Cost-effective synthesis and characterization of CuO NPs as a nanosize adsorbent for As (III) remediation in synthetic arsenic-contaminated water

Facile synthesis, characterisation and application of zinc ferrite in removal of uranium from water by adsorption

The present study features about the adsorption efficacy of Zinc ferrite (ZnFe₂O₄) in removing uranium from both synthetic and real groundwater samples. ZnFe₂O₄ was synthesized via the Solution Combustion Method and subsequently characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and spectroscopic techniques, including Fourier transform Infrared (FTIR) spectroscopy and Raman spectroscopy, to assess its structural properties. The textural characteristics of the synthesized material were examined through N₂ adsorption-desorption isotherm analysis. Furthermore, X-ray photoelectron spectroscopy (XPS) and Electron spin resonance (ESR) spectroscopy were used to check and investigate the electronic states and magnetic properties of ZnFe₂O₄, respectively. Parametric batch adsorption experiments were conducted at ambient conditions by varying the uranyl (U(VI)) concentration (10-50 ppm), contact time (0-90 min), adsorbent dosage (0.1-1 g), and solution pH (3-10). The ZnFe₂O₄ nanoparticles exhibited >90 % of U (VI) adsorption at a contact time of 60 min, at pH 6, and an adsorbent dosage of 0.3 g for a 10-ppm U(VI) solution. The adsorption process was best described by the Langmuir model, with a maximum adsorption capacity of 5 mgg-1. Additionally, kinetic studies revealed a pseudo-second-order kinetic model with an equilibrium adsorption capacity of 28.68 mgg-1. The application of 0.3 g of ZnFe₂O₄ was also found to facilitate approximately 90 % U(VI) removal from groundwater samples. The ZnFe₂O₄ nanoparticles demonstrated notable adsorption efficiency and regeneration capability, sustaining performance over five consecutive adsorption-desorption cycles. These findings suggest that ZnFe₂O₄ has potential for remediation of U(VI)-contaminated water under ambient conditions.

Fabrication of novel glutathione-Fe3O4-loaded/activated carbon encapsulated sand bionanocomposites for enhanced removal of diethyl phthalate from aqueous environment in a vertical flow reactor

The extensive use of plasticizers in various industries has made Diethyl phthalate (DEP), a serious threat to the environment and ecological water security, owing to its complex-structure and low-biodegradability. Thus, the present study aimed to design a sustainable sand-coated nano glutathione (GSH) -Fe3O4-loaded/activated carbon (AC) bionanocomposite (AC-GSH-Fe3O4@sand bionanocomposite) for effective removal of DEP from water. Characterization results suggested bionanocomposites' rough and irregular texture due to the uneven distribution of AC and Fe3O4 nanoparticles over the sand. The XRD spectra indicated high crystallinity of bionanocomposites, while the FTIR spectra confirmed the presence of all individual components, i.e., GSH, AC, Fe3O4, and sand. EDX-mapping, AFM, and TGA further verified its elemental composition, topographical changes and thermal stability. The influence of pH (3, 7, 9), bed height (2, 4, 6) cm, and flow rate (2.5, 3.5, 4.5) mL min-1 were studied in a dynamic system with an initial DEP concentration of 50 mg L-1 to investigate the removal behavior of the bionanocomposites. The best DEP removal efficiency (90.18 %) was achieved over 28-h at pH 9, bed-height-4 cm, and flow-rate-3.5 mL min-1, with an optimum qmax-200.25 mg g-1 as determined through Thomas-model. Breakthrough curves were predicted using various column models, and the corresponding parameters essential for column-reactor process design were calculated. The high reusability up to the 10th cycle (≥83.32%) and the effective treatment in complex matrices (tap-water: 90.11 %, river-water: 89.72 %, wastewater: 83.83%) demonstrated bionanocomposites' prominent sustainability. Additionally, the production cost at 6.64 USD per Kg, underscores its potentiality for industrial application. Phytotoxicity assessment on mung-bean revealed better root (5.02 ± 0.27 cm) and shoot (17.64 ± 0.35 cm) growth in the bionanocomposite-treated DEP samples over the untreated samples. Thus, AC-GSH-Fe3O4@sand bionanocomposites could be considered a highly-sustainable, low-cost technique for the effective removal of DEP and other phthalate-esters from contaminated matrices.

Efficient water purification: CuO-enhanced biochar from banana peels for removing Congo red dye

Treating dye-containing wastewater poses numerous challenges due to its high chemical complexity and its persistent nature. Thus, the present study aims to synthesize biochar derived from banana peel (BC) and its nanocomposites with copper oxide nanoparticles (CuOx/BC1-x) for the purpose of adsorptive removing Congo red (CR) dye from water. Several analytical methods were utilized to describe the physicochemical features of the CuOx/BC1-x nanocomposites. It was found that the crystallinity of the nanocomposites gradually improved, while the specific surface area and the surface electronegativity were reduced with increasing x value. The effects of x values (0-0.5), interaction time (10-120 min), adsorbent dose (0.01-0.05 g), initial CR concentration (20-200 mg/L), and the solution temperature (20-60 °C) were evaluated on CR removal. The obtained results revealed that the CuO0.5/BC0.5 nanocomposite showed the highest adsorption efficiency with a maximum adsorption capacity of 233.6 mgg-1. Analysis of the equilibrium experimental data revealed that the Langmuir and the pseudo-2nd-order models were the most proper to describe the current adsorption process. Moreover, the thermodynamics studies demonstrated that the adsorption process was spontaneous, endothermic, and random.

Effects and Mechanisms of Copper Oxide Nanoparticles with Regard to Arsenic Availability in Soil-Rice Systems: Adsorption Behavior and Microbial Response

Copper oxide nanoparticles (CuO NPs) are widely used as fungicides in agriculture. Arsenic (As) is a ubiquitous contaminant in paddy soil. The present study was focused on the adsorption behavior of CuO NPs with regard to As as well as the characteristics of the microbial community changes in As-contaminated soil-rice systems in response to CuO NPs. The study found that CuO NPs could be a temporary sink of As in soil; a high dose of CuO NPs promoted the release of As from crystalline iron oxide, which increased the As content in the liquid phase. The study also found that the As bioavailability changed significantly when the dose of CuO NPs was higher than 50 mg kg^-1 in the soil-rice system. The addition of 100 mg kg^-1 CuO NPs increased the microbial diversity and the abundance of genes involved in As cycling, decreased the abundance of Fe(III)-reducing bacteria and sulfate-reducing genes, and decreased As accumulation in grains. Treatment with 500 mg kg^-1 CuO NPs increased the abundance of Fe(III)-reducing bacteria and sulfate-reducing genes, decreased Fe plaques, and increased As accumulation in rice. The adverse effects of CuO NPs on crops and associated risks need to be considered carefully.

Regulatory Mechanism of Copper Oxide Nanoparticles on Uptake of Different Species of Arsenic in Rice

Copper oxide nanoparticles (CuO NPs) are widely used as a fungicide in agriculture. The application of CuO NPs in agriculture affects the growth of rice and metal accumulation in rice. However, the mechanism of CuO NPs on arsenic (As) accumulation in rice remains unclear. In this study, a hydroponic culture was produced to investigate the mechanism of the effect of 50 and 100 mg L-1 CuO NPs on As accumulation in rice. Our results showed that CuO NPs decreased As(III/V) accumulation in the roots and shoots by adsorbing As(III/V), oxidizing of As(III) on the surface, and thickening the root cell wall. The addition of CuO NPs regulated the expression of the OsNIP1;1, OsHAC1;1, and OsHAC4 genes, which decreased As(III) transport and promoted As(V) reduction in the roots. Moreover, when CuO NPs were co-exposed to As, a negative correlation between the concentration of Cu and As in rice was also found in our study. However, CuO NPs significantly increased Cu accumulation in rice and constrained the rice growth. In conclusion, CuO NPs might be a promising way to decrease As accumulation in rice, but the negative effects such as growth inhibition should be further considered. Therefore, the application of CuO NPs in rice plants should take a more restrained approach.

Arsenic exposure from groundwater: environmental contamination, human health effects, and sustainable solutions

Arsenic (As) occurs naturally in geologic conditions, but groundwater contamination might also be found due to the consequences of mining, agricultural and industrial processes. Human exposure to As after drinking contaminated water is commonly associated with acute toxicity outcomes and chronic effects ranging from skin lesions to cancer. Integrated actions from environmental and health authorities are needed to reduce exposure, monitoring outcomes, and promotion of actions to offer sustainable As-safe water alternatives. Considering recent research trends, the present review summarizes and discusses current issues associated with the process and effects of contamination and decontamination in an environmental health perspective. Recent findings reinforce the harmful effects of the consumption of As-contaminated water and broaden the scope of related diseases including intestinal maladies, type 2 diabetes, cancers of bladder, kidneys, lung, and liver. Among the main strategies to diminish or remove As from water, the following are highlighted (1) ion exchange system and membrane filtration (micro, ultra, and nanofiltration) as physicochemical treatment systems; (2) use of cyanobacteria and algae in bioremediation programs and (3) application of nanotechnology for water treatment.