Utilization of lignite coal as heavy metal adsorbent in chemistry laboratory wastewater

Wastewater from Chemistry Laboratory contains heavy metals which need treatment before being discharged into the environment. This study investigates the treatment of chemistry laboratory wastewater using activated carbon. The activated carbon was made from lignite coal with ZnCl2 activation and carbonization was carried out at a temperature of 500°C for 2 hours. The highest iodine number is 1529.20 mg/g on activated carbon with a grain size of 80 mesh of coal and a composition of 40% ZnCl 2 -60% coal. Adsorption of Fe, Cr and Pb metals using activated carbon was carried out at 2 variations of initial concentrations. At an initial concentration of 75.8 ppm Fe, metal adsorption is 84%, while at an initial concentration of 37.9 ppm it is 87%. The adsorption of Cr metal is 44% at an initial concentration of 1.37 ppm, and it is 79% at an initial concentration of 0.69 ppm. The adsorption of Pb metal is 91% at an initial concentration of 11.2 ppm, and it is 91% at an initial concentration of 5.6 ppm. The results showed that activated carbon from lignite coal could adsorb Fe, Cr and Pb metals, and the initial concentration influenced the effectiveness of metal adsorption.