查看更多>>摘要：Biochars have attracted widespread attention as a low-cost adsorbent for antibiotic removal.High surface area and hierarchical porous biochars,originating from five types of feedstocks,were prepared via simple carbonization and alkaline activation route and tested for chloramphenicol removal from the water environment.All biochars showed a maximum adsorption capacity of over 300 mg g~(-1)at room temperature,with a large specific surface area of 1687-2003 m2 g~(-1).Adsorption isotherms and kinetics adhered well to Langmuir and pseudo-first-order models.The structure-performance correlation was analyzed to explore the effects of adsorbents'physical properties,morphology,and functional groups on adsorption performance.The pseudo-first-order kinetic constant,representing the adsorption rate,was strongly correlated with the external surface area and mesoporous pore volume.The maximum monolayer adsorption capacity,calculated by the Langmuir model,was strongly correlated with the microporous surface area and pore volume.A higher proportion of graphite and stronger hydrophilicity decreased the adsorption capacity.The primary adsorption mechanism appears to be physical adsorption through micropore filling,along with π-π electron donor-acceptor,electrostatic and hydrophobic interactions.Thus,a key factor influencing adsorption performance is the ratio of the microporous and mesoporous pore volume of adsorbents.To simultaneously enhance the adsorption rate and capacity,it is crucial to regulate the ratio of microporous and mesoporous pores of biochars.Establishing this relationship could have important implications for regulating the adsorbent structure and improving adsorption behavior.
查看更多>>摘要：The bismuth(Bi)-based materials have been considered as a promising Cl-storage electrode for electrochemical desalination(EDI),with high theoretical capacity and excellent Cl~ selectivity.Unfortunately,the desalination application of Bi-based materials is greatly restricted by poor cycling stability due to the volume expansion and pulverization in the chlorination/dechlorination process.Hence,bismuth-titanium alloy nanoparticles encapsulated in porous carbon matrix composite(Bi-Ti@C)were fabricated by facile pyrolysis of the Bi-Ti bimetallic organic framework(Bi-Ti-MOF).The introduction of Ti and carbon nanocages can effectively buffer the volume expansion and improve the BiTi-C interface binding force during the desalination/salinization process.With these advantages,the alloyed Bi-Ti@C-600 composite exhibited outstanding electrochemical properties,with high specific capacitance of 430.72F g~(-1)and low charge transfer resistance.Furthermore,the excellent desalination performance was achieved as an anode coupling with an activated carbon cathode,which delivered an impressive Cl~ removal capacity of 106.5 mg g~(-1)and superior cycling stability of 80% retention rate after 100 desalination/salination cycles.Importantly,ex-situ XRD patterns revealed the desalination/salinization mechanism of Bi-Ti@C-600 composites involving the reversible transformation between Bi and BiOCl.Our findings shed light on the rational design for high-performance alloyed Bi-based Cl-storage electrode and offer new insights into the applications of EDI.
查看更多>>摘要：Anaerobic membrane bioreactor(AnMBR)technology has been considered promising to transform domestic wastewater(DWW)treatment as a net energy producer via bioenergy recovery.However,ammonium-nitrogen(NH4-N)in DWW cannot be removed by anaerobic process,which raises the risk of eutrophication and prevents the wide-scale adoption of AnMBRs.This study proposed adsorption/desorption by poly(acrylic acid)(PAA)hydrogel as the post-treatment of AnMBRs to remove and recover NH_4~+-N,thus simultaneously promoting AnMBR technology and the circular economy.Batch experiment results showed that NH_4~+-N could be rapidly adsorbed by PAA hydrogels within 30 min with excellent maximum adsorption capacities of 110.6-120.8 mg N/L(10-50 ℃).Furthermore,PAA hydrogels retained 81.1 % of NH_4~+-N adsorption capacity when treating AnMBR effluent,preliminarily suggesting their practical feasibility in complex water matrix.Thereafter,PAA hydrogels were packed into a bench-scale fixed-bed column.Up to 98.5% of NH_4~+-N in AnMBR effluent could be captured in the hydrogel column at the breakthrough point at flow rate of 0.5 mL/min,achieving a polished effluent concentration of<1.5 mg N/L and thus meeting the strictest discharge regulations.The hydrogel column could be regenerated for 10 adsorption/desorption cycles with an insignificant decline in adsorption capacity of ~4.7%,highlighting its excellent reusability.More importantly,we for the first time proposed the strategic recirculation of 1 mol/1 HCl solution as eluent and obtained an NH_4~+-N enrichment factor of ~10 over four rounds of adsorption/desorption,demonstrating the promise of this strategy to concentrate NH4-N as resources.The economic analysis based on our experimental results showed that PAA hydrogel-based adsorption/desorption process coupled with eluent recirculation has the potential to remove and recover NH_4~+-N from AnMBR effluent cost-effectively.Overall,this study could potentially expand the application of AnMBRs and foster innovations in sustainable wastewater treatment.
查看更多>>摘要：This study developed an innovative and cost-effective electrochemical membrane filtration system,which utilized electrocoagulation(EC)with electrically conductive membranes(ECMs)as cathode and membrane stripping(MS)for simultaneous ammonia recovery and contaminant removal.The novel system takes advantages of the two complementary processes(EC and MS)when sequentially performed.Electrocoagulation produced positively charged coagulants which removed contaminants.ECMs served as cathode of EC in-situ generated OH~-,which converted NH_4~+ ions to volatile NH3.MS recovered NH3 and prevented from membrane fouling or wetting due to the protection of ECMs.The mechanism involves electrocoagulation,electrolysis and electrostatic interaction.Operating conditions(e.g.,current density,electrolyte concentration and pollutants concentration)have significant impacts on process performance.Increasing the current density from 0 to 40 A/m~2 exerted a positive effect on humic acid(HA)removal,ECM fouling mitigation and ammonia recovery.However,excessive current density(60 A/m~2)shortened the contact time between NH_4~+ and OH~-,and thus decreased ammonia recovery.High electrolyte concentration enhanced ammonia recovery,which can be attributed to increased pH and longer contact time between NH4 and OH~-.On the contrary,low electrolyte concentration was beneficial for ECM fouling mitigation through enhancing electrostatic repulsion between membrane electrode and HA contaminants.The improvement of HA concentration not only aggravated ECM fouling,but also had adverse effect on ammonia recovery.NH4C1 concentration had negligible effect on HA removal and membrane fouling,but the generation of OH~-became a rate-limiting factor for ammonia recovery at high NH4Cl concentration.Our results demonstrated that the novel system exhibited a competitive performance with other alternatives,with HA removal efficiency of 99.2% and ammonia recovery efficiency of 68.6% at a current density of 40 A/m~2,electrolyte concentration of 100 mmol/L,HA concentration of 30 mg/L and NH4Cl concentration of 300 mg/L,which can be considered as an appealing technology for ammonia resource recovery.
查看更多>>摘要：In this study,a clean and effective integrated process for selectively separating base metals and high-efficiency enriching precious metals from scrap copper anode slime was investigated.O2-enriched roasting combined with H2SO4-NaCl leaching was used in the decopperized process to avoid the scattered distributions of As & Sn and enhance the selective leaching efficiencies of Cu,Ni,and As.The obtained leachate containing Cu,Ni,and As can be sent to the existing electrolyte purification process.Then,alkaline xylitol leaching was applied to selectively separate Pb greatly avoiding its negative impact on the subsequent process,and Pb-containing leaching solution was used to prepare lead electrodeposition electrolyte.Sn was recovered in the form of sodium stannate by soda roasting-alkaline leaching.Results of scale-up experiment showed that the direct leaching efficiencies of Cu,Ni,As,Pb,and Sn under the optimum conditions were 99.3 %,96.9 %,98.6 %,98.1 %,and 98.9 %,respectively.Ag and Au were maximally remained in the residue.Furthermore,three leaching solutions generated in the proposed process can be treated in an environmentally friendly way.Therefore,it was a high-efficiency and eco-friendly method for SCAS to realize the comprehensive utilization of the base metals and reduced risks of secondary pollution.
查看更多>>摘要：Benzene(PhH)/isobutanol(IBA)is one of untraditional binary azeotropes with opposite non-ideal behaviors under different pressure in the chemical industry.An untraditional pressure-swing distillation configuration(UPSD)can effectively separate this type of mixture,which is characterized by IBA being at the bottom of low-pressure column(LPC)and PhH being at the top of high-pressure column(HPC).According to this feature,two important methods to improve energy efficiency-vapor recompression(VRC)and internally heat-integrated distillation column(HIDiC)are applied to this configuration.Specifically,five variants are designed and optimized to minimize total annual cost(TAC).As compared to the UPSD configuration,the results show that two variants called VRC-UPSD and HIDiC-UPSD can respectively reduce energy costs by 74.26% and 69.74% and CO2 emission by 66.61% and 57.48%.Importantly,despite the use of expensive compressors in both configurations,TAC is reduced by 38.13% and 44.96%,respectively.
查看更多>>摘要：Microalgae have attracted great interest for biofuel production,wastewater treatment,and CO2 capture from dilute sources,but its broad implementation is limited by the high energy consumption of algae dewatering.Membrane technology has emerged as a key process for algae dewatering,but its performance is restrained by the fouling of organic matter in the algae solutions,resulting in low water permeance.This review presents state-of-the-art comprehensive strategies adopted to mitigate membrane fouling.We first discuss the complex nature of the algae solutions and elucidate the fouling mechanisms of the commercial membranes.Second,the modifications of the membrane surface to improve antifouling properties are exhaustively described,such as imparting organic functional groups and inorganic nanoparticles.Third,we concisely review operating designs to enhance the dewatering performance of the membranes,including pretreatment of algae solution,enhancement of feed flow rate or shear force,and membrane cleaning.Finally,the development needed to expand the technology implementation is assessed.
查看更多>>摘要：Rubidium(Rb)is an important resource with economic value.However,extracting Rb resources from nature faces enormous challenges due to its low concentration and being in a complex system.In this study,a novel magnetic potassium cobalt hexacyanoferrate composite(MKCoFC)was synthesized,which had excellent adsorption properties for Rb+ and allowed rapid separation from the liquid phase by outside magnetic force.The effective grafting of potassium cobalt hexacyanoferrate on magnetic carriers was verified by analyzing chemical composition(FTIR,XPS),crystal structure(XRD),and micromorphology(SEM,TEM)of the material.The effects of various factors(pH,concentration,time and temperature for adsorption)on the extraction capacity of MKCoFC towards to Rb~+ were explored by batch experiments.The adsorption process was explained quite easily by the Langmuir model,and the actual adsorption performance(208.8 mg/g)was consistent with it.The adsorption was a monolayer process and the active sites were uniformly located.MKCoFC maintained the brilliant adsorption performance of KCoFC by the in situ grafting technique.In addition,the pseudo-second-order model agreed with the sorption behavior,which was governed by the ion exchange mechanism of Rb+ with K~+ in the lattice.MKCoFC displays promising selectivity,with high adsorption for Rb+ and hardly any adsorption for Na~+,Mg~(2+),Li~+ and Ca~(2+)in coexisting solution.Furthermore,MKCoFC can be regenerated by 1 mol/L KC1 and maintains 92.1% adsorption efficiency(relative to initial adsorption)after five adsorption-desorption cycles.
查看更多>>摘要：Metal-organic framework materials(MOFs)and MOFs-based composite materials have been extensively applied to adsorb heavy metals due to their high specific surface area and high porosity.Herein,the MOF-801 and its complex Fe3O4/MOF-801 were respectively prepared and employed as adsorbents to capture the Se(IV)in an aqueous solution.And the Fe3O4/MOF-801 composite was post-synthesized from MOF-801 by a simple cryogenic hydrothermal process.The experimental results showed that the maximum adsorption capacity of MOF-801 and Fe3O4/MOF-801 was 101.2 and 206.6 mg/g under acidic conditions,respectively.The coexisting anions,except phosphate and sulfate ions,had negligible effect on the Se(IV)adsorption.The mechanism of Se(IV)removal by the two adsorbents was thoroughly analyzed by Zeta potential,Fourier transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS).And the results illustrates that the Se(IV)was captured on the surface hydroxyl sites of the MOF-801,while the Fe3O4/MOF-801 captured Se(IV)through electrostatic attraction,inner-sphere complexation,and the reduction effect.Furthermore,the existence of charge transfer in the Fe3O4/MOF-801,which facilitated the adsorption and reduction of Se(IV),was confirmed by the XPS analysis.This work provides a promising strategy to design high-performance magnetic MOFs composites for the removal of Se(IV)from wastewater.
查看更多>>摘要：High energy consumption during harvesting is one of the main bottlenecks for sustainable microalgae production.Membranes can efficiently separate microalgae from liquids with low energy consumption,but membrane fouling remains an important issue.Flocculation prior to membrane filtration can increase membrane fluxes and decrease fouling,thus offering a low-cost and efficient solution to harvest microalgae.Biobased cationic cellulose nanocrystals were successfully used as flocculants for microalgae and were effective over a wide pH-range and for both freshwater and marine microalgae.Such flocculation was for the first time combined with vibration-assisted filtration using a charged,surface patterned membrane,enabling operation at very high flux(95 L/m2 h)using a vibration frequency of only 1 Hz,and even under sub-optimal flocculation conditions.Intermittent vibration decreased energy consumption further while keeping excellent filtration performance to finally achieve a record-low energy consumption for the membrane filtration of only 6.7 Wh/m3,which is>25-times lower than that of normal membrane filtration.Interaction forces revealed that increasing particle size through flocculation prior to membrane filtration can significantly prevent microalgae attachment on the vibrating membrane surface.This work opens a new direction for sustainable microalgae harvesting with an ultra-low energy consumption,combined with a very high microalgae recovery,reduced use of chemicals,and lower membrane investment cost.
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