Lignin-based electrospun nanofiber membrane decorated with photo-Fenton Ag@MIF-100(Fe) heterojunctions for complex wastewater remediation

Membrane technology for wastewater remediation has aroused wide interest owing to its unique properties and potential applications.However,it remains challenging to explore green,efficient and robust membrane material and technique for complex wastewater treatment.Herein,we proposed using a simple electrospinning and in situ seeding method to fabricate a lignin-based electrospun nanofiber membrane(LENM)decorated with photo-Fenton Ag@MIL-100(Fe)heterojunctions for efficient separation of oil/water emulsions and degradation of organic dye.Thanks to the embedded lignin in LENM,an ultrahigh MIL-100(Fe)loading(53 wt%)with good wettability and high porosity was obtained.As a result,the hybrid Ag@MIL-100(Fe)/LENM exhibited excellent oil/water emulsions separation efficiency(more than 97%)without a compromise of water flux.Moreover,the hybrid membrane showed an excellent dye removal with degradation of 99%methylene blue within 30 min under illumination,which is attributed to a synergy of dye adsorption/enrichment and photo-Fenton catalytic degradation from Ag@MIL-100(Fe).Therefore,the lignin-based photo-Fenton hybrid membrane can lay the foundation for the preparation and application of green,sustainable and versatile membrane materials and technologies for efficient complex wastewater remediation.

Immobilization of nano-zero-valent irons by carboxylated cellulose nanocrystals for wastewater remediation

Nano-zero-valent irons(nZVI)have shown great potential to function as universal a nd low-cost magnetic adsorbents.Yet,the rapid agglomeration and easy surface corrosion of nZVI in solution greatly hinders their overall applicability.Here,carboxylated cellulose nanocrystals(CCNC),widely available from renewable biomass resources,wer e prepared and applied for the immobilization of nZVI.In doing so,carboxylated cellulose nanocrystals supporting nano-zero-valent irons(CCNC-nZVI)were obtained via an in-situ growth method.The CCNC-nZVI were characterized and then evaluated for their performances in wastewater treatment.The results obtained show that nZVI nanoparticles could attach to the carboxyl and hydroxyl groups of CCNC,and well disperse on the CCNC surface with a size of〜10nm.With the CCNC acting as corrosion inhibitors improving the reaction activity of nZVI,CCNC-nZVI exhibited an improved dispersion stability and electron utilization efficacy.The Pb(II)adsorption capacity of CCNC-nZVI reached 509.3 mg·g^-1(298.15 K,pH=4.0),significantly higher than that of CCNC.The adsorption was a spontaneous exothermic process and could be perfectly fitted by the pseudo-second-order kinetics model.This study may provide a novel and green method for immobilizing magnetic nanomaterials by using biomassbased resources to develop effective bio-adsorbents for wastewater decontamination.

Recent advances in waste-derived functional materials for wastewater remediation

Water pollution is a major concern for public health and a sustainable future.It is urgent to purify wastewater with effective methods to ensure a clean water supply.Most wastewater remediation techniques rely heavily on functional materials,and cost-effective materials are thus highly favorable.Of great environmental and economic significance,developing waste-derived materials for wastewater remediation has undergone explosive growth recently.Herein,the applications of waste(e.g.,biowastes,electronic wastes,and industrial wastes)-derived materials for wastewater purification are comprehensively reviewed.Sophisticated strategies for turning wastes into functional materials are firstly summarized,including pyrolysis and combustion,hydrothermal synthesis,sol–gel method,co-precipitation,and ball milling.Moreover,critical experimental parameters within different design strategies are discussed.Afterward,recent applications of waste-derived functional materials in adsorption,photocatalytic degradation,electrochemical treatment,and advanced oxidation processes(AOPs)are analyzed.We mainly focus on the development of efficient functional materials via regulating the internal and external characteristics of waste-derived materials,and the material’s property-performance correlation is also emphasized.Finally,the key future perspectives in the field of waste-derived materials-driven water remediation are highlighted.

Chemically Induced Bioremediation of Heavy MetalContaminated Sewage-irrigated Soils in Tianjin Municipality

Festuca arundinacea L.was planted in sewage-irrigated soils from the sewage irrigation regions of Tianjin.Different concentrations of nitrilotriacetic acid（NTA）and sodium dodecylsulphate（SDS）were applied in bioremediation of Cd,Cu and Zn in sewage irrigation regions.According to the results,under the treatment of 15 mmol/kg NTA＋1 mmol/kg SDS,the concentrations of Cd and Zn reached the highest in shoots of F.arundinacea,which were 3.03 and 9.28 times over that in control,respectively;the concentrations of Cd and Zn in roots of F.arundinacea displayed the same trend as shoots.The combined addition of surfactant SDS and chelator NTA significantly increased Cd concentration in F.arundinacea,but the effect was not significant on Cu enrichment.Considering comprehensively the biomass,bioaccumulation effect and economic cost,it is economical and effective to remediate heavy metal-contaminated sewage-irrigated soils with 5mmol/kg NTA＋1 mmol/kg SDS or 10 mmol/kg NTA＋1 mmol/kg SDS.

Preparation of solar-enhanced AlZnO@carbon nano-substrates for remediation of textile wastewaters

Photoactive aluminum doped ZnO(AlZnO)was synthesized by sol-gel method.After that,AlZnO photocatalyst was deposited on five carbon-based materials(CBMs)using ultrasonic route followed by solid-state mixing using ball mill.The CBMs used were poly aniline(PANI),carbon nitride(CN),carbon nanotubes(CNT),graphene(G),and carbon nanofibers(CNF).The crystal phases,elemental compositions,morphological,and optical properties of the AlZnO@CBMs composites were investigated.Experimental results revealed that two of AlZnO@CBMs composites exhibited superior bleaching efficiency(100%removal)and photocatalytic stability(three cycles)for 50μmol/L Methylene Blue(MB)contaminated water after 60 min irradiation in visible light at pH 6.5,0.7%H2O2,and 5 g/L inorganic salts.Under optimum conditions,AlZnO@CBMs nanocomposites were employed for the treatment of mixed dyestuffs composed of MB,Methyl Orange(MO),Astrazone Blue FRR(BB 69),and Rhodamine B(RhB)dyes under dark,ultraviolet,visible,and direct sunlight.For mixed dyestuffs,the AlZnO@G achieved the highest dye sorption capacity(60.91μmol dye stuffs/g)with kinetic rate 8.22×10^-3 min^-1 in 90 min via multi-layer physisorption(Freundlich isotherm)on graphene sheet.In additions,AlZnO@CN offered the highest photo-kinetic rate(Kphoto)of^54.1×10^-3 min^-1(93.8%after 60 min)under direct sunlight.Furthermore,the selective radical trapping experiment confirmed that the holes and oxidative superoxide radicals are crucial on dyes photodegradation pathway.Owing to their superior performance,AlZnO@G and AlZnO@CN nanocomposites can offer an effective in-situ solar-assisted adsorption/photocatalytic remediation of textile wastewater effluents.

Preparation of Co/S co-doped carbon catalysts for excellent methylene blue degradation

S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800℃at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate(PMS)for methylene blue(MB)degradation.The effects of two different mixing routes were identified on the MB degradation performance.Particularly,the catalyst obtained by the alcohol solvent evaporation(MOF-AEP)mixing route could degrade 95.60%MB(50 mg/L)within 4 min(degradation rate:K=0.78 min^(-1)),which was faster than that derived from the direct grinding method(MOF-DGP,80.97%,K=0.39 min^(-1)).X-ray photoelectron spectroscopy revealed that the Co-S content of MOF-AEP(43.39at%)was less than that of MOF-DGP(54.73at%),and the proportion of C-S-C in MOF-AEP(13.56at%)was higher than that of MOF-DGP(10.67at%).Density functional theory calculations revealed that the adsorption energy of Co for PMS was -2.94 eV when sulfur was doped as C-S-C on the carbon skeleton,which was higher than that when sulfur was doped next to cobalt in the form of Co-S bond(-2.86 eV).Thus,the C-S-C sites might provide more contributions to activate PMS compared with Co-S.Furthermore,the degradation parameters,including pH and MOF-AEP dosage,were investigated.Finally,radical quenching experiments and electron paramagnetic resonance(EPR)measurements revealed that ^(1)O_(2)might be the primary catalytic species,whereas·O~(2-)might be the secondary one in degrading MB.

Application of microalgal-ZnO-NPs for reusing polyester/cotton blended fabric wastes after modification by cellulases enzymes

Polyester/cotton(PET/C)blended fabric wastes are produced daily in huge amounts,which constitutes an economic loss and an environmental threat if it is not reused appropriately.Modern textile waste recycling technologies put much effort into developing fabric materials with unique properties,such as bioactivity or new optical goods based on modern technologies,especially nano-biotechnology.In this study,zinc oxide nanoparticles(ZnO-NPs)were biosynthesized using the aqueous extract of Dunaliella sp.and immobilized on PET/C waste fabrics after enzymatically activated with cellulases.The produced Dunaliella-ZnO-NPs(10–20 nm with a spherical shape)were characterized by High-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectroscopy(FTIR),X-Ray diffraction analysis(XRD),and Scanning electron microscopy-energy dispersive X-ray analyzer(SEM-EDAX),and some functional groups,such as CH,CO,NH,and CN(due to the presence of carboxyl,proteins and hydroxyl groups),were detected,revealing the biosynthesis of ZnO-NPs.The analysis showed that the resulting ZnO-NPS had potent antimicrobial effects,Ultraviolet(UV)protection capabilities,and no cytotoxic effects on the normal human fibroblast cell line(BJ1).On the other hand,enzymatic treatments of PET/C fabric waste with cellulases enhanced the immobilization of biosynthetic nanoparticles on their surface.Modified PET/C fabrics loaded with Dunaliella-ZnO-NPs showed antibacterial and UV protection capabilities making them an eco-friendly and cost-effective candidate for numerous applications.These applications can include the manufacture of active packaging devices,wastewater treatment units,and many other environmental applications.

Evaluating the Efficiency of Cadmium Removal by Alginate Hydrogels from Water Using 5,7-Dibromo-8-hydroxyquinoline as a Complexing Reagent

Cadmium toxicity in wastewater is a rising concern due to industries like batteries,metallurgy,electroplating,plastic stabilizers,and pigments.The quantitative detection of Cd^(2+)and its remediation from wastewater samples are of major concern from an environmental point of view.In the present work,an effective spectrophotometric method has been reported using 5,7-dibromo-8-hydroxyquinoline(DBHQ)as a complexing agent for Cd^(2+).This method has advantages like using recyclable,less toxic solvents and easy sample preparation.The limit of detection,limit of quantification,and sensitivity of the proposed method were found to be 33.30,36.70 mg L^(−1),and 2×10^(−3),respectively.The DBHQ method was validated using atomic absorption spectroscopy,and the recovery percentage was more than 98%.These results indicate that DBHQ can be effectively used for monitoring Cd^(2+)in aqueous systems.The method developed was further employed for monitoring Cd^(2+)adsorption on calcium alginate(AL)hydrogels.Batch adsorption studies were done to optimize parameters of Cd^(2+)removal using AL hydrogels,and the data obtained were used for kinetic and thermodynamic studies.Kinetic studies indicated that the pseudo-first-order model showed better fitting,and thermodynamic studies showed Freundlich-like adsorption.The maximum adsorption capacity of Cd^(2+)on AL hydrogels was found to be 56.45 mg g^(−1).The validation studies of DBHQ were performed using statistical analysis methods like t-tests and one-way variance.

Removal of toxic elements from aqueous environments using nano zero-valent iron-and iron oxide-modified biochar:a review

Biochar(BC)has gained attention for removal of toxic elements(TEs)from aqueous media;however,pristine biochar often exhibits low adsorption capability.Thus,various modification strategies in BC have been developed to improve its removal capability against TEs.Nanoscale zero-valent iron(nZVI)and iron oxides(FeOx)have been used as sorbents for TE removal.However,these materials are prone to agglomeration and also expensive,which make their usage limited for large-scale applications.The nZVI technical demerits could be resolved by the development of BC-based composite sorbents through the loading of nZVI or FeOx onto BC surface.Nano zero-valent iron modified BC(nZVIBC),FeOx-modified BC(FeOxBC)have attracted attention for their capability in removing pollutants from the aqueous phases.Nonetheless,a potential use of nZVIBC and FeOxBC for TE removal from aqueous environments has not been well-realized or reviewed.As such,this article reviews:(i)the preparation and characterization of nZVIBC and FeOxBC;(ii)the capacity of nZVIBC and FeOxBC for TE retention in line with their physicochemical properties,and(iii)TE removal mechanisms by nZVIBC and FeOxBC.Adopting nZVI and FeOx in BC increases its sporptive capability of TEs due to surface modifications in morphology,functional groups,and elemental composition.The combined effects of BC and nZVI,FeOx or Fe salts on the sorption of TEs are complex because they are very specific to TEs.This review identified significant opportunities for research and technol-ogy advancement of nZVIBC and FeOxBC as novel and effective sorbents for the remediation of TEs contaminated water.

“1+1>2”:Highly efficient removal of organic pollutants by composite nanofibrous membrane based on the synergistic effect of adsorption and photocatalysis

Adsorption and photocatalysis are regarded as two desirable technologies for wastewater remediation,but are still unsatisfactory in removal effect,eco-friendly regeneration and facile reusability.In this study,we developed a composite nanofibrous membrane material with excellent removal performance for organic pollutants based on synergistic adsorption and photocatalysis.A novel boron-doped,nitrogen-deficient graphitic carbon nitride(B-C3N4)photocatalyst as well as an amphiphilic copolymer of methyl methacrylate and acrylic acid(p(MMA-AA))were synthesized respectively,and then used to modify polyethersulfone for the fabrication of composite nanofibrous membrane with improved hydrophilicity,negativelycharge property and enhanced visible light response simultaneously.Subsequently,the synergistic effect of adsorption and photocatalytic degradation for organic pollutants were identified especially and resulted in an excellent removal efficiency even superior to the combination of adsorption and photocatalytic degradation,which could be called a“1+1>2”effect.In addition,the regeneration and reusability,the purification ability for multicomponent wastewater,and the photocatalytic mechanism,were investigated and discussed systematically.In this work,we not only prepared the nanofibrous membrane with synergistic effect of adsorption and photocatalysis,but also provided a versatile approach to design dualfunctional support material to ensure the practical applications of powdery photocatalyst in wastewater treatment.

Facile and scalable preparation of ZIF-67 decorated cotton fibers as recoverable and efficient adsorbents for removal of malachite green

Recently,metal–organic frameworks(MOFs)have received considerable attention as highly efficient adsorbents for dye wastewater remediation.However,the immobilization of MOFs on the substrate surfaces to fabricate easy recy-clable adsorbents via a facile route is still a challenge.In this work,ZIF-67/cotton fibers as adsorbents for dye removal were prepared in a large-scale using a simple coordination replication method.The successful fabrication of the ZIF-67/cotton fibers was confirmed by FTIR,XRD,XPS,SEM and BET analysis,respectively.As expected,the as-prepared ZIF-67/cotton fibers exhibited high adsorption capacity of 3787 mg/g towards malachite green(MG).Meanwhile,the adsorption kinetics and isotherm obeyed the pseudo-second-order kinetics and Langmuir model,respectively.Moreover,its removal efficiency towards MG was not significantly influenced by the pH and ionic strength of aque-ous solution.Most importantly,the ZIF-67/cotton fibers can remove MG from synthetic effluents,and it can be easily regenerated without filtration or centrifugation processes,with the regeneration efficiency remaining over 90%even after 10 cycles.Additionally,the ZIF-67/cotton fibers presented excellent antimicrobial performance against E.coli and S.aureus.Hence,the distinctive features of the as-prepared ZIF-67/cotton fibers make it promisingly applicable for the colored wastewater treatment.