PURIFICATION OF PRODUCED WATER BY CUTTLEFISH BONE ADSORBENTS

Abstract

The cuttlefish bone powder (CFB) which is mostly composed of calcium carbonate was prepared, characterized, and modified to use it for the purification of emulsified oil/water mixtures from produced water. The focus was on the treatment of polluted water containing very low oil content (around 100 ppm) that belongs to the tertiary treatment of polluted waters. The highest challenge in tertiary treatment technologies is the removal of colloidal oil droplets (below 500 nm) that cannot be removed using common industrial sorbents such are walnut shell powder. This study demonstrated a fairly efficient method for this application, and, this treatment is efficient at very low adsorbent content. Alkali modification of CFB with sodium hydroxide (NaOH) was done to enhance porosity, and the total surface area of sorbent to improve the efficiency of oil adsorption. A batch adsorption experiments with different adsorption parameters were examined such as adsorbent dosage, contact time, temperature, and initial oil concentration for alkali-treated CFB. Alkali treatment of CFB showed an enhancement of oil adsorption efficiency from 52.7% to 71%. Kinetic studies evaluating the removal rate of CFB-NaOH were conducted. The results showed that equilibrium was reached within 60 min and the results were well fitted using pseudo-first-order kinetics with a very high correlation coefficient, R2 > 0.99, which demonstrates that during the adsorption of crude oil by CFB-NaOH, physical interaction is dominant. Adsorption capacities were very well described by Henry's isotherm since the experimental results showed linear dependence of qe versus ce. Moreover, detailed morphological, and chemical characterization of both produced water and adsorbents were conducted. Overall, the study indicated the effectiveness of CFB as a low-cost adsorbent for the removal of oil from produced water, and it may serve as one of the steps prior final treatment of water by membrane technologies, for instance.