Removal of Octyl Phenol Ethoxylate (OPE) Using Processed and Unprocessed Industrial Biological Waste Sludge

Abstract

This study investigated the Octyl Phenol Ethoxylate (OPE) removal potentials of raw and treated industrial treatment sludges (ITS) at different pH. Experiments were conducted in a set of 500 ml Erlenmeyer flasks, into which OPE solutions of 300 ml with different initial concentrations (50–300 μg/l) were added into. Adsorption of Octyl Phenol Ethoxylate from an aqueous solution into ITS105 (T=105°C), ITS300 (T=300°C), ITS600 (T=600°C) and ITS450 (pyrolyzed, T=450°C) was carried out at a room temperature. The OPE adsorption rate increase in the treatment sludge processed at 600°C. As opposed to the sludge treated at 105°C, the adsorption rate decreased as the concentration increased. The reason for this was that the porous structure was degraded at 600°C, and the surface charge balance was disrupted. ITS300 had a lower adsorption capacity for Octyl Phenol Ethoxylate removal than ITS105, ITS600 and ITS450 (pyrolyzed). The treatment sludge pyrolyzed at 450°C conformed with the Freundlich isotherm at pH 4 (R2=0.94) and pH 7 (R2=0.89). The treatment sludge heat-treated at 600°C conformed with the Freundlich isotherm at pH 4 (R2=0.97), pH 7 (R2=0.98) and pH 10 (R2=0.99). Additionally, for ITS600, the Brunauer, Emmett and Teller (BET) isotherm was valid at neutral pH. The OPE adsorption coefficient for ITS600 at pH 4 and pH 7 was calculated as 1.05 L/μg and 1.083 L/μg, respectively. According to the BET isotherm (for ITS600) the qm values at pH 4 and pH 7 were respectively 8.21 μg/g and 2.92 μg/g. The temperature of the adsorption value obtained with the Temkin isotherm showed that the interaction between the OPE and the adsorbent substances was not a chemical or ionic interaction but probably a physical interaction.

Keywords

• waste sludge
• adsorption
• octyl phenol ethoxylate
• pyrolyzed sludge