Comparison of Activated Carbon Prepared from Olive Stones by Microwave and Conventional Heating for Iron (Ⅱ), Lead (Ⅱ), and Copper (Ⅱ) Removal from Synthetic Wastewater

摘要

Activated carbon with high surface area was prepared from olive stone by microwave heating (MHOS) for the removal of a group of heavy metals Fe~(2+), Pb~(2+), and Cu~(2+) from synthetic wastewater. As a comparison, activated carbon was also prepared by conventional heating (CHOS) method. The effects of different reaction parameters, such as adsorbent dosage, contact time, stirring speed, and initial pH, on pollutant removal efficiency were determined. The microwave heating requires significantly lesser holding time as compared to conventional heating method to produce activated carbon of comparable quality, with higher yield. The BET surface area of carbon using microwave heating is noticeably higher than the conventional heating. Although the mesopore surface area of carbon is not vary significantly, the activation time and power consumption are considerably lower than the conventional heating rendering that the activation process via microwave is more economical than that via conventional heating. The adsorption capacity was found higher using microwave heating as compared with conventional heating. The adsorption equilibrium data were best represented by the Langmuir model and the adsorption capacity for Fe~(2+), Pb~(2+) and Cu~(2+) were found to be 62.50, 23.47, and 22.73 mg/g for MHOS; while 57.47, 22.37, and 17.83 mg/g for CHOS, respectively at pH 5, 3 h contact time and 200 rpm shaking speed. Regeneration studies showed that MHOS and CHOS could be used several times by desorp-tion with an HCl reagent. A pseudo second-order model sufficiently described the adsorption kinetics for both carbons, which indicates that the adsorption process was controlled by chemisorption. Both carbons can be used for the efficient removal of Fe~(2+), Pb~(2+), and Cu~(2+) (＞99%) from contaminated wastewater.