Journal of Water Chemistry and Technology最新文献

The objective of this study is to investigate the removal of selected pharmaceuticals such as ibuprofen (IBP), diclofenac (DCF), and carbamazepine (CBZ) by activated carbon (AC) when they are present in the aqueous solution as an individual entity or as a mixture. The coconut (AC_Eco) and lignite (AC_Darco) derived ACs after and before the impregnation of cerium were used as the adsorbent. Batch experiments were carried out for assessing the removal efficiency under varying conditions. The removal efficiencies of those pharmaceuticals were in the range of 66.2–99.8%. In the case of IBP and DCF, the removal was found to decrease slightly by AC_Eco and AC_Eco-Ce when the mixture of pharmaceuticals was used as compared to individual pharmaceuticals. The sorption kinetics results indicated that IBP (for both AC_Eco and AC_Darco) and CBZ (AC_Eco) were best fitted to the pseudo-first-order kinetics model, whereas the DCF (both for AC_Eco and AC_Darco) and CBZ (AC_Darco) fits better to pseudo-second-order model. The outcome of the study indicates that selected ACs were found effective in removing IBP, DCF, and CBZ when they are present as an individual entity or as a mixture in the aqueous solution.

The present study was carried out with Kolmé clay in Liptako. X-rays diffraction results suggest that kaolinite was the predominant phase in this clay. The zero charge point of the pHpzc clay is about 7.1. The adsorption value and the percentage of fluoride ion removal by the clay increase up to a contact time of 1 h. Beyond this value, however, the fluctuation varies very little. This adsorption value increases with the fluoride ion concentration of the solution. However, it decreases considerably as the pH increases. The process of elimination of fluoride ions is done in three steps, including the diffusion of fluoride ions on the surface of the clay, the migration of fluoride ions from the surface of the clay to the active intra-particle sites and finally the chemisorption of fluoride ions on the active sites. The study of the sorption equilibrium of fluoride ions for the different concentrations indicates that the adsorption process appears to be both monolayer and multilayer and corresponds well to the Langmuir and Freundlich models. The fluoride ion adsorption kinetics can be fitted to the first and pseudo second order Lagergren models. The different velocity constants reflect a slow diffusion of fluoride ions, so this clay can be used in water defluorination.

Nenensangcuo is a typical karst travertine scenic spot in the eastern margin of Qinghai−Tibet Plateau. Studying its hydrochemical evolution characteristics and driving factors is of great significance to local economic and social development and scientific management of water resources. The characteristics of hydrochemistry are analyzed by mathematical statistics, and the types of hydrochemistry are analyzed by Piper’s three-line diagram. The sources of main ions in surface water and their influencing factors are discussed by Gibbs diagram and ion correlation analysis. The pH value of water body varies from 6.6–8.2, and the TDS value varies from 210–747 mg/L. The main sources are Ca²⁺, ({text{HCO}}_{3}^{ - }), Mg²⁺, Cl^– and ({text{SO}}_{4}^{{2 - }}). The dominant cation is Ca²⁺, the dominant anion is ({text{HCO}}_{3}^{ - }), and the hydrochemical type is HCO₃–Ca. The hydrochemical composition is comprehensively influenced by weathering, mineral dissolution and precipitation of rocks, in which Ca²⁺ and ({text{HCO}}_{3}^{ - }) mainly come from weathering and dissolution of carbonate rocks.

Wastewater containing high concentrations of polyvinyl alcohol (PVA) resists conventional methods such as biological oxidation and requires high doses of chemicals in the case of chemical processes such as coagulation and adsorption. Due to these features, a comparative study has been conducted for the treatment of PVA in textile industrial wastewater by classic Fenton (CF) and electro-Fenton (EF). According to the results of CF, the optimum removal efficiency of the total organic carbon was obtained as 81% at pH 3.0, 43.5 g/L of H₂O₂ dose, 2.5 g/L of FeSO₄·7H₂O during 24 h and it reached 85.5% at 120 min in EF at the optimum values (pH 3, H₂O₂ dose = 43.5 g/L and 0.58 A of the current). When the cost of treatment by the CF method was found as 78.206 €/m³, it was 78.046 €/m³ by the EF process. For the first time in the literature, a comparative study of EF and CF in treatment of the PVA-containing wastewater was presented and high treatment efficiency was achieved. In this study, pH change in the EF process and its negative effects on the treatment efficiency were observed. Determining the need for constant pH adjustment to eliminate these negative effects is one of the most important outputs of this study. In addition, higher treatment efficiencies by EF have been obtained compared to CF.

This work is an attempt to remove Cr(VI) from simulated wastewater using electrocoagulation (EC) process where stainless steel (SS) is used as a sacrificial electrode. The central composite design (CCD) of response surface methodology (RSM) is used to optimize different operating parameters including initial pH (pH_i: 1.5–9.5), current density (j: 20.75–104.15 A/m²), electrode gap (g: 1.5–2.5 cm), and treatment time (t: 0–30 min), with respect to the removal of Cr(VI) from simulated water. The high coefficient of determination for Cr(VI) (R² = 0.9922) was found by the analysis of variance (ANOVA) between the experimental data and the predicted data using a second-order regression model. The maximum Cr(VI) removal of 88.9% was achieved at optimum conditions (pH 3.5, j = 83.3 A/m², g = 1.75 cm, and t = 24 min) as reflected by ANOVA analysis. A foam and residues analysis has also been incorporated.

El-Zafarana silica sand (ZSS) was modified with ZnO and CuO forming the new adsorbent ZnO−CuO/ZSS for removing U(VI) and Th(VI) from aqueous solutions. The removal process was performed in a series of batch experiments. The prepared adsorbent was characterized using different analysis techniques: scanning electron microscopy/energy-dispersive X-ray (SEM/EDX), X-ray diffraction (XRD), and Fourier-transforms infrared spectroscopy (FTIR). The influence of various parameters: pH, contact time, initial concentration, and temperature, on the adsorption process was studied. Kinetics and isothermal data reveal the chemisorption and the homogenous adsorption process with maximum adsorption capacities of 73.31 and 64.93 mg/g for at pH 6 and 5 for U(VI) and Th(IV), respectively. The thermodynamic parameters (ΔH°, ΔS°, ΔG°) confirm the endothermic nature of the adsorption process. The desorption study was carried out and found that ZnO–CuO/ZSS can effectively recover U(VI) and Th(IV) by 0.01 M HNO₃. The results indicate that ZnO–CuO/ZSS is an efficient adsorbent for U(VI) and Th(IV) from aqueous solutions.

Adsorption of Fe(III) ions and Fe(III) complexes on selected adsorbents in aqueous solutions is reported. Fe(III) complexes with ribose, lactic acid, glycine and valine were prepared, and FTIR spectra validated their formation. The structural data of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis also confirm the structure of the iron-ligand complexes and their adsorption on selected ligands (celite, cellulose, bentonite, activated carbon, carbon nanoparticles). Fe(III) adsorption from Fe−ligand complexes (FeLCs) on adsorbents in an aqueous solution was higher than the adsorption of metal ions alone. Compared with non-carbon adsorbents, carbon adsorbents carbon nano particles (CNP) and activated carbon (AC) showed higher adsorption of FeLCs. The atomic absorption spectroscopy (AAS) studies showed that the Fe−valine complex demonstrated the maximum adsorption (1719.18 ppm) compared to other samples. energy dispersive X-ray spectroscopy (EDS) studies confirmed a 2.16-fold increase in Fe(III)−Val complex adsorption compared with the pure metal ions. The current strategy provides an efficient proto-type to remediate Fe(III) contaminated water and to fortify Fe(III) through diet.

Employing the sol-gel method, a novel molecularly imprinted Ni and F co-doped TiO₂ photocatalyst has been synthesized, which is active in visible light. The synthesized photocatalyst has been subsequently characterized by XRD, N₂ adsorption/desorption analysis, EDS, FESEM, FTIR, and TEM analysis. Paracetamol has been decomposed during photodegradation. CCD under RSM has been used for the assessment of the effect of individual variables and also their possible interaction effects. Obtained optimum values for the maximum efficiency (83.6% by the desirability function value of 1.0) were at pH of 6.150, the photocatalyst mass of 87.0 mg, the paracetamol concentration of 0.01 mg/L, and the irradiation time of 224.2 min. Under optimum experimental conditions, this method exhibited linear range of 0.0050–0.0150 mg/L for paracetamol with the detection limit of 0.001 mg/L. Repeatability and the intermediate precision for paracetamol concentration have also been evaluated and the resultant RSDs were 2.07 and 2.11%, respectively. This method provides a good selectivity against phenol. The five-time regeneration and the recovery percentage of photocatalyst were evaluated that demonstrated bewildering results and confirmed its susceptibility. The photocatalyst, demonstrated the stunning efficiency degradation of paracetamol under the exposure to white LED as a visible light source. The surface and photocatalytic performance of synthesized photocatalyst have been upgraded as a result of doping with Ni and F elements.