Enhanced Sb(V) removal of sulfate-rich wastewater by anaerobic granular sludge assisted with Fe/C amendment.

Antimony (Sb) and sulfate are two common pollutants in Sb mine drainage and Sb-containing textile wastewater. In this paper, it was found that iron­carbon (Fe/C) enhanced Sb(V) removal from sulfate-rich wastewater by anaerobic granular sludge (AnGS). Sulfate inhibited Sb(V) removal (S + Sb, k = 0.101), while Fe/C alleviated the inhibition and increased Sb(V) removal rate by 2.3 times (Fe/C + S + Sb, k = 0.236). Fe/C could promote the removal of Sb(III), and Sb(III) content decreased significantly after 8 h. Meanwhile, Fe/C enhanced the removal of sulfate. The 3D-EEM spectrum of supernatant in Fe/C + S + Sb group (at 24 h) showed that Fe/C stimulated the production of soluble microbial products (SMP) in wastewater. SMP alleviated the inhibition of sulfate, promoting AnGS to reduce Sb(V). Sb(V) could be reduced to Sb(III) both by AnGS and sulfides produced from sulfate reduction. Further analysis of extracellular polymeric substances (EPS) and AnGS showed that Fe/C increased the adsorbed Sb(V) in EPS and the c-type cytochrome content in AnGS, which may be beneficial for Sb(V) removal. Sb(V) reduction in Fe/C + S + Sb group may be related to the genus Acinetobacter, while in Sb group, several bacteria may be involved in Sb(V) reduction, such as Acinetobacter, Pseudomonas and Corynebacterium. This study provided insights into Fe/C-enhanced Sb(V) removal from sulfate-rich wastewater.

Bioelectrocatalytic reduction by integrating pyrite assisted manganese cobalt-doped carbon nanofiber anode and bacteria for sustainable antimony catalytic removal.

A novel manganese cobalt metal-organic framework based carbon nanofiber electrode (MnCo/CNF) was prepared and used as microbial fuel cell (MFC) anode. Pyrite was introduced into the anode chamber (MnCoPy_MFC). Synergistic function between pyrite and MnCo/CNF facilitated the pollutants removal and energy generation in MnCoPy_MFC. MnCoPy_MFC showed the highest chemical oxygen demand removal efficiency (82 ± 1%) and the highest coulombic efficiency (35 ± 1%). MnCoPy_MFC achieved both efficient electricity generation (maximum voltage: 658 mV; maximum power density: 3.2 W/m3) and total antimony (Sb) removal efficiency (99%). The application of MnCo/CNF significantly enhanced the biocatalytic efficiency of MnCoPy_MFC, attributed to its large surface area and abundant porous structure that provided ample attachment sites for electroactive microorganisms. This study revealed the synergistic interaction between pyrite and MnCo/CNF anode, which provided a new strategy for the application of composite anode MFC in heavy metal removal and energy recovery.

Underlying the mechanisms of pathogen inactivation and regrowth in wastewater using peracetic acid-based disinfection processes: A critical review.

Peracetic acid (PAA) disinfection is an emerging wastewater disinfection process. Its advantages include excellent pathogen inactivation performance and little generation of toxic and harmful disinfection byproducts. The objective of this review is to comprehensively analyze the experimental data and scientific information related to PAA-based disinfection processes. Kinetic models and modeling frameworks are discussed to provide effective tools to assess pathogen inactivation efficacy. Then, the efficacy of PAA-based disinfection processes for pathogen inactivation is summarized, and the inactivation mechanisms involved in disinfection and the interactions of PAA with conventional disinfection processes are elaborated. Subsequently, the risk of pathogen regrowth after PAA-based disinfection process is clearly discussed. Finally, to address ecological risks related to PAA-based disinfection, its impact on the spread of antibiotic-resistant bacteria and the transfer of antibiotic resistance genes (ARGs) is also assessed. Among advanced PAA-based disinfection processes, ultraviolet/PAA is promising not only because it has practical application value but also because pathogen regrowth can be inhibited and ARGs transfer risk can be significantly reduced via this process. This review presents valuable and comprehensive information to provide an in-depth understanding of PAA as an alternative wastewater disinfection technology.

Solar-Driven Reforming of Methane and Nitrogen to Methanol and Ammonium on Iron-Modified Zeolite under Ambient Conditions in Water.

Artificial photosynthesis from selective methane oxidation or nitrogen reduction to value-added chemicals provides a promising pathway for the sustainable chemical industry, while still remaining a great challenge due to the extreme difficulty in C-H and N≡N bond cleavage under ambient conditions. Catalysts that can cocatalyze these two reactions simultaneously are rarely reported. Here, Fe-ZSM-5 with highly dispersed extra-framework Fe-oxo species enables efficient and selective photocatalytic conversion of methane and nitrogen to coproduce methanol and ammonia using H2O as the redox reagent under ambient conditions. The optimized Fe-ZSM-5 photocatalyst achieves up to 0.88 mol/molFe·h of methanol products with 97% selectivity. Meanwhile, the productivity of ammonia is 0.61 mol/molFe·h. In situ EPR and DRIFT studies disclose that water serves as a redox reagent to provide hydroxyl radicals for methane oxidation and protons for nitrogen hydrogenation. Quantum chemical calculations revealed that Fe-oxo species play a significant role in the coactivation of methane and nitrogen molecules, which lowers the energy barriers of rate-determining steps for methanol and ammonia generation.

Integrating reverse osmosis and forward osmosis (RO-FO) for printing and dyeing wastewater treatment: impact of FO on water recovery.

Reverse osmosis (RO) alone has low water recovery efficiency because of membrane fouling and limited operating pressure. In this study, a combined reverse osmosis-forward osmosis (RO-FO) process was used for the first time to improve the water recovery efficiency of secondary effluent in printing and dyeing wastewater. The effects of operating pressure and pH on water recovery and removal efficiency of RO-FO were investigated. The results showed that the optimum conditions were an operating pressure of 1.5 MPa and a feed solution pH of 9.0. Under optimal operating conditions, most of the organic and inorganic substances in the wastewater can be removed, and the rejection of total organic carbon (TOC), Sb, Ca, and K were 98.7, 99.3, 97.0, and 92.7%, respectively. Fluorescence excitation-emission matrices coupled with parallel factor (EEM-PARAFAC) analysis indicated that two components (tryptophan and tyrosine) in the influent were effectively rejected by the hybrid process. The maximum water recovery (Rw, max) could reach 95%, which was higher than the current single RO process (75%). This research provided a feasible strategy to effectively recover water from printing and dyeing wastewater.

MIL-101(Fe) based biomass as permeable reactive barrier applied to EK-PRB remediation of antimony contaminated soil.

Numerous studies have demonstrated that electrokinetic-permeable reactive barrier (EK-PRB) can be used for the remediation of heavy metal contaminated soils, and their remediation efficiency is mainly determined by the filler material selected. By growing MIL-101(Fe) in situ on hollow loofah fiber (HLF), a novel material entitled HLF@MIL-101(Fe) was developed. The morphological characteristics and loading conditions were investigated, the adsorption characteristics were analyzed, and finally the synthesized composite material was applied to treat antimony-contaminated soil with EK-PRB as the reaction medium. The results show that MIL-101(Fe) is stably loaded on HLF. The adsorption capacity of Sb(III) can reach up to 82.31 mg g-1, and the adsorption is in accordance with the quasi-secondary kinetic model, which indicates that chemisorption is dominant. The isothermal adsorption model indicates that the adsorption form of HLF@MIL-101(Fe) is mainly monolayer adsorption with more uniform adsorption binding energy. In the EK-PRB experiment, when ethylenediaminetetraacetic acid (EDTA) is used as the cathodic electrolyte, it can effectively enhance the electromigration and electroosmotic effects, and the overall remediation efficiency of the soil is increased by 38.12% compared with the citric acid (CA) group. These demonstrate the feasibility of HLF@MIL-101(Fe) in collaboration with EK-PRB in the treatment of antimony-contaminated soil.

Evaluation of aquaporin based biomimetic forward osmosis membrane in terms of rejection performance for contaminants in greywater and its membrane fouling properties.

Forward osmosis (FO) technology is regarded as an alternative to wastewater treatment due to its high permeate flux, excellent solute selectivity and low fouling tendency. In this study, two novel aquaporin based biomimetic membranes (ABMs) were used for comparison in short-term experiments to investigate the impact of membrane surface properties on greywater treatment. The impact of feed solution (FS) temperature on the filtration performance and membrane fouling behavior of ABM was further analyzed in the sequential batch experiments. Results indicated that the membranes with rough surface morphology and low zeta potential (absolute value) facilitated the adsorption of linear alklybezene sulfonates (LAS), thus improving the water flux and the rejection of Ca2+ and Mg2+. The increase in FS temperature enhanced the diffusion of organic matter and the water flux. In addition, sequential batch experiments showed that the membrane fouling layer was mainly in the form of organic and inorganic composite fouling, which was mitigated at FS temperature of 40 °C. Microbial community analysis revealed that the increase in FS temperature affected the diversity of microbial communities. More heterotrophic nitrifying bacteria were enriched in the fouling layer at FS 40 °C than at FS 20 °C. This study provides a novel strategy for employing ABM FO in greywater treatment and reuse.

Waste lignin-based cationic flocculants treating dyeing wastewater: Fabrication, performance, and mechanism.

Lignin is often considered to be a complex polymeric structural material with excellent scalability. Reduced pressure distillation, a novel effective way, was proposed to recover reusable waste lignin from textile degumming black liquor. The structure of the recovered material was determined by Fourier Transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC) and Klason Component Analysis. Recycled lignin (RL) was used as the basis for the synthesis of a cationic recycled lignin-based polymers (CRLM) through graft polymerizing cationic monomer (DMC). The optimum synthesis conditions were obtained by conducting orthogonal experiments using the cationicity as the studied parameter, while selecting pH, DMC/RL, reaction temperature and time as independent variables. Recovery experiments showed that the maximum recovery concentration of RL in the black liquor was 5 g/L, with a purity of approximately 83 %. Orthogonal experiments showed that a low DMC/RL ratio was crucial for the synthesis of flocculants. When the molar ratio of DMC/RL was 3:1, the cationicity of the prepared CRLM was as high as 11.32 %. Zeta potential and decolorization experiments also confirmed the stable decolorization performance of CRLM in three kinds of anionic dye wastewater. The experimental results showed that charge neutralization, chemical bonding forces and auxiliary effects play great role to remove anionic dyes, resulting in 94 %, 89 % and 94.9 % removal against Reactive Red 195 (RR195), Acid Red 18 (AR18) and Direct 168 (DB168) respectively. Therefore, this study demonstrated the potential of using recycled waste lignin as synthesize lignin-based flocculants in the field of printing and dyeing wastewater by treating waste with waste.

A Review on Electrospinning as Versatile Supports for Diverse Nanofibers and Their Applications in Environmental Sensing.

Rapid industrialization is accompanied by the deterioration of the natural environment. The deepening crisis associated with the ecological environment has garnered widespread attention toward strengthening environmental monitoring and protection. Environmental sensors are one of the key technologies for environmental monitoring, ultimately enabling environmental protection. In recent decades, micro/nanomaterials have been widely studied and applied in environmental sensing owing to their unique dimensional properties. Electrospinning has been developed and adopted as a facile, quick, and effective technology to produce continuous micro- and nanofiber materials. The technology has advanced rapidly and become one of the hotspots in the field of nanomaterials research. Environmental sensors made from electrospun nanofibers possess many advantages, such as having a porous structure and high specific surface area, which effectively improve their performance in environmental sensing. Furthermore, by introducing functional nanomaterials (carbon nanotubes, metal oxides, conjugated polymers, etc.) into electrospun fibers, synergistic effects between different materials can be utilized to improve the catalytic activity and sensitivity of the sensors. In this review, we aimed to outline the progress of research over the past decade on electrospinning nanofibers with different morphologies and functional characteristics in environmental sensors.

Iron cobalt-doped carbon nanofibers anode to simultaneously boost bioelectrocatalysis and direct electron transfer in microbial fuel cells: Characterization, performance, and mechanism.

A self-supporting electrode (FeCo-MOF/CNFs) combining iron cobalt bimetallic metal-organic frameworks (FeCo-MOFs) with carbon nanofibers (CNFs) was applied as the anode of a microbial fuel cell (MFC). The introduction of FeCo-MOFs enhanced graphitization degree and electrical conductivity, which endowed FeCo-MOF/CNFs with excellent electrocatalytic performance and good biocompatibility. The hierarchical porous structure of FeCo-MOF/CNFs provided abundant attachment sites for electroactive bacteria (EAB) and facilitated rapid electron transfer. The MFC equipped with FeCo-MOF/CNFs anode (FeCo/CNFs-MFC) exhibited considerable power generation output (maximum power density: 5.3 ± 0.2 W/m2, coulombic efficiency: 54 ± 4 %). In addition, FeCo/CNFs-MFC achieved a direct electron transfer (DET) catalytic current density of 0.63 A/m2. FeCo-MOF/CNFs could simultaneously enhance the bioelectrocatalysis activity and promote the DET process of EAB, which provided an effective way to improve the sluggish extracellular electron transport process of the MFC anode.

Research progress in external field intensification of forward osmosis process for water treatment: A critical review.

Forward osmosis (FO) is an emerging permeation-driven membrane technology that manifests advantages of low energy consumption, low operating pressure, and uncomplicated engineering compared to conventional membrane processes. The key issues that need to be addressed in FO are membrane fouling, concentration polarization (CP) and reverse solute diffusion (RSD). They can lead to problems about loss of draw solutes and reduced membrane lifetime, which not only affect the water treatment effectiveness of FO membranes, but also increase the economic cost. Current research has focused on FO membrane preparation and modification strategies, as well as on the selection of draw solutions. Unfortunately, these intrinsic solutions had limited success in unraveling these phenomena. In this paper, we provide a brief review of the current state of research on existing external field-assisted FO systems (including electric-, pressure-, magnetic-, ultrasonic-, light- and flow-assisted FO system), analyze their mitigation mechanisms for the above key problems, and explore potential research directions to aid in the further development of FO systems. This review aims to reveal the feasibility of the development of external field-assisted FO technology to achieve a more economical and efficient FO treatment process.

Treating waste with waste: Metals recovery from electroplating sludge using spent cathode carbon combustion dust and copper refining slag.

Electroplating sludge is a hazardous waste and secondary metal resource because of its heavy metal content, which poses a huge threat to environmental safety if not properly disposed. An innovative process of oxidizing roasting followed by water leaching and smelting reduction to recover Cr, Cu, and Ni from electroplating sludge was proposed in this research, in which other two hazardous wastes of spent cathode carbon combustion dust and copper refining slag were co-treated. The NaF from spent cathode carbon combustion dust could convert Cr2O3 to Na2CrO4 using the oxidizing roasting process, resulting in a Cr recovery through the subsequent water leaching. The Na2CrO4 formation was promoted by CaO owing to it transferring the Cr spinel phase of FeCr2O4 [1+] to CaCrO4 and then to Na2CrO4. Under optimal conditions, the Cr recovery reached 97.1 %, and most 'F' was solidified into CaF2. In the next smelting reduction of the leaching residue, the Cu and Ni were recovered mainly in the form of Cu-Ni alloy. The addition of copper refining slag promoted their recovery, due to it modifying the molten slag and alloy structures and increasing the Cu-Ni alloy separation from molten slag. Some generated high-melting-point Cu-Ni-Fe and Ni-Fe alloys were converted to a Cu-Ni alloy with a low melting point in presence of Co from the copper refining slag, simultaneously with which the Fe was transferred out from Cu-Ni-Fe and Ni-Fe alloys and combined with Co to form a Fe-Co alloy. It increased Cu-Ni alloy droplets aggregation from molten slag and decreased their contents in the residual slag. Under optimized conditions, the Cu and Ni contents in the residual slag decreased to 0.37 and 0.06 wt%, respectively. Besides, the residual slag mainly composed of CaO, CaF2 and SiO2 could be used to prepare building materials rendering it harmless.

Quinone-mediated Sb removal from sulfate-rich wastewater by anaerobic granular sludge: Performance and mechanisms.

Antimony (Sb) is a typical pollutant in sulfate-rich industrial wastewater. This study investigated the Sb removal efficiency in sulfate-rich water by anaerobic granular sludge (AnGS) and the stimulation of amended anthraquinone-2-sulfonate (AQS). Results showed that 89.0% of 5 mg/L Sb(V) was reduced by AnGS within 24 h, along with the observed first accumulation (up to 552.2 µg/L) and then precipitation of Sb(Ш); coexistence of 2 g/L sulfate inhibited the removal of Sb(V) by 71.4% within 24 h, along with gradual accumulation of Sb(Ш) by 3257.4 µg/L, indicating the potential competition of adsorption sites and electron donors between Sb(V) and sulfate. Amendment of 31 mg/L AQS successfully removed the inhibition from sulfate, contributing to 99.5% Sb(V) removal and minimum Sb(Ш) accumulation in Sb(V) + sulfate+AQS group. Further test results suggested that Sb(V) removal by AnGS was mainly through dissimilatory reduction instead of bio-sorption, while Sb(Ш) removal mainly relied on instant bio-sorption by AnGS followed by precipitation in the form of Sb2O3 and Sb2S3. Extracellular Polymeric Substances (EPS) characterization showed that AQS promoted the accumulation of Sb(V) and Sb(Ш) in EPS. High-throughput sequencing analysis showed the enrichment of sulfate-reducing bacteria (SRB) in Sb(V) + sulfate group and suppressed SRB growth in Sb(V) + sulfate+AQS group.

Bacterial Inactivation and Biofilm Disruption through Indigenous Prophage Activation Using Low-Intensity Cold Atmospheric Plasma.

Biofilms can be pervasive and problematic in water treatment and distribution systems but are difficult to eradicate due to hindered penetration of antimicrobial chemicals. Here, we demonstrate that indigenous prophages activated by low-intensity plasma have the potential for efficient bacterial inactivation and biofilm disruption. Specifically, low-intensity plasma treatment (i.e., 35.20 W) elevated the intracellular oxidative reactive species (ROS) levels by 184%, resulting in the activation of prophage lambda (λ) within antibiotic-resistant Escherichia coli K-12 (lambda+) [E. coli (λ+)]. The phage activation efficiency was 6.50-fold higher than the conventional mitomycin C induction. Following a cascading effect, the activated phages were released upon the lysis of E. coli (λ+), which propagated further and lysed phage-susceptible E. coli K-12 (lambda-) [E. coli (λ-)] within the biofilm. Bacterial intracellular ROS analysis and ROS scavenger tests revealed the importance of plasma-generated ROS (e.g., •OH, 1O2, and •O2-) and associated intracellular oxidative stress on prophage activation. In a mixed-species biofilm on a permeable membrane surface, our "inside-out" strategy could inactivate total bacteria by 49% and increase the membrane flux by 4.33-fold. Furthermore, the metagenomic analysis revealed that the decrease in bacterial abundance was closely associated with the increase in phage levels. As a proof-of-concept, this is the first demonstration of indigenous prophage activations by low-intensity plasma for antibiotic-resistant bacterial inactivation and biofilm eradication, which opens up a new avenue for managing associated microbial problems.

Enhanced capacitive removal of hardness ions by hierarchical porous carbon cathode with high mesoporosity and negative surface charges.

Capacitive deionization (CDI), as a promising desalination technology, has been widely applied for water purification, heavy metal removal and water softening. In this study, the hierarchical porous carbon (HPC) with extremely large specific surface area (∼1636 m2 g-1), high mesoporosity and negative surface charges, was successfully prepared by one-step carbonization of magnesium citrate and acid etching. HPC carbonized at 800 ℃ exhibited an excellent specific capacitance (207.2 F g-1). The negative surface charge characteristic of HPC was demonstrated by potential of zero charge test. With HPC-800 as a CDI cathode, the super high adsorption capacity of hardness ions (Mg2+: 472 µmol g-1, Ca2+: 425 µmol g-1) with ultrafast adsorption rate was realized, attributed to its abundant mesoporous structure and negative surface charges. The priority order of ion adsorption on HPC in the multi-component salt solution was Mg2+ > Ca2+ > K+ ≈ Na+. The desalination and softening of the actual brackish water have been simultaneously achieved by three-cell CDI stack after four times of adsorption, with 63% decrease of total dissolved solids and 76% reduction of hardness. The current HPC material with outstanding adsorption performance for hardness ions shows great potential in brackish water purification.

Enhanced remediation of heavy metals contaminated soils with EK-PRB using ß-CD/hydrothermal biochar by waste cotton as reactive barrier.

Heavy metals in the soil are major global environmental problems. Waste cotton was used to synthesize a novel ß-CD/hydrothermal biochar (KCB), which is a low-cost and environment-friendly adsorbent for heavy metal soil remediation. KCB were used as reactive materials of electrokinetic-permeable reactive barrier (EK-PRB) to explore the removal characteristics of heavy metals. FTIR and XPS analysis revealed that KCB contained large numbers of surface functional groups. Adsorption of KCB for Pb2+ and Cd2+ reached 50.44 mg g-1 and 33.77 mg g-1, respectively. Metal ions in contaminated soil were removed by reactive barrier through electromigration, electrodialysis and electrophoresis, the removal efficiency of Pb2+ and Cd2+ in soil reached 92.87% and 86.19%. This finding proves that KCB/EK-PRB can be used as a cheap and green process to effectively remediate soils contaminated with heavy metals.

Carbon-doped WO3 electrochemical aptasensor based on Box-Behnken strategy for highly-sensitive detection of tetracycline.

Aptamer has been proved to be an important probe for antibiotic detection. Here, the electrical signal was doubly amplified by the synergistic effect of C-WO3 and AuNPs. The probe structure has a specific recognition effect on tetracycline, which improves the selectivity and anti-interference of the sensor. With the assistance of BBD strategy, the experimental errors of the C-WO3@AuNPs aptasensor were reduced and the best conditions for its preparation were obtained. This was conducive to obtain the best electrical signal transmission capacity of the electrode, greatly improved the sensor sensitivity. Under this mechanism, the antibiotic sensor achieved a low detection range (0.1 nM-100 nM) and a low detection limit (4.8 × 10-2 nM). The sensor showed excellent selectivity even in the presence of coexisting pollutants. This work explored the mechanism of charge change and demonstrated the role of probes in antibiotic sensing, providing important prospects of future applications in electrochemical sensors.

Carbon nanotube enhanced membrane distillation for salty and dyeing wastewater treatment by electrospinning technology.

Membrane distillation (MD) is considered as a promising and attractive technology due to its effective production of fresh water. However, the low permeability and easy wetting of MD membranes limit its practical applications. Herein carbon nanotubes (CNTs) and polyvinylidene fluoride-co-hexafluoropropylene (PcH) were used to fabricate nanofiber membranes by electrospinning. Effects of heat-press temperature and CNTs concentration on the morphology and performance of the as-fabricated membranes were systematically investigated. Dye rejections of CNTs/PcH membranes were also studied and role of CNTs played in the as-prepared MD membranes were analyzed. Results suggest that heat-press treatment effectively improved the mechanical strength as well as liquid entry pressure of membranes, and the optimal heat-press temperature was 150 °C. CNTs were proved to be successfully blended in nanofibers. Hydrophobicity and mechanical strength of membranes increased with CNTs incorporation. The 0.5 wt % CNTs loaded membrane heat-pressed at 150 °C exhibited the highest permeate flux (16.5-18.5 L m-2 h-1), which signified an increase of 42-50 % compared to the commercial MD membrane (11-13 L m-2 h-1) when 35 and 70 g L-1 NaCl solutions were used as feed solutions, respectively. It was noteworthy that salt rejection efficiencies of tested membranes achieved more than 99.99 %. When CNTs/PcH nanofiber membrane was applied to the treatment of dyeing wastewater, the removal rates of acid red and acid yellow reached 100 %. The removal rates of methylene blue and crystal violet were 99.41 % and 99.91 %, respectively. The present study suggested that the as-prepared membranes showed high potential towards MD application.

Enhanced bioelectricity output of microbial fuel cells via electrospinning zeolitic imidazolate framework-67/polyacrylonitrile carbon nanofiber cathode.

In this study, the zeolitic imidazolate framework-67 (ZIF-67) and electrospinning polyacrylonitrile membrane were combined to prepare electrospinning carbon nanofibers composite cathode (ZIF-67/CNFs) which could enhance the oxygen reduction reaction (ORR) performance of microbial fuel cells (MFCs) cathode. The optimum electrode 3 wt% ZIF-67/CNFs revealed the excellent ORR performance with a half-wave potential of -0.03 V vs. Ag/AgCl, which was more positive than Pt/C-CC (-0.09 V vs. Ag/AgCl). The highest output voltage (607±9 mV) and maximum power density (1.191±0.017 W m-2) were obtained when the prepared ZIF-67/CNFs electrode was applied to the cathode of MFC (ZIF-67/CNFs-MFC). In addition, ZIF-67/CNFs-MFC showed the best pollutant removal effect. Geobacter was the highest proportion of microbial in ZIF-67/CNFs-MFC. The results have shown that the application of ZIF-67/CNFs electrode to MFC cathode is promising.

Insights into ion imprinted membrane with a delayed permeation mechanism for enhancing Cd2+ selective separation.

Ion imprinted polymers exhibit great potential in ion separation from wastewater. However, the difficulty of ion separation by membrane is proverbial, which severely restricts the application of membrane in metal resource recovery from industrial wastewater. Herein, a rational molecular-level design approaches for membrane fabrication was developed to modify a layer of ion imprinted polymer onto the PVDF membrane. Batch rebind and permeation experiments suggest that specific host-guest binding sites had been fabricated along the membrane pore in ion imprinted membranes (IIM). A higher monomer dose leads to a higher rejection of Cd2+, and the more bind sites in IIM. The binding of IIM to Cd2+ was 1.84 times that of non-ion imprinted membranes (NIM). Permselectivity factors (γ) of IIM are larger than 5.39 in mixture ions solutions. Chemical characterization and density functional theory (DFT) calculation reveal that the Cd2+ recognition sites of functional groups are C-S and C˭S. Cd2+ mass transport in IIM suggest that the imprint effects provide a binding force that would delay Cd2+ to permeate through IIM, so as to selectively separate Cd2+ with other ions. The imprint effects may enlighten a novel molecular-level design approaches for membrane fabrication to enhance the selectivity of ion-ion.