Water, Air, & Soil Pollution最新文献

Biochar (BC) can be coated with microbial extracellular polymeric materials (EPS) to form BC-EPS corona in an aqueous environment, which may significantly alter its ecological toxicity caused by EPS-facilitated accumulation of environmental contaminants. This work examined the EPS corona formation on the surface of shrub branch BC and wheat straw BC, pyrolyzed at 450 °C and 650 °C, and evaluated its effect on the sorption of divalent metals Cd²⁺, Pb²⁺, Cu²⁺, and Ni²⁺. In single metal systems, the formation of a BC-EPS corona shows little enhancement on Cd²⁺ and Cu²⁺ accumulation, but significantly elevated Ni²⁺ and Pb²⁺ adsorption: Ni²⁺ sorption increased from 20 mg/g for pristine BCs to 30 mg/g, Pb²⁺ sorption increased from below 25 mg/g to above 90 mg/g. In multiple metal systems, the binding distribution of Pb²⁺ and Cu²⁺ on BC-EPS corona appeared to be more extensive compared to that of Cd²⁺ and Ni²⁺. The toxicity of BC-EPS increased by about 2 to 3 times in aquatic organisms compared to pristine BC, attributed to the higher accumulation of heavy metals in BC-EPS corona. In summary, BC-EPS corona enhanced BC’s sorption capacity for metals, especially for Pb²⁺ and Ni²⁺, thus elevating the BC’s ecological risks owing extra amount of pollution loading.

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A hybrid composite, denoted as arginine-functionalized polyaniline@jujube shells (Arg-PANI@JS), was designed by oxidative polymerization of monomer-aniline on the surface of jujube shells matrix in the occurrence of arginine. This adsorbent was subsequently characterized and used in hexavalent chromium Cr(VI) adsorption assays. An experimental batch adsorption setup was utilized to assess the effectiveness of the newly developed adsorbent in detoxifying Cr(VI) ions from the solution. The experimental results were successfully anticipated by a pseudo-second-order model (PSO) and the Freundlich isotherm with a maximum uptake capacity of 1142.86 mg.g⁻¹. The thermodynamic investigation showed that the process was both spontaneous and endothermic. The pivotal driving force behind elucidating the binding mechanism of Cr(VI) species was determined to be electrostatic interactions. Furthermore, our assessment demonstrated that the Arg-PANI@JS composite can be readily regenerated using a NaOH solution and effectively reutilized for removing Cr(VI) from aqueous solutions. Consequently, these findings underscore the promising practical utilization of the Arg-PANI@JS composite in wastewater treatment.

This study aimed to accelerate photocatalytic treatment of sulfamethoxazole (SMX) and cefixime (CFM) and alleviate the toxicity of photocatalysis effluents to improve further biodegradability. An efficient and fast reactive photocatalyst (Fe₂O₃/ZnO@VC) was synthesized, characterized and applied for photocatalytic removal of the targeted compounds. Results further confirmed the complete removal of SMX (1 mgL^-1) within 30-min photocatalytic treatment. Acidic condition favored SMX removal due to the formation of negative ions, which were attracted by the surface of the catalyst comprising positive charge in pH values below the point of zero charge. The ideal degradation environment for CFM (1 mgL^-1) was at neutral pH, and 97.2±0.1% of CFM was degraded over 60-min. A quenching test revealed that superoxide radial (^•O₂⁻) and e⁻ played a major role in the photocatalytic degradation of SMX, while hydroxyl radical (^•OH) showed an identical effect during photocatalytic treatment of CFM. The degradation efficiency of SMX was marginally reduced in synthetic wastewater (SWW) and CFM in tap water (TW) due to the quenching effects of phosphates and carbonates anions in SWW and chloride ions in TW, respectively. As a result of the excellent mineralization properties of the photocatalyst, the photocatalysis effluents were highly detoxified, reaching 93.5±11.8% and 87.0±5.1% for SMX and CFM, respectively.

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Faulty irrigation practices and industrial activities lead to the pollution of metals in agricultural soil, resulting in adverse effects on human health. The present study was conducted for the assessment of source identification, probabilistic health hazard assessments, and analysis of dietary risks associated with metals pollution in the calcareous soil of India. The mean content of total and bioavailable forms of metals (Cr, Ni, Cd, Pb, Cu) surpassed the permissible limits in sample areas Baruraj (zone 1) and Kanti (zone 2), with zone 1 showing higher level of pollution compared to zone 2. The free ion activity model (FIAM) was employed to detect metals in polluted soil and assess their potential transfer to rice grains. Hazard quotient values were notably higher than the safe threshold (FIAM-HQ < 0.5) for Cr (2.87E-01), Ni (1.08E-01), and Pb (1.88E-01), except for Cd (1.49E-02) and Cu (1.27E-03), which remained within safe limits. Severity adjustment margin of exposure (SAMOE)-Risk thermometer indicates high and moderate human health risk for Cr (Cr_SAMOE = 0.006) and Ni (Ni_SAMOE = 0.03), respectively. Self-organizing map (SOM) and positive matrix factorization (PMF) identify pollution sources in the calcareous region. Monte Carlo simulation (MCS) unveiled that children were more vulnerable to total carcinogenic risk (TCR) compared to adults through the ingestion pathway. A geostatistical approach was employed to predict the spatial distribution patterns of various metals across the area. This comprehensive evaluation, utilizing appropriate and reasonable methods, serves as a valuable resource for environmental scientists and policymakers aiming to manage and mitigate metal pollution in agricultural soils near residential areas.

Development in industrial sectors such as textile, paints, paper, and cosmetics creates a complicated problem in the ecosystem and human health by utilizing binary coloring materials (methylene blue, rhodamine B, etc.). Photocatalysis is one such most widely used technology for environmental remediation, in which a sunlight-based initialing factor was utilized. However, issues related to conventional photocatalysis, like fast recombination of photo-generated electron and hole pairs, limited visible light absorption property, and poor redox abilities of the charge carriers, must be addressed to improve semiconductor photocatalysts properties and catalytic performance. Enormous efforts have been undertaken to overcome these problems. Modeling of semiconductor photocatalysts is beneficial for understanding and optimizing the functional property. Engineering of semiconductor photocatalyst was done by various techniques such as Schottky, Type-I, Type-II, and Type-III heterojunction formation, through which an efficient photocatalyst retarding the demerits (optical property, spatial charge distribution, recombination, etc.) faced by normal (non-heterojunction) semiconductor photocatalyst can be obtained. The basic principle behind heterojunction formation and its utilization was discussed. The synergistic effect between two different materials significantly impacted their photocatalytic activity improvement. In this review, we have exemplified the purpose of heterojunction formation, their types, and the band potential findings necessary for evaluating semiconductors' ability for the redox process. Furthermore, the future perspective for enhanced photocatalytic material design providing a newer pathway for upcoming research works was provided.

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Multifunctional adsorbents are significant for the treatment of water-soluble dyes in contaminated aquatic systems and oily dyes in colored organic effluents. However, the existing adsorbent for both water-soluble and oil-soluble dyes is rare and the cleanup effect is not ideal. In this study, alginic acid carbon aerogel (AACA) as an effective wide-spectrum adsorbent was prepared through wet-spinning, ion-exchanging, drying, and high-temperature carbonization. AACA obtained a specific surface area of 1046.0 m² g⁻¹ and a mean pore size of 2.82 nm. The adsorption capacities of AACA for methylene blue (cationic dye), methyl orange (anion dye), and oil red O (oil-soluble dye) were 493.5, 389.5, and 244.2 mg g⁻¹, respectively, which were improved in comparison with those of previously reported calcium alginate and ferric alginate carbon aerogels. The adsorption kinetics of AACA for the three dyes were fit for the pseudo-second-order kinetic model and the adsorption isotherms could be explained by the Langmuir model. ACCA revealed good adsorption performance for other eleven different sorts of dyes and binary dye systems. The adsorption mechanism was mainly confirmed to be π–π interactions.

CeO₂-ZnO nanocomposites were successfully synthesized using Parkia speciosa Hassk bark aqueous extract by one pot phytosynthesis method. Parkia speciosa Hassk bark extract was used for the first time, in a novel approach, for phytosynthesis of CeO₂-ZnO nanocomposites through this work. The properties of nanocomposites were characterized by Fourier-Transform Infrared (FTIR), Scanning Electron Microscopy—Energy Dispersive X-ray Spectroscopy (SEM–EDX), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Raman, and UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS). The CeO₂-ZnO nanocomposites were successfully formed with well-dispersed and small particle size (22.2 nm). The nanocomposites exhibit superior photocatalytic activity under sodium light irradiation toward reduction of nitroaromatic compound within 4 min reaction time. This result demonstrated promising green CeO₂-ZnO nanocomposites for sustainable wastewater treatment.

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This work describes a simple technique for producing bio-synthesized Magnesium oxide modified magnetite nanoparticles (MgO@MNPs) for the removal of AO dyes using Almond (Terminalia catappa) leaf extract (ALE). ALE is employed as capping, stabilizing, and reducing agent. This work presents an investigation of the removal of dye using nanoparticles. In this study synthesized nanoparticles get characterized using various analytical techniques such as UV–Vis, XRD, FT-IR, TGA, SEM, EDX, and VSM. The adsorption conditions were tuned for the maximal removal of AO dyes by altering many physicochemical factors, including pH (8.0), initial concentration of AO dye (30 mg/L), MgO@MNPs dosage (8 mg), contact time (8 min), and reaction temperature (298 K). The results of isotherm study indicated that Langmuir model adequately described the adsorption process and effectively removed the dye with a high adsorption capacity (q_max) 526.31 mg/g. Additionally, the study evaluated the kinetic and thermodynamic aspects of the adsorption process. Moreover, the adsorption process was found to be spontaneous, exothermic, and followed a pseudo-second-order kinetic model. HCl was found to be an effective desorbing agent in the desorption experiment. The adsorbent could be reused for seven cycles effectively with at least 96% removal of AO dye. The comparison table provided in this work further highlights the effectiveness of the present study. Overall, this study offers a promising approach for the efficient removal of AO dye from wastewater, with potential for practical applications in the field of wastewater treatment.

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Present research investigates synthesis of silica-coated zinc oxide nanocomposite (Si-ZnO NC) from plant material and its application in remediation of Cr(VI) from water systems. The synthesized nanocomposite was assessed using XRD, FTIR, SEM-EDAX, and BET analysis. Si-ZnO NC possessed a mean pore diameter and volume, 27.964 nm and 0.1895 cm³g^-1_, respectively and a specific surface area of 27.113 m²g^-1. The nanocomposite had roughly spherical particles in agglomerated form as per SEM analysis. Effects of pH, metal concentration, adsorbent dose, temperature and time on Cr(VI) removal were investigated in batch mode experiments. The adsorption conditions including pH 2, metal concentration 10 mg/L, nanocomposite dose 0.4 g/L with a contact time 60 min at 25 ± 2 ^o C temperature showed 92% Cr(VI) removal. Langmuir isotherm model (R² = 0.9978) and pseudo-second-order model (R² = 0.9998) proposed a decent explanation for Cr(VI) adsorption rate. The process was found spontaneous and endothermic. Adsorption mechanism involved electrostatic interaction, redox reactions and adsorption coupled reduction. The regeneration ability of Si-ZnO NC was 86% Cr(VI) after three reusability cycles with 0.1M NaOH desorbing reagent as compared to 15% ammonia water. Si-ZnO NC proved to be sustainable and eco-accommodating due to its low-cost raw substance value, efficient adsorption efficiency and regeneration ability.

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In the work, bismuth tungstate (Bi₂WO₆, orthorhombic system) photocatalyst nanomaterial was synthesized by hydrothermal method. The photocatalytic ozonation oxidation synergistic degradation on organic pollutants in coal chemical phenol-ammonia wastewater by Bi₂WO₆ was studied. The effects of ozone (O₃) concentration, catalyst dosage, pH and O₃ flow rate on the degradation efficiency of wastewater were investigated, respectively. The study found that the degradation processes of these four single factors were fitted kinetically and aligned with the pseudo second order kinetics model, and the maximum chemical oxygen demand (COD) removal rate of the coal chemical phenol-ammonia wastewater was 56.34%, 79.03%, 78.63%, and 79.66%, respectively. The COD removal rate reached 80.37% under the optimum reaction conditions. Additionally, the degradation process was optimized, which conformed to the pseudo second order kinetics model. Density functional theory (DFT) calculations showed that the adsorption energies of O₃ at the Bi, W, and O atomic sites were -0.477 eV, -2.604 eV, and -0.421 eV, respectively, on the exposed crystalline surface of (131), indicating that O₃ had a stronger interaction force with W, which was easy to be activated by the surface-transferred electrons to form reactive oxygen species and mineralize the organic pollutants. The catalytic mechanism indicates that the photocatalytic ozonation oxidation is primarily accomplished by producing •OH, ¹O₂, and (bullet O_2^-), which results in the degradation on organic pollutants in coal chemical phenol-ammonia wastewater. The analysis of water quality and GC–MS indicated that most pollutants present in coal chemical phenol-ammonia wastewater had degraded upon treatment. Furthermore, the BOD/COD ratio of coal chemical phenol-ammonia wastewater was increased from 0.25 to 0.32. Moreover, the COD removal rate only decreased to 70.25% after five cycles of the experiment, which demonstrated that the Bi₂WO₆ catalysts had a high stability and reusability, implying that it has great potential for application in coal chemical phenol-ammonia wastewater treatment.