Potential of Citrus limetta peel powder (CLPP) for adsorption of hazardous Congo red dye from wastewater

Abstract

Abstract In this study, Congo red anionic dye was removed from an aqueous solution using powdered Citrus limetta peel. The adsorbent was evaluated with the use of FTIR and SEM. The highest dye removal was achieved when the operating parameters were optimized, including pH = 6.0, adsorbent dose = 0.4 g, contact time = 90 min, initial adsorbate conc. = 10 ppm, and temperature = 60 °C. The pseudo-second-order model was investigated to have the best fit for the kinetics of the process, with R2 = 0.9918 and Qe(cal) = 0.206 mg g-1, which is very close to the experimental Qe(exp) = 0.191 mg g-1. These two models’ plots showed that both physical and chemical adsorption were feasible. ΔG and ΔH being negative suggest that the adsorption was thermodynamically favorable and spontaneous. Testing the suggested technique with groundwater resulted in an 82% CR adsorption efficiency. Due to the incredible removal capacity of CR dyes from industrial effluents, research suggests that CLPP can be used as substitute adsorbents for the treatment of wastewater from the weaving and dyeing industries.