseudo-second order pattern. • The concentration and valence of heavy metals influence the adsorption process. • Toxicity of complex pollutants are mainly caused by metal ions and ciprofloxacin. [ABSTRACT FROM AUTHOR]

In this study, several columns of different lengths were filled with composite soils sampled from the field at corresponding depths and then loaded intermittently with influent of a high phosphorus concentration to evaluate phosphorus fate and transport in soil. The results indicate that the height of the mass transfer zone, solvent pore velocity, and soil's life expectancy for phosphorus removal increased with depth, while the retained phosphorus per kilogram of soil and the linear adsorption equilibrium coefficient, R, decreased with depth. An equation was developed to link liquidphase phosphorus with solvent traveling time and soil depth. The results of X-ray diffraction and washout tests indicate that calcium-phosphorus precipitation and/or crystal growth occurred in the columns. The new protocol is useful for evaluation of phosphorus fate and transport in other subsurface systems, because it allows flexible adjustments in hydraulic loadings, feed solution, and sampling schemes. Water Environ. Res., 79, 2343 (2007). [ABSTRACT FROM AUTHOR]

A conventional tracer study using Li+ and Cl- was conducted on four Fe0-packed column reactors for nitrate removal. Both Li+ and Cl- showed strong adsorption onto iron media and thus were not ideal tracers for the study. Tests using an impulse loading of nitrate were then innovated to investigate the transport and reduction of nitrate in the reactors. The impulse loading was superposed on a continuous constant feeding of nitrate which generated a steady effluent baseline. A multivariable model incorporating hydraulic dispersion, adsorption/desorption, and reduction of nitrate was developed and numerically solved. Both Langmuir adsorption and linear adsorption isotherms were separately applied to describe nitrate adsorption on the reactive surface. The parameters of the model were estimated by fitting the model with the response curves from the impulse loading tests. These estimated parameters were consistent with previous studies. Specifically, the modeling results suggest a significant adsorption of nitrate by the iron media, causing an evident retardation effect. The research may lead to new methods for studying the fate of contaminants in porous reactive environments. [ABSTRACT FROM AUTHOR]

The "emerging contaminants" (ECs) are predominantly unregulated anthropogenic chemicals that occur in air, soil, water, food, and human/animal tissues in trace concentrations. The ECs are persistent in the environment, capable of perturbing the physiology of target receptors and, therefore, are regarded as contaminants of emerging environmental concerns in recent years. The prominent classes of ECs include pharmaceuticals and personal care products (PCPs), surfactants, plasticizers, pesticides, fire retardants, and nanomaterials. Some of the ECs with harmful effects on endocrine systems have been recognized as endocrine disrupting chemicals (EDCs). Since the 1990s intensive research has been done covering environmental occurrence, fate, ecological effects, and treatment technologies of ECs. However, a comprehensive summary of the EC removal techniques, particularly in wastewater treatment plants (WWTPs) are limited. Though the WWTPs are inefficient when it comes to ECs removal, they act as primary barriers against the spread of ECs. Therefore, this paper reviews the treatment technologies currently engaged for ECs removal in WWTPs for further possible upgrades of the existing designs. Results of this review indicate that the fate and distribution of ECs can be approximately estimated based on physicochemical properties like octanol-water partitioning coefficient (e.g., log K OW > 4, maximum sorption potential) and solid-water distribution coefficient [e.g., K d < 300–500 L/kg MLSS (mixed liquor suspended solids), insignificant sorption into sludge]. Biodegradation potential of ECs can be predicted from biodegradation constant values (e.g., K bio < 0.01 = low biodegradation and >10 = high biodegradation). In WWTPs, the EC removal efficiency varies in the range of 20–50%, 30–70%, and >90% during the primary, secondary, and tertiary treatment steps, respectively. Tertiary treatment technologies are considered as the most suitable alternatives for ECs treatment, but complete ECs removal is yet to be achieved. Further advancements in the treatment technologies will unquestionably be necessary in the future. Unlabelled Image • Treatment technologies for emerging contaminants (ECs) are comprehensively reviewed. • The ECs with risk quotient, RQ > 1 have high environmental risk potential. • The ECs with biodegradation kinetics, K bio > 10 are highly biodegradable in nature. • ASP and MBR are effective biological technologies for ECs removal. • Ozonation and activated carbon treatment are best performing tertiary treatments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Cu/NBC was fabricated by modifying N-doped biochar with Cu MOF-derived Cu. • Cu/NBC exhibited superior desulfurization capacity of 158.28 mg/g at low temperature. • The main desulfurization products of H 2 S were composed of sulfur and copper sulfide. • Desulfurization mechanism involved synergistic catalytic oxidation and adsorption. Hydrogen sulfide (H 2 S) is a highly toxic and corrosive gas that poses significant risks to human health and the environment. Therefore, the development of an adsorbent capable of efficiently purifying H 2 S at room temperature remains a challenging task. In this study, a novel composite adsorbent with a specific surface area of 434 m2·g−1 was fabricated by modifying porous N-doped biochar with Cu nanoparticles (Cu/NBC) derived from Cu-MOFs for low-temperature desulfurization of H 2 S. The effect of pyrolysis temperature and the doping ratio of Cu-MOFs to biochar on the desulfurization performance of H 2 S for the as-prepared Cu/NBC was comprehensively investigated. Experimental results indicated that the desulfurization capability of the optimized Cu/NBC-600-1 adsorbent (synthesized at a pyrolysis temperature of 600 °C and a doping ratio of 1:1) was significantly affected by the desulfurization conditions, and the optimal conditions were determined to be at 25 °C, with 20 % oxygen content and 70 % relative humidity. Under the optimized conditions, the Cu/NBC-600-1 adsorbent exhibited a high H 2 S removal capacity of 158.28 mg·g−1, which was about 3.8 times higher than that of the pristine N-doped biochar. The desulfurization mechanism of the Cu/NBC composite was demonstrated to involve reactive adsorption and catalytic oxidation, resulting in the formation of elemental sulfur and copper sulfides as the main products. This study not only provides a promising approach to modify porous biochar with MOF derivatives, but also offers an effective strategy to remove low concentration H 2 S at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zr-doped Fe-MOFs/GO nanocomposites were successfully fabricated by an in-situ growth approach. • FeZr-MOFs/GO nanocomposites delivered an excellent adsorption capacity of up to 91.69 mg·g−1. • Appropriate doping of Zr(IV) led to a substantially improved water stability of MIL-101(Fe)/GO. • Adsorption mechanism of As(V) on FeZr-MOFs/GO was ascribed to chemical complexation and hydrogen bonding. Eliminating arsenic contaminants has become an imperative issue due to its persistent and serious harm to the environment and human health. Herein, a novel FeZr-MOFs/GO nanocomposite for effectively removing As(V) was fabricated by growing Fe-based metal–organic frameworks (Fe-MOFs) of MIL-101(Fe) on the graphene oxide (GO) surface with the addition of Zr(IV) dopants. The presence of GO, the doping amount of Zr ions, and the functional groups of the ligands were found to have an impact on the adsorption performance of Fe-MOFs. Notably, doping an appropriate amount of Zr(IV) resulted in a significant increase in water stability of MIL-101(Fe) and MIL-101(Fe)/GO nanocomposites. This improvement, along with chemical complexation and hydrogen bonding, played a pivotal role in the adsorption of As(V). The optimized FeZr-MOFs-0.2/GO (0.2 represented the molar ratio between Zr and Fe) nanocomposites demonstrated superior As(V) adsorption performance with an adsorption capacity of up to 91.69 mg·g−1. Moreover, this system proven effective across a wide range of pH (2–10) and environmental matrices. This study not only provides attractive MOF nanocomposites for broadening the application of aqueous solutions, but also opens up a novel avenue for the rational design and development of nanocomposites with exceptional properties and stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic Fe 3 O 4 /GO nanocomposites were synthesized using solvothermal and pyrolysis methods. • Fe 3 O 4 /GO nanocomposite exhibited a fully-formed MOF morphology and crystal structure. • Fe 3 O 4 /GO nanocomposite delivered a remarkable adsorption capacity of 49.88 mg/g at 298.15 K. • Fe 3 O 4 /GO nanocomposite displayed excellent resistance to ionic interference and wide pH applicability. • The adsorption mechanism of As(V) was ascribed to both chemical complexation and electrostatic interaction. The urgent need to remove arsenic from groundwater stems from the irreversible damage it causes to aquatic systems and biological health. In this study, unique magnetic Fe 3 O 4 /graphene oxide (GO) nanocomposites derived from MIL-100(Fe)/GO precursor were rationally and precisely developed by combination of solvothermal synthesis and pyrolysis methods. The optimized MIL-100(Fe)/1%GO-400 magnetic nanocomposite (where 1% and 400 represent the mass ratio of GO to MIL-100(Fe) and pyrolysis temperature, respectively) exhibited exceptional adsorption capacity for As(V) and possessed magnetic separation properties. The novel nanocomposite had complete MOF morphology and crystal structure, as well as good resistance to interference from ions and could be used effectively over a wide pH range (2–9) for adsorption of As(V). The As(V) adsorption on the nanocomposite was found to follow the pseudo-second-order (PSO) kinetic model and Temkin adsorption isotherm model, as well as a spontaneous endothermic process dominated by chemisorption. The incorporation of GO and pyrolysis of the Fe-MOFs was proven to enhance the adsorption capacity of nanocomposite, water stability, and magnetic recovery ability. The adsorption mechanism was attributed to the synergistic effect of chemical complexation, hydrogen binding and electrostatic interaction. This work not only presents a feasible strategy for the development of Fe-MOFs-based derivatives, but also offers a promising approach to expanding the application of functional Fe-MOFs-based derivatives in arsenic-contaminated wastewater treatment. [ABSTRACT FROM AUTHOR]

The fastest-growing microbe Vibrio natriegens is an excellent platform for bioproduction processes. Until now, this marine bacterium has not been examined for bioremediation applications, where the production of substantial amounts of biomass would be beneficial. V. natriegens can perform extracellular electron transfer (EET) to Fe(III) via a single porin-cytochrome circuit conserved in Vibrionaceae. Electroactive microbes capable of EET to Fe(III) usually also reduce toxic metals such as carcinogenic Cr(VI), which is converted to Cr(III), thus decreasing its toxicity and mobility. Here, the performance of V. natriegens was explored for the bioremediation of Cr(VI). At a density of 100 mg/mL, V. natriegens removed 5–20 mg/L Cr(VI) within 30 s and 100 mg/L Cr(VI) within 10 min. In comparison, the model bacterium Escherichia coli grown to a comparable cell density removed Cr(VI) 36 times slower. To eliminate Cr(VI), V. natriegens had to be metabolically active, and functional outer-membrane c -type cytochromes were required. At the end of the Cr(VI) removal process, V. natriegens had reduced all of it into Cr(III) while adsorbing more than half of the metallic ions. These results demonstrate that V. natriegens , with its fast metabolism, is a viable option for the rapid treatment of aqueous pollution with Cr. [Display omitted] • The fast-growing microbe Vibrio natriegens can reduce and adsorb toxic chromium. • High-density V. natriegens removed 5–20 mg/L Cr(VI) within 30 s. • V. natriegens at the same density also removed 100 mg/L Cr(VI) within minutes. • Cr(VI) was reduced extracellularly and Cr(III) was adsorbed by the microbes. • A porin-cytochrome complex is likely involved in Cr(VI) conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The P-doped biochar was derived from pyrolysis of phytic acid-activated lemon peel. • The CuSiO 3 /PBC composite was synthesized by loading CuSiO 3 on the P-doped biochar. • Such CuSiO 3 /PBC delivered NH 3 adsorption capacity of 6.36 mmol/g at 298 K and 1 bar. • The NH 3 adsorption on CuSiO 3 /PBC was verified a reactive adsorption process. Ammonia (NH 3) is a typical malodorous pollutant and one of the key factors causing PM2.5. It is of great significance to develop an efficient material with outstanding adsorption ability for NH 3 capture. Herein, a novel CuSiO 3 /PBC composite adsorbent is fabricated by first producing phosphorous-doped porous biochar (PBC) via pyrolysis of lemon peel with phytic acid as both the phosphorous source and activator, and subsequent loading of cupric silicate (CuSiO 3) onto the PBC with an ultrasonic dipping process. Among these as-fabricated composites, the CuSiO 3 /PBC-2-500-0.2 adsorbent (where 2 = the mass ratio of phytic acid to LP; 500 = the activation temperature; 0.2 = the atomic percentage of Cu) with a large surface area of 726.3 m2 g−1 delivers an excellent NH 3 batch adsorption ability of 6.36 mmol g−1 at 298 K and 1 bar, and a high dynamic adsorption ability of 1.96 mmol g−1 under 200 ppm NH 3 and a total flow rate of 50 mL min−1. The CuSiO 3 /PBC-2-500-0.2 composite also maintains circa 80% of the initial adsorption capacity after 8 cycle reuses, conducive to continuous operation. Furthermore, the postulated adsorption mechanism is demonstrated that NH 3 reacts with acidic sites such as H+ of HPO 4 2− to form NH 4 + and forms [Cu(NH 3) 4 ]2+ with Cu2+, and the porous structure of the composite material also plays an important role. This work not only provides a promising adsorbent for NH 3 capture, but also displays a novel idea for the development of excellent composite adsorbents derived from biomass waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • The RZF was synthesized via one-step carbonation activation of kitchen leftover rice. • ZnCl 2 and FeCl 3 were employed as both activator and precursor for preparing RZF. • The as-obtained RZF delivered outstanding desulfurization capacity and regeneration ability. • The postulated mechanisms of H 2 S removal on the RZF was proposed and verified. Hydrogen sulfide (H 2 S) is a major air pollutant posing a serious threat to the environment and public health. It is highly attractive to develop state-of-the-art adsorbent to remove H 2 S. Herein, a novel ZnFe 2 O 4 -loaded porous biochar (RZF) with a high surface area of 1065 m2/g was synthesized via one-step carbonation activation of kitchen leftover rice with ZnCl 2 and FeCl 3 as activators. The optimized RZF-500-1:1 was obtained by rationally adjusting the activation ratio (the mass ratio of leftover rice and ZnFe 2 O 4) and pyrolysis temperature. Such RZF-500-1:1 delivered high-performance H 2 S removal with the breakthrough capacity up to 228.29 mg/g at 25 °C, whilst the inactivated biochar (carbonization without activator) only showed a much lower adsorption capacity at circa 12.11 mg/g of H 2 S. The desulfurization conditions had a significant effect on the H 2 S breakthrough capacity, and the adsorbent exhibited better desulfurization performance at room temperature and in the presence of oxygen. The desulfurization mechanism on the ZnFe 2 O 4 -loaded biochar was proposed to be an adsorption-catalytic oxidation coupled process. Moreover, the as-fabricated sample showed high regeneration ability, retaining 91.6% of the initial breakthrough capacity after five regeneration cycles. This novel one-step preparation method would permit a gain of time and energy to obtain efficient activated carbons intended to capture H 2 S. [ABSTRACT FROM AUTHOR]

With the development of industry, heavy metal (HM) pollution of soil has become an increasingly serious problem. Using passivators made of industrial by-products to immobilize HMs in contaminated soil is a promising in-situ remediation technology. In this study, the electrolytic manganese slag (EMS) was modified into a passivator (named M-EMS) by ball milling, and the effects of M-EMS on adsorption of As(V) in aquatic samples and on immobilization of As(V) and other HMs in soil samples were investigated under different conditions. Results demonstrated that M-EMS had a maximum As(V) adsorption capacity of 65.3 mg/g in the aquatic samples. Adding M-EMS to the soil reduced the leaching of As (from 657.2 to 319.8 μg/L) and other HMs after 30 d of incubation, reduced the bioavailability of As(V) and improved the quality and microbial activity of the soil. The mechanism for M-EMS to immobilize As in the soil are complex reactions, ion exchange reaction with As and electrostatic adsorption. This work provides new ideas of using waste residue matrix composites for sustainable remediation of Arsenic in the aquatic environment and soil. [Display omitted] • A novel EMS/pyrite-based passivator (M-EMS) was developed. • M-EMS can passivate As and other heavy metals in soil and reduce their bioavailability. • The immobilization mechanisms include precipitation, adsorption, and ion exchange. [ABSTRACT FROM AUTHOR]

Arsenic-containing wastewater and arsenic-contaminated soils can cause serious environmental pollution. In this study, mixtures of electrolytic manganese residues (EMRs) and calcite were superheated to different temperatures to prepare a novel passivator for arsenic [As(V)] removal in an aqueous environment, as well as for passivating As and other heavy metals (HMs) (e.g. Cr, Cd, and Pb) in the soil. The results showed that the optimal passivator superheated at 800 °C (C-EMR-800) and had a maximum As(V) adsorption capacity of 35 mg/g in solution. The excellent adsorption performance could be modelled using a second-order kinetic model, which demonstrated that adsorption is more consistent with chemisorption. The leaching concentration of As in contaminated soil amended with C-EMR-800 was reduced from 62.81 to 5.84 μg/L within 10 d, which is lower than that of the Chinese national standard (GB/T 5085.3–2007); C-EMR-800 also showed excellent passivating effects on other HMs (Cr, Cd, and Pb). The mechanisms for As removal by C-EMR-800 are linked to chemical reactions (e.g. precipitation), adsorption, and microbial passivation. Collectively, this study demonstrates an eco-friendly "waste-to-soil remediation" strategy that can address issues related to the reutilization of solid waste and remediation of HM-contaminated soil. [Display omitted] • A novel EMR/calcite-based passivator (C-EMR-800) was developed. • C-EMR absorbed As(V) in solution and passivated As, Pb, Cd, and Cr in soil. • Mechanisms for HMs removal include precipitation, adsorption and microbial passivation. • Solid waste reutilization and remediation of HM-contaminated soil were addressed. • The function of the microbial community is altered for soil remediation. [ABSTRACT FROM AUTHOR]

The magnetic poly(N -isopropylacrylamide)/chitosan hydrogel with interpenetrating network (IPN) structure was designed based on the functional groups of targeted emerging contaminants, represented by hydrophilic sulfamethoxazole (SMZ) and hydrophobic bisphenol A (BPA). The average particle size, specific surface area, and total pore volume of the hydrogel were turned out to be 103.7 μm, 60.70 m2/g and 0.0672 cm3/g, respectively. Adsorption results indicated that the maximum adsorption capacity occurred at the pH where SMZ was anionic and BPA was uncharged. When the adsorption temperature increased from 25 °C to 35 °C, the amount of adsorbed SMZ hardly changed, but that of BPA increased by two times. The adsorption capacity of the binary system (i.e., with both SMZ and BPA) was almost the same as that of the single system, indicating that simultaneous adsorption of SMZ and BPA was achieved. The adsorption equilibrium was reached quickly (within 5 min) for both SMZ and BPA. For adsorption isotherm, the Freundlich model fitted well for SMZ at 25, 35 and 45 °C. However, the adsorption of BPA exhibited the sigmoidally shaped isotherm at 25 °C with the Slips model fitting well, and both the Freundlich isotherm and the Slips isotherm fitted the data well at 35 °C and 45 °C, suggesting that the adsorption force was initially weak but greatly enhanced with an increase in adsorbate concentration or ambient temperature. The main adsorption mechanism was inferred to be electrostatic interactions for SMZ, and hydrophobic interactions as well as hydrogen bonding for BPA. The hydrogel adsorbent maintained favorable adsorption capacity for BPA after five adsorption-desorption cycles. These findings may provide a strategy for designing high performance adsorbents that can remove both hydrophilic and hydrophobic organic contaminants in the aquatic environment. Unlabelled Image • The hydrogel adsorbent was designed and synthesized based on the functional groups of the target contaminants. • Good adsorption capacity for both hydrophilic sulfamethoxazole and hydrophobic bisphenol A was achieved. • Electrostatic interactions, hydrophobic interactions and hydrogen bonding dominated the adsorption process. • The adsorbent exhibited good reusability for bisphenol A. [ABSTRACT FROM AUTHOR]

Abstract Currently, there is a growing trend in employing natural biomaterials (e.g., alginate) to prepare a novel bead adsorbent for phosphorus (P) elimination. However, the utilization of alginate beads to remove and recover P from effluents possesses limitations associated with its physical characteristics such as a dense gel layer, poor mechanical strength and low stability. To overcome the limitations and improve the adsorption performances, we synthesized a novel alginate-derived bead constituted of PNIPAM network interpenetrated in alginate-Zr4+ network (PNIPAM/SA-Zr) decorated with polyethylene glycol as a pore-forming agent, and then investigated its ability to remove and recover P from effluents. The morphology, functional groups, surface area, and mechanical strength of the beads were evaluated by SEM, FTIR, BET, and swelling analysis. The adsorption of P was investigated by varying various factors. The adsorption kinetics, isotherms, and thermodynamics were studied. Particularly, the P-loaded beads exhibited a faster desorption rate under thermal stimulus, and remained good desorption efficiency and reusability within five consecutive cycles. Zeta-potential and XPS results revealed that the adsorption mechanisms were related to electrostatic interactions, ligand exchange, and the formation of inner-sphere complexes. The beads possessed favorable fixed-bed column operation performances for P removal and recovery from real wastewater. Graphical abstract Unlabelled Image Highlights • Macroporous thermosensitive alginate-Zr4+ bead adsorbent was prepared. • The mechanisms of phosphorus adsorption onto the beads were explored. • The introduced Zr4+ and macroporous structure enhanced phosphorus removal. • The beads showed a faster desorption rate by thermal stimuli and good reusability. • The beads possessed good fixed-bed column operation performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • ECS as a substrate for S-nZVI can effectively avoid agglomeration. • S-nZVI@ECS can effectively remove Cd(II), Cu(II) and Pb(II) in a wide pH range. • The mechanisms include reduction, complexation, and precipitation. • Cu(II) and Pb(II) removal are almost unaffected in the presence of Cd(II). Exhausted copper slag (ECS) is an industrially utilized secondary waste, and due to its large volume and potential environmental risks, the utilization of ECS in a safe manner is required. In this study, a novel synthetic composite (S-nZVI@ECS) was prepared by loading sulfidized nanoscale zerovalent iron (S-nZVI) onto ECS for the removal of Cd(II), Cu(II), and Pb(II) from aqueous solutions. The composite not only provides a new idea for utilizing ECS but also prevents S-nZVI particles from agglomerating. The optimized S-nZVI@ECS can achieve efficient removal of the three heavy metals over a wide pH range without being affected by coexisting ions (Na+, K+, Mg2+, Ca2+). With the respective maximum adsorption capacities of these three cationic heavy metals being as high as 173.01, 93.81, and 338.98 mg/g (based on the Langmuir model), the elimination of S-nZVI@ECS for these three cationic heavy metals could be fitted with the Langmuir and Freundlich models well, and the associated mechanisms (including redox reactions, complexation, and precipitation) were elucidated. The novel S-nZVI@ECS composites prepared in this study using secondary waste as a substrate have good potential for removing cationic heavy metals from aqueous solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MgFe 2 O 4 -loaded and N -doped biochar (MgFe 2 O 4 @NBC) was fabricated by one-pot pyrolysis method. • MgFe 2 O 4 @NBC realized synergistic desulfurization of H 2 S by metal oxide loading and N doping. • MgFe 2 O 4 @NBC delivered superior desulfurization capacity of 1052.83 mg/g at room temperature. • The desulfurization mechanism of H 2 S on MgFe 2 O 4 @NBC was verified by in-situ DRIFTS and XPS. • The desulfurization process of H 2 S was a combination of catalytic oxidation and reactive adsorption. To improve their low-temperature desulfurization performance, the activated carbon-based materials have typically been modified by either metal oxide loading or nitrogen doping. However, most of the aforementioned materials are limited to only one of the above modification methods, resulting in relatively poor desulfurization performance. Herein, a novel MgFe 2 O 4 -loaded N -doped biochar (MgFe 2 O 4 @NBC) was fabricated by one-pot pyrolysis of a nitrogen containing precursor of g-C 3 N 4 , cooked rice waste, and metal salts for efficient low-temperature desulfurization of H 2 S. Different fabrication conditions such as pyrolysis temperature and the nitrogen mixing ratio (i.e., the mass ratio of cooked rice waste to g-C 3 N 4) have been extensively studied. The optimized MgFe 2 O 4 @NBC-500–2 sample delivered a superior breakthrough capacity of 1052.83 mg/g in an atmosphere of O 2 content of 20% and relative humidity of 80% at 25 °C, and demonstrated high tolerance and stability of desulfurization performance to harsh environmental conditions with 80% relative humidity and no oxygen. The desulfurization mechanism of H 2 S on the surfaces of the MgFe 2 O 4 @NBC composites was attributed to the synergistic effects of reactive adsorption and catalytic oxidation process. The composite also demonstrated excellent reusability, retaining 85% of the initial breakthrough capacity after 5 recycled uses. Therefore, the as-prepared MgFe 2 O 4 @NBC composite offers a potentially promising carbon-based desulfurizers for practical applications in the low-temperature desulfurization field. [ABSTRACT FROM AUTHOR]

[Display omitted] • ECSs are reused as an adsorbent for Cr(VI) from wastewater. • The maximum experimental removal capacity of ECSs for Cr(VI) was 110.50 mg/g. • Removal mechanisms include redox, electrostatic adsorption, and flocculation. Exhausted copper slags (ECSs) are secondary slags produced in the reusing process of copper smelting fly ashes and have the potential to synthesize adsorbent for the elimination of toxic elements. This study focuses on the potential of the original ESCs for the detoxication and removal of Cr(VI) from aqueous solutions. Batch adsorption experiments showed that ESCs present an excellent performance on Cr(VI) eliminate, and the maximum adsorption capacity is 110.50 mg∙g−1 at acid solutions (pH = 2) with a mild temperature condition (308 K). Furthermore, the adsorption efficiency of Cr was barely effected by the comment co-existing elements, such as NO 3 – and SO 4 2-, indicating its specific adsorption capacity for Cr. The elimination of Cr onto ESCs fits well with the Langmuir adsorption model, indicating that the adsorption process was controlled by monolayer adsorption. Moreover, Cr(VI) adsorption onto ESCs also followed the Pseudo-second-order kinetics with the adsorption rate constant k at 2.65 × 10-3 g·mg−1·min−1. Mechanistic analysis indicated that ECSs eliminated Cr(VI) by electrostatic adsorption and flocculation precipitation, and reduced Cr(III) by Fe2+, Mo2+, S2-, and SO 3 2-. The environmental risks during its adsorption implication process were also accessed and the toxic elements, such as Cu, As, and Pb in the materials were barely detected in the residue solutions. Thus, ECSs could be used as a facile and cost-effective adsorbent for Cr(VI) removal, even without any further pre-treatment process, which is meaningful to the disposal of this typical industrial waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MWCNTs/MIL-53(Fe) nanocomposite is fabricated by one-pot hydrothermal process. • MWCNTs/MIL-53(Fe) delivers a superior high removal efficiency of As(V) at 95.1%. • MWCNTs/MIL-53(Fe) exhibits better water stability than the pure MIL-53(Fe). • The As(V) adsorption conforms to PSO kinetic and Redlich-Peterson isotherm models. • The adsorption mechanism is caused by interactions of hydrogen bond and complexation. Arsenic is a toxic carcinogen, and arsenic pollution in groundwater is one of the most serious environmental problems in the world. Thus, it is an urgent problem to efficient removal of arsenic from groundwater. In this work, a novel MWCNTs/MIL-53(Fe) nanocomposite was successfully synthesized to improve the water stability of MIL-53(Fe) by incorporation of carboxylated multi-walled carbon nanotubes (MWCNTs) using a one-pot hydrothermal method, and was then used to efficiently adsorb As(V) ions from groundwater. Adsorption experimental results demonstrated an ultrafast adsorption rate of As(V) on the MWCNTs/MIL-53(Fe) nanocomposites in solution pH values of 3 to 10, and the adsorption equilibrium could be reached in circa 20 min with an adsorption capacity of 27.24 mg·g−1 in a low As(V) concentration of 10 mg·L−1. The adsorption kinetics of As(V) on the MWCNTs/MIL-53(Fe) was found in line with the pseudo-second-order (PSO) kinetic model, and was simultaneously controlled by both internal diffusion and liquid film diffusion. The adsorption isotherm data conformed to the Redlich-Peterson isotherm model, indicating both physical and chemical adsorption occurred at heterogeneous interfaces. Moreover, the postulated adsorption mechanism of As(V) on MWCNTs/MIL-53(Fe) nanocomposites was ascribed to hydrogen-bond interaction, electrostatic attraction and chemical complexation. Therefore, the as-prepared MWCNTs/MIL-53(Fe) nanocomposites not only exhibit superior water stability and outstanding adsorption performance in removing arsenic-contaminated groundwater, but also offer a novel insight for rational preparation of water-stable MOF-based composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical CuC 2 O 4 @Cu-MOFs nanostructure was fabricated to construct underoil superhydrophilic surface. • Superwetting CuC 2 O 4 @Cu-MOFs-coated membrane exhibited excellent underoil water absorption capacity. • The CM@CuC 2 O 4 @Cu-MOFs delivered high separation efficiency for both O/W and W/O emulsions. • The CM@CuC 2 O 4 @Cu-MOFs showed outstanding removal efficiency of soluble dyes and complex emulsions. Underoil superhydrophilic surface is of great significance for the separation of water-in-oil emulsions, but its preparation is still a great challenge due to limited wetting thermodynamics. Herein, a well-designed hierarchical CuC 2 O 4 @Cu-MOFs (HKUST-1) core-shell nanosheets-coated copper mesh membrane was fabricated by facile immersion processes for on demand separation of oil-in-water and water-in-oil emulsions as well as highly efficient removal of soluble dyes. The as-fabricated hierarchical CuC 2 O 4 @HKUST-1 core-shell nanostructure endowed the mesh membrane with underwater superoleophobicity, underoil superhydrophilicity and excellent underwater oil anti-adhesion capability. Such superwetting MOFs-coated membrane delivered an outstanding separation performance for oil-in-water emulsion with high water flux of up to 1800 L m−2 h−1and the chemical oxygen demand (COD) value of lower than 110 mg L−1 by selective water filtration, whilst it efficiently separated water-in-oil emulsion by adsorption with a water content of lower than 120 ppm. Furthermore, the as-prepared mesh membrane also exhibited high removal efficiency of soluble dyes at circa 94% within 165 min by the adsorption-photocatalytic coupled process. The postulated photocatalytic mechanism of CuC 2 O 4 @HKUST-1 composite was ascribed to the photogenerated superoxide (O 2 −) and hydroxyl radicals (OH). With the desirable separation performance to complex oil-in-water emulsion containing both emulsified oil droplets and soluble dyes, the as-synthesized mesh membrane enriches the preparation path of underoil superhydrophilic surface, and expands the application of MOFs-based membrane for complex oily wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Functionally-designed adsorbent hydrogel beads were synthesized by a simple method. • The g-C 3 N 4 /CS/PVA hydrogel beads showed high adsorbing capacity for SMX. • Interactions between hydrogel and SMX were inferred to the electrostatic interactions and hydrogen bonds. • The hydrogel beads could be regenerated by light. Adsorption method has been widely used in the removal of emerging contaminants. However, many adsorbents are puzzled by key obstacles for effective and simple regeneration. In this work, the functionally-designed graphitic carbon nitride (g-C 3 N 4) embedded chitosan-polyvinyl alcohol composite (g-C 3 N 4 /CS/PVA) hydrogel beads were synthesized for the adsorptive removal of sulfamethoxazole (SMX) from water, and they could be regenerated by light. The adsorption kinetics, isotherm, thermodynamics, and impacting factors were systematically investigated. And the adsorption capacity of the hydrogel for SMX was relatively stable at pH of 4–8, with the maximum adsorption capacities being 5.8 mg g−1 at pH 5. The main adsorption force may be inferred to the electrostatic interactions between SMX and hydrogel beads, and hydrogen bonds between the amino or hydroxyl groups of the hydrogel and the amino of the SMX. The dominance of electrostatic interactions resulted in SMX adsorption being highly dependent on ionic strength. Being irradiated with an ultraviolet lamp for 5 recycles, the hydrogel beads still kept good adsorption capacity. The regeneration behavior was attributed to the photocatalytic degradation of SMX by g-C 3 N 4. Namely, photocatalytic oxidation reactivated the adsorption sites and increased the release of adsorbed pollutants with improved desorption performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel flower-like Mg/Al/Fe-CLDH was synthesized for As(V) removal. • Mg/Al/Fe-CLDH exhibited excellent acid and alkali resistance and reusability. • The maximum adsorption capacity of the Mg/Al/Fe-CLDH was 70.7 mg/g. • As(V) ions intercalated into the interlayer region to reconstruct the hydrotalcite. Mg/Al-LDH is widely used in the removal of aqueous pollutants due to the large surface and high anion exchange capacity, but the traditional Mg/Al-LDH for arsenic removal has a narrow range of pH application. The present study focused on the modifying of the lamellar Mg/Al-LDH to synthesize flower-like nanoparticles for arsenate removal in a wide pH range. Results showed that Mg/Al/Fe-CLDH (calcined Mg/Al/Fe-LDH) exhibited an extremely high arsenate removal efficiency (e.g., reducing As(V) from 10 mg/L to 1 µg/L) in a wide pH range (2–12). Furthermore, it can keep excellent removal efficiency for arsenate under a complex anions environment (co-existing with CO 3 2−, SO 4 2−, PO 4 3−, and F−), and maintain 80% removal efficiency for arsenate after 4 regeneration cycles. SEM, XRD, and XPS results unveiled the following enhancing mechanism for arsenate removal by using this modified Mg/Al-LDH: 1) partial content of ferric ions were successfully insert into the layers of Mg/Al-LDH and substituted by aluminium ions, which produce more affiliative sites for arsenate and expand its feasibility in a wide pH ranges; 2) the flower-like structures facilitate to offer more adsorption sites for arsenate due to its larger specific surface area. In brief, this flower-like Mg/Al/Fe-CLDH has great application potential for eco-friendly purity of arsenate from complicated industrial wastewater. [ABSTRACT FROM AUTHOR]

• FLAL exhibited higher adsorption ability for Cu2+ ions than Pb2+ ions. • The -CSS functional group carried by FLAL was confirmed as the main binding site. • The binding energy of S Cu S was lower than that of S Pb S. • FLAL had higher adsorption capacity for Cu2+/Pb2+ ions as compared with other materials. A kind of alkaline lignin (AL)-based modified material (FLAL) was fabricated, in which CS 2 was selected as the modifier. FLAL can be used to treat Pb2+ and Cu2+ ions loaded water. When the initial concentrations of Pb2+ and Cu2+ ions were 30 mg/L, the removal efficiencies were 97% for Pb2+ at 100 min while 98% for Cu2+ at 5 min, respectively. The maximum adsorption capacities (q m) of Pb2+ and Cu2+ ions were 0.322 and 1.010 mmol/g, indicating that the adsorption capacity of FLAL for Cu2+ ions was better than for Pb2+ ions. The groups of hydroxyl, methoxyl and dithiocarbamate carried by FLAL contributed to binding with Pb2+/Cu2+ ions. Dithiocarbamate (CSS) was proved to be the primary active site, in which the binding energy (E ad) of S Cu S and S Pb S were −1.1739 and −0.8709 Ha. These results suggest the interaction between FLAL and Cu2+ ions was stronger and FLAL-Cu2+ complexes were more stable, revealing the reason why the uptake of Cu2+ ions by FLAL was quicker in speed and larger in amount. The reusing ability of FLAL was evaluated through a four-adsorption–desorption cycle. The values of q m for Pb2+ and Cu2+ ions were 0.258 and 0.878 mmol/g corresponding to the fourth regeneration, decreased by 19.87% and 13.06% compared to fresh FLAL. The adsorption performance of both fresh and regenerated FLAL is better than many other biomass-based adsorbents. FLAL can be regarded as a promising material with high application potential, which warrants future studies on optimizing FLAL for real-world applications. [ABSTRACT FROM AUTHOR]

• Adsorption/desorption of cellulase on enzymatic residual lignin (ERL) was studied. • Dilute acid (DA) pretreatment of ERL at higher severity intensified the adsorption. • Desorption capacity of cellulase from ERL was decreased by DA pretreatment. • Recoveries of cellulase from ERLs decreased with the increase of severity factors. • Bound-cellulase on DA pretreated ERLs exhibited activity, but was hard to be reused. Desorption of cellulase from lignin is necessary to recycle cellulase in enzymatic hydrolysis. Currently, the knowledge about cellulase desorption from lignin is still limited. In present work, the adsorption and desorption of cellulase on/from enzymatic residual lignins (ERLs) pretreated with dilute acid at different severities were investigated. The results showed that the molecular weights of dilute acid-pretreated ERLs (DA-ERLs) decreased with the increase of severity. The hydrophobicity and contents of condensed phenolic structures in ERLs increased after DA pretreatment with the increase of severity. Compared with un-pretreated ERL, DA-ERLs pretreated with severity factors of 1.17, 1.51, and 1.69 increased the inhibition degree of cellulose hydrolysis from 21.5 % (ERL) to 24.6 %, 28.5 % and 31.9 %, respectively. DA-ERLs pretreated at higher severities exhibited larger adsorption capacities with individual cellulase components. DA pretreatment of ERL at higher severities intensified the binding with cellulase. The binding strength between lignin and cellulase increased from 236.0 mL/g to 261.5–410.9 mL/g with the increase of severity. DA pretreatment decreased the desorption capacity of cellulase from ERLs. The recovery of cellulase from lignin decreased from 78.6% to 36.9%–14.7 % with the increase of severity. The cellulase desorbed from ERLs remained portion of activities, but the cellulase bound on DA-ERLs was hard to be released and provided a lower glucose yield (4.8 %–5.9 %) than that on un-pretreated ERL (16.2 %). The results reported here will aid cellulase recycling and efficient hydrolysis of lignocellulose after dilute acid pretreatment. [ABSTRACT FROM AUTHOR]

In this research, electrolytic manganese residues (EMRs) modified by NaOH, ultrasonic etching and microwave-assisted heating treatment (called M-EMRs hereafter) were used as a novel adsorbent to remove Arsenic (V) [As(V)] from synthetic wastewater. Results showed that M-EMRs were of nanosheet structure in sizes of about 100–300 nm; the percentage of Fe and Mn on the surface of M-EMRs increased, and Fe and Mn existed in the forms of FeS, FeOOH, Fe 3 O 4 , and MnO 2. The As(V) concentration in the liquid decreased from 50 to 0.038 mg/L. The maximum adsorption capacity of E-EMRs for As(V) was 23.96 mg/g. The presence of low concentration of salt such as NaCl, Na 2 CO 3 , Na 2 HPO 4 , and Na 2 SO 4 showed limited inhibition on the adsorption of As(V). Moreover, M-EMRs could be regenerated with 3% NaOH solution and reused for 5 times. Preliminary analysis indicates the application potential of M-EMRs in As-contaminated industrial wastewater. Image 1 • For the first time, EMRs were modified to be an As(V) adsorbent (M-EMRs). • The adsorption capacity of M-EMRs for arsenic is 23.96 mg/g. • The adsorption capacity is greater than hematite, halloysite, and steel slag. • The treated As(V)-wastewater is below the tolerance level of national standards. • The M-EMRs is stable in a wide pH range and with the coexistence of multiple ions. [ABSTRACT FROM AUTHOR]