Real Wastewater Research Articles

Pre-treatment of composite industrial wastewater by Fenton and electro-Fenton oxidation processes.

The present study aims to characterize three industrial wastewater samples collected from petrochemical, food and beet sugar industries to determine the pollution potential and select the appropriate pre-treatment approach. According to the biodegradability profile of the multi-sourced mixed (composite) sample, the advanced oxidation process (AOPs) namely, Fenton (F) and Electro-Fenton (EF) were adopted as pre-treatment techniques and the operating parameters such as time, type of electrodes, pH, voltage, iron and H2O2 concentrations were critically examined. Analysis of Variance (ANOVA) was conducted to compare the performance efficiency of F& EF AOPs for treating the composite samples and the total operating costs for both approaches were assessed. The results revealed that, the initial values of the composite sample were 7.11, 19.2, 32.6, 19.3, 937, 1512, 860, 3.9, 2110 and 2.34 for pH, Total Dissolved Solids (TDS), Electrical Conductivity (EC), Salinity, BOD, COD, Oil and grease (O&G), Total Phosphorous (TP), Total Suspended Solids (TSS) and Total Kjeldahl Nitrogen (TKN), respectively. In addition, EF process achieved more removal efficiency for COD, O&G, BOD, TSS, and TKN (84.3%, 69%, 85%, 72% and 71.27%) compared to Fenton which displayed 78.43%, 66%, 69%, 70.1%, and 61%, respectively. Moreover, there are statistically significant differences (p < 0.05) between the initial and final (pretreated) values of the composite industrial wastewater for the addressed parameters and EF was significantly (p < 0.05) more effective than F process. The total operating costs were 3.117 and 2.063$ for F and EF, respectively, which confirmed that EF is more efficient and cost effective than F process. It was concluded that electro-Fenton process is favorable, eco-friendly and cost-effective option for pretreating real complicated multi-sourced industrial wastewater. The present study demonstrated a new avenue for achieving efficient management of industrial wastewater generated from similar industries.

Harnessing natural light: Novel nanoheterojunction photocatalyst NaGdF4:Yb,Tm@TiO2/Cu2(OH)2CO3 for actual wastewater remediation

This study introduces NaGdF4:Yb,Tm@TiO2/Cu2(OH)2CO3 (UTCu), an innovative nanophotocatalyst designed to address global energy crises and water contamination issues. Our developed photocatalyst, NaGdF4:Yb,Tm@TiO2/0.5mol%Cu2(OH)2CO3 (UTCu0.5), demonstrated exceptional efficiency, degrading 96.3% of malachite green (MG) within 2 h under Xenon lamp irradiation. The photocatalytic degradation rate of UTCu0.5 surpassed those of UT, Cu2(OH)2CO3, and P25 (Commercial TiO2) by 3.3, 9, and 2.8 times, respectively. The process effectively mineralized MG into less harmful compounds, marking its potential for eco-friendly wastewater treatment. Furthermore, UTCu0.5 exhibited robust degradation capabilities across various organic dyes and maintained its efficacy in mixed dye systems. Detailed mechanistic analysis revealed that the ·OH and ·O2− radicals play pivotal roles in the degradation process, facilitated by the formation of heterojunctions that enhance carrier separation and photocatalytic performance. Theoretical studies supported the significance of S-scheme heterojunctions in boosting the photocatalytic activity of UTCu0.5. Additionally, the catalyst was effective in degrading organic pollutants in different water matrices under both Xenon lamp irradiation and direct sunlight. Remarkably, it achieved a 77.4% removal rate of NH4⁺-N in real municipal wastewater under natural sunlight, with a selective conversion rate of 95.3% to N2, underscoring its practical applicability in environmental remediation. This research not only progresses photocatalysis technology but also provides vital insights for enhancing natural condition wastewater treatment strategies.

Establishing robust ZnO-sodium alginate nanocomposite for dye wastewater treatment: characterization, RSM methodology, and mechanism evaluation.

In today's world, water is a highly valued resource, and enhancing the quality of this natural endowment is a significant concern and a worldwide endeavor. This study sought to purify real wastewater and water tainted with methylene blue (MB) by immobilizing ZnO nanoparticles onto an alginate matrix using a straightforward approach and a three-dimensional structure. After analyzing the impact of , it was determined that 93.84% of MB was successfully removed (time = 120 min, dye concentration = 15 mg/L, catalyst amount = 2.5 g). The effects of inorganic ions and water types were investigated to simulate real wastewater conditions, and the catalyst performed satisfactorily. Alginate played a significant role in selectively removing dye, and the catalyst effectively removed 80.36% of MB and, in contrast, 20% of methyl orange (MO). The practical application of the catalyst was evaluated in textile wastewater treatment, and the catalyst showed satisfactory performance. An average 2.49% reduction in dye removal was observed after five stages of using the catalyst, demonstrating the beads' excellent stability. The composites were subjected to free radical trapping experiments to ascertain the active species. According to the results, and acted as the main reaction species in the degradation of MB. At the end, the synergistic mechanism of adsorption and degradation in MB removal was presented.

Optimizing Dye Wastewater Purification: Ultrasonic and Flotation With Ozonation Synergy

ABSTRACTThe article presents the results of experimental studies of the efficiency of purification of model and real wastewater from dyeing and finishing industries using pneumatic flotation using an ozone‐air mixture instead of air and a combination of ultrasonic treatment and ozonation. The influence of gas mixture consumption, dye concentration, and ozone concentration in the gas mixture on the cleaning efficiency was studied. The purification efficiency was assessed by optical density and COD. By using an ozone‐air mixture instead of air in the flotation process, an efficiency increase of up to 12 times was achieved. It has also been shown that wastewater treatment efficiency increases by up to 12% when combining ozone‐air flotation with ultrasonic treatment at 630 W and operating frequency 22% ± 10% kHz. This effect may be associated, first of all, with the dispersion of bubbles of the ozone‐air mixture, which leads to an increase in their total surface and, accordingly, to the rise in the kinetics of mass transfer—ozone dissolution.

Utilizing Waste Biomass from Agricultural and Forestry Sustainable Resources: Biomass Conversion to Functional Adsorbent Material for Efficient Removal of Total Phosphate in Practical Water.

The promotion of the utilization of waste agricultural and forestry resources (AFRs) as a means of combating environmental pollution represents an advanced and necessary development approach with the potential to achieve sustainable development. In this work, an advanced adsorbent with a functional Mg-Al bimetallic layer was prepared using waste sawdust biomass (WSD) as a raw material. The layer serves as the primary active component for adsorbing total phosphate from both simulated and real wastewater. The hierarchical structure of the Mg-Al bimetallic hydroxide-modified waste sawdust biomass (MA@WSD) has an abundance of nanosheets on its surface, providing ample binding sites and an enhanced specific surface area of 175.99 m2/g. Under the optimal conditions, the maximum removal efficiency toward phosphate can reach 99.99%. The adsorption of phosphate by MA@WSD follows the pseudo-second order kinetic (PSOK) model, indicating that chemisorption is the rate-determining step. Moreover, the thermodynamic data demonstrate the spontaneous nature of the adsorption process, indicating the favorable characteristics of the developed material. The adsorption mechanism can be summarized as the collaboration of physical adsorption, electrostatic interaction, and chemical adsorption. The results of the regeneration process indicate that MA@WSD exhibits a retention of 50.3% of its initial adsorption performance following the fifth testing cycle, thereby suggesting its potential for comparable reusability. The MA@WSD performs well in adsorbing total phosphate in real river water, and the removal efficiency of MA@WSD is evidently superior to commercial activated carbon, which is at least 70% higher than that of the commercial activated carbon. Besides, the 5-time average removal efficiency toward total phosphate by MA@WSD is 62.9%, evidently higher than the 29.1% of commercially available activated carbon, indicating its potential as an alternative for treating phosphorus-containing wastewater. The research provides theoretical support for harmless treatment, resource utilization, carbon sequestration, and emission reduction of waste biomass.

Comediating Adsorption and Electron Transfer via Dual‐Active Site Catalyst Construction for Improving the Treatment of Extraction Wastewater

Solvent extraction is widely applied, while extraction wastewater treatment remains a huge challenge because of the stability of extractants. Heterogeneous Fenton‐like catalysis is a promising method, but the short half‐life of hydroxyl radicals (•OH) generated by hydrogen peroxide (H2O2) activation results in unsatisfactory •OH utilization and organics removal. Herein, an efficient strategy for treating extraction wastewater based on comediating adsorption and electron transfer by fluorine and nitrogen co‐doped carbon (FNC) catalyst with dual‐active site was developed. Specially, N sites adsorb organics and F sites activate H2O2, shortening the migration distance of •OH. Theoretical calculation and di(2‐ethylhexyl) phosphoric acid (D2EHPA) extraction wastewater degradation experiment showed that F site with electron acquisition can transfer electrons provided by electron‐rich D2EHPA enriched at N sites to H2O2, facilitating the continuous generation of •OH through lowering the energy barrier for H2O2 activation. As a result, 96.49% D2EHPA in simulated wastewater and 90.26% total organic carbon in real extraction wastewater were removed. Moreover, FNC catalyst exhibited excellent reusability and ionic adaptability, and can be extended to the removal of various extractants. The proposed dual‐active site catalyst provides an effective strategy for Fenton‐like reaction to treat refractory extraction wastewater, promoting sustainable development of solvent extraction industry.

Utilizing electrooxidation for textile effluent wastewater treatment and simultaneous electrocatalytic hydrogen production: Transforming waste into energy and promoting water reuse in a circular economy context

Textile effluent wastewater poses a serious environmental risk because of its high concentration of pollutants, which include organic compounds, heavy metals, and dyes. The present study investigates the technical and economic feasibility of hybrid water electrolysis performances. Specifically, real textile effluent wastewater was utilised to examine simultaneous abatement and electrochemical hydrogen production. The treated water can be recycled in the textile mill, offering the benefits of trash-to-treasure and cost savings through the circular economy. In addition to reducing the environmental impact of textile wastewater, the synergistic approach seeks to maximise its potential for producing hydrogen as clean energy. Here, the commercially available stainless sheet was used as the anode in the electrochemical setup system and the two-dimensional Ti3C2TX MXene was used as the catalyst embedded cathode. The optimal electrode-electrolyte parameter settings resulted in an 83 % decrease in COD level and a degradation efficiency of about 88 %. The potential for widespread adoption in the textile industry is highlighted by the discussion of the economic viability and environmental advantages of using wastewater from textile effluents for pollutant degradation and hydrogen production. Hence, the energy estimation was looked at and estimated in order to evaluate the process viability. For instance, the hybrid electrolysis process uses a very small amount of electricity (0.825 kWh m−3 order−1) and has an apparent operating current (30 mA/cm2). This work could serve as a guide for the methodical assessment and choice of hybrid water electrolysis using actual wastewater. The electrode's recyclability and reuse were proven for possible commercial applications. The stability of the Ti3C2TX electrode over a wide pH range was investigated in order to produce hydrogen on a big scale at a reasonable cost.

Screening of metal-modified biochars for practical phosphorus recovery

The utilization of metal-modified biochars (MBCs) for practical phosphorus recovery has attracted significant research interest recently. However, the optimal choice of metals and modification methods for MBCs remains unclear. This study addresses this gap by comparing the phosphate adsorption capabilities of various MBCs using real municipal wastewater. The results show that zinc-modified biochar exhibits superior phosphate adsorption compared to biochars modified with calcium, magnesium, aluminum, and iron. Specifically, zinc-modified biochar prepared through metal-mediated biomass pyrolysis with alkaline soaking (ZnBC-OH) demonstrates the highest adsorption capacity, achieving 36.6 mg P/g in wastewater with a phosphate concentration of 5 mg P/L. This performance surpasses that of previously reported non-lanthanide modified biochars and is comparable to lanthanide-modified biochars. Mechanistic investigations reveal that the exceptional performance of ZnBC-OH is due to the presence of highly dispersed ZnO sites, which facilitate the formation of Zn3(PO4)2·4H2O precipitation, effectively retaining phosphate. Furthermore, a techno-economic analysis indicates that using ZnBC-OH in a fixed-bed column system can reduce phosphate levels from 6 mg L−1 to below 0.5 mg L−1 at a cost of 1.834 USD per ton of secondary treated wastewater, underscoring its promising application potential.

Enhanced Organics Removal Using 3D/GAC/O3 for N-Containing Organic Pharmaceutical Wastewater: Accounting for Improved Biodegradability and Optimization of Operating Parameters by Response Surface Methodology

Pharmaceutical industry effluents often contain high concentrations of refractory organic solvents, chemical oxygen demand (COD), and total dissolved solids (TDSs). These wastewaters, including N-containing organic solvents known for their persistence and toxicity, pose significant environmental challenges. The study evaluated the efficacy of 3D/Granular Activated Carbon (GAC)/O3 treatment compared to linear process additions when treating real pharmaceutical wastewater, and revealed a 2.73-fold enhancement in COD mineralization. The process primarily involves the direct oxidation of monoprotic organic acids found in real pharmaceutical effluents, such as acetic and formic acid, crucially influencing mineralization rates. Optimal conditions determined via the response surface methodology were 125 g/L GAC, 30 mA/cm2, and 75 mg/L O3, achieving high total organic carbon (TOC) and COD removal efficiencies of 87.19 ± 0.19% and 89.67 ± 0.32%, respectively (R2 &gt; 0.9), during verification runs. Current density emerged as the key parameter for organic abatement, aligning with the emphasis on direct oxidation at the anode surface. This integrated approach enhances biodegradability (BOD5/COD) and reduces acute toxicity associated with persistent N-containing solvents, demonstrating promising applications in pharmaceutical wastewater treatment.

Enhanced biodegradation of glyphosate by Chlorella sorokiniana engineered with exogenous purple acid phosphatase

Organophosphate pesticides, particularly glyphosate, persist in aquatic environments due to widespread agricultural usage, posing substantial environmental and health risks. This study explores the bioremediation potential of genetically engineered Chlorella sorokiniana, expressing purple acid phosphatase (PAP) from Phaeodactylum tricornutum, for glyphosate biodegradation. The engineered strain (OE line) demonstrated complete glyphosate biodegradation at concentrations below 10 ppm within 4–6 days, surpassing the wild type (WT). Enhanced biodegradation in the OE line was attributed to increased growth and ATP levels due to the release of inorganic phosphate, indicating enhanced metabolic efficiency. Photosynthetic parameters, as well as chlorophyll, and carotenoid contents, were significantly improved, driving higher biomass accumulation. Metabolic shifts toward lipogenesis were observed, supported by the upregulation of triacylglycerol-related genes. Additionally, antioxidant enzyme activities (GPx, SOD, CAT) were elevated in the OE line, mitigating oxidative stress. Importantly, the overexpression of PAP activated and upregulated the level of endogenous CsPAP18, which displayed stable binding with glyphosate and its metabolite aminomethylphosphonic acid, highlighting the synergistic role of PAP and CsPAP18 in glyphosate biodegradation. The OE line effectively treated glyphosate-contaminated real wastewater, confirming the feasibility of engineered strain for environmental remediation. This study provides valuable insights into the potential of engineered microalgae for effective and sustainable wastewater treatment, specifically targeting the removal of organophosphate contaminants in freshwater environments.

Enhancing effect of conductive materials and rumen microorganisms on the anaerobic digestion performance of a real traditional Chinese medicine wastewater

This work evaluated the effect of different concentrations of conductive materials and rumen microorganisms on the anaerobic digestion (AD) performance of real traditional Chinese medicine (TCM) wastewater. The experiments first determined the optimal organic concentration of 0.25 L/L for the AD system and removed suspended solids from real TCM wastewater to reduce the inhibition effect on methanogenesis. Analysis of the modified Gompertz model showed that the addition of activated carbon, biochar, cow manure, and rumen fluid at doses of 12 g/L, 12 g/L, 12 mL/L, and 125 mL/L, respectively, had the greatest effect on CH4 production, increasing the cumulative CH4 yield by 13.5 %, 10.4 %, 26.8 %, and 32.9 %. Through microbial community and metabolism pathway analyses, the conductive materials promoted direct interspecies electron transfer (DIET) between Clostridium and Methanothrix, and the acetoclastic methanogenic pathway dominated by acetyl-CoA synthase. Rumen microorganisms enhanced AD performance by promoting the growth of hydrogenotrophic methanogens and the abundance of genes dominated by formylmethanofuran dehydrogenase in the hydrogenotrophic methanogenic pathway, illustrating the relationship between microbial community and metabolism pathway. Rumen microorganisms increased CH4 production more than conductive materials in real TCM wastewater. This study helps to better understand the internal mechanisms by which different materials enhance AD performance.

Robust PD/A biofilms sustain advanced real municipal wastewater treatment: Reinforcement of interspecific communication and electron transfer

In this study, a robust partial denitrification/anammox (PD/A) biofilm system was efficiently established within merely 83 days using solely conventional activated sludge as the inoculum, employing a multivariate regulation strategy involving the addition of biofillers, optimization of municipal wastewater feeding ratios, prolongation of hydraulic retention time, and introduction of hydrazine. The performance variability of PD/A system within a long-term, intricate mainstream substrate environment was further investigated by incrementally elevating municipal wastewater proportion (50 % → 75 % → 100 %). The results demonstrated that PD/A system ultimately achieved an impressive total nitrogen removal efficiency of 93.6 % and an effluent total nitrogen concentration of 8.6 mg/L, accompanied by anammox contributing over 85 % to nitrogen removal. The biofilm’s layered spatial structure nurtured Candidatus Brocadia, enabling it to reach an abundance of 2.5 % under high real municipal wastewater loading. Metabolic function analyses revealed that biofilm enhanced the abundance of genes associated with interspecies electron transfer and quorum sensing communication in PD/A consortia after prolonged exposure to municipal wastewater. These findings underscore the significances of interspecific interactions, bacterial communications, and synergistic metabolic traits within PD/A biofilm systems in the stabilization of real municipal wastewater treatment.

Evaluation of large-scale poultry manure-derived biochar for efficient cadmium removal in zinc smelter wastewater

Cadmium (Cd), a carcinogen, is released from industrial activities like metal refineries and battery runoff, with significant contamination reported near zinc smelters in Korea. This study addresses the issue using an efficient, economical adsorption process with waste-derived biochar-based adsorbents known for high Cd removal. Poultry manure (PM), typically used as fertilizer, can lead to environmental pollution if mismanaged; therefore, it was pyrolyzed to produce biochar. The resulting poultry manure biochar (PMBC) was produced on a large scale (15 ton/day), demonstrating feasibility for large-scale implementation. The effectiveness of PMBC as an adsorbent for Cd was evaluated using wastewater discharged from a zinc smelter. The Cd adsorption capacity of PMBC (60.39 mg/g) was lower than that (302.0 mg/g) of hen manure biochar produced at a laboratory scale in our previous study but was comparable to other biochars reported in the literature. Response surface methodology analysis indicated that reaction time, dose, and agitation significantly influenced Cd removal by PMBC, whereas pH had a negligible impact. Notable contributions to Cd adsorption include the release of K+ from PMBC and the presence of O-containing functional groups. Under continuous flow conditions with real wastewater, Cd was not detected in the effluent for the initial 8 h, and PMBC sustained a removal efficiency of 40.77% until saturation was reached. The results from wastewater treatment and large-scale biochar production offer valuable insights into the potential of biochar as a medium for addressing environmental issues in real-world applications.

Filtro empacado con residuos de lodos de Al para la eliminación de fósforo como sistema de pulimento en una planta de tratamiento de aguas residuales

Recently, using residual aluminum sludge (Al-sludge) from drinking water treatment plants for phosphorus removal has been assessed and it has shown to be highly efficient. However, most of the studies have been conducted using synthetic water. Only a few works have applied this method to real wastewater (WW), and none of them have been tested in continuous mode, as a polishing step, in a pilot-scale, decentralized wastewater treatment plant (WWTP). This paper aimed to evaluate the performance of an immersed filter packed with a bed of residual Al-sludge as a polishing system for Phosphorous removal, in a pilot-scale, decentralized WWTP. The study determined at laboratory-scale the capacity for phosphorus removal through batch and continuous tests using both synthetic and real wastewater and evaluated the effect of retention time. Based on the results, an Al-sludge immersed filter (Al-sludge Filter) at pilot-scale was constructed, implemented, and evaluated as a polishing step for the effluent of a decentralized-WWTP. The results showed that during continuous testing with real WW, the phosphorus removal capacity was 2.55 mg P-PO43-∙g-1 per gram of Al sludge using a retention time of 120 min. The Al-sludge filter as a polishing system presented an average removal efficiency of 94 ± 8 % and an effluent concentration of under 0.50 mg P-PO43-∙l-1 during the first 20 operational days. For the next 17 days, the system removed 85 ± 9 % on average, showing an effluent concentration of under 1.0 mg P-PO43-∙l-1. From operational day 32 onwards, the removal efficiency was 63.6 ± 10.7 %, with an average effluent concentration of 2.20 ± 0.39 mg P-PO43-∙l-1.

Magnesium Bicarbonate-Walnut Shell Dual-Template Synthesis of Multifunctional Layered Porous Carbon for Enhanced Adsorption of Aqueous Chlorinated Organic Compounds.

Chloride ions readily react with organic matter and other ions, resulting in the formation of disinfection by-products (DBPs) that exhibit heightened levels of toxicity, carcinogenicity, and mutagenicity. This study creatively employed waste walnut shells as self-templates and low-cost magnesium bicarbonate as a rigid template to successfully synthesize multifunctional porous carbon derived from walnut shells. Employing a series of characterization techniques, it was ascertained that the porous carbon material (WSC/Mg) synthesized via the dual-template method exhibited a distinct layered microscopic surface structure, with a predominance of C and O elements on the surface. The material displayed a high degree of graphitization, significant specific surface area, and abundant oxygen-containing surface functional groups. The incorporation of magnesium bicarbonate as a hard template improved the structure of the walnut shell porous carbon, resulting in a significant enhancement in mass transfer efficiency for the target product on the adsorbent and a substantial improvement in removal efficiency. In comparison with walnut shell-derived carbon using only self-templating, WSC/Mg exhibited a 17.26-fold increase in adsorption capacity for 2,4-dichlorophenol. Furthermore, even after four adsorption-desorption cycles, WSC/Mg-12 maintained an adsorption efficiency above 90%. It is remarkable that WSC/Mg-12 demonstrated exceptional resistance to interference from natural organic matter and pH variations. Moreover, the adsorbed saturated WSC/Mg-12 effectively treated real coke wastewater, resulting in an 80% color removal rate, 20% COD removal rate, and 15% ammonia nitrogen removal rate. In conclusion, this study presents an innovative approach for cost-effective and versatile porous carbon materials with extensive applications in water environment purification and biomass utilization.

Removal of phosphate from wastewater using zirconium/iron embedded chitosan/alginate hydrogel beads: An experimental and computational perspective

Adsorptive removal of phosphate plays a crucial role in mitigating eutrophication. Herein, the Zr/Fe embedded chitosan/alginate hydrogel bead (Zr/Fe/CS/Alg) is reported as an effective phosphate adsorbent. This polymer nanocomposite is synthesized by the in-situ reduction of the metals on the polymer matrix. The synthesized adsorbent was characterized by the FTIR, SEM-EDX, TGA, BET, and XPS. The adsorbent showed a maximum phosphate adsorption capacity of 221.72 mg/g at pH 3. The experimental data fit well with the Freundlich isotherm and pseudo-second-order kinetics model, indicating a heterogeneous multilayer surface formation and a chemisorption-dominated adsorption process. Density Functional Theory (DFT) and Monte Carlo (MC) calculations revealed high negative adsorption energy due to the chemisorption of phosphate on the adsorbent. Hence, the major interactions such as electrostatic attraction, hydrogen bonding, and inner-sphere complexation of phosphate adsorption and Zr/Fe/CS/Alg hydrogel beads were investigated from the experimental and computational analysis. The negative values of thermodynamic parameters indicated a spontaneous, exothermic, and less random adsorption process. The synthesized adsorbent exhibited excellent selectivity toward phosphate and maintained 73 % efficiency after six adsorption/desorption cycles. The Zr/Fe/CS/Alg hydrogel beads reduced the phosphate concentration in real wastewater samples from 19.02 mg/L to 0.985 mg/L, suggesting that these nanocomposite hydrogel beads could be a promising adsorbent for real-world applications.

Attracting magnetic BDD particles onto Ti/RuO2-IrO2 by using a magnet: A novel 2.5-dimensional electrode for electrochemical oxidation wastewater treatment

Boron-doped diamond (BDD) is a well-known anode material with a high pollutant degradation ability for electrochemical oxidation wastewater treatment. Nevertheless, the cost of production and mechanical strength of BDD membranes remain unsatisfactory. Magnetic BDD particles derived from industrial waste may represent a promising alternative to BDD membranes, although the challenge remains in assembling these particles into a usable electrode. In this study, magnetic BDD particles were attracted to a Ti/RuO2-IrO2 electrode using a magnet, thus constituting a novel 2.5-dimensional (2.5D) electrode. To ascertain the structure-activity relationship of the novel electrode, essential characterizations, multi-physics simulations, pollutant degradation and electrosynthesis experiments were conducted. The results indicate that an appropriate quantity of BDD particles (0.1 g/cm2) can enhance the number of active sites by approximately 20%. A strong synergistic effect was observed between the Ti/RuO2-IrO2 and BDD particles in the degradation of various pollutants, including azo dye, p-benzoquinone, succinic acid and four kinds of real wastewaters, as well as glycerol conversion. The joint active sites on the interface between Ti/RuO2-IrO2 and BDD particles, as well as the inner active sites on BDD particles, have been identified as crucial in the mineralization of pollutants and the generation of value-added products. The optimal amount of BDD particles (0.1 g/cm2) is sufficient to preserve the joint active sites and to maintain an adequate polarization on the BDD particles. Nevertheless, the hybrid feature of the 2.5D electrode is diminished when a greater quantity of BDD particles (0.3 g/cm2) is loaded.

Electrochemical activation of periodate with graphite electrodes for degradation of high concentrations of thiocyanogen (SCN−) in mineral processing tail liquid

Cyanide has been widely used in gold extraction due to its cost-effectiveness, high selectivity and recovery. Regrettably, its wide application also leads to the presence of a large amount of thiocyanogen (SCN−) in the tail liquid of mineral processing plants, which affects the quality of the effluent water, and thus poses a threat to the ecological environment and human health. This paper investigates the degradation of high concentration of SCN− in water using electrochemical oxidation/periodate (E-GP/PI) system. A degradation rate of 90.25 % of SCN− was achieved by optimising various operating parameters. The effects of organic matter and typical heavy metal ion concentrations on the degradation of SCN− were investigated, and it was found that Cu2+ was able to promote the degradation of SCN− through the formation of stable complexes with SCN−, which enhanced the degradation rate to 96.48 %. However, the presence of Octadecyltrimethylammonium bromide (OTAB) and butylxanthin hindered the degradation process, where 500 mg/L of OTAB reduced the degradation rate of SCN− to 80.88 %, while 100 mg/L of butylxanthin reduced the degradation rate to 78.66 %. On this basis, experiments were carried out using real wastewater samples and SCN− degradation efficiencies of about 90 % were obtained. Afterwards, through electron paramagnetic resonance analysis, free radical burst, ion chromatograph and other research techniques, IO3 and O2– were obtained as the main drivers of SCN− degradation and SCN− degradation pathways were elucidated. Finally, the E-GP/PI system was shown to be effective in reducing the ecotoxicity of SCN− by increasing the 24-h LC50 from 12.5 % to 48.5 % in a toxicity test with daphnia. This study provides a new idea for the green and efficient treatment of SCN− rich beneficiation tail liquid.

Novel 3D plate-like g-C3N4/BiOCl heterojunction as a highly efficient photocatalyst for the degradation of carbofuran in wastewater under visible light irradiation

The g-C3N4/BiOCl (gCN-BCl) heterojunction photocatalyst was synthesized using a low-temperature precipitation method for effective photocatalytic degradation of carbofuran (CBF). All gCN-BCl composites demonstrate greater efficacy in removing CBF compared to its individual constituents. The synergistic effect of incorporating the 0D structured BiOCl onto the 2D structured g-C3N4 was comprehensively examined using various microscopic, X-ray, and spectroscopic analytical techniques. Additionally, optical and photoelectrochemical analyses were conducted. The findings validated that the interaction between the two semiconductors at the heterointerfaces enhanced remarkable physical and structural stability, promoted high charge separation and transfer properties, and improved photocatalytic degradation. Under optimal conditions, 5-gCN-BCl (0.25 g/L) achieved a CBF (5 mg/L) removal efficiency of 95.7 % under visible light irradiation of 120 min, achieving 3.1- and 5.9-times higher degradation rate than the pure BiOCl and g-C3N4, respectively. The radical trapping experiments indicated that the h+ and •O2− were the primary reactive species involved in the CBF degradation. Furthermore, the potential toxicity of CBF and its intermediates was assessed, revealing that the photocatalytic degradation process significantly lowered the ecotoxicity of pesticide wastewater. The potency of 5-gCN-BCl was also evaluated in tap water and real wastewater samples, with CBF degradation efficiencies of 85.8 %, 47.6 %, and 38.7 % in tap water, municipal, and pesticide industry wastewater, respectively. Additionally, artificial neural network (ANN) modeling was employed to predict and optimize the photocatalytic degradation process, providing further insights into the system’s performance. The outcomes of this work offer valuable insights into the development of heterojunction photocatalysts with superior stability and efficacy for eliminating pesticides from water bodies.

Scalable Ir-Doped NiFe2O4/TiO2 Heterojunction Anode for Decentralized Saline Wastewater Treatment and H2 Production

HighlightsIr-doped NiFe2O4 (NFI) spinel with TiO2 heterojunction overlayer brought about outstanding chlorine evolution reaction in circumneutral pH.Electroanalyses including operando X-ray absorption spectroscopy uncovered the active role of TiO2 for Cl− chemisorption.NFI/TiO2 anode boosted both NH4+-to-N2 conversion and H2 generation in wastewater, and the practical applicability was confirmed with scaled-up anodes and real wastewater.