TREATMENT OF MERCURY IONS FROM PETROLEUM CO-PRODUCED WATER VIA SEMI-CONTINUOUS HOLLOW FIBER SUPPORTED LIQUID MEMBRANE SYSTEM

Abstract

This study investigated the separation of mercury ions from produced water via hollow fiber supported liquid membrane (HFSLM). The influences of types and concentration of extractant / stripping agent, i.e. Aliquat 336 / Thiourea and Calix[4]arene nitrile / DI- water, pH in feed solution, flow patterns, operating time, and flow rates were investigated. The optimum condition was identified and reported: Aliquat 336/Thiourea hybrid at 1 pH of feed solution, 4% (v/v) Aliquat 336, 0.1 M Thiourea an operating temperature of 301 K; Calix[4]arene nitrile/DI-water at 4.5 pH of feed solution, 0.004 M of Calix[4]arene nitrile, DI-water as stripping solution and an operating temperature of 313 K. A single-pass flow pattern of feed solution and circulating flow pattern of the stripping solution of 100 mL/min were found to be the most practical setup to deal with continuous and large feed of the produced water, whilst, the mercury waste is manageable following the circulation of the stripping solution in a limited volume. In conjunction with experimental work, the new mathematical model to predict the concentration of mercury ions via HFSLM was developed by factoring mass transfer fluxes from convection, diffusion and reaction in the model. From the verification, the hypothetical concentrations of mercury ions aligned closely with the experimental results. Average standard deviations for predicting the extraction and recovery were 1.5% and 1.8%. The results imply that the combination of convection, diffusion and reaction is crucial for accurate prediction in this unsteady state model. This robust model with its high accuracy provides a greater understanding of transport mechanism across the feed to the stripping solution; a design scale-up for industrial application could prove useful.