Chemosphere最新文献

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .

This study highlights the use of loblolly pine derived biochar for the removal of harmful algal bloom toxin, Saxitoxin (STX), from water. Biochar samples were prepared at varying pyrolysis temperatures (400, 600 and 800 °C) for 60 min. As pyrolysis temperature increases, enhancement in surface porosity was observed (S_BET = 7.26 ± 0.2 m²/g to 408.15 ± 6.19 m²/g) while a decline in oxygen-containing functional groups was observed (1517.80 ± 14.98 μmol/g to 823.01 ± 7.72 μmol/g). This study aimed to discover the effects of adsorption parameters such as biochar dosage amount, contact time, initial concentration and initial pH on Saxitoxin adsorption. These studies revealed impressive results with >90 % toxin removal with dosage rate of 0.01 g/L, contact time of 30 min, and increasing percent removal with increasing initial STX concentration and initial pH in water. Maximum uptake was calculated for P400 with adsorption capacity of 314.37 μg/g. This showed that surface functionality showed higher affinity for STX uptake, which may be possible due to hydrogen bonding, electrostatic interactions, ion-exchange, and π-π interactions. Applied kinetic models indicated both physisorption and chemisorption interactions with best fit supporting the Elovich models. Complementary, adsorption isotherm analysis confirmed the multilayer adsorption behavior of the Freundlich model. Therefore, these findings support the viable use of biochar material for the remediation of STX waters.

Tungsten oxide (WO₃) nanoparticles (WO₃NPs) were prepared using beetroot (Beta vulgaris) extract. The synthesis was optimized by evaluating the effect of pH during the reduction of the WO₃ precursor and sintering temperature. Physicochemical characterization of the formed nanoparticles was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance UV-visible spectroscopy. Furthermore, the prepared WO₃NPs were employed as photocatalyst for rhodamine B removal over the photocatalytic oxidation mechanism. Synthesis optimization revealed that a single phase of WO₃NPs obtained by reduction at pH 4 and a sintering temperature of 550 °C. XRD and XPS measurements revealed that the single-phase WO₃NPs was obtained with a crystallite size of 26.4 nm. SEM and transmission electron microscopy (TEM) indicated polymorphic forms, predominantly as nanorods, with a mean particle size of 24 nm. The WO₃NPs have a band gap energy of 2.9 eV, supporting their performance as a photocatalyst. Evaluation of the photocatalytic activities of WO₃NPs represents high activity and reusability of the material. A removal efficiency of 99.67% was achieved during 30 min of treatment under UV light illumination. A study on the effect of scavengers revealed the important role of hydroxy radicals in the photocatalysis mechanism. WO₃NPs can be recycled and reused for photocatalysis, maintaining photoactivity for five cycles.

Invincible growth in waste production is the consequence of overpopulation, which should be addressed to reduce the occupied landfill surface needed for their disposal and to alleviate the leachate of extremely hazardous material into the soil and water bodies. In this study, copper (Cu) was extracted from fly ash of a municipal solid waste incinerator by an electro-chemical method, which was optimized to recover the highest amount of Cu, and then it was chelated with 4-aminobenzoic acid (AM) and terephthalic acid (TM) in an aqueous phase. The obtained composites were then heated to form a porous calcinated copper-carbon composite and utilized to adsorb the forever contaminant of PFOS from aqueous solutions. As the calcinated composite of Cu/AM with a ratio of 1:1 removed a greater amount of PFOS from the aqueous solution than Cu/TA, it was utilized as the ultimate adsorbent. The platform adsorbent was subjected to multiple characterizations, including XRD, FESEM, elemental mapping, TEM, BET, EDS, ICP-OES, FTIR, DLS, and point of zero charges, as well as optimization of several operational parameters involving pH, adsorbent dosage, initial PFOS concentration, and contact time. At the neutral pH, under the optimal conditions (adsorbent dosage of 1 g L^-1 and 5 h), 97.23% of PFOS was eliminated from the solution spiked with 5 mg L^-1 of PFOS. The equilibrium data were best fitted with Frundlich isotherm, and the maximum adsorption capacity of 402 mg g^-1 was achieved. The optimal conditions were also applied to PFOA, demonstrating high adsorption of different types of PFAS. The recovery tests of the adsorbent conducted 5 times on the solution spiked with 10 mg L^-1 of PFOS showed a slight decrease in PFOS removal at least for 5 regeneration cycles, demonstrating the high adsorption capacity and its reusability, thereby validating its feasibility for large-scale applications.