Removal of Remazol brilliant blue r and Remazol brilliant violet 5r dyes from aqueous solution by adsorption using coffee residue

Abstract

AbstractAs a crucial ingredient for human and animal survival, clean water also contributes significantly to a nation's ever‐expanding economy. However, the availability of clean water has deteriorated as contaminants, such as dyes, have a significant detrimental effect on the pure and clean main waters. Coffee residue with micro‐ and macropores is a potential biosorbent for the removal of synthetic dyes from aqueous solutions. This study aims to determine the efficacy of adsorption of synthetic colors by coffee dregs. Using the Central Composite Design (CCD), the impacts of four adsorption factors (contact time, pH, starting concentration, and adsorbent dosage) were investigated (CCD). For the percent elimination of Remazol brilliant blue R (RBBR) and Remazol brilliant violet 5R, quadratic models were created (RBV‐5R). The ideal adsorption conditions consisted of a pH of 3, a dosage of 5 g of adsorbent, an initial concentration of 10 mg/L, and a contact period of 30 min for RBBR and 60 min for RBV‐5R, resulting in a removal of 49.98% and 93.8%, respectively. The experimental and projected values for RBBR were 96.57% and 95.2% for RBV‐5R, respectively, demonstrating high agreement with minimal errors. The Langmuir isotherm model fit the equilibrium adsorption data of the two selected dyes the best. In addition, the pseudo‐second‐order kinetic model was able to better characterize the experimental data with good respective regression coefficients.