Degradation Of Organic Pollutants Research Articles

Novel superhydrophobic sponge with flower-like architecture for oily emulsion separation and organic pollutants photodegradation

Design functionalized absorbent materials that fulfillment complex requirements in sophisticated water-treatment fields remains challenging. In this paper, a novel superhydrophobic/superoleophilic sponge with flower-like channel structures and a photodegradation functionality was fabricated via in-situ chelation of zinc oxide (ZnO) and nano-Ag particles. After low surface energy modification with POTS, the as-prepared sponge displayed remarkable superwettability, with a water contact angle (WCA) of 158.8° ± 1.3°. This endowed it with the ultrafast, selective absorption of diverse oils that are 33.9–135.2 times of their own weight. The prepared sponge’s emulsified oil separation efficiency can reach 99.87%, owing to its superhydrophobic/superoleophilic properties and the electrostatic attraction demulsification, guiding effect of ZnO layer crystal plane. Furthermore, the construction of Schottky barrier at the ZnO@Ag interface reduced the recombination rate of photoexcited electrons and electron-holes. Thereby, the prepared sponge’s photodegradation efficiency reached up to 97.07% after 4 h sunlight irradiation. Notably, the stress attenuation of the prepared sponge was only 14.6% after 100 absorption cycles, indicating its excellent mechanical stability. Moreover, the prepared sponge showed excellent environmental tolerance under severe conditions with its WCA stably exceeding 150.0°. Thus, this durable superwetting sponge can be effectively used for oil/water emulsion separation and organic pollutant degradation.

Singlet Oxygen Formation Mechanism for the H2O2-Based Fenton-like Reaction Catalyzed by the Carbon Nitride Homojunction.

The singlet oxygen (1O2) oxidation process activated by metal-free catalysts has recently attracted considerable attention for organic pollutant degradation; however, the 1O2 formation remains controversial. Simultaneously, the catalytic activity of the metal-free catalyst limits the practical application. In this study, carbon nitride (HCCN) containing an intramolecular homojunction, a kind of metal-free catalyst, exhibits excellent activity compared to g-C3N4 (CN) and crystalline carbon nitride (HCN) for tetracycline hydrochloride degradation through the H2O2-based Fenton-like reaction. The rate constant for HCCN increased about 16.1 and 8.9 times than that of CN and HCN, respectively. The activity of HCCN was enhanced, and the dominant reactive oxygen species (ROS) changed from hydroxyl radicals (•OH) to 1O2 with an increase in pH from 4.5 to 11.5. A novel formation pathway of 1O2 was revealed. This result is different from the normal reference, in which •OH is always the primary ROS in the H2O2-based Fenton-like reaction. This study may provide a possible strategy for the investigation on the nonradical oxidation process in the Fenton-like reaction.

Synthesis and photocatalytic activity of BiOI particles: An efficient visible-light-driven degradation of organic pollutants in aqueous environments

Bismuth oxyiodide (BiOI) particles were successfully fabricated through solvothermal activation using bismuth (III) nitrate pentahydrate and potassium iodide as precursors. The photocatalytic activities of BiOI were investigated under the influence of synthesis temperature (120–200 °C) with a fixed duration of 12 h. The physical-chemical properties of the samples were systematically investigated using X-ray diffraction, scanning electron microscopy, N2-sorption isotherm techniques, and pH of the point of zero charge (pHpzc). The prepared BiOI exhibited a single phase with a non-uniform 2D morphology with different sizes, an average crystallite size of 30 nm, and a BET surface area of 20.71 m²g−1. The zero-point charge was determined to be 7.7. The photocatalytic performance under simulated solar light irradiation was investigated by examining the effects of dye initial concentration, catalyst dose, and dye pH. Remarkably, BiOI synthesized at 160 °C demonstrated an impressive 85% removal efficiency of 10 ppm MO (methyl orange) at normal pH levels (pH 6.8) within 120 min under visible light irradiation, along with the highest rate constant of 0.01418 min−1. The quenching effects of different scavengers indicate the significant role of reactive O2•– and a minor role of hVB+ and •OHads in the photocatalytic process. These findings underscore the potential of BiOI particles as efficient photocatalysts for environmental applications, particularly in the degradation of organic pollutants in water using solar light irradiation.

Halogen-doped ultrathin Bi2WO6 for promoted separation of photogenerated carriers and efficient photocatalysis

Although photocatalysis is a viable and sustainable technique to remove refractory pollutants from wastewater, it is plagued by the low separation efficiency of photo-generated carriers. Herein, in situ surfactants (CTAC, CTAB, and DTAI) assisted synthesis of halogen-doped ultra-thin Bi2WO6 (BWO) nanosheets with oxygen vacancies, which efficiently degraded RhB and TC under visible light. Surfactant as a halogen source can also prevent the formation of BWO layered structures, thus making the sample thinner and thus reducing the transmission distance of photogenerated electrons. The degradation rates of rhodamine B (RhB) and tetracycline (TC) by BWO-Cl-90 and BWO-Br-90 upon visible light illumination are 5.8 times / 5.5 times and 2.5 times / 2.8 times by those of pure BWO, respectively. The free radical trapping experiments and ESR reveal that singlet oxygen (1O2) and photogenerated holes (h+) are the main active free radicals in the degradation of organic pollutants by BWO-Cl-90, while the superoxide radical (·O2-) and photogenerated holes (h+) play the main roles for BWO-Br-90. The photocatalytic mechanism is proposed. In addition, the EIS, photocurrent and photoluminescence (PL) experiments show that halogen doping improves the separation ability of photogenerated carriers. This study reveals a practical method to modify Bi2WO6-based materials for effective wastewater treatment and purification.

Development of a novel pH-Responsive PVA/GO-Glu/TiO2 nanocomposite hydrogel for efficient degradation of organic pollutants

Water pollution poses a grave threat to public health and the environment. There is an urgent need for sustainable remediation strategies to remove toxic contaminants from water sources. In this study, we report the development of a novel pH-responsive nanocomposite hydrogel for the effective degradation of organic pollutants. The hydrogel was synthesized using polyvinyl alcohol, graphene oxide, glutamic acid, and titanium dioxide through an in-situ crosslinking method. Characterization using SEM, FTIR and UV–vis spectroscopy confirmed the successful formation of the nanocomposite structure. Batch experiments demonstrated that the hydrogel was able to degrade over 90% of methylene blue dye within 35 min under sunlight irradiation, owing to the synergistic effect of pH-sensitivity and the photocatalytic activity of titanium dioxide. Degradation efficiency increased with rising pH, reaching a maximum at pH 11. This eco-friendly nanohybrid holds tremendous potential for water remediation applications through low-cost, solar-powered degradation of toxic pollutants.

Enhancing photocatalytic degradation of crystal violet dye with g‐C3N4/ZnTiO3 nanocomposites synthesized via a facile approach

AbstractPhotocatalysts that exhibit exceptional performance could be further enhanced for wastewater treatment, particularly in the degradation of organic pollutants and reduction of inorganic heavy metal ions concentrations. This study employed sol–gel techniques was used to create a Type II scheme g‐C3N4/ZnTiO3 (CZT‐2, CZT‐4, and CZT‐6) photocatalyst. FT‐IR, UV‐DRS, XRD, SEM, BET, HR‐TEM, and XPS analysis were conducted to investigate the physical and chemical properties of the g‐C3N4/ZnTiO3 photocatalyst's. An investigation was conducted to evaluate the photocatalytic performance of the synthesized samples. The samples exhibit remarkable efficacy in the degradation of organic contaminants. Among them, CZT‐2 showcased superior photocatalytic performance in the solar light‐induced photodegradation of crystal violet. The photocatalytic activity of g‐C3N4/ZnTiO3 has been significantly enhanced through the establishment of a Type‐II scheme at the interface. This innovative approach efficiently facilitates the separation of photogenerated electron–hole pairs, thereby boosting the photodegradation activity. The discussion also included the chemical process between photocatalysts and crystal violet. The mechanism of the crystal violet‐photocatalyst reaction was also discussed. After undergoing five cycles of reuse, the photocatalyst that was manufactured demonstrated remarkable stability, leading to a reduction in the cost associated with wastewater treatment. The as‐synthesized g‐C3N4/ZnTiO3 composites are very safe for the environment, which suggests that the CZT‐2 composite is very good at getting rid of pollutants.

Construction of A-FeOx/LaFeO3 hybrid microreactors for efficient photocatalytic degradation of organic pollutants

Low-dimensional hybrid nanocrystals are newly emerging active photocatalysts for separating electron-hole pairs, but the instability and low quantum efficiency caused by particle aggregation and hybrid structure relaxation remain great challenges. To this end, herein we constructed amorphous FeOx (A-FeOx) and crystalline LaFeO3 hybrids by a sol-gel method. The amorphous-crystalline hybrids, A-FeOx/LaFeO3, not only improve the surface area and alter the band position, but also form numerous channels that are conducive to the transport of electrons and separation of electron–hole pairs, acting as microreactors. Photocatalytic tests show that the A-FeOx/LaFeO3 is highly active for the degradation of various organic pollutants, with reaction rate constant of 1.19 × 10–2 min–1 for ciprofloxacin degradation, for example, which is 1.82 and 1.87 times higher than that of LaFeO3 and Fe2O3/LaFeO3, respectively, owing to the formation of microreactors between A-FeOx and LaFeO3. Cycling tests show that the material has good stability in the reaction, and trapping experiments demonstrate that the photo-induced holes are the main reactive species of the reaction. This work provides a novel and feasible insight into the design of high performance low-dimensional hybrid nanocatalysts for photocatalysis.

A Highly Synergistic Dual-Cathode Electro-Fenton Process with Self-Regulation of pH and Coating Stability for the Effective Degradation of Refractory Pollutants

As a result of issues related to pH control and the competition between H2O2 production and activation at the same sites, the applications of electro-Fenton (EF) pollutant remediation systems are limited. This work designed a synergistic dual-cathode EF system that exhibits self-adjustment of pH and stable electrode coatings. This system is based on using biomass as the active cathode material for H2O2 generation and the interaction between a stainless-steel mesh and FeOCl to reduce Fe3+ ions. The synergistic factor for this dual-cathode system was calculated to be 85.2%. Significantly, the production and activation of H2O2 in this composite system are unaffected by pH and the pH value can be adjusted between 9.67 and 3.7 without adding any acidic reagents. This process allows for the degradation of recalcitrant organic pollutants over the pH range of 3 to 9 without pre-acidification or challenges related to iron sludge and effluent chromaticity. Various organic pollutants, including antibiotics and organic dyes, can be effectively decomposed using this technology, which also exhibits good stability throughout 22 continuous trials over 1400 min. This work demonstrates a novel yet viable approach to highly efficient, inexpensive pollutant treatment with good reusability, a wide pH range and no iron leaching.

Pd-Co bimetallic nanoparticles modified α-FeOOH nanorod for the catalytic reduction of organic pollutants

The development of most effective reduction catalysts is an essential for promoting the sustainability by minimizing the waste and safeguard the environment. Herein, we prepared palladium-cobalt bimetallic nanoparticles modified on goethite nanorods (PdCo/α-FeOOH) as a catalyst for the catalytic degradation of various organic pollutants under mild reaction conditions. The structure and morphology of synthesized catalysts were tested by XRD, FT-IR, BET, SEM, TEM, HR-TEM and XPS techniques. The ultra-small PdCo bimetallic NPs (2.95 ± 0.5 nm) synthesized onto the surface of α-FeOOH nanorod were confirmed by HR-TEM analysis. The prepared catalysts were played an important role in the reduction of toxic nitrocompounds such as (4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 4-(4-nitrophenyl)morpholine (4-NM) and 4-(2-fluoro-4-nitrophenyl)morpholine (4-FNM)) and rhodamine B (RhB) dye. The PdCo/α-FeOOH nanocatalyst displayed a greater rate constant (∼1.5 min and kapp = 2.631 min−1) compared to their respective mono-metallic counterparts (Pd/α-FeOOH and Co/α-FeOOH). The reusability results indicated that >97 % of conversion for 4-NP, and RhB dye over 10 consecutive reaction cycles in the batch method. Furthermore, the continuous flow reactor with PdCo/α-FeOOH catalyst was constructed, and it showed the ability to eliminate > 99 % of both 4-NP and RhB dye and maintained a degradation rate of >98 % for 20 consecutive recycles. The superior catalytic activity of the PdCo/α-FeOOH catalyst compared to other mono-metallic catalysts could be attributed to their particle size and synergistic effect. This study has the potential to facilitate the utilization of the synthesized bimetallic nanostructure in a wider range of other wastewater treatments.

Waste to worth: Facile preparation of CaO2 derived from oyster shells for highly efficient degradation of organic contaminants based on Fenton-like system

In recent years, CaO2 has been frequently used as a substitute for H2O2 to address the limitations of H2O2. However, commercially available CaO2 are facing the shortcomings of low purity and limited preparation conditions. Oyster shells can provide superior and abundant biomass calcium element with low cost for developing CaO2. In this work, highly purified CaO2 functional biomaterials were prepared via a facile approach derived from waste oyster shells, which were applied in a Fenton-like system to remove organic pollutants. Experimental results indicated that the oyster shells-derived CaO2 with 100% purity exhibited a greatly enhanced catalytic performance compared with other CaO2 materials in Fenton-like catalytic degradation of organic pollutants, which can be completely removed within 60 s. The high purity of CaO2 would facilitate the release of H2O2 during the Fenton-like catalytic reaction and promote the generation of more active species to oxidize pollutants. Besides, the abundant trace metal elements originated from oyster shells can further motivate the Fenton-like reaction and accelerate the degradation of pollutants, endowing oyster shells-derived CaO2 an excellent catalytic activity. Furthermore, the Fenton-like catalytic mechanism was proposed on basis of tests of radicals trapping and electron spin resonance, validating the vital roles of ⋅OH, ⋅O2– and 1O2 generated throughout the reaction process. This work not only provides a novel and low-cost approach to exploit CaO2 with highly efficient catalytic ability, but also realizes the effective resource utilization of waste shells.

Sunlight driven photocatalytic degradation of organic pollutants by solvothermally synthesized rGO-BiVO4 nanohybrids

This study reports photocatalytic degradation of organic dyes by rGO-BiVO4 nanohybrids. rGO- BiVO4 nanohybrids were solvothermally prepared with different rGO loading (1.5, 3 and 6 %) and their structural, optical and photocatalytic properties were investigated. Effect of rGO loading on photocatalytic dye degradation was studied and the factors responsible were analyzed. Structural analysis was done using XRD and Raman analyses which clearly showed monoclinic phase of the BiVO4. FESEM images showed sub-micron spheres of BiVO4 along with sheet-like structures corresponding to rGO. A slight change in the band gap was observed from 2.2 eV for BiVO4 to around 2 eV for the rGO-BiVO4 nanohybrids. Band to band transitions as well as the transitions from the defect bands were observed from the PL spectra. Photocatalytic degradation studies of organic pollutant MB under natural sunlight showed 3 % rGO-BiVO4 to be the best photocatalyst which degraded 88.4 % of MB in 80 min with rate constant of 0.0244 min−1. It was observed that for obtaining a maximum catalytic efficiency an optimum loading of rGO proved to be best. In either case of higher or lower loading of rGO showed a lower degradation performance. Amongst the samples synthesized 3 % rGO loading was found to be the optimum rGO loading to have the lowest band gap (2 eV) as well as the reduced recombination that has resulted in highest photocatalytic efficiency under solar irradiation.

Crafting defective ZnO nanoparticles: A green synthesis for enhanced photocatalytic degradation of organic pollutants

Surface defect engineering is a promising strategy for enhancing the number of surface-active sites to facilitate efficient redox reactions that occur on the surface of a photocatalyst. A green approach was employed to prepare urea- and choline-chloride-based deep eutectic solvent (DES) for the synthesis of ZnO/Zn(OH)2 supported by a DES complex (Zn precursor). Surface defects on ZnO nanoparticles (NPs) were tailored by decomposing the Zn precursor in air. In addition, calcination improved the crystallinity and surface-active sites of the defective ZnO by creating surface oxygen vacancies (Vo). The appearance of an Electron paramagnetic resonance peak at a g value of 1.96 confirms the formation of single-charged Vo defects on the surface of ZnO. The photocatalyst prepared at a reaction bath temperature of 75 °C (Vo-ZnO-75) showed the highest photocatalytic activity. The observed green emission in the photoluminescence spectrum and X-ray photoelectron spectroscopy analysis suggests the formation of defects on the ZnO surface. Consequently, Vo-ZnO-75 enhanced surface donor density (14.4×1020 cm−3) and lower charge transfer resistance (88.89 × 103 Ω). The optimized photocatalyst of Vo-ZnO-75 has 94% removal efficiency for rhodamine B degradation within 60 min. This study sheds new light on the development of an efficient and eco-friendly approach for preparing defective ZnO NPs for photocatalytic applications.

Two-dimensional Ti3C2Tx anchored on three-dimensional SiC honeycomb framework for efficient and cyclic photocatalytic degradation of organic pollutants

The excellent recyclability of SiC foam renders it an ideal catalyst in the field of photocatalytic degradation, however to further improve its photocatalytic efficiency remains a major challenge in current research. In this regard, a honeycomb-like porous SiC foam was successfully constructed through freeze-drying and polymer-to-ceramic derivation method, with two-dimensional Ti3C2Tx nanosheets anchored on its three-dimensional framework. Their photocatalytic performances were evaluated by the degradation of methylene blue (MB) under visible-light irradiation. All Ti3C2Tx/SiC hybrid foams show superior photocatalytic degradation capability compared with SiC foam, with a highest removal rate (adsorption and degradation) reaching 94.4% for TSF-4, denoting an increasement of 50.4%. Even after five cycles, the removal rate remained at 91.4% with only a slightly loss of 3%, suggesting its excellent recycling performance. These desirable results stem from the unique structural design, in which the porous structure facilitates the contact between catalyst and pollutant, while the Ti3C2Tx/SiC heterojunction promotes effective separation of photogenerated carriers. This work paves the way for the development of lightweight, efficient and easily recyclable photocatalyst for wastewater purification.

Insight into the activation of peroxymonosulfate by N-doped copper-based carbon for efficient degradation of organic pollutants: Synergy of nonradicals

Insight into the activation of peroxymonosulfate by N-doped copper-based carbon for efficient degradation of organic pollutants: Synergy of nonradicals

Sulfur poisoned PtNi/C catalysts toward two-electron oxygen reduction reaction for acidic electrosynthesis of hydrogen peroxide

Selective electrocatalysis of two-electron oxygen reduction reaction (2e– ORR) has been recognized as a sustainable and on-site process for hydrogen peroxide (H2O2) production. Great progress has been achieved for 2e– ORR in alkaline media. However, it is challenged by insufficient activity and selectivity of the catalysts in acidic electrolytes. Herein, we report sulfur-poisoned PtNi/C catalysts (PtNiSx/C) that could regulate ORR from the 4e– to 2e– pathway. The identified PtNiS0.6/C offers high activity in terms of onset potential of ∼0.69 V (vs. RHE) and ∼80% selectivity. The mass activity is also comparable and outperforms representative Pt-based precious and transition-metal-based catalysts. In addition, it is interestingly found that the Faradaic efficiency further increased to 95% during the long-term electrolysis test due to Ni atom surface migration. The electrochemical production of the H2O2 system was applied to the electro-Fenton process, which has realized the effective degradation of organic pollutants in wastewater. This work offers a strategy by sulfur poisoning PtNi/C catalyst to realize Pt-based 2e– ORR active catalysts to electrolysis of H2O2 in acidic media.

Engineering d-band center of cobalt active sites via dual coordination with nitrogen-doped carbon nanotube and Ti3C2Tx MXene toward electrocatalytic oxygen reduction for H2O2 production

Manipulating the selective adsorption of oxygen-containing species is crucial for tailoring the electrocatalyst to select dual-electron pathway in the oxygen reduction reaction (2e- ORR). Herein, dual-coordination electrocatalyst structure (Co-NCNT/MXene) is proposed based on the modulation of oxygenated species adsorption by coordination microenvironment at the interface of metal nanocatalysts. The Co-NCNT/MXene achieves excellent H2O2 selectivity (95.25 %), yield (162 mg L-1h−1) and Faraday efficiency (94.81 %) for ORR, surpassing the most Co-based-electrocatalysts. In-situ EPR techniques reveal the selective *OOH desorption dynamic process on Co-NCNT/MXene. Density functional theory calculations confirm that asymmetric coordination of Co nanoparticles by oxygen-terminated Ti3C2-MXene and NCNT modulates the delocalized state of Co extranuclear electrons, resulting in a reduction of the d-band center of Co, thus turning the adsorption energy of *OOH within the Co-NCNT/MXene interface towards a path more conducive to H2O2 electrosynthesis. In-situ H2O2 generated in the ORR is applied to achieve excellent degradation of organic pollutants.

Synthesis and characterization of bi-functional Cu and Ni co-doped ZnO photocatalysts for organic pollutant degradation and antimicrobial activity

The study of visible light active photocatalysts for organic pollutants degradation and antimicrobial activity has gained significant attention in recent years. Herein, we report the synthesis of pure ZnO, Ni-doped ZnO (Ni-ZnO), Cu-doped ZnO (Cu-ZnO), and Cu and Ni co-doped ZnO (CuNi-ZnO) photocatalysts via a facile coprecipitation method. These photocatalyst materials were characterized using various analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–Vis), photoluminescence (PL), and total organic carbon (TOC) analysis. XRD patterns confirm the presence of a mixed phase in the CuNi-ZnO sample. The presence of Cu, Ni, and Zn in CuNi-ZnO was verified through the XPS spectra. The nanoparticle-like morphology of the CuNi-ZnO photocatalyst was confirmed using HRTEM analysis. The FTIR spectra reveal the chemical bonds present in the materials. UV–visible spectroscopy was employed to determine the band gap of the materials, revealing a value of 3.10 eV for CuNi-ZnO. The mitigation in recombination of excited electrons (e−) and holes (h+) in CuNi-ZnO is validated through photoluminescence (PL) studies. The synthesized materials were used for the degradation of Indigo carmine (IC) dye and antimicrobial activity. The results showed that the optimized CuNi-ZnO sample displayed a better visible light photocatalytic performance (93.32 % IC dye degradation efficiency in 60 min) than the other samples. A notable degree of mineralization was observed with a reduction in total organic carbon (TOC) reaching 65.91 %. Additionally, the photocatalyst showed antimicrobial activity against both S. aureus and E. coli. Furthermore, a plausible visible light photocatalytic mechanism was proposed for the degradation of IC dye using the CuNi-ZnO photocatalyst.

Graphene‐Reinforced Hybrid Polymer Nanocomposites‐Based Biosensor Implementation for Environmental Remediation

AbstractBiosensor which is used in wide range of research areas is a type of device which analyzes chemical and biological reactions by responding with electrical output. In this process graphene has become a “miracle material” due to its chemical and physical properties and it is synthesized in this process by native graphite powder (Black Lead) with slight moderation of Hummers method. For membrane formation, PVB (polyvinyle butryl) is used. This copolymer is totally amorphous in nature. An additional, most important eminence of polymer based composite materials is that they can modify chemically to enhance their elasticity biocompatibility and reactivity. The novel nanocomposite membrane can be used for photocatalytic materials for organic pollutant degradation. This experimental study is focused on synthesis and catalytic activity of electrochemical biosensing polymer nanocomposites. In fact, there are many other fields where graphene‐enhanced sensors are on the rise, such as microelectromechanical systems (MEMS) sensors, pressure sensors, pH sensors, environmental contamination sensors, gas sensors, DNA sensors, and more.

Efficient degradation of organic pollutants with sodium percarbonate by activation with CuFeS2 prepared from precursors of different valence states

Four chalcopyrite (CuFeS2) catalysts were fabricated by a hydrothermal method using different copper and iron precursors at different valence states. The prepared CuFeS2 samples were then evaluated for the oxidative degradation of Congo red (CR) using sodium percarbonate (SPC) as the oxidant. The sample of CuFeS2-1, which was prepared from Cu (I) and Fe (II) precursors, exhibited the highest CR removal efficiency of 96.6% among the four CuFeS2 samples. Using CuFeS2-1 as the optimum catalyst, the effects of operation and environmental factors on the removal efficiency of CR were investigated in detail. Mechanism studies showed that CO3•− was the main reactive oxidative species in the reaction process, while O2•− and low-valent sulfur species together promoted the regeneration of Fe (II) and Cu (I) sites on the catalyst. Furthermore, density functional theory (DFT) calculations were used in combination with liquid chromatography-mass spectrometer (LC-MS) to propose the plausible degradation pathway. Finally, toxicity prediction showed that most of the degradation products showed decreased toxicity compared to the parent CR, and toxicity evaluation with Vigna radiata further revealed the declined toxicity.

Biogas upgrading and membrane anti-fouling mechanisms in electrochemical anaerobic membrane bioreactor (EC-AnMBR): Focusing on spatio-temporal distribution of metabolic functionality of microorganisms

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.