Decolourisation of direct red dye 81 from aqueous solutions by SnO2/H2O2 hybrid process

The aim of this study was to use tin oxide (SnO2) nanoparticle along with hydrogen peroxide (H2O2) and to evaluate their potential in removing direct red 81 (DR 81) dye from aqueous solution.This study was performed on a laboratory scale in a batch mode. To evaluate the structural properties of SnO2 nanoparticles, X-ray diffraction (XRD), and electron microscopy (SEM) images were used.According to BrunauerEmmettTeller (BET) analysis, the particle size is 10 nm. Laboratory results showed that the DR 81 removal efficiency by SnO2/H2O2 hybrid process reached 97.73% under the conditions including H2O2 concentration of 0.1 mmol/L, SnO2 concentration of 0.12 g, initial dye concentration of 25 mg/L, and pH of 3 after 60 min. DR 81 dye removal efficiency has a direct relationship with an increase in reaction time and SnO2 concentration while there is an inverse relationship between removal efficiency with the increase in pH, hydrogen peroxide concentration, and initial dye concentration.Considering the obtained results, the hydrogen peroxide activated by the SnO2 catalyst has a good ability for removal ofDR 81 dye, and this process can be used to remove DR 81 dye and other anionic dyes from wastewaters containing these pollutants. According to the results of the reaction rate, it can be concluded that the process follows the pseudo-second-order kinetics.

Automated summary

This study successfully removed direct red 81 dye from aqueous solution using tin oxide nanoparticles and hydrogen peroxide. The results showed that an increase in reaction time and SnO2 concentration improved the removal efficiency, while an increase in pH, hydrogen peroxide concentration, and initial dye concentration decreased the removal efficiency.