Contaminants In Industrial Wastewater Research Articles

Optimization of the electro-photocatalytic process for the removal of formaldehyde from water using the Taguchi model

The most significant environmental issue in many nations across the world is industrial wastewater contamination with formaldehyde (a priority pollutant). Any natural water that has had industrial effluent discharged into with formaldehyde concentrations between 100 and 1000 mg/l is deemed toxic to humans. This is an applied analytical research project aimed at examining formaldehyde removal from urban drinking water using a batch electro-photocatalytic (EPC) reactor that uses ultraviolet-A (UV-A) lamp dynode and immobilized ZnO NPs on a zinc sheet-copper electrode. pH, formaldehyde content, lamp intensity, radiation duration, lamp-electrode distance, ZnO NP stacking, and current density are the factors under investigation. They were found to be in the ranges 3–11, 110–330 mg/l, 480–720 mW/cm2, 8–32 min, 1.5 cm, 1–3, and 4–12 mA/cm2, respectively. The findings demonstrate the relationship between UV-A lamp intensity, radiation duration, and current density with the elimination of formaldehyde. The experimental data better fit a first-order reaction (R2 = 0.9982). The most optimal conditions elimination (0 mg/l) of formaldehyde are achieved at pH = 11, radiation period = 8 min, two layers of ZnO NPs, and current density = 8 mA/cm2 by the Taguchi model. The results show that increasing pH, radiation period, lamp intensity, and current density all increase removal efficiency. The results show that EPC is a practical and efficient method for treating formaldehyde-contaminated drinking water at high concentrations.

Multiple effects of microbially induced calcium precipitation on bacteria under different molar volumes of organic pollutants

Microbially induced calcium precipitation (MICP) has been extensively discussed as a water treatment method. However, the impact of MICP on the selective adsorption of different organic contaminants in industrial wastewater and the metabolism and growth of bacteria has not been elucidated in detail. In this study, by comparing the differences in the metabolism and removal of bacteria by phenol, bisphenol A (BPA), and tetracycline (TC), it was found that bioprecipitates had significant differences in the adsorption capacity of organic pollutants with different molar volumes. Concurrently, bacteria produced more extracellular polymeric substances (EPS) under the influence of organic pollutants, and the self-protection mechanism of bacteria would reduce the amount of gaseous nitrogen. However, the points on the surface of EPS promoted the process of MICP, and MICP encapsulated bacteria to form precipitates to regulate bacteria in water and further improve the removal of carbon and nitrogen in water through biomineralization. This experiment provides new insights into the selective adsorption of bioprecipitates and its multiple effects on bacteria.

Efficient degradation of methylene blue at near neutral pH based on heterogeneous Fenton-like system catalyzed by Fe2O3/MnO2

The contamination of aquatic environments by organic dye contaminants in industrial wastewater has attracted widespread global attention. The heterogeneous Fenton-like process presents an attractive method for degrading dye pollutants, especially when such reactions are conducted under neutral pH. In this study, Fe2O3/MnO2 composite was employed as a novel heterogeneous catalyst for activating hydrogen peroxide (H2O2) to oxidize and subsequently degrade methylene blue (MB) under neutral pH. Multiple characterization results have confirmed the presence of MnO2 and Fe2O3 as the primary phases of the synthesized compound catalyst. Degradation experiments have demonstrated that the degradation efficiency of MB approaches 100% under the conditions of H2O2 concentration of 0.30% and Fe2O3/MnO2 amount of 0.888 g/L. Furthermore, the Fe2O3/MnO2 catalyst exhibits consistent and outstanding catalytic activity within a broad pH range from 5 to 9 benefiting from the strong interface interaction in Fe2O3/MnO2. The investigation into the kinetics of the Fenton-like reaction indicates that the catalytic degradation of MB by Fe2O3/MnO2 in conjunction with H2O2 follows pseudo-first-order kinetics. Moreover, supplementary scavenging experiments have demonstrated the crucial role played by hydroxyl radicals (·OH) in the catalytic oxidation mechanism of MB. This study offers a promising catalyst for the treatment of dye-containing wastewater under neutral pH condition.

Cadmium Remediation from Water Using Low-Cost Modified Biochar: An Approach Towards Sustainable Remediation

Biochar is increasingly recognized as an effective adsorbent for the removal of Cadmium (Cd²⁺), a prevalent contaminant in industrial wastewater. This study utilizes rice husk biochar to target aqueous Cd²⁺. The biochar was synthesized through rapid pyrolysis at 450°C. To enhance its Cd²⁺ removal efficiency, the biochar was modified with chitosan, using a treatment with a 2% aqueous acetic acid chitosan solution followed by sodium hydroxide (NaOH) processing. Both the chitosan-modified biochar (CMBC) and the non-modified biochar (NMBC) underwent comprehensive characterization via proximate and ultimate analysis, Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). At pH 5, the Langmuir maximum adsorption capacity of CMBC was 134 mg/g, compared to 48.2 mg/g for NMBC at 318 K. CMBC exhibited a significantly higher Cd²⁺ removal efficiency, attributed to the introduction of amine groups from chitosan modification that enhance Cd²⁺ adsorption. The adsorption mechanisms on CMBC were further explored through FT-IR and SEM comparisons before and after Cd²⁺ uptake. The chitosan modification notably improved the Cd²⁺ adsorption capacity, which was also influenced by pyrolysis temperature; higher temperatures led to reduced biochar yield but increased porosity, surface area, and adsorption capacity. The adsorption process was pH-dependent, with a peak capacity of 161 mg/g observed at pH 5. The Freundlich model effectively described the adsorption equilibrium, suggesting contributions from both chemisorption and physisorption on the heterogeneous biochar surface. In summary, rice husk biochar, especially when modified with chitosan, proves to be a cost-effective, sustainable material for Cd²⁺ removal from aqueous solutions, enhancing water treatment efficiency through improved adsorption capabilities.

Adsorption of cationic dye onto Raphanus seeds: optimization, adsorption kinetics, thermodynamic studies

Dyes are one of the common contaminants in industrial wastewater. Adsorption is the most widely method which used to treat dye-contaminated water due to their easy use, cost-effectiveness, and their efficiency was high. The aim of this study is the investigating of the utilization of the activated carbon which prepared from Raphanus seeds solid residual (ACRS) as a low cost adsorbent for removing of cationic Methylene Blue dye (MB)from wastewater. measuring the surface area using BET methods and SEM. The FT‒IR and XRD was measured. Different variables (e.g.: initial concentration of the dye, pH, contact time, and dosage) have been studied. Process has been systematically investigated experimentally at (25 ± 1 °C). The % removal of MB reached 99.4% after 90-min MB adsorption (40 mg/L) was observed within 5 min of contact time for the Raphanus seeds solid residual (ACRS) dosage of 4 g/L. MB initial concentration (10 ppm) Raphanus seeds solid residual (ACRS) effectively adsorbed MB (> 99%) over a widely range of pH (from pH 2 to pH 8). However, a swift decline in removal was observed when the pH was set at 7. The results of the adsorption kinetics analysis indicate a strong correlation with the pseudo-second-order model, as evidenced by the high regression coefficients. However, the adsorption capacity diminished with a rise in temperature. Thermodynamic calculations of (MB) onto Raphanus seeds solid residual (ACRS) is an exothermic reaction. The results have been indicated that the effectiveness of MB removal by activated carbon prepared from Raphanus seeds solid residual is favorable under neutral conditions, Raphanus seeds solid residual (ACRS) can be considered an efficient, environmentally friendly, readily available, and economical adsorbent that could treat industrial wastewater contaminated with cationic textile dyes. The objective of the experiments was to investigate the impact of various factors on the response of a process or formulation. To accomplish this goal, response surface methodology (RSM) has employed as a statistical model. RSM is an efficient and effective method for optimizing processes through the use of a quadratic polynomial model. The utilization of RSM allows for a reduction in the number of experiments needed, thus minimizing the associated costs of extensive analysis. This method has been done using Box–Behnken Design (BBD) to optimize % removal of MB. The optimal conditions as obtained from the RSM is pH 7,contact time 120 min, initial concentration 10 ppm, ACRS dosage 1 g, adsorption temperature 45 °C.

Enhancing methyl violet 2B pollutant removal from wastewater using Al-MOF encapsulated with poly (itaconic acid) grafted crosslinked chitosan composite sponge: Synthesis, characterization, DFT calculation, adsorption optimization via Box-Behnken Design

In this research, aluminum metal-organic framework encapsulated with poly (itaconic acid) grafted crosslinked chitosan composite sponge (Al-MOF@PIC) was prepared. SEM, FTIR, XPS, XRD, and BET techniques were employed to thoroughly characterize the synthesized material and establish its structure and characteristics. The study discovered that the Al-MOF@PIC is an efficient way to remove dyes, which constitute a significant number of contaminants in industrial wastewater. Subsequently the adsorption of methyl violet 2B (MV-2B) dye, the surface area, pore size, and pore volume of the adsorbent decreased from 1860.68 m2/g, 1.62 nm, and 1.52 cc/g to 1426.45 m2/g, 1.11 nm, and 0.92 cc/g, individually. This modification suggested that a portion of the MV-2B dye had been removed by adsorption over the adsorbent's pores. The excellent adsorption capacity of the material was further confirmed by batch adsorption tests, which displayed a maximum adsorption capability of 646.76 mg/g for the elimination of MV-2B dye. The high adsorption energy of 26.8 kJ/mol designates that chemisorption is primarily responsible for MV-2B dye adsorption against the sponge adsorbent. The Al-MOF@PIC composite sponge demonstrated exceptional reusability over six cycles, demonstrating its strength and durability. The Al-MOF@PIC composite sponge successfully removes MV-2B from water by pore filling, π-π stacking, hydrogen bonding, and electrostatic interactions, which are the key mechanisms behind the adsorption of the dye pollutant. Its potential for practical applications is further demonstrated using Box Behnken-design (BBD) to optimize the adsorption consequences.

Influence of Nd3+ ions modified CoAl2O4 nanomaterials for high efficiency dye degradation application

This study aims to elucidate the possible application of cobalt aluminate nanoparticles (CoAl2O4) as a photocatalyst for the removal of organic dyes. The sol-gel method was employed to synthesise Ndx/CoAl2O4 nanoparticles with varying weight percentages (x = 0.0, 0.2, 0.4, and 0.6 wt %). The experimental investigation focused on the photocatalytic destruction of colour, employing a visible light irradiation source. The structural and optical properties of the synthesised nanoparticle were examined through various analytical techniques, including X-Ray Diffraction (XRD), Ultra Violet-Diffuse Reflectance Spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX), Tunnelling Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). The cubic spinel structure was confirmed through the study of the X-ray diffraction (XRD) pattern of the Ndx/CoAl2O4 nanoparticles. For the compositions x = 0.0, 0.2, 0.4, and 0.6, the nanoparticles exhibited average crystallite sizes of 23.73, 22.99, 21.69, and 21.65 nm, respectively. The synthesised nanoparticle exhibited heterogeneous photocatalytic potential when employed as a model pollutant for the oxidative destruction of crystal violet dye. The experimental findings validated that the CoAl2O4 nanoparticle exhibited a dye degradation rate of 64 % during a 100-min timeframe. Additionally, the 0.6 wt % Nd CoAl2O4 nanoparticle shows a quick dye degradation rate of 91 % for crystal violet dyes when exposed to visible light sources. Hence, the synthesised nanoparticle exhibits catalytic activity and holds potential for utilisation in the treatment of hazardous contaminants in industrial wastewater.

Musa acuminata free tepal (MAFT) crop- mediated synthesis of copper oxide nanocatalyst (MAFT-CuO nanocatalyst): Investigation of aerobic oxidation and dye decolourization via eco-friendly approach

Crop development is used to address environmental problems in the industry. Environmental pollutants, particularly humble or toxic chemicals and dyes, are contaminants in industrial wastewater. Recently, green technology has become important for controlling the chemical risks associated with environmental issues. This study focused on valuable crop materials to form green catalysts that can be used to control chemical toxicity in industrial wastewater. In this study, Musa acuminata-free tepal (MAFT) crops and musa were used to mediate the formation of copper nanocatalyst for environmental pollution. The synthesised nanocatalyst was analysed by XPS, XRD, TEM, SEM, FT-IR, GC-EI-MS, and TGA-DSC. The production of Cu–O in the 512 cm−1 peak range was verified by FT-IR analysis. The XRD peaks associated with the cubic crystalline structures of copper (110) and (200) were used to confirm the Musa acuminata-free tepal CuO nanocatalyst. The SEM images of the Cu and CuO nanocatalyst in the Musa acuminata free tepal showed that the particles were almost spherical. The size of the synthesised Musa acuminata free tepal CuO nanocatalyst core-shell nanostructures was identified using HR-TEM. GC-MS investigations also verified the aerobic oxidation of the main alcohol to aldehyde, with a retention time of 30.34. The MAFT was 80 % of CBB G250 dye decolourised at 24 h, and the MAFT-CuO nanocatalyst was decolourised the CBB G250 dye at 80 % in 20 min and aerobic oxidation at the same time (dual application). Furthermore, our nanocatalyst could be effectively recycled without significant loss of catalytic activity, and the use of safe, environmentally benign MAFT-Cu and CuO nanocatalyst is considered a green chemistry approach that helps avoid wastewater treatment. MAFT-Cu and CuO nanocatalyst were successfully synthesised using Musa acuminata free tepal extract assisted by reflux sample preparation system instruments as a new, green, eco-friendly, and fast process for nanocatalyst synthesis. In the past, there have been no reported applications of MAFT-Cu and CuO nanocatalyst for decolourisation and aerobic oxidation. Nevertheless, we were able to accomplish these procedures with the help of CuO and MAFT-Cu nanocatalyst. Therefore, the most effective naturally occurring environmental catalysts for aerobic oxidation processes are MAFT-CuO nanocatalyst. They are non-toxic and environmentally benign, exhibit strong aerobic oxidation catalytic performance, and have long-lasting benefits for water quality. Additionally, they are more recoverable and biodegradable.

Functionalization of cellulose acetate nanofibrous membranes for removal of particulate matters and dyes

Particulates and organic toxins, such as microplastics and dye molecules, are contaminants in industrial wastewater that must be purified due to environmental and sustainability concerns. Carboxylated cellulose acetate (CTA-COOH) nanofibrous membranes were fabricated using electrospinning followed by an innovative one-step surface hydrolysis/oxidation replacing the conventional two-step reactions. This approach offers a new pathway for the modification strategy of cellulose-based membranes. The CTA-COOH membrane was utilized for the removal of particulates and cationic dyes through filtration and adsorption, respectively. The filtration performance of the CTA-COOH nanofibrous membrane was carried out; high separation efficiency and low pressure drop were achieved, in addition to the high filtration selectivity against 0.6-μm and 0.8-μm nanoparticles. A cationic Bismarck Brown Y, was employed to challenge the adsorption capability of the CTA-COOH nanofibrous membrane, where the maximum adsorption capacity of the membrane for BBY was 158.73 mg/g. The self-standing CTA-COOH membrane could be used to conduct adsorption-desorption for 17 cycles with the regeneration rate as high as 97.0 %. The CTA-COOH nanofibrous membrane has excellent mechanical properties and was employed to manufacture a spiral wound adsorption cartridge, which exhibited remarkable separation efficiency in terms of treated water volume, which was 5.96 L, and retention rate, which was 100 %.

STUDENTS' ATTITUDES TOWARD SUSTAINABILITY IN THEIR DESIGN PERSPECTIVES

In 2002, the United Nations designated the years 2004-2015 as the "Decade of Education for Sustainable Development," with the purpose of integrating education into social development that adheres to sustainable principles. The deficiency of attachment to one's garments and their disposal after a single usage have become the standard of the day. The fashion business adds to the burden on Earth's limited resources. Global warming has been progressively growing; it reached 1.2°C in 2022, and there is a strong risk of topping 1.5°C within ten years. In 2022, global carbon dioxide (CO2) emissions reached a new high of 36.8 giga tones. The fashion sector accounts for 10% of all global carbon dioxide emissions. This industry accounts for 20% of industrial wastewater contamination. The Sustainable Development Goal (SDG) Index assesses 193 nations' progress toward sustainable goals. The Sustainable Development Goals are far off-track midway through the 2030 Agenda. The globe is also far from meeting Sustainable Development Goal 13 and the Paris Agreement's climate goals. This study seeks to investigate the attitudes and understanding of design students aged 18 to 25 regarding sustainability. A sustainability survey was done utilizing a questionnaire among 110 first-year students and 110 fourth-year students. A questionnaire survey was carried out using Google Forms. This study exposed that, despite spending three years more in college than first-year students, fourth-year students do not have a significantly greater understanding of sustainability.

Evaluating the effects of pH and temperature on sulphate-reducing bacteria and modelling of their effects in stirred bioreactors

ABSTRACT Sulphate (SO4) abundance in the earth’s crust contributes largely to industrial wastewater contamination lowering the pH, which exuberates the dissolution of metals forming acidic drainages. Biological sulphate reduction as a remediation process can be affected by factors such as pH, temperature and high sulphide concentrations. In this study, sulphate-reducing bacterial community enriched from mine wastewaters was applied in semi-automated bioreactors to assess the effects of these factors on microbial sulphate reduction capacities. Low pH (3.5) and temperature (10°C) were observed to promote the toxicity of sulphur-reduced species on the consortium while mesophilic temperature (25°C) and near neutral pH (6.2) were observed to induce optimum SO4 reduction attaining a maximum of 95% SO4 reduction. Obtained SO4 reduction dynamics data was then applied in formulating a unique non-competitive inhibition equation that models biogeochemical events during SO4 reduction under varied pH and temperature conditions and predicts the efficacy of a bioremediation system.

Electrochemical oxidation and sensing of para benzoquinone using a novel SPE based disposable sensor

Para-benzoquinone (PBQ) is an emerging micro-contaminant owing to its chronic toxicity to plants and animals as well as its potential to induce cytotoxicity in primary rat hepatocytes and kidney cell injury. Hence, it is of utmost importance to monitor this contaminant in industrial wastewater and groundwater. In this article, we devised a unique disposable sensor that is based on a screen-printed electrode using MnO2@Co–Ni MOFs/fMWCNTs nanocomposite and is able to detect PBQ. The as-produced nanocomposite was prepared via ultrasonic assisted reflux condition and thoroughly examined by several physicochemical characterisation methods such as SEM, EDX, TEM, Raman, AFM, UV–visible, and FT-IR. Moreover, electrochemical methods like CV, DPV, EIS, and chronoamperometry were used for detecting PBQ on MnO2@Co–Ni MOFs/fMWCNTs/SPCE. Sensor performance has been investigated thoroughly and optimized to enhance the analytical potential of the fabricated sensor. DPV analysis was done on MnO2@Co–Ni MOFs/fMWCNTs that exhibit high selectivity, low peak potential, a broader linear detection range (0.005 mM–30 mM), and a LOD of 0.0027 ± 0.0005 mM. The designed electrode has shown remarkable reproducibility and excellent repeatability, with relative standard deviations of 0.12%, and 0.17%, respectively. Additionally, MnO2@Co–Ni MOFs/fMWCNTs/SPCE have been used to analyse PBQ in industrial wastewater samples, and the results have shown a significant level of recovery between 96.91 and 105.67%. Moreover, the PBQ sensor displays high applicability and was verified via the use of HPLC techniques. This disposable sensor is quick, easy, and cost-effective, so it can be useful in the future for analysing other phenolic contaminants present in environmental samples.

Challenges of Distillery Effluent Treatment and its Bioremediation Using Microorganism: A Review.

Waste management is a global issue with which the entire globe is currently grappling. The composition and characteristics of the pollutants in effluents are unknown, which poses the greatest worry. The Industrial Revolution has captured the attention of environmentalists worldwide. Their concern regarding the lethal effects of untreated industrial effluent wastewater is growing daily. Dealing with a range of hazardous compounds is costly and complicated, which hinders wastewater treatment. Recent years have paved the way for microorganisms to act as a low-cost source for detoxifying such a complex effluent mixture. Their simple availability and moderate cost make them the preferred technique. Bioremediation is the method of utilising the high and diversified metabolic activity of microorganisms to breakdown contaminants in industrial wastewater, particularly distillery effluent. Their readily available nature and affordable price make them the preferred option. Bioremediation is the process of using bacteria and other organisms with strong metabolic activity to breakdown contaminants in industrial effluents, particularly distillery effluents. Microorganisms like Bacteria fungi etc.,alone or in conjunction with other organisms, create an environment conducive to not only the breakdown of toxicants but also the production of some useful byproducts. This review focuses on distillery effluents, particularly melanoidins, and the reported microorganisms utilised for decolorization. The study combines a vast array of microorganisms that are utilised alone or in conjunction with other organisms in the decolorization process.

Is cavitation a truly sensible choice for intensifying photocatalytic oxidation processes? – Implications on phenol degradation using ZnO photocatalysts

Phenols are recalcitrant compounds that constitute the majority of organic contaminants in industrial wastewaters. Their removal at large scales require a combination of various processes to reach the desired discharge quality. An extensive body of work has already been published in the area of phenol removal from wastewater, however none of them have focussed on a truly ‘sensible’ approach for coupling advanced oxidation processes (AOPs). Rather, a higher removal efficiency was targeted by unduly complicating the process by combining multiple AOPs. The most influential AOP as the primary method typically driven by the nature of the pollutant should form the basis for a hybrid AOP followed by a complementary AOP to intensify the oxidation process. This strategy is lacking in current literature. We address this knowledge gap directly by systematically identifying the best hybrid process for ZnO mediated photocatalysis of phenol. Either a cavitation mediated pre-treatment of ZnO or cavitation-photocatalysis-peroxide based hybrid AOP was investigated. While the pre-treatment approach led to >25% increase in phenol oxidation compared to bare ZnO photocatalysis, the hydrodynamic cavitation-photocatalysis-peroxide based system was found to have a cavitational yield 5 times higher than its acoustic cavitation counterpart. A new phenomenon known as the ‘pseudo staggered effect’ was also observed and established in hydrodynamic cavitation mediated photocatalysis-peroxide hybrid process for the first time. While we demonstrated that cavitation is a truly ‘sensible’ choice to enhance photocatalysis, the nature of the pollutant under investigation must always be the key driver when designing such hybrid AOPs.

Biological treatment solutions using bioreactors for environmental contaminants from industrial waste water

AbstractHuman needs have led to the development of various products which are produced in the industries. These industries in turn have become a source of various environmental concerns. As industries release regulated and unregulated contaminants into the water bodies, it has become a serious concern for all living organisms. Various emerging contaminates from industries like pesticides, pharmaceuticals drugs like hormones, antibiotics, dyes, etc., along with byproducts and new complexes contaminate the water bodies. Numerous traditional approaches have been utilized for the treatment of these pollutants; however, these technologies are not efficient in most cases as the contaminants are mixed with complex structures or as new substances. Advanced technologies such as bioreactor techniques, advanced oxidation processes, and so on have been used for the treatment of industrial wastewater and have served as an alternative way for wastewater treatment. Overall, biological treatment techniques based on bioreactors provide a long-term and ecologically useful solution to industrial wastewater contamination. They play an important role in saving water resources and encouraging a greener sustainable future for mankind. The current review outlines the industrial effluents that are released into water bodies, contaminating them, as well as the numerous traditional and novel treatment procedures used for industrial wastewater treatment. Graphical abstract

Degradation of tartrazine by Oxone® in the presence of cobalt based catalyst supported on pillared montmorillonite - Efficient technology even in extreme conditions

The catalytic degradation of hazardous organic contaminants in industrial wastewater is a promising technology. Reactions of tartrazine, the synthetic yellow azo dye, with Oxone® in the presence of catalyst in strong acidic condition (pH 2), were detected by using UV–Vis spectroscopy. In order to extend the applicability profile of Co-supported Al-pillared montmorillonite catalyst an investigation of Oxone® induced reactions were performed in extreme acidic environment. The products of the reactions were identified by liquid chromatography–mass spectrometry (LC-MS). Along with the catalytic decomposition of tartrazine induced by radical attack (confirmed as unique reaction path under neutral and alkaline conditions), the formation of tartrazine derivatives by reaction of nucleophilic addition was also detected. The presence of derivatives under acidic conditions slowed down the hydrolysis of tartrazine diazo bond in comparison to the reactions in neutral environment. Nevertheless, the reaction in acidic conditions (pH 2) is faster than the one conducted in alkaline conditions (pH 11). Theoretical calculations were used to complete and clarify the mechanisms of tartrazine derivatization and degradation, as well as to predict the UV–Vis spectra of compounds which could serve as predictors of certain reaction phases. ECOSAR program, used to estimate toxicological profile of compounds to aquatic animals, indicated an increase in the harmfulness of the compounds identified by LC-MS as degradation products from the reaction conducted for 240min. It could be concluded that an intensification of the process parameters (higher concentration of Oxone®, higher catalyst loading, increased reaction time, etc.) is needed in order to obtain only biodegradable products.

Recycling of waste aluminum scraps to fabricate sulfidated zero-valent iron-aluminum particles for enhanced chromate removal

Massive waste aluminum scraps produced from the spent aluminum products have high electron capacity and can be recycled as an attractive alternative to materials based on zero-valent iron (Fe0) for the removal of oxidative contaminants from wastewater. This study thus proposed an approach to fabricate micron-sized sulfidated zero-valent iron-aluminum particles (S-Al0@Fe0) with high reactivity, electron selectivity and capacity using recycled waste aluminum scraps. S-Al0@Fe0 with a three-layer structure contained zero-valent aluminum (Al0) core, Fe0 middle layer and iron sulfide (FeS) shell. The rates of chromate (Cr(VI)) removal by S-Al0@Fe0 at pH 5.0‒9.0 were 1.6‒5.9 times greater than that by sulfidated zero-valent iron (S-Fe0). The Cr(VI) removal capacity of S-Al0@Fe0 was 8.2-, 11.3- and 46.9-fold greater than those of S-Fe0, zero-valent iron-aluminum (Al0-Fe0) and Fe0, respectively. The chemical cost of S-Al0@Fe0 for the equivalent Cr(VI) removal was 78.5% lower than that of S-Fe0. Negligible release of soluble aluminum during the Cr(VI) removal was observed. The significant enhancement in the reactivity and capacity of S-Al0@Fe0 was partially ascribed to the higher reactivity and electron density of the Al0 core than Fe0. More importantly, S-Al0@Fe0 served as an electric cell to harness the persistent and selective electron transfer from the Al0-Fe0 core to Cr(VI) at the surface via coupling Fe0-Fe2+-Fe3+ redox cycles, resulting in a higher electron utilization efficiency. Therefore, S-Al0@Fe0 fabricated using recycled waste aluminum scraps can be a cost-effective and environmentally-friendly alternative to S-Fe0 for the enhanced removal of oxidative contaminants in industrial wastewater.

Enhanced removal of metal-cyanide complexes from wastewater by Fe-impregnated biochar: Adsorption performance and removal mechanism

Metal-cyanide complexes are common contaminants in industrial wastewater. Removal of these refractory contaminants is essential before their discharge into the environment. This study investigated a biochar (BC)-based sorbent material that could be applied for the efficient removal of metal-cyanide complexes from wastewater. In consideration of the strong electrostatic repulsion of the pristine BC toward anions, iron-modified BC (Fe-BC) composites were fabricated by a one-step co-pyrolysis of corn straw and FeCl3 at 600–800 °C. The adsorption performance and corresponding sorption mechanisms of representative metal-cyanide complexes (ferricyanide [Fe(CN)6]3- and tetracyanonickelate [Ni(CN)4]2-) onto the Fe-BC composites were investigated. The results indicated that the Fe-BC composites had significantly high affinity toward the metal-cyanide complexes, reaching a maximum sorption capacity of 580.96 mg/g for [Fe(CN)6]3- and 588.86 mg/g for [Ni (CN)4]2-. A mechanistic study revealed that Fe-impregnation during BC fabrication could effectively alter the negatively charged BC surface, forming more functional groups that could interact with the metal-cyanide complexes. Moreover, the transformation of carbon structure promoted the carbothermal reduction process, leading to the formation of various reductive-Fe minerals in the resulting Fe-BC composites. These modification-induced alterations to the surface and structural characteristics of BC were expected to facilitate the adsorption/precipitation of target contaminants. Different sorption mechanisms were proposed for the two metal-cyanide complexes that were the focus of this study. For [Fe(CN)6]3-, precipitation by Fe-bearing species in the Fe-BC composites was the major factor controlling [Fe(CN)6]3- removal, while for [Ni(CN)4]2- hydrogen bonding interactions between surface functional groups (especially hydroxyl (-OH) and carboxyl (-COOH)) and [Ni(CN)4]2- were the main factors controlling removal.

Evaluation and remediation protocol of selected organochlorine pesticides and heavy metals in industrial wastewater using nanoparticles (NPs) in Nigeria

Limited knowledge of the level of contaminants in industrial wastewater within the Nigerian states together with the global challenge of water supply have compelled our investigation into the analyses and removal of organochlorine pesticides (OCPs) and heavy metal contents in industrial wastewater. Wastewater samples were collected from 13 industries across five states in Nigeria. The OCPs content of the samples was extracted, cleaned up and analysed using gas chromatography-mass spectrometry. The results indicate that the mean concentrations of the OCPs in the effluent samples ranged from 1.76 ng L−1 (Dieldrin) to 0.89 ng L−1 (endrin). Cadmium (Cd), chromium (Cr) and lead (Pb) were evaluated in all the effluent water samples. The results show that the average concentrations of the heavy metal ions in the effluent samples ranged from 0.008 ± 0.003 mg L−1 (Cd) to 2.215 ± 0.841 mg L−1 (Pb). For the removal of the identified contaminants, biomagnetite nanoparticles (BioMag), magnetite nanoparticles (MagNPs), biomagnetite-CMC nanocomposite (BioMag-CMC) and magnetite-CMC nanocomposite (MagNPs-CMC) were synthesised and characterised using Braunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and high resolution-transmission electron microscopy (HR-TEM). This study demonstrates the successful application of nanoparticles (NPs) and nanocomposites in the removal of OCPs and heavy metal ions in industrial effluents. The routine assessment and continuous removal become important to attain a state of clean and healthy aquatic ecosystem due to rapid industrial and technological advances.

Selective NOx- Electroreduction to Ammonia on Isolated Ru Sites.

Nitrate and nitrite (NOx-) are widespread contaminants in industrial wastewater and groundwater. Sustainable ammonia (NH3) production via NOx- electroreduction provides a prospective alternative to the energy-intensive industrialized Haber-Bosch process. However, selectively regulating the reaction pathway, which involves complicated electron/proton transfer, toward NH3 generation relies on the robust catalyst. A specific consideration in designing selective NOx--to-NH3 catalysts should meet the criteria to suppress competing hydrogen evolution and avoid the presence of neighboring active sites that are in favor of adverse N-N coupling. Nevertheless, efforts in this regard are still inadequate. Herein, we demonstrate that isolated ruthenium sites can selectively reduce NOx- into NH3, with maximal Faradaic efficiencies of 97.8% (NO2- reduction) and 72.8% (NO3- reduction) at -0.6 and -0.4 V, respectively. Density functional theory calculations simulated the reaction mechanisms and identified the *NO → *NOH as the potential rate-limiting step for NOx--to-NH3 conversion on single-atom Ru sites.