The utilization of water hyacinth (Eichhornia crassipes) harvested from the phytoremediation process as activated carbon in Cr(VI) adsorption

Abstract

Water hyacinth (Eichhornia crassipes) is one aquatic plant widely used in phytoremediation. Water hyacinths can absorb organic, inorganic, and heavy metal pollutants. Cr(VI) is one of the heavy metals found in industrial waste. Adsorption is one of the techniques used to remove the heavy metal content. Activated carbon is one of the good adsorbents because it has a high adsorption ability. The ability of activated carbon to adsorb is influenced by surface area, solution pH, and adsorbent dose. This study aims to utilize water hyacinth-activated carbon to absorb Cr(VI) and determine the optimum adsorption conditions based on pH, contact time, activated carbon weight, and variations in the optimum concentration of Cr(VI) solutions. Conducted the research experimentally with the stages covering: (1) the manufacture of activated carbon from water hyacinth, (2) the carbonization process at temperatures of 300°C and 600°C for 2.5 hours, (3) the chemical activation process with ZnCl2 10%, (4) quality testing of activated carbon based on SNI No. 06-3730-1995 on moisture content, ash content, iodine absorption, methylene blue absorption, (5) characteristics of water hyacinth-activated carbon functional groups by FTIR, (6) preliminary tests, (7) optimization of optimum adsorption conditions on variations in pH, contact time, activated carbon weight, concentration Cr(VI) solutions with UV-Vis spectrophotometer. The results showed that the characteristic test of water hyacinth-activated carbon had met the requirements of SNI No. 06-3730-1995 for moisture content, iodine absorption, and methylene blue absorption. A preliminary test showed that the activated carbon of water hyacinth leaves had the highest adsorption capacity. The optimum conditions for the adsorption of Cr(VI) by water hyacinth leaves were at pH 1, the weight of activated carbon 1 gram, a contact time of 24 hours, and a concentration of Cr(VI) solutions of 200 mg/L.