Degradation of mixed dye via heterogeneous Fenton process: Studies of calcination, toxicity evaluation, and kinetics

Effective degradation of synthetic micropollutants and real textile wastewater via a visible light-activated persulfate system using novel spinach leaf-derived biochar

A novel biochar (BC), derived from spinach leaves, was utilized as an activator for persulfate (PS) in the degradation of methylene blue (MB) dye under visible light conditions. Thorough analyses were conducted to characterize the physical and chemical properties of the biochar. The (BC + light)/PS system exhibited superior MB degradation efficiency at 83.36%, surpassing the performance of (BC + light)/hydrogen peroxide and (BC + light)/peroxymonosulfate systems. The optimal conditions were ascertained through the implementation of response surface methodology. Moreover, the (BC + light)/PS system demonstrated notable degradation ratios of 90.82%, 81.88%, and 84.82% for bromothymol blue dye, paracetamol, and chlorpyrifos, respectively, under optimal conditions. The predominant reactive species responsible for MB degradation were identified as sulfate radicals. Notably, the proposed system consistently achieved high removal efficiencies of 99.02%, 96.97%, 94.94%, 92%, and 90.35% for MB in five consecutive runs. The applicability of the suggested system was further validated through its effectiveness in treating real textile wastewater, exhibiting a substantial MB removal efficiency of 98.31% and dissolved organic carbon mineralization of 87.49%.

The remediation of textile wastewater using solid Bauxite Residue waste as a potential Fenton catalyst in the fluidized bed Fenton process

The synergistic relationship between the reactor and the catalysts has gained immense popularity in the field of Chemical Engineering due to their wide application. Catalytic processes have evolved over the decades from expensive commercial catalysts to low-cost solid waste catalysts for the sustainable development and reduction of their impacts on the environment. This alternative use of solid waste can greatly decrease the cost of wastewater treatment and addresses solid wastes issues. Bauxite Residue (BR) is one such waste from alumina-based industries with excellent catalytic properties. The fluid dynamics of fluidized bed technology improves profoundly the hydrodynamics and mass transfer of the heterogeneous Fenton process. This paper presents the preparation of the catalyst with minimum processing effort. It was characterized and factors affecting the degradation efficiency of synthetic dye wastewater were investigated. The optimum conditions for the eosin yellow dye were observed at a pH of five, oxidant concentration of 30 mM, catalyst dosage of 4 g/L. The removal efficiency at these optimum conditions was observed to be 91%. The residence time distribution (RTD) study was aimed to determine the behavior of the reactor using the mean residence time, variance, and dispersion number for the fluidized bed reactor.

Modeling and optimization of simultaneous degradation of rhodamine B and acid red 14 binary solution by homogeneous Fenton reaction: a chemometrics approach

This study aimed to propose a mathematical method to investigate and optimize the simultaneous elimination process of multiple organic pollutants using the Fenton process. Hence, the treatment of rhodamine B (RB) and acid red 14 (AR14) dyes in their binary solution was studied. Multivariate curve resolution alternating least square (MCR-ALS), a novel chemometric method, was applied along with correlation constraints to resolute the UV-Vis spectrophotometric data, enabling quantification of investigated dyes despite a high spectral overlapping. Response surface methodology was adopted to assess the model and optimize individual and interactive effects of three independent factors (Fe²⁺, H₂O₂ and initial pH) on the simultaneous elimination of RB and AR14. The values of the regression coefficient for RB and AR14 were determined as 98.48 and 98.67 percent, respectively, revealing the reliability of the obtained polynomial models to predict decolorization efficiencies. Desirability function was employed to optimize the independent variables to attain the highest possible degradation performance for both dyes in their binary solution. At the optimum point of operation ([Fe²⁺] = 143.88 mg/L, [H₂O₂] = 126.89 mg/L and pH = 3.71), degradation efficiencies of RB and AR14 were found as 81.58% and 80.22%, respectively, which were nearly identical to the experimental results.