Colloids and Surfaces C: Environmental Aspects最新文献

A research study examined the origins, human health impacts, and risks associated with pollutants in vegetables grown in soil irrigated with wastewater. The study analyzed 164 samples from water sources, irrigated soil, and harvested vegetables for eight heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) using atomic absorption spectrophotometry. The focus was on the potential health effects of consuming heavy metal-contaminated vegetables grown in wastewater-irrigated soil. The findings revealed significant accumulation of heavy metals in soil and plants from Mianwali, Pakistan, posing potential health risks to consumers. When compared to vegetables produced with freshwater irrigation, the concentration levels of heavy metals in the soil irrigated with untreated wastewater were significantly greater (P≤0.001) and above the recommended limits set by the World Health Organization (WHO). The results showed that heavy metals in the soil had significantly increased, and crops had subsequently absorbed these metals. Produce raised in soil watered with wastewater showed higher levels of heavy metals than the US Environmental Protection Agency (EPA) and the WHO recommended. Among the veggies, lead (Pb) and cadmium (Cd) were found to have higher Hazardous Quotient Indices (HRIs) than one. This indicates that both adults and children may have been exposed to dangerous levels of these metals. Additionally, for Brassica oleracea, Raphanus sativus, and Spinacia oleracea, nickel (Ni) surpassed HRIs larger than 1, indicating a significant health risk connected to these veggies' ingestion.

In this study, we developed and characterized a novel chitosan-alginate-based polyelectrolyte complex impregnated with zinc oxide nanoparticles (CS-ZnO-Alg PEC) for the enhanced removal of Cd(II), Cu(II), and Ni(II) from simulated paint industrial wastewater. The prepared PEC was characterized by X-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS), X-ray Photoelectron Spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis/Differential Thermal Analysis (TGA/DTA). The equilibrium data for said metal ions was best appropriated by Freundlich isotherm with maximum adsorption capacity of 217.72 mg/g for Cd(II), 130.41 mg/g Cu(II), and 159.06 mg/g for Ni(II), illustrating the multilayer adsorption of metal ions on the heterogeneous surface sites of the adsorbent. The kinetics of all three metal ions adsorption process onto discussed PEC was consistent with pseudo-second-order model. The thermodynamics results illustrate exothermic and spontaneous processes for Cd(II) (ΔH° = −3.57 KJ/mol, ΔS° = 0.009 KJ/mol*K, ΔG° = −6.42 to −6.61 KJ/mol) and Cu(II) (ΔH° = −3.32 KJ/mol, ΔS° = 0.006 KJ/mol*K, ΔG° = −5.25 to −5.37 KJ/mol), and spontaneous but less favorable adsorption for Ni(II) (ΔH° = −0.82 KJ/mol, ΔS° = −0.001 KJ/mol*K, ΔG° = −0.39 to −0.36 KJ/mol). Notably, the PEC could be easily recycled and regenerated, maintaining adsorption efficiency after five cycles. Overall, the CS-ZnO-Alg PEC, due to its amphoteric nature, high adsorption efficiency, cost-effectiveness, excellent recyclability, and biodegradability, could be a promising adsorbent for paint industrial wastewater.

Addressing the significant emissions and severe pollution hazards posed by coal fly ash waste in the coal chemical industry, as well as the challenges in recovering phenolic substances from coal chemical wastewater, this study utilized coal fly ash as a raw material to construct two types of spherical grain adsorbents: coal fly ash and coal gangue spherical grain (CFAGsg) and coal fly ash and pyrite spherical grain (CFAPsg). The adsorption performance of CFAGsg and CFAPsg towards phenolic substances in coal chemical wastewater was investigated. The research results demonstrated that CFAGsg and CFAPsg exhibited adsorption capacities of 20.31 mg/L and 30.42 mg/L for phenol, respectively, and maintained stable adsorption performance even after multiple regeneration cycles. Further analysis using kinetic, isotherm, and thermodynamic models, along with various characterization techniques, revealed that the adsorption of phenol onto CFAGsg and CFAPsg was primarily governed by physical and chemical adsorption, involving an endothermic reaction. Moreover, the study on the adsorption mechanism of phenol revealed that the adsorption behavior of CFAGsg and CFAPsg was mainly driven by pore filling, π-π stacking, and hydrogen bonding. Additionally, hydrophobic interactions were involved in the adsorption of phenol onto CFAGsg, while surface complexation forces played a role in the adsorption of phenol onto CFAPsg. Overall, the research findings provide vital theoretical support and practical application prospects for the high-value utilization of coal fly ash and the clean production of the coal chemical industry.

The membrane distillation (MD) has been considered as an attractive technique for the desalination and water treatments. However, the membrane with the superhydrophobic surface is still urgently needed for the wide application of MD process. Inspired by nature, the membranes with the highly porous structure have been fabricated by electrospinning to enhance the water vapor permeation in MD process. In this work, a hydrophobic layer with the hierarchical reentrant architecture was fabricated by electrostatically depositing silicon dioxide (SiO₂) nanoparticles on the surface of polyvinylidenefluoride electrosprayed layer followed by the fluorination treatment. The properties of hydrophobic layers were evaluated by varying the electrospraying time and SiO₂ loading amount. The optimal membrane had a water contact angle value of 145.7° and surface roughness of ∼275 nm, demonstrating a water flux of 21.2 L^.m^−2.h⁻¹ and superior salt rejection of >99.9 % when 3.5 wt% NaCl solution was used as the feed solution and the temperature difference was set as 40 °C. The membrane showed an excellent operation stability and effective mitigation in scaling and fouling tendency. The prepared membrane could be applied as a good candidate for the MD-based water treatment processes.

This research investigated the ability of acid-modified pomegranate peel to remove malachite green (MG) dye from aqueous solutions. Pomegranate peel, an abundant agricultural byproduct, was modified using hydrochloric acid to enhance its adsorption capacity. The effects of parameters like particle size, pH, initial MG concentration, contact time, temperature and adsorbent dosage on the dye removal efficiency were studied. Under optimized conditions of pH 8, 40 min contact time, 25°C temperature and 0.01 g/ml adsorbent dose with 5 mg/L MG solution, about 96.8 % dye removal was achieved. Kinetic data fitted well to the pseudo-second order model, indicating chemisorption with electrostatic interactions governing the adsorption. Equilibrium data were best described by the Temkin isotherm model, suggesting a heterogeneous binding energy distribution. Thermodynamic calculations revealed the exothermic and spontaneous nature of MG adsorption. FTIR analysis confirmed introduction of functional groups like carboxyl, amine and alkyl groups on the adsorbent surface after acid modification, enabling interactions with dye cations. SEM images displayed increased surface roughness and porosity for the modified biosorbent relative to the raw form. The acid-modified pomegranate peel proved to be an economical, eco-friendly and effective adsorbent for removing the hazardous cationic dye MG from wastewater. The findings support agricultural waste valorization for environmental remediation applications.