Application In Wastewater Treatment Research Articles

Green Fabrication of ZnO Nanoparticles and ZnO/rGO Nanocomposites from Algerian Date Syrup Extract: Synthesis, Characterization, and Augmented Photocatalytic Efficiency in Methylene Blue Degradation

This innovative article provides a detailed description of the successful biosynthesis of zinc nanoparticles (ZnO-NPs) using an aqueous extract of Algerian Date Syrup, also known as molasses. A meticulous process was carried out to determine the optimal calcination temperature for ZnO-NPs, a crucial step in the preparation of these nanoparticles. The study was further extended by creating ZnO/rGOx nanocomposites through a hydrothermal method, varying the concentrations of reduced graphene oxide (rGO) at 5%, 10%, and 15%. The characteristics of the nanocomposites were thoroughly explored, encompassing chemical, optical, and morphological aspects, using sophisticated analysis techniques such as scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (UV DRS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). These analyses provided an in-depth understanding of the structure and properties of the nanocomposites. The centerpiece of this study is the evaluation of the photocatalytic degradation capacity of ZnO-NPs and ZnO/rGOx nanocomposites. These materials have demonstrated their ability to act as cost-effective and environmentally friendly photocatalysts for wastewater treatment. Experiments on methylene blue degradation under UV irradiation were conducted, yielding impressive results: a degradation efficiency of 86.6% was achieved in 140 min using 1 g/L of ZnO-NPs, and this rate reached 100% with the ZnO/rGO catalyst in the same time frame, highlighting its superiority as a photocatalyst. Furthermore, this study examined the variables affecting the photocatalysis experiment, including the solution’s pH and the amount of catalyst. The results revealed that the ZnO/rGO photocatalyst reached its optimal efficiency under neutral pH conditions and at a concentration of 1 g/L, providing crucial information for practical use of these materials. This enriched article highlights the promising potential of ZnO-NPs and ZnO/rGOx nanocomposites as efficient photocatalysts for methylene blue degradation, paving the way for significant environmental applications in wastewater treatment.

Recent progress in two-dimensional materials for generation of hydrogen peroxide by two-electron oxygen reduction reaction

Hydrogen peroxide (H2O2) is an important green oxidant with a wide range of applications in wastewater treatment, pulp bleaching and chemical synthesis. In recent years, two-electron oxygen reduction reaction (2e-ORR) is expected to be a greener and safer alternative to the more energy-intensive and also carcinogenic anthraquinone process. Among the various electrocatalysts for 2e-ORR, two-dimensional nanomaterials have special advantages in the electrosynthesis of H2O2 due to their large specific surface area, abundant basal and edge sites, and tunable atomic structure. This review article summarizes the synthesis methods, and the strategies and mechanisms for enhancing 2e-ORR properties of 2D materials. Practical problems and serious challenges faced by 2D nanomaterials in the synthesis and 2e-ORR applications are elaborated. The aim of this review is to provide researchers with an understanding of 2D nanomaterials in electrocatalytic applications and to promote the further development of novel 2D nanoelectrocatalytic materials.

Enhanced charge carriers separation/transportation via S-scheme ZnCeS–ZnWO heterostructure nanocomposite for photodegradation of synthetic dyes under sunlight

Domestic wastage and liquid discharge from industries cause serious water pollution and severely damage the life cycle of living species. Therefore, it is necessary to construct efficient photocatalysts for the removal of toxic pollutants from water. Herein, a novel heterostructure ZnWO–ZnCeS nanocomposite was prepared by the sol-gel route and studied its physical and photocatalytic properties using various analytical techniques. Under sunlight irradiation, the ZnWO–ZnCeS photocatalyst eliminated 99.7, 99.1, 99.0 % rhodamine-B (RhB), methylene blue (MB), and safranin-O (SO) dyes within 70 min with excellent performance higher than individual ZnWO and ZnCeS catalysts. The optimization tests exhibit the catalyst loading = 30 mg, dye content = 25 ppm, solution pH = 8 of ZnWO–ZnCeS against MB dye for practical application. The heterojunction of coupled ZnWO and ZnCeS leads to a synergistic effect that facilitates the charge transport and hampers the recombination of photo-induced charge carriers thereby leading to boosted photocatalytic performance. Furthermore, based on the scavenging test, the hydroxyl and superoxide radicals were the reactive species during the photodegradation reaction. The designed photodegradation reaction mechanism has proposed the formation of an S-scheme in ZnWO–ZnCeS that led to the accumulation of electrons at ZnCeS and holes at ZnWO, favoring the formation of reactive species for dye degradation. Moreover, this work provides a novel direction to synthesize S-scheme heterostructure photocatalysts for application in wastewater treatment.

Plant-based synthesis of ZnO–CeO2–MgO nanocomposite using Ocimum Basilicum L seed extract: Biological effects and photocatalytic activity

Recently, ternary nanocomposites have attracted the attention of researchers because of their extraordinary photocatalytic, biological, and optical attributes. In this study, for the first time, ZnO–CeO2–MgO ternary nanocomposite successfully was synthesized by green chemistry approach using Ocimum Basilicum L extract seed as a stabilizing agent. This perspective is noteworthy because it could reduce the environmental impacts of chemical synthesis methods. Various methods, including X-ray diffraction pattern (XRD), Field emission scanning electron microscopy (FE-SEM)/Mapping/Energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM), Diffuse reflectance spectroscopy (DRS), and Fourier-transform infrared spectroscopy (FTIR) were utilized to assess the structural, morphological, and size of the nanocomposite. According to the XRD and FESEM results, the crystal structure and spherical morphology of the nanocomposite were confirmed. The photocatalytic activity of the produced ternary nanocomposite was assessed for degradation of methylene blue (MB) dye below UV irradiation. The results show that nanocomposites have potential applications in wastewater treatment. Finally, the MTT method was carried out on Huh-7 cancer cells to determine the cytotoxicity of the produced nanocomposite, so that the dose-dependent cytotoxic behavior of the nanocomposite was reported with an IC50 value of about 500 μg/mL.

Harnessing advanced nanomaterials: Wastewater treatment with sustainable approach using 2D g-C3N4 based Ho-doped LaCoO3 nanocomposite

This study presents novel materials for improving wastewater treatment by producing a holmium-doped lanthanum cobaltite (Ho-LaCoO3) nanomaterial, and its composites with graphitic carbon nitride (g-C3N4). Powder X-ray diffraction (P-XRD) analysis of the synthesized samples verified their high crystallinity. FTIR spectroscopy analyses the existence of significant functional groups like La–O and Co–O. These results show that incorporating Ho and two-dimensional materials into the LaCoO3 matrix successfully increased the surface area and catalytic activity. The morphological analysis indicates the Ho-doped LaCoO3 nanoparticles embedded on the surface of Ho-LaCoO3/g-C3N4. Mott-Schottky analysis was employed to investigate the electrochemical properties of LC and HLC. Optical analysis revealed that adding g-C3N4 sheets to Ho-Doped LaCoO3 significantly reduced the optical bandgap energy. The photocatalytic performance of these materials was assessed by studying the photodegradation of rhodamine B (RhB) dye, which serves as a model pollutant in wastewater treatment applications. Remarkably, the synergistic effects between Ho-doped LaCoO3 nanoparticles and g-C3N4 exhibited significantly improved photocatalytic performance compared to pure g-C3N4 and LaCoO3, achieving a notable 75 % degradation rate. The kinetic analysis of these degradation reactions revealed that all reactions followed pseudo-first-order rate kinetics. Among all the tested catalysts, the highest rate was observed for g–C3N4–based Ho-Doped LaCoO3 nanocomposite, with a rate constant of 0.009 min−1. These findings highlight the significance of Ho-Doped LaCoO3 and its nanocomposite with g-C3N4 as promising candidates for sustainable and effective wastewater treatment processes.

Effect of montmorillonite nanosheets on the adsorption performance of hydrogel beads and the study of column adsorption

In this work, hydrogel beads with 3D network structure were successfully prepared using montmorillonite nanosheets (MMTNS) combined with macromolecule polymers. Batch adsorption tests revealed that the increase in exfoliation degree of MMTNS was beneficial to improve the methylene blue (MB) adsorption on hydrogel beads (HB). In addition, the HB with 25 % MMTNS-3 dosage achieved high mechanical strength and reached the maximum adsorption capacity of 543.1 mg/g. Effects of MB concentration (40–120 mg/L), adsorbent dosage (1–1.5 g) and flow rate (5–15 mL/min) on fixed-bed column adsorption indicated that the HB column exhibited an excellent dynamic adsorption performance and recycling performance, much better than the D113 resin. The good fits of Pseudo-first-order model and Pseudo-second-order model and a better Langmuir model fitting result implied a monolayer chemical adsorption and physical adsorption nature of MB on HB. Moreover, scanning electron microscope combined with the energy dispersive spectrometer, fourier transform infrared spectroscope and X-ray photoelectron spectroscopy measurements indicated that the adsorption mechanism was mainly attributed to Ca ion-exchange and chemical bonding of –COOH and –OH groups with MB. Such hydrogel beads showed a good potential in the application of practical wastewater treatment.

2D/2D Ni-MOF/BiOCl S-scheme heterojunction with boosted charge transfer and photocatalytic degradation of tetracycline

Constructing S-scheme heterojunction with boosted charge separation efficiency and high photoredox ability is a promising strategy in photocatalytic wastewater treatment. Herein, we report a novel S-scheme photocatalyst composed of two-dimensional (2D) nanosheets (NSs) of Ni-based metal-organic framework (Ni-MOF) and 2D BiOCl NSs. Such a unique 2D/2D stacking structure affords a large contact area at the interface, which promotes electron transfer and ensures the construction of S-scheme heterojunction between Ni-MOF and BiOCl. Benefitting from the efficient charge transfer and sufficient redox ability, the developed Ni-MOF/BiOCl heterojunctions exhibit enhanced photocatalytic performance for tetracycline (TC) degradation. Especially, the optimum 0.1Ni-MOF/BiOCl catalyst achieves a remarkable TC removal rate constant of 0.00274 min−1, 7.21 folds larger than that of single BiOCl (k = 0.00038 min−1). This study offers an ideal strategy for designing and fabricating novel S-scheme heterojunction photocatalysts with applicability in wastewater treatment

Synthesis of AZO-Coated ZnO Core-Shell Nanorods by Mist Chemical Vapor Deposition for Wastewater Treatment Applications.

AZO-coated ZnO core-shell nanorods were successfully fabricated using the mist chemical vapor deposition method. The influence of coating time on the structural, optical, and photocatalytic properties of zinc oxide nanorods was investigated. It was observed that the surface area of AZO-coated ZnO core-shell nanorods increased with an increase in coating time. The growth orientation along the (0001) crystal plane of the AZO thin film coating was the same as that of zinc oxide nanorods. The crystallinity of AZO-coated ZnO core-shell nanorods was significantly improved as well. The optical transmittance of AZO-coated ZnO core-shell nanorods was greater than 55% in the visible region. The degradation efficiency for methyl red dye solution increased with an increase in coating time. The highest degradation efficiency was achieved by AZO-coated ZnO core-shell nanorods with a coating duration of 20 min, exhibiting a degradation rate of 0.0053 min-1. The photodegradation mechanism of AZO-coated ZnO core-shell nanorods under ultraviolet irradiation was revealed.

Think before throw: waste chili stalk powder for facile scavenging of cationic dyes from water.

Chili stalk powder (CS), a non-conventional adsorbent, has been exercised for facile removal of cationic dyes from simulated and wastewater by batch technique. The prepared material has been characterized by Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller analysis (BET), powder X-ray diffraction (powder XRD), and pHZPC and tested best with methylene blue and crystal violet under ambient conditions. FTIR denotes the presence of carbonyl and polyphenolic groups, responsible for dye adsorption. BET surface area analysis evaluates the porous nature and specific surface area of the material, and powder XRD confirms its amorphous nature. The porous structure could be ascertained from the FESEM image, and energy dispersive X-ray analysis (EDX) confirms the elemental composition. The pH above pHzpc shows an increase in removal efficiency. The maximum adsorption capacities are 49.53 and 36.88mg/g for methylene blue (MB) and crystal violet (CV) respectively. Linear as well as non-linear plots for kinetic and isotherm models were studied. Both dye uptake fits the linear plot of Langmuir adsorption isotherm (R2 = 0.999 and 0.995) and pseudo-second-order kinetics (R2 = 0.998 and 0.999). In the non-linear plot, the adsorption process for both dyes fit Langmuir (R2 = 0.999 for MB and R2 = 0.983 for CV) as well as Freundlich adsorption (R2 = 0.999 for MB and R2 = 0.994 for CV). 75.48% crystal violet (CV) and 73.35% methylene blue (MB) regeneration were successful in 1:1 methanol medium and reused for up to three cycles. The uptake mechanism is suggested to be a union of π-π stacking, electrostatic interaction, and weak hydrogen bonding. The material was tested with industrial effluent to prove its application in real wastewater treatment. Moreover, the material shows superior adsorption capacity than contemporary phytosorbents. To conclude, a zero-cost adsorbent using green chili stalk has been demonstrated for wastewater treatment.

Microplastics fouling mitigation in forward osmosis membranes by the molecular assembly of sulfobetaine zwitterion

Forward osmosis (FO) membranes have potential for the efficient water and wastewater treatment applications. However, their development has faced significant challenges due to their fouling propensity. In this study, FO membranes modified with sulfobetaine zwitterions (i.e., [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide) were fabricated and used for the first time to address microplastic (MP) fouling issue. Water flux, reverse salt flux (RSF), fouling, and flux recovery were evaluated for the membranes loaded with different quantities of the zwitterions ranging from 0.25 % to 2 %. The developed membranes were tested over 49 h with feed solutions containing polyethylene MPs and bovine serum albumin (BSA) to evaluate their fouling resistance. The synergistic effects of the two foulants indicated that the MPs were the primary cause of fouling. The presence of BSA effectively reduced the blocking effect of MPs and therefore lowers overall fouling. Additionally, improved water flux, structural parameter (S), and RSF were reported for the modified membranes. The zwitterion's unique structure with hydrophilic groups (CO and OSO) resulted in high flux recovery rates of over 90 % for all modified membranes within only 30 min of physical cleaning upon fouling tests. The results demonstrate the high potential of the modification method for targeting the removal of MPs in TFC-based membranes.

Multifaceted application of modified biochar for water and wastewater treatment

AbstractBiochar, a carbon‐rich material produced through the pyrolysis of biomass, has been shown to have the potential to remove contaminants from water and wastewater. However, due to the weak adsorption capacity and narrow adsorption range of pure biochar, it is modified, either chemically or physically, in order to optimize its applications in water and wastewater treatment. This study summarizes the recent advancements in the application of modified biochar for water and wastewater treatment. Modification of biochar increases its surface area and porous structure, which makes it an effective adsorbent to immobilize a range of contaminants, such as heavy metals, dyes, and organic contaminants. It can also be used as a catalyst in the biodegradation of organic pollutants as it can provide a substrate for microbial growth and metabolism, enhancing pollutant degradation. This study also summarizes various biochar modifications such as gas, acid, alkali, metal, organic compounds, and oxidizing agents. Among the metal‐modified biochar, Iron‐modified biochar has shown the highest tetracycline (TC) removal efficiency (90.7%) and nitrate adsorption capacity (32.33 mg g−1). N‐doped biochars were found to be the most effective biochars for removing heavy metals such as Cd2+ or Cu2+ and aromatic compounds as they can increase the adsorption of raw biochar by up to 70%. Increasing the number of functional groups on the surface of the biochar by using organic compounds like acrylonitrile and chitosan showed a two to three‐fold increase in the adsorption capacity of pollutants such as Cd2+ and Hg2+. According to this review, modified biochar technology is a cost‐effective and environmentally friendly wastewater treatment method.

Fruit waste-derived cellulose-polyaniline composite for adsorption-coupled reduction of chromium oxyanions.

Hexavalent chromium oxyanions, known as potentially toxic micropollutants, exist in the effluents and discharges of metallurgical, electroplating, refractory, chemical, and tanning industries. The exposure of chromium-contaminated water causes severe health hazards. The present work outlines a facile approach to grow polyaniline (PANI) on fruit-waste-derived cellulose (CEL) via oxidative polymerization of aniline; followed by chemical processing with NH4OH to obtain CEL-PANI-EB composites for adsorptive separation-coupled reduction of highly toxic hexavalent chromium oxyanions. The spectroscopic analyses of the CEL-PANI-EB composite before and after adsorption of Cr(VI) oxyanions revealed hydrogen bonding, electrostatic, and complexation as major interactive pathways. The adsorbed hexavalent chromium oxyanions are reduced into Cr(III) species by oxidation of PANI-based benzenoid amine into quinoid imine in the CEL-PANI-EB composite. The adsorption of Cr(VI) oxyanions by the CEL-PANI-EB composite showed negligible effects of other anionic co-pollutants, like NO3- and SO42-. The CEL-PANI-EB composite adsorbed Cr(VI) oxyanions with a removal capacity of 469mgg-1, based on the Langmuir adsorption isothermmodel. The hydroxyl functionalities in cellulose and amine/imine functionalities in PANI facilitate the electrostatic attraction between the CEL-PANI-EB and Cr(VI) oxyanions in an acidic environment beside the hydrogen linkages. The adsorbed Cr(VI) oxyanions are reduced to Cr(III)-based species by the benzenoid amines of PANI, as revealed from the XPS analyses. The CEL-PANI-EB composite showed excellent recyclability and maintained 83.4% adsorption efficiency after seven runs of chromium adsorption-desorption. The current findings reveal the potential of CEL-PANI-EB composites for the adsorptive removal of Cr(VI) oxyanions and their conversion into a lesser toxic form, making them promising materials for wastewater treatment applications.

Bacterial nano-factories as a tool for the biosynthesis of TiO2 nanoparticles: characterization and potential application in wastewater treatment.

The development of reliable and eco-conscious processes for nanoparticle synthesis constitutes a significant element in nanotechnology. TiO2 nanoparticles (NPs) are becoming essential due to their potential uses in dentistry, surgery, agriculture, and pharmacy. This leads to the development of various procedures for producing TiO2 NPs using various physicochemical methods. Still, the drawbacks of these conventional methods are associated with the emission of toxic chemicals into the atmosphere and high energy demands in production, hence endangering the health and the environment. Problems issued are solved by green nanotechnology, which offers tools as nano-factories by utilizing biological sources to subside the improper effects of conventional methods and produces nanoparticles through synthesis methods that are clean, safe, energy-efficient, and cost-effective. Among the biogenic sources, microbial cells such as bacteria possess intrinsic pathways of converting metallic salt to nanoparticles due to their ability to produce reductase enzymes. Also, they can offer features to products such as high dispersity and produce sustainable nanoparticles at a large scale. Biosynthesized TiO2 NPs have high oxidizing potential and a wide range of applications, specifically as photosensitizers and antimicrobial agents. This review will address bacterial nano-factories that can be utilized for the biosynthesis of TiO2 NPs, the characterization of biosynthesized nanoparticles, and their potential application in wastewater treatment.

Crafting an innovative bimetallic MOF-on-MOF/TiO2 composite for effective removal of Imatinib anticancer agent through adsorption and photodegradation

Imatinib (IMB), a widely employed anticancer agent, poses significant environmental concerns due to its release into aquatic ecosystems via pharmaceutical industries and hospital effluents, contributing to water source contamination and consequential impacts on both human and animal health. In light of this, a novel bimetallic MIL-53(Co-Fe)@MIL-53(Ni)/TiO2 composite material has been synthesized utilizing hydrothermal approaches for the efficient adsorption and photodegradation of IMB. Comparative assessments were conducted between this composite and MIL-53(Ni), bimetallic MIL-53(Co-Fe)@MIL-53(Ni), bare TiO2 for their respective capacities in IMB removal through adsorption and photodegradation. Remarkably enhanced efficacy was observed in the synthetic composite's performance for both adsorption and photodegradation, surpassing that of other compounds. Through systematic exploration, critical parameters influencing the adsorption and photodegradation processes were meticulously examined and subsequently optimized utilizing experimental design strategies. Optimal conditions led to the identification of a pseudo-second-order kinetic model for IMB adsorption with a notable rate constant of 8.39 and an equilibrium time of 75 min. The adsorption process conformed favorably to the Freundlich isotherm, as evidenced by the Freundlich constant of 25.498 mg g−1 and adsorption intensity of 2.09. These values underscored the heightened affinity of the synthetic composite relative to IMB, ascribed to the favorable absorption. A complementary investigation into the kinetics of IMB photodegradation unveiled a substantially elevated rate constant of 0.0407 min−1, coupled with a proper half-life of 17.03 min. These collective findings validate the exceptional capacity of the synthesized composite for dual-mode IMB elimination, encompassing both adsorption and photodegradation pathways. This advancement holds significant promise for addressing the environmental repercussions of IMB contamination and points to the potential for broader applications in wastewater treatment and ecological restoration endeavors.

Uncovering the potential of yttrium doped zinc oxide nanoparticles as an efficient catalyst for photodegradation of recalcitrant pollutant and a contributor antibacterial property

This work focused on the development of photocatalytic and antibacterial ZnO doped nanoparticles for wastewater treatment application. ZnO nanoparticle was successfully doped via a sol-gel method with different concentration of yttrium (Y), a rare-earth element. The improved properties of the structural, optical, photocatalytic and antibacterial after the nanoparticles doping modification were analyzed. XRD analysis confirmed the hexagonal (wurtzite) structure with average crystalline size between 10 and 22.7 nm. The exhibited XRD peaks that shifted towards lower angles after doping confirmed the Y3+ substitution in the ZnO structures. High-resolution transmission electron microscopy (HRTEM) showed an increase in grain size as the concentration of Y3+ ions inside the ZnO matrix increased. Ultraviolet-visible-near-infrared spectroscopic measurement revealed a red shift of the bandgap energy of 0.128 eV, which confirmed the substitution process. It was observed that the Y-dopant significantly improved the photocatalytic activity of the ZnO nanoparticles; 91.8 %, 72.9 %, 29.2 % and 85.0 % of 20 ppm of humic acid, 20 ppm of BPA, 20 ppm of phenol and 20 ppm of caffeine respectively under UVA light irradiation. In addition, Y-doped ZnO nanoparticle was found to be highly effective against S. aureus as compared to E. coli. The 9 wt% Y-doped ZnO (9YZnO) nanoparticles have shown no bacterial growth at both minimum inhibitory concentration/minimum bacterial concentration MIC/MBC concentration which served as evidence of the improved antibacterial properties of the modified ZnO nanoparticles. Overall, in this study Y-doped ZnO nanoparticle had shown good performance as photocatalysis material in degrading organic compounds (natural, industrial and consumable organic compounds) and antibacterial material against germ positive microorganism. Considering the developed nanoparticle's performance, its application could be an efficient alternative for water and wastewater treatment applications.

Synergistic effects of PVDF membrane surface functionalization with polydopamine and titanium dioxide for enhanced oil/water separation and photocatalytic behavior

This study investigates the surface modification of poly(vinylidene fluoride) (PVDF) membranes using polydopamine (PDA) and titanium dioxide (TiO2) for effective separation of oily compounds and self-cleaning photocatalytic behavior. The aim was to improve the antifouling properties of the membrane, which was modified by varied PDA and TiO2 concentrations and evaluated regarding the water permeance, total organic carbon (TOC) rejection, and photocatalytic degradation activity. The results demonstrated considerable improvements in the membrane's antifouling properties, achieving a water permeance of 781 kg h−1 bar−1 m−2, TOC rejection of 87%, and methylene blue photocatalytic degradation of 97%, using dopamine (DA) and TiO2 concentration of 0.92 g L−1 and 1.4% (w/w), respectively, and a solution agitation speed of 106 rpm. Additionally, flux recovery reached 86% after the photocatalytic self-cleaning process, indicating that TiO2 improved the membrane's antifouling properties. These findings highlight the potential of PDA and TiO2 as effective surface modifiers for enhancing oil/water separation, reducing fouling, and promoting self-cleaning effect in photocatalytic PVDF membranes. This study’s outcomes provide valuable insights for developing efficient and sustainable membrane-based separation processes for oily wastewater treatment applications.

Synergistic design and fabrication of g-C3N4 decorated Ni-doped CeO2 nanocomposite: A highly efficient photo and electrocatalyst for enhanced energy storage and environmental remediation

Environmental pollution and energy storage are two of the most important problems in the modern world. There is an urgent need for the development of materials with multifunctional properties to successfully address these issues. In this study, we investigate the potential applications of the g-C3N4/Ni-doped CeO2 binary composite, specifically focusing on supercapacitor and photocatalytic performance. To synthesize the pristine CeO2, Ni-doped CeO2 and g-C3N4/CeO2 hybrid samples, we employed an ultrasonic-assisted hydrothermal method and employed various characterization techniques to gain insights into their morphological, structural, optical and compositional characteristics. The synthesized materials are studied for their electrochemical behavior as supercapacitor electrodes using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Additionally, their photocatalytic performance is evaluated under sunlight with Methylene Blue (MB) dye. The hybrid composite electrode demonstrated a peak specific capacitance (Cs) of 269 F/g at a current density of 1 A/g. Moreover, the device maintained an 85.22 % retention rate even after undergoing 5000 consecutive charge/discharge cycles. Moreover, following 60 min of exposure to natural light irradiation, the photocatalytic degradation rates for MB were observed to be 52.5 %, 69.3 %, and 82.3 % for pristine CeO2, Ni-CeO2, and g-C3N4/Ni-CeO2, respectively. The hybrid composite material, g-C3N4/Ni-CeO2, outperforms both CeO2 and Ni-doped CeO2 nanoparticles in terms of enhanced photocatalytic efficiency and improved electrochemical performance, making it highly promising for applications in wastewater treatment and supercapacitors.

Extrusion of Silicon Carbide Based Tubular Membrane Incorporated With Coal Fly Ash and Performance Evaluation in Water Treatment

Development of an efficient membrane from waste resources has been receiving growing interest. The utilization of industrial waste coal fly ash (CFA) for the preparation of SiC based tubular membrane has reduced the raw material cost and sintering temperature, and hence beneficial in both economic and environmental points. In the present work, tubular membrane was prepared by extrusion of ceramic paste formulated using SiC powder, CFA, suitable dispersant, plasticizer and additives. The extruded green body was dried and then sintered at 850°C. The membrane was characterized by measuring porosity, morphology by scanning electron microscopy, linear shrinkage, mechanical strength. The membrane performance was evaluated using synthetically prepared oil-water emulsion, turbid water, kitchen wastewater and industrial wastewater. The membrane was found to remove 93-95% of oil depending on the oil concentration in the feed water. The oil rejection potential of the membrane was compared with other membranes reported in the literature and the results indicated that the membrane prepared in this study had a strong potential applications in wastewater treatment.

Biotreatment of swine wastewater by mixotrophic Galdieria sulphuraria

Biotreatment of swine wastewater via microalgae is an environmentally sustainable and economical efficient strategy capable to transform nitrogen, phosphorous, and organic/inorganic carbons into value added products as lipids, carbohydrates, and proteins, while high ammonium tolerant microalgal species with efficient COD and ammonium removal efficiency is lacking, limiting its practical application. Thermophilic and acidophilic Galdieria sulphuraria (G. sulphuraria) are reported to have high ammonium removal efficiency, while its application in ammonium rich swine wastewater treatment without dilution is rarely reported. Accordingly, mixotrophic cultivation of G. sulphuraria has been tested for biotreatment of swine wastewater. The results indicate that G. sulphuraria can grow well in swine wastewater with maximum growth rate of 0.72 g/(L.d) when 15 g/L of glucose is added. Simultaneously, a maximum COD removal efficiency of 94.8% and ammonium removal rate of 550.5 mg/(L.d) are observed. The addition of glucose leads to decreases of lipid, protein and ash contents, and simultaneous increase of carbohydrates owing to the varied C/N ratios. The final microalgal biomass has relatively lower carbon content of 48.5% with 20 g/L glucose than 49.3% of control, consequently leads to a relatively lower HHV value of 20.64 MJ.kg−1. Above all, mixotrophic cultivation of G. sulphuraria are promising strategy for swine wastewater treatment with high energy recovery, potentially providing an economical strategy for swine wastewater treatment.

Enhancing Commercially Iron Powder Electron Transport by Surface Biosulfuration to Achieve Uranium Extraction from Uranium Ore Wastewater.

The zero-valent iron (ZVI) has attracted increasing attention due to the enhanced reactivity of ZVI to uranium wastewater. However, ZVI practical application is hampered due to its susceptibility to oxidation and the formation of passivation layers during storage and in situ restoration. To address these issues, we used a biosulfuration approach to modify ZVI for application in uranium ore wastewater treatment. A series of physicochemical characterization tools and photoelectronic analyses showed that BS-ZVI considerably increased carrier separation efficiency and visible light absorption capacity, resulting in a significant photoassisted enhancement effect on uranium extraction. Accordingly, the uranium removal efficiency of BS-ZVI reached 91% within 60 min, and its maximum adsorption capacity was 336.3 mg/g. By analyzing the mechanism, the improved U(VI) removal performance was mostly responsible on the dissolution of the passivation layer on the surface of ZVI, the generation of Fe(II) and FeS, and the important role of Shewanella putrefaciens extracellular polymers (EPS). Overall, the BS-ZVI biohybrid merges with the high activity of ZVI, bio-FeS, and self-regeneration ability of bacteria, expanding a promising new approach for sustainable treatment of uranium mine wastewater.