Enhanced Removal of Copper from Synthetic Wastewater Using a Water Hyacinth-Based Activated Carbon and Chitosan Composite Adsorbent

Abstract

Copper (Cu) contamination of rivers or groundwater is a worldwide problem caused by anthropogenic activities, commonly from the industrial sector. Cu accumulation in the body could have detrimental effects on human health as well as pose a major threat to the aquatic environment. We report the rate of Cu removal by a composite made from activated carbon of water hyacinth and chitosan in an artificial aqueous Cu solution which is likely to be encountered in terrestrial environments. In this investigation, water hyacinth has been processed by carbonization in a batch reactor at 350°C for 90 minutes. The chars were also chemically modified with HCl 6 N for 24 hours to investigate the potential for sorption enhancement. The properties of the resulting chars including their water content, ash content, volatile matter, fixed carbon, and iodine absorption capacity properties have been determined and compared to Indonesia’s standard (SNI 06-3730-1995). Composites have been produced by mixing the activated carbon with chitosan (1% w/v; 2% w/v; 3% w/v) from crab shells in an STTP-Ethanol solution. The composite was characterised using Fourier transform infrared spectroscopy (FT-IR). The effects of contact time parameters on batch system adsorption were investigated. Adsorption isotherm models including Langmuir and Freundlich were applied to interpret the equilibrium data in aqueous solutions. For a kinetic model consistent with experimental data, pseudo-first-order and pseudo-second-order models were examined. The maximum adsorption capacity was calculated as 0,006510 mg/g. Meanwhile, the most suitable isotherm and kinetic models were Langmuir and pseudo-second-order kinetic models, respectively. Adsorption has optimum results at room temperature, with an initial metal concentration of 0.135 mg/L, contact time of 60 min, and 1 g dosage for the adsorbent. The highest removal rate for Cu was observed for the composite with typical rates ranging from 95.74 – 96.41%. The removal rate for activated carbon from water hyacinth is lower and ranges from 94.12 – 95.07%. Meanwhile, the removal rate using chitosan alone is 95.33%. This study confirms that the addition of chitosan improves the efficiency of activated carbon to remove Cu compared to the original state.