Adsorption of hydrocarbon pollutants from wastewater using Cu‐ and Zn‐loaded activated carbon derived from waste tires

Abstract

Abstract Petroleum refinery effluents contain hazardous aromatic and polyaromatic hydrocarbons that causes environmental degradation, that is, water, land, and air pollution; therefore, it should be properly treated before its discharge into environment. Adsorption serves an efficient route to treatment of refinery wastewater; but the high production cost and selectivity of the modern adsorbent used limits their industrial scale application. On the other hand, activated carbon due to desirable adsorption characteristics and low cost seems to hold the promise if properly modified to improve its efficiency. In this study, Cu and Zn impregnated on activated carbon (AC) derived from waste tires was used for adsorption of hydrocarbon pollutants from wastewater. AC was prepared from scrap tires through thermal pyrolysis, followed by chemical activation with KOH. Cu and Zn were loaded on AC through wet impregnation method. Initial batch mode adsorption experiments were carried out using aniline and phenol as model hydrocarbons, which indicated that maximum adsorption of aniline and phenol over Zn/AC and Cu/AC occurs in 10 min contact time, temperature 30°C, pH 6, 100 ppm initial concentration, and adsorbent dose of 0.1 g/10 mL. The removal of hydrocarbon pollutants from real refinery wastewater was also investigated under optimized conditions. Results show that the COD of the refinery wastewater decreased from 963 to 73 mg/L in case of Cu/AC (92% removal) and 78 mg/L in case of Zn/AC (91% removal), respectively. The adsorbent showed many folds reusability, and in first cycle, the removal efficiency of phenol and aniline was observed to be above 95%, whereas in second, third and fourth cycles, the removal percentage was 85%, 80%, and 70%, respectively.