Removal of hydrocarbon pollutants from aqueous media using hydrophobic cellulose-based adsorbents

Abstract

The current work was carried out to eliminate hydrocarbon contaminants from oily wastewater. The alpha-cellulose-based aerogels were synthesized by sol-gel method and hydrophobic modification was applied with methyltrimethoxysilane (MTMS) through chemical vapor deposition (CVD). The FT-IR, SEM, and BET analyses were used to characterize the adsorbents. The effects of several factors such as hydrophobic modification, alpha-cellulose weight percentage, contact time, temperature, and pollutant type on adsorption were studied. The results revealed that the maximum adsorption capacities for engine oil, crude oil, and kerosene oil and mixture (with same proportions) were 28.4, 25.2, 22.8, and 25.7 (g/g), respectively. The difference in density and viscosity are the main reasons for different adsorption capacities. The adsorption capacity increased with increasing density, as well as in higher temperatures. Lower viscosity causes easier penetration, which is eventuated in increasing the adsorption capacity. However, after 40 °C with more viscosity decrease, the release rate increased and the adsorption capacity decreased. The adsorption equilibrium time for the three oil compounds is approximately 8 min. The adsorption kinetics follows the pseudo-second-order model, showing that chemisorption dominates. Also, the thermodynamic studies showed that the adsorption was endothermic and non-spontaneous. In addition, the synthesized adsorbent showed acceptable regeneration performance up to 5 cycles.