Removal of arsenic as a potentially toxic element from drinking water by filtration: A mini review of nanofiltration and reverse osmosis techniques

Innovative techniques for combating a common enemy forever chemicals: A comprehensive approach to mitigating per- and polyfluoroalkyl substances (PFAS) contamination

The pervasive presence of per and polyfluoroalkyl substances (PFAS), commonly referred to as "forever chemicals," in water systems poses a significant threat to both the environment and public health. PFAS are persistent organic pollutants that are incredibly resistant to degradation and have a tendency to accumulate in the environment, resulting in long-term contamination issues. This comprehensive review delves into the primary impacts of PFAS on both the environment and human health while also delving into advanced techniques aimed at addressing these concerns. The focus is on exploring the efficacy, practicality, and sustainability of these methods. The review outlines several key methods, such as advanced oxidation processes, novel materials adsorption, bioremediation, membrane filtration, and in-situ chemical oxidation, and evaluates their effectiveness in addressing PFAS contamination. By conducting a comparative analysis of these techniques, the study aims to provide a thorough understanding of current PFAS remediation technologies, as well as offer insights into integrated approaches for managing these persistent pollutants effectively. While acknowledging the high efficiency of adsorption and membrane filtration in reducing persistent organic pollutants due to their relatively low cost, versatility, and wide applicability, the review suggests that the integration of these methods could result in an overall enhancement of removal performance. Additionally, the study emphasizes the need for researcher attention in key areas and underscores the necessity of collaboration between researchers, industry, and regulatory authorities to address this complex challenge.

Synthesis and characterization of amine functionalized silylated clay for heavy metal adsorption: Thermodynamic and kinetic studies on Fe(III) ion

Amine functionalized bentonites were used as adsorbents for the bioremoval of Fe(III) ions, which led to the inclusion of functional groups such as -OH, -NH2, -OCH3, etc. FTIR, XRD, SEM, AFM, TG, BET, XRF, and CHNS analyzer were used to analyze the surface and textural characteristics. The influence of adsorption factors, such as pH, contact time, temperature, and initial concentration, have been investigated and tailored in batch adsorption experiments of Fe (III) metal ions. The maximum adsorption efficiency and capacity of modified BNT-APTMS is 100.90 % and 103.91 mg/g respectively. The adsorption process is best fit with Freundlich model (R2=0.998) than Langmuir model (R2=0.788) and the Temkin model D-R isotherm parameters indicating a physisorption process. A mechanism of spontaneous complexation was accomplished, because of the heterogeneity of the surface, electrostatic forces, pore filling, and π-π stacking. Follows PSO kinetics and favours Freundlich isotherm. The adsorbent substance showed a remarkable capacity for regeneration, assuring the substance's stability and reusability.

Microwave-assisted supramolecular double crosslinked chitosan-based molecularly imprinted polymer for synergistic recognition and selective recovery of Cd(II) and As(V) from water: Performance and mechanistic insights

A novel model of the sustainable double crosslinked molecularly imprinted polymer (D-Crosslinked MIP) represented as a supramolecular imprinted polymer was synthesized via the bulk polymerization method. The primary crosslinking was fabricated using biomacromolecule chitosan as a functional monomer and glutaraldehyde as a crosslinker. The primary crosslinked was subjected to dynamic interactions in a secondary crosslinking by binding Al2O3-NPs and TiO2-NPs, forming the supramolecular D-Crosslinked-MIP. The dually crosslinked formed from combining three distinct crosslinkers in one system for the interaction with As(V) and Cd(II). A microwave was employed to evaluate the performance of the designed material in selectivity and extraction of metal ions from water. The FT-IR, XRD, TG/DTA, SEM-EDX, TEM, and XPS were used to verify the characteristics of (D-nano-Al2O3@Crosslinked Chitosan@D-nano-TiO2). The type of solvents, selectivity, interferences, microwave-contact time, pH, temperatures, concentrations, and regeneration were investigated. By using the D-Crosslinked-MIP, at 15 s, Cd(II) revealed a recovery capacity of 99.03 %, Qmax 862.07 mg/g, while As(V) demonstrated a recovery capacity of 99.06 %, Qmax 850.75 mg/g. The D-Crosslinked-MIP exhibited BETs of 69.01 m2/g with a pore volume of 0.2340 cm3/g owing to polymeric crosslinking by metal oxide NPs. The kinetics, isotherm models, and mechanisms of dually crosslinking and extraction of toxic metals were discussed.

Flaxseed (Linum usitatissimum) mucilage: A versatile stimuli-responsive functional biomaterial for pharmaceuticals and healthcare

The present review is novel as it discusses the main findings of researchers on the topic and their implications, as well as highlights the emerging research in this particular area and its future prospective. The seeds of Flax (Linum usitatissimum) extrude mucilage (FSM) that has a diverse and wide range of applications, especially in the food industry and as a pharmaceutical ingredient. FSM has been blended with several food and dairy products to improve gelling ability, optical properties, taste, and user compliance. The FSM is recognized as a foaming, encapsulating, emulsifying, suspending, film-forming, and gelling agent for several pharmaceutical preparations and healthcare materials. Owing to stimuli (pH) -responsive swelling-deswelling characteristics, high swelling indices at different physiological pHs of the human body, and biocompatibility, FSM is considered a smart material for intelligent, targeted, and controlled drug delivery applications through conventional and advanced drug delivery systems. FSM has been modified through carboxymethylation, acetylation, copolymerization, and electrostatic complexation to get the desired properties for pharma, food, and healthcare products. The present review is therefore devoted to the isolation techniques, structural characterization, highly valuable properties for food and pharmaceutical industries, preclinical and clinical trials, pharmacological aspects, biomedical attributes, and patents of FSM.

Adsorptive removal of toxic heavy metals from wastewater using water hyacinth and its biochar: A review

Heavy metal contamination in aquatic ecosystems worsens due to rapid industrial expansion. Biochar, an efficient and economical adsorbent, has attracted much interest in environmental science, particularly in removing heavy metals (HMs). The paper covers basic details on biochar, its preparation, and potential chemical and inorganic modifications. Possible adsorption mechanisms of HMs on biochar, which include electrostatic attraction, ion exchange, surface complexation, chemical precipitation, and hydrogen bonding, are also discussed. These mechanisms are affected by the type of biochar used and the species of HMs present. Research findings suggest that while biochar effectively removes HMs, modifications to the carbon-rich hybrid can enhance surface properties such as surface area, pore size, functional groups, etc., and magnetic properties in a few cases, making them more efficient in HM removal. The choice of feedstock materials is one of the key parameters influencing the sorption capacity of biochars. This review aims to investigate the use of various forms of water hyacinth (WH), including aquatic plants, biomass, biochar, and modified biochar, as effective adsorbents for removing HMs from aqueous solutions and industrial effluents through a comparative analysis of their adsorption processes. However, further studies on the diverse effects of functional groups of modified biochar on HMs adsorption are necessary for future research.

Removal of Heavy Metals from Wastewaters and Other Aqueous Streams by Pressure-Driven Membrane Technologies: An Outlook on Reverse Osmosis, Nanofiltration, Ultrafiltration and Microfiltration Potential from a Bibliometric Analysis

A bibliometric study to analyze the scientific documents released until 2024 in the database Scopus related to the use of pressure-driven membrane technologies (microfiltration, ultrafiltration, nanofiltration and reverse osmosis) for heavy metal removal was conducted. The work aimed to assess the primary quantitative attributes of the research in this field during the specified period. A total of 2205 documents were identified, and the corresponding analysis indicated an exponential growth in the number of publications over time. The contribution of the three most productive countries (China, India and USA) accounts for more than 47.1% of the total number of publications, with Chinese institutions appearing as the most productive ones. Environmental Science was the most frequent knowledge category (51.9% contribution), followed by Chemistry and Chemical Engineering. The relative frequency of the keywords and a complete bibliometric network analysis allowed the conclusion that the low-pressure technologies (microfiltration and ultrafiltration) have been more deeply investigated than the high-pressure technologies (nanofiltration and reverse osmosis). Although porous low-pressure membranes are not adequate for the removal of dissolved heavy metals in ionic forms, the incorporation of embedded adsorbents within the membrane structure and the use of auxiliary chemicals to form metallic complexes or micelles that can be retained by this type of membrane are promising approaches. High-pressure membranes can achieve rejection percentages above 90% (99% in the case of reverse osmosis), but they imply lower permeate productivity and higher costs due to the required pressure gradients.

Enhanced Removal of Cd(II) Ions from Aqueous Media via Adsorption on Facilely Synthesized Copper Ferrite Nanoparticles

In this study, magnetic copper ferrite (CuFe2O4) nanoparticles were synthesized via the Pechini sol-gel method and evaluated for the removal of Cd(II) ions from aqueous solutions. PF600 and PF800 refer to the samples that were synthesized at 600 °C and 800 °C, respectively. Comprehensive characterization using FTIR, XRD, FE-SEM, HR-TEM, and EDX confirmed the successful formation of CuFe2O4 spinel structures, with crystallite sizes of 22.64 nm (PF600) and 30.13 nm (PF800). FE-SEM analysis revealed particle diameters of 154.98 nm (PF600) and 230.05 nm (PF800), exhibiting spherical and irregular shapes. HR-TEM analysis further confirmed the presence of aggregated nanoparticles with average diameters of 52.26 nm (PF600) and 98.32 nm (PF800). The PF600 and PF800 nanoparticles exhibited exceptional adsorption capacities of 377.36 mg/g and 322.58 mg/g, respectively, significantly outperforming many materials reported in the literature. Adsorption followed the Langmuir isotherm model and pseudo-second-order kinetics, indicating monolayer adsorption and strong physisorption. The process was spontaneous, exothermic, and predominantly physical. Reusability tests demonstrated high adsorption efficiency across multiple cycles when desorbed with a 0.5 M ethylenediaminetetraacetic acid (EDTA) solution, emphasizing the practical applicability of these nanoparticles. The inherent magnetic properties of CuFe2O4 facilitated easy separation from the aqueous medium using a magnet, enabling efficient and cost-effective recovery of the adsorbent. These findings highlight the potential of CuFe2O4 nanoparticles, particularly PF600, for the effective and sustainable removal of Cd(II) ions from water.

Effect of long-term inorganic arsenic exposure on erythropoietin production in vitro

Arsenic is widely present in the environment in trivalent and pentavalent forms; long-term arsenic exposure due to environmental pollution has become a problem. Previous reports have shown that 24-h exposure to arsenate (as pentavalent arsenic) potentiates erythropoietin (EPO) production via reactive oxygen species (ROS) in EPO-producing HepG2 cells. However, the effects of long-term arsenate exposure on EPO production remain unclear. In HepG2 cells subcultured for 3 weeks in the presence of arsenate, EPO mRNA levels were lower than those in untreated cells. Levels of ARSENITE METHYLTRANSFERASE mRNA, as well as those of Nuclear factor erythroid 2-related factor 2, glutathione, and superoxide dismutase proteins, were increased compared to untreated cells, but levels of malondialdehyde were not significantly altered. Thus, long-term exposure to arsenate enhances ROS scavenging, suggesting that the ROS-induced accumulation of EPO mRNA is attenuated by arsenate exposure. The induction of EPO accumulation by hypoxia also was attenuated by long-term arsenate exposure, suggesting an impairment in responsivity of EPO production. Furthermore, mRNA levels of SIRTUIN-1, which affects EPO transcription, were potentiated by long-term arsenate exposure. These results suggest that long-term arsenate exposure has multiple, distinct effects on EPO production in vitro.

Efficient removal of Zn(II) ions from aqueous media using a facilely synthesized nanocomposite based on chitosan Schiff base

The development of nanomaterials incorporating organic components holds significant importance in addressing the efficient removal of metal ions through adsorption. Hence, in this study, a novel MnFe2O4/chitosan/Schiff base nanocomposite was successfully synthesized by crosslinking MnFe2O4 nanoparticles with functionalized chitosan using a novel Schiff base. The Schiff base was created through the condensation reaction between 2-aminophenol and terephthalaldehyde. Comprehensive characterization of the synthesized nanocomposite was performed through FT-IR, XRD, SEM, and VSM analyses, revealing a less crystalline arrangement compared to pure chitosan, a rough and non-uniform surface morphology, and a reduced magnetization value of 30 emu/g. Furthermore, the synthesized MnFe2O4/chitosan/Schiff base nanocomposite was working as an adsorbent for the effective disposal of Zn(II) ions from aqueous solutions. The synthesized nanocomposite exhibited a maximum sorption capacity of 289.86 mg/g for Zn(II) ions. Additionally, the results indicated that the removal of Zn(II) ions by the synthesized nanocomposite was a spontaneous, chemical, and endothermic process, aligning well with the Langmuir isotherm as well as the pseudo-second-order model. Furthermore, at pH 7.5, with a contact duration of 100 min and a temperature of 328 K, the fabricated nanocomposite reached its maximum sorption capacity for Zn(II) ions. The results of this study demonstrate the effectiveness of the newly synthesized MnFe2O4/chitosan/Schiff base nanocomposite in removing Zn(II) ions from aqueous media. The novel synthesis approach and the high adsorption capacity of 289.86 mg/g underscore the potential of this composite for practical applications in industrial wastewater treatment. The dual removal mechanism involving electrostatic attraction and complexation processes further enhances its utility, making it a valuable contribution to the field of environmental remediation.

Epicatechin as a promising agent against arsenic-induced neurobehavioral toxicity in NMRI mice: behavioral and biochemical alterations

Epicatechin (Epi) is one of the most abundant flavonoids present in different fruits and tea leaves. Emerging research illuminates the promising potential of catechins to serve as a shield against the damaging effects of arsenic (As) exposure in diverse organs.This study sought to discern whether Epi exhibits a therapeutic efficacy against arsenic-induced neurotoxicity in a murine model.The Naval Medical Research Institute (NMRI) mice were randomly partitioned into six distinct groups, which included a control group receiving normal saline, a group receiving a daily oral dose of arsenic (10 mg/kg) for 5 weeks, groups receiving As (10 mg/kg/day) orally for 5 weeks along with different doses of Epi (25-100 mg/kg) orally for the last 2 weeks, and a group receiving Epi (100 mg/kg) orally for 2 weeks. To assess the potential effects of Epi, neurobehavioral tests, various parameters of oxidative stress, and inflammation were evaluated.The findings of this investigation revealed that As-induced neurobehavioral toxicity was associated with a notable surge in lipid peroxidation and nitric oxide (NO) concentration, accompanied by a reduction in the levels of antioxidant markers. As heightened pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α) levels were observed alongside amplified nuclear factor kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) expression. However, treatment with Epi reversed these effects.On the whole, these findings indicate that Epi may hold promise therapeutic efficacy on As-induced neurotoxicity by improving antioxidant status and mitigating oxidative stress and inflammation. Nevertheless, further research is imperative to comprehensively grasp the potential protective effects of Epi in this particular context.

Hand-crafted potent hydroxyl-rich husk succoured Fe3O4 @ Cu, Mn, Ni, Co - tetra-metallic heterogenous nanocomposite as a catalytic accelerant

An innovative means of synthesizing mechanically recoverable ternary nanocomposite (NC) comprising Fe3O4 supported on Oryza sativa husk (OSH) and ornamented with 3d tetra-metals (M = Mn, Co, Ni, Cu) is proposed using a manual grinding method. This NC was prepared via a one-step manual method. The added advantage of this method is the non-usage of solvents during the synthesis of the NC. In situ, the NPs were grown on OSH-supported magnetite NPs, where they combined to form a matrix to facilitate the formation of the metal NPs in it. The as-crafted Oryza sativa husk-supported magnetite @ tetra-metallic nanocore hybrid (OSFTC) was confirmed via several characterisation techniques, such as XRD, FT-IR, HR-TEM, FE-SEM, XPS, VSM, NMR, and UV-vis analysis. The interesting twist in this NC is that the leaching-in of metals toward the core of the NC increases the magnetic nature of the composite as evidenced by VSM analysis. The electrostatic attraction between NPs formed and the matrix plausibly results in enhanced photocatalytic degradation of pharma-waste in an efficient way. The activity of the OSFTC increases for ciprofloxacin and paracetamol by 67 and 71%. Furthermore, the hydrogenation of anthropogenic pollutants via a foreign agent yields a good conversion percentage of 92%. In addition, the noxious hexavalent chromium is converted to a trivalent cation with the help of OSFTC, indicating good conversion under ambient conditions. Herein, OSFTC also exhibited effective activity against both Gram-positive and Gram-negative bacteria. Moreover, the ternary composite demonstrates consistent and commendable activity against pharmaceutical compounds and carcinogenic pollutants. The OSFTC was designed in a way to perform the cleavage of bonds for toxic materials efficiently.

Titanium Carbide (Ti3C2Tx) MXene for Sequestration of Aquatic Pollutants

The rapid expansion of industrialization has resulted in the release of multiple ecological contaminants in gaseous, liquid, and solid forms, which pose significant environmental risks to many different ecosystems. The efficient and cost-effective removal of these environmental pollutants has attracted global attention. This growing concern has prompted the synthesis and optimization of nanomaterials and their application as potential pollutant removal. In this context, MXene is considered an outstanding photocatalytic candidate due to its unique physicochemical and mechanical properties, which include high specific surface area, physiological compatibility, and robust electrodynamics. This review highlights recent advances in shaping titanium carbide (Ti3C2Tx) MXenes, emphasizing the importance of termination groups to boost photoactivity and product selectivity, with a primary focus on engineering aspects. First, a broad overview of Ti3C2Tx MXene is provided, delving into its catalytic properties and the formation of surface termination groups to establish a comprehensive understanding of its fundamental catalytic structure. Subsequently, the effects of engineering the morphology of Ti3C2Tx MXene into different structures, such as two-dimensional (2D) accordion-like forms, monolayers, hierarchies, quantum dots, and nanotubes. Finally, a concise overview of the removal of different environmental pollutants is presented, and the forthcoming challenges, along with their prospective outlooks, are delineated.

Bisphenol A adsorption using modified aloe vera leaf-wastes derived bio-sorbents from aqueous solution: kinetic, isotherm, and thermodynamic studies

Reactive-oxygen-species are produced more often in the body when bisphenol A (BPA), an endocrine-disrupting-substance, is present. In this investigation, bio-sorbents from an aqueous solution adapted from Aloe-vera were used to survey BPA removal. Aloe-vera leaf wastes were used to create activated carbon, which was then analyzed using Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Zeta potential, and Brunauer-Emmett-Teller (BET) techniques. It was revealed that the adsorption process adheres to the Freundlich isotherm model with R2>0.96 and the pseudo-second-order kinetic model with R2>0.99 under ideal conditions (pH = 3, contact time = 45 min, concentration of BPA = 20 mg.L-1, and concentration of the adsorbent = 2 g.L-1). After five-cycle, the efficacy of removal was greater than 70%. The removal of phenolic-chemicals from industrial-effluent can be accomplished with the assistance of this adsorbent in a cost-effective and effective-approach.

Chemical modification of Aloe vera leaf hydrogel for efficient cadmium-removal from spiked high-hardness groundwater

Herein, the hydrogel from the leaf of the Aloe vera plant (ALH) was succinylated (SALH) and saponified (NaSALH). The FTIR, solid-state CP/MAS 13C NMR, and SEM-EDX spectroscopic analyses witnessed the formation of SALH and NaSALH from ALH. The pHZPC for NaSALH was found to be 4.90, indicating the presence of -ve charge on its surface. The Cd2+ sorption efficiency of NaSALH was found to be dependent on pH, NaALH dose, Cd2+ concentration, contact time, and temperature. The maximum Cd2+ removal from DW and HGW was found to be 227.27 and 212.77 mg g-1 according to the Langmuir isothermal model (>0.99) at pH of 6, NaSALH dose of 40 mg g-1, Cd2+ concentration of 90 mg L-1, contact time of 30 min, and temperature of 298 K. The kinetic analysis of Cd2+ sorption data witnessed that the Cd2+ removal by chemisorption mechanism and followed pseudo-second-order kinetics (>0.99). The -ve values of ΔG° and ΔH° assessed the spontaneous and exothermic nature of sorption of Cd2+ by NaSALH. The regeneration and sorption/desorption studies indicated that the sorbent NaSALH is regenerable.

Hydrochar-nanoparticle integration for arsenic removal from wastewater: Challenges, possible solutions, and future horizon

Arsenic (As) contamination poses a significant threat to human health, ecosystems, and agriculture, with levels ranging from 12 to 75% attributed to mine waste and stream sediments. This naturally element is abundant in Earth's crust and gets released into the environment through mining and rock processing, causing ≈363 million people to depend on As-contaminated groundwater. To combat this issue, introducing a sustainable hydrochar system has achieved a remarkable removal efficiency of over 92% for arsenic through adsorption. This comprehensive review presents an overview of As contamination in the environment, with a specific focus on its impact on drinking water and wastewater. It delves into the far-reaching effects of As on human health, ecosystems, aquatic systems, and agriculture, while also exploring the effectiveness of existing As treatment systems. Additionally, the study examines the potential of hydrochar as an efficient adsorbent for As removal from water/wastewater, along with other relevant adsorbents and biomass-based preparations of hydrochar. Notably, the fusion of hydrochar with nanoparticle-centric approaches presents a highly promising and environmentally friendly solution for achieving the removal of As from wastewater, exceeding >99% efficiency. This innovative approach holds immense potential for advancing the realms of green chemistry and environmental restoration. Various challenges associated with As contamination and treatment are highlighted, and proposed solutions are discussed. The review emphasizes the urgent need to advance treatment technologies, improve monitoring methods, and enhance regulatory frameworks. Looking outlook, the article underscores the importance of fostering research efforts, raising public awareness, and fostering interdisciplinary collaboration to address this critical environmental issue. Such efforts are vital for UN Sustainable Development Goals, especially clean water and sanitation (Goal 6) and climate action (Goal 13), crucial for global sustainability.

Unraveling the roles of microporous and micro-mesoporous structures of carbon supports on iron oxide properties and As (V) removal performance in contaminated water

This study investigates the impact of microporous (SP-C) and micro-mesoporous carbon (DP-C) supports on the dispersion and phase transformation of iron oxides and their arsenic (V) removal efficiency. The research demonstrates that carbon-supported iron oxide sorbents exhibit superior As(V) uptake capacity compared to unsupported Fe2O3, attributed to reduced iron oxide crystallite sizes and As(V) adsorption on carbon supports. Maximum As(V) uptake capacities of 23.8 mg/g and 18.9 mg/g were achieved for Fe/SP-C and Fe/DP-C at 30 wt% and 50 wt% iron loading, respectively. The study reveals a nonlinear relationship between As(V) sorption capacity and iron oxide crystallite size after excluding As(V) adsorption capacity on carbon supports, suggesting the iron oxide phase (Fe3O4) plays a role in determining adsorption capacity. Iron oxide-loaded DP-C sorbents exhibit faster adsorption rates at low As(V) concentrations (5 mg/L) than SP-C sorbents due to their bimodal pore structure. Adsorption behavior varies at higher As(V) concentrations (45 mg/L), with Fe/DP-C reaching maximum capacity more slowly due to limited available adsorptive sites. All adsorbents maintained near-complete As(V) removal efficiency over five cycles. The findings provide insights for designing more efficient adsorbents for As(V) removal from contaminated water sources.

Isotope hydrology tools in the assessment of arsenic contamination in groundwater: An overview

Groundwater is important for the survival of humanity and the demand for the same is drastically increasing globally. The precious water resources are under constant threat, either as a result of natural processes or due to the influence of the anthropogenic activities. Arsenic contamination of groundwater is one of those threats that have affected approximately over 500 million people in 107 countries globally. Although, many studies (∼1000 Nos.) have been carried out on arsenic hydrogeobiochemistry, only a few have reported, on the use of different isotopes in understanding the arsenic hydrochemistry, and its release mechanism and mobilization. Determination of the isotopic composition of a groundwater sample and its dissolved compounds enable a better insight into the hydrological processes that control the distribution and migration of arsenic in the subsurface hydrological system. The environmental isotopes of water molecules (δ18O and δ2H) have been widely used to assess the groundwater origin, its recharge mechanisms, the rock-water interactions and quality. The stable isotopes of dissolved compounds of water (δ34S, δ15N, δ13C, δ56Fe etc.) give better information on the reaction processes within these elements and thus act as a tracer for contaminants, while the radioactive isotopes, such as 14C, 3H, 81Kr, 36Cl, 39Ar etc., can be used to assess the residence time of groundwater and its renewability. This article reviews the different uses of environmental isotopes as tools for providing critical information on various hydrological processes in the arsenic contaminated regions that can't be obtained through conventional tools for better management of the groundwater resources.

Significant photocatalytic decomposition of malachite green dye in aqueous solutions utilizing facilely synthesized barium titanate nanoparticles

The release of malachite green dye into water sources has detrimental effects on the liver, kidneys, and respiratory system. Additionally, this dye can impede photosynthesis and disrupt the growth and development of plants. As a result, in this study, barium titanate nanoparticles (BaTiO₃) were facilely synthesized using the Pechini sol-gel method at 600 °C (abbreviated as EA600) and 800 °C (abbreviated as EA800) for the efficient removal of malachite green dye from aqueous media. The Pechini sol-gel method plays a crucial role in the production of barium titanate nanoparticles due to its simplicity and ability to precisely control the crystallite size. The synthesized barium titanate nanoparticles were characterized by several instruments, such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy, and a diffuse reflectance spectrophotometer. The XRD analysis confirmed that the mean crystallite size of the EA600 and EA800 samples is 14.83 and 22.27 nm, respectively. Furthermore, the HR-TEM images confirmed that the EA600 and EA800 samples exhibit irregular and polyhedral structures, with mean diameters of 45.19 and 72.83 nm, respectively. Additionally, the synthesized barium titanate nanoparticles were utilized as catalysts for the effective photocatalytic decomposition of malachite green dye in aqueous media. About 99.27 and 93.94% of 100 mL of 25 mg/L malachite green dye solution were decomposed using 0.05 g of the EA600 and EA800 nanoparticles within 80 min, respectively. The effectiveness of synthesized BaTiO₃ nanoparticles as catalysts stems from their unique characteristics, including small crystallite sizes, a low rate of hole/electron recombination owing to ferroelectric properties, high chemical stability, and the ability to be regenerated and reused multiple times without any loss in efficiency.

High-efficient removal of arsenic(III) from wastewater using combined copper ferrite@biochar and persulfate

Arsenic (As) is a potentially toxic element with variable valence states. Due to high toxicity and bioaccumulation, As can pose a severe threat to the quality of the ecology as well as human health. In this work, As(III) in water was effectively removed by biochar-supported copper ferrite magnetic composite with persulfate. The copper ferrite@biochar composite exhibited higher catalytic activity than copper ferrite and biochar. The removal of As(III) could reach 99.8% within 1 h under the conditions of initial As(III) concentration at 10 mg/L, initial pH at 2-6, and equilibrium pH at 10. The maximum adsorption capacity of As(III) by copper ferrite@biochar-persulfate was 88.9 mg/g, achieving superior performance than mostly reported the metal oxide adsorbents. By means of a variety of characterization techniques, it was found that ∙OH acted as the main free radical for removing As(III) in the copper ferrite@biochar-persulfate system and the major mechanisms were oxidation and complexation. As a natural fibre biomass waste-derived adsorbent, ferrite@biochar presented a high catalytic efficiency and easy magnetic separation for As(III) removal. This study highlights the great potential of copper ferrite@biochar-persulfate application in As(III) wastewater treatment.

Efficiency of Ag3PO4/TiO2 as a heterogeneous catalyst under solar and visible light for humic acid removal from aqueous solution

Nowadays, the presence of humic acid (HA) in water sources is highly regarded due to the production of extremely harmful byproducts such as trihalomethanes. In this study, the effectiveness of an Ag₃PO₄/TiO₂ catalyst produced by in situ precipitation as a heterogeneous catalyst for the degradation of humic acid in the existence of visible and solar light was evaluated. The Ag₃PO₄/TiO₂ catalyst's structure was characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), after which the catalyst dosage, HA concentration, and pH parameters were adjusted. After a 20-min reaction, the highest HA degradation of 88.2% and 85.9% in presence of solar light and visible light were attained at the ideal operating conditions of 0.2 g/L catalyst, 5 mg/L HA, and pH 3, respectively. It was discovered that, based on kinetic models, the degradation of HA matched both Langmuir-Hinshelwood and pseudo-first-order kinetics at concentrations of 5 to 30 mg/L (R² > 0.8). The Langmuir-Hinshelwood model had surface reaction rate constants (K_c) of 0.729 mg/L.min and adsorption equilibrium constants (K_L-H) of 0.036 L/mg. Eventually, a real-water investigation into the process' effectiveness revealed that, under ideal circumstances, the catalyst had a reasonable HA removal efficiency of 56%.