Adsorption of azo and anthraquinone dye by using watermelon peel powder and corn peel powder: equilibrium and kinetic studies

Clean water is an essential element for the survival of humans and nature. However, the tremendous growth in industrialization has degraded the water quality by introducing pollutants such as dyes into the main water bodies such as rivers. In this research, the locally collected agricultural wastes such as watermelon peel (Citrullus lanatus) and corn peel (Zea Mays) were tested on two types of synthetics dyes such Remazol Brilliant Violet 5R (RBV5) and Remazol Brilliant Blue R (RBBR). From the screening test, the watermelon peel achieved the highest color removal percentage with 44.8% and followed by corn's peel with 18.89%. Both adsorbents were selected for the batch adsorption test by varying the parameters. Based on the results achieved from the batch adsorption test, the optimum removal of dye particles was achieved at the lowest concentration of dye solutions. The optimum pH value to achieve a high percentage of color removal is at pH3, which is acidic. In this case, the 3 g of adsorbent dosage achieved the highest percentage of color removal compared to 5 g. This could due to insufficient contact time. In addition, the chemical and physical characteristics of the adsorbents were analyzed using FESEM and FTIR respectively. By analyzing the surface texture and functional group, differences in the adsorbents before and after adsorption were noticed. Besides that, based on the obtained R-2 values from the linear plotting, the Temkin isotherm model and pseudo-second-order kinetic model fitted well compared to other isotherm and kinetic models. In conclusion, the watermelon peel and corn peel are capable of removing dye particles in the industrial effluent under selective conditions with low cost while being environmentally friendly.