ABSORPTION CHARACTERISTICS OF NAPA SOIL AS CONGO RED DYE ADSORBENT IN SOLUTION WITH CONTINUOUS SYSTEM.

Waste dyes such as Congo red at certain levels can damage the environment because of toxicity and may cause malfunctioning of the liver, kidneys, and nerves. Therefore, this study aims to analyze optimum pH, concentration, particle size of the adsorbent, and the eluent flow rate on the adsorption of Congo red by Napa soil (NS). The results showed optimum pH of 6, an initial concentration of 20 mg/L, and a particle size of 75 µm and the optimum flow rate of the eluent of 40 drops/minute. Furthermore, the determination of adsorption at the optimum condition of the NS as adsorbent without treatment (fresh) has a higher capacity than the purified Napa soil. The absorption capacity was 0.37 mg/g and 0.25 mg/g, and desorption at the optimum condition (recovery column) showed that the highest percentage is by using ethanol. Besides reducing the concentration of the Congo red dye and determining the absorption capacity of the adsorbent, the other aim of the adsorbent application is for pre-concentration. The results showed that the number of concentrated Congo red dye is equal to 0.11 mg/g. [ABSTRACT FROM AUTHOR]