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.

Synergistic Effects of Earthworms and Plants on Chromium Removal from Acidic and Alkaline Soils: Biological Responses and Implications.

Soil heavy metal pollution has become one of the major environmental issues of global concern and solving this problem is a major scientific and technological need for today's socio-economic development. Environmentally friendly bioremediation methods are currently the most commonly used for soil heavy metal pollution remediation. Via controlled experiments, the removal characteristics of chromium from contaminated soil were studied using earthworms (Eisenia fetida and Pheretima guillelmi) and plants (ryegrass and maize) at different chromium concentrations (15 mg/kg and 50 mg/kg) in acidic and alkaline soils. The effects of chromium contamination on biomass, chromium bioaccumulation, and earthworm gut microbial communities were also analyzed. The results showed that E. fetida had a relatively stronger ability to remove chromium from acidic and alkaline soil than P. guillelmi, and ryegrass had a significantly better ability to remove chromium from acidic and alkaline soil than maize. The combined use of E. fetida and ryegrass showed the best effect of removing chromium from contaminated soils, wih the highest removal rate (63.23%) in acidic soil at low Cr concentrations. After soil ingestion by earthworms, the content of stable chromium (residual and oxidizable forms) in the soil decreased significantly, while the content of active chromium (acid-extractable and reducible forms) increased significantly, thus promoting the enrichment of chromium in plants. The diversity in gut bacterial communities in earthworms decreased significantly following the ingestion of chromium-polluted soil, and their composition differences were significantly correlated with soil acidity and alkalinity. Bacillales, Chryseobacterium, and Citrobacter may have strong abilities to resist chromium and enhance chromium activity in acidic and alkaline soils. There was also a significant correlation between changes in enzyme activity in earthworms and their gut bacterial communities. The bacterial communities, including Pseudomonas and Verminephrobacter, were closely related to the bioavailability of chromium in soil and the degree of chromium stress in earthworms. This study provides insights into the differences in bioremediation for chromium-contaminated soils with different properties and its biological responses.

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.

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.

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.

Synergistic impacts of Cu2+ on simultaneous removal of tetracycline and tetracycline resistance genes by PSF/TPU/UiO forward osmosis membrane.

Cu2+, tetracycline (TC), and corresponding tetracycline resistance genes (TRGs) are common micropollutants in aquaculture wastewater, which have great impact on environment and human health. In this study, we developed a thin-film nanocomposite (TFN) forward osmosis (FO) membrane with an electrospinning thermoplastic polyurethane/polysulfone (PSF/TPU) substrate and a UiO-66-NH2 particle interlayer modified active layer. The effects of Cu2+ concentration on the synergetic removal of TC and TRGs (e.g., tetA/M/X/O/C, int1, and 16 S rRNA gene) were analyzed to determine the role of Cu2+ in FO process. The rejection mechanism was also analyzed in depth. Results demonstrated that the rejection of TC and Cu2+ was 99.53% and 97.99%. The rejection of TRGs exceeded 90% (specifically, over 99% for tetC) at a Cu2+ concentration of 500 µg/L when 0.5 M (NH4)2HPO4 was used as draw solution. Complexation reaction between Cu2+ and TC, electrostatic interaction, and the adsorption of Cu2+ on membrane surface were the main contributing factors for the high rejection efficiencies. Altogether, the as-prepared FO membrane holds great potential for simultaneously removing heavy metals, antibiotics, and resistance genes in real wastewater.

Ultrasensitive detection of amoxicillin by TiO2-g-C3N4@AuNPs impedimetric aptasensor: Fabrication, optimization, and mechanism.

The trace amount of antibiotics in water can be enriched in the human body through the food chain, leading to extremely harmful effects on people's health. Therefore, it is urgent to develop new methods to detect trace pollutants in various aquatic phase. An analytical method utilizing the synergistic effect between the sensing strategy and catalytic material with high electron transfer capacity can be used to detect trace antibiotics. In this paper, an ultrasensitive impedimetric aptasensor was fabricated by the synergy between functionalized materials (TiO2-g-C3N4) and gold nanoparticles (Au NPs). Due to the formation of the 'Au-S' bond between the thiol-aptamer and Au NPs, amoxicillin and the aptamer can be specifically recognized on the modified glassy carbon electrode (GCE), and the impedance signal increased rapidly. Meanwhile, the Box-Behnken Design (BBD) strategy was used to reduce the random error of the experiment, so that the prepared aptasensor has the highest sensitivity to the detection of amoxicillin. Under optimized conditions, the sensor successfully achieved the detection of amoxicillin in the ultra-low detection range (0.5-3 nM) and reached the ultra-low detection limit (0.2 nM). The detection strategy has good selectivity, reproducibility, and stability, and thus has good potential to detect amoxicillin in actual wastewater.

Application of advanced anodes in microbial fuel cells for power generation: A review.

Microbial fuel cells (MFCs) the most extensively described bioelectrochemical systems (BES), have been made remarkable progress in the past few decades. Although the energy and environment benefits of MFCs have been recognized in bioconversion process, there are still several challenges for practical applications on large-scale, particularly for relatively low power output by high ohmic resistance and long period of start-up time. Anodes serving as an attachment carrier of microorganisms plays a vital role on bioelectricity production and extracellular electron transfer (EET) between the electroactive bacteria (EAB) and solid electrode surface in MFCs. Therefore, there has been a surge of interest in developing advanced anodes to enhance electrode electrical properties of MFCs. In this review, different properties of advanced materials for decorating anode have been comprehensively elucidated regarding to the principle of well-designed electrode, power output and electrochemical properties. In particular, the mechanism of these materials to enhance bioelectricity generation and the synergistic action between the EAB and solid electrode were clarified in detail. Furthermore, development of next generation anode materials and the potential modification methods were also prospected.

Comparison of novel functionalized nanofiber forward osmosis membranes for application in antibacterial activity and TRGs rejection.

Antibiotic resistance genes (ARGs) are serious pollutants in municipal sewage treatment plants and may cause significant harm to ecological systems, microbial fouling is also inevitable in membrane process. Herein, novel forward osmosis (FO) membranes made of electrospun nanofibers (TFN0) and further impregnated with titanium dioxide (TiO2) (TFN1) nanoparticles and titanium dioxide/silver composite nanoparticles (TiO2/AgNPs) (TFN2). The FO membranes were used to compare the antimicrobial performance and rejection of tetracycline-resistant genes (TRGs). Characterizations revealed that the TiO2/AgNPs were evenly scattered in the polysulfone (PSf) nanofibers and resulted in a TFN2 membrane that exhibited excellent physicochemical properties, filtration, and antibiofouling performance in real wastewater. The cell viability analysis revealed that the antibacterial effect of the TFN2 membranes was significantly better than that of TFN1, as indicated by about 65 % of E. coli cells killed after contact with the TFN2 membrane. TFN2 membranes had greater rejection rates of TRB and TRGs than TFN1. The TRG permeation rates of the TFN2 membrane in the FO mode (active layer facing the feed solution) were 39.62 % and 33.02 % lower than the TFN0 and TFN1 membranes, respectively. FO membranes modified by the TiO2/AgNPs nanocomposites hold promise to remove ARGs and pathogens from wastewater treatment plant effluents.

ß-Cyclodextrin-loaded minerals as novel sorbents for enhanced adsorption of Cd2+ and Pb2+ from aqueous solutions.

The use of minerals to capture heavy metal pollution is limited by their capacity. Here, ß-cyclodextrin (ß-CD) with a good ability to capture heavy metals is loaded onto the surface of zeolite and vermiculite to adsorb lead and cadmium ions. Using epichlorohydrin (EPI) as a crosslinking agent, ß-CD is loaded onto zeolite and vermiculite, as confirmed by a characterization analysis. Isothermal adsorption of Cd2+ and Pb2+ by the loaded minerals is tested at different concentrations, while contact time, pH, and kinetic and thermodynamic characteristics of the adsorption processes are analyzed. The amount of ß-CD and crosslinker loaded onto a unit mass of zeolite is higher than that of vermiculite due to the unique porous structure of the zeolite surface. After ß-CD loading, the adsorption saturation of zeolite for Cd2+ and Pb2+ are 93.06 and 175.25 mg/g, respectively. The adsorption saturation of Cd2+ and Pd2+ by ß-CD-loaded vermiculite is 68.65 and 126.35 mg/g, respectively. The mechanism study revealed that the adsorption process of lead and cadmium ions by ß-CD-loaded minerals was combined by diffusional movement with a chemical exchange of ionizable protons or cations, as well as by chemical bonding among heavy metal ions and functional groups (-OH, -COOH and CO).

ß-cyclodextrin functionalized biochars as novel sorbents for high-performance of Pb2+ removal.

The aim of this study was to synthesize the functionalized biochars with ß-cyclodextrin (ß-CD), compare the two kinds of adsorption capability, and try to explore the possible mechanism for the adsorption Pb2+ by ß-CD functionalized rice straw and palm biochars in the aquatic environment. The performance of the functionalized biochars was matched against the activated and raw biochars. Rice straw biochar loaded with ß-CD performed better than functionalized palm biochar with the adsorption capabilities of 130.60 mg/g and 90.30 mg/g at Pb2+ concentration of 3000 mg/L and 2000 mg/L, respectively. Maximum adsorption capability of functionalized rice straw and palm biochars from the Langmuir isotherms were all fitted out to be 131.24 mg/g and 118.08 mg/g for Pb2+. Kinetics and thermodynamics are combined to investigate the Pb2+ removal by the two functionalized biochars, e.g, Pb2+ is mainly removed by chemical process for functionalized palm biochar, whereas by both physical and chemical factors for functionalized rice straw biochar.