Removal of volatile organic compounds (VOCs) from groundwater by reverse osmosis and nanofiltration

A comprehensive study was conducted to examine the removal of volatile organic compounds (VOCs) which exist in groundwater at Southlands-Botany Bay (Sydney region). The ability of nanofiltration (NF) and reverse osmosis (RO) as advanced treatments was investigated using two commercially available NF or RO membranes. Laboratory-scale tests were used with cross-flow; tests were conducted with 16 ubiquitous compounds that represented the significant volatile organic compounds found in the contaminated groundwater. The results reported in this study indicate that the removal efficiency of reverse osmosis (RO) was better than NF in rejecting the VOCs detected in groundwater. This study revealed that the performance of NF and RO membranes in rejecting hydrophilic volatile organic compounds was higher than that for hydrophobic compounds and the highest rejection achieved by NF and RO membranes amounted 98.4% and 100%, respectively. Hydrophilic compounds can be effectively rejected by NF/RO membranes using the size exclusion mechanism (steric hindrance), whereas hydrophobic compounds can be adsorbed into NF/RO membranes and then diffuse through the dense polymeric matrix, resulting in the lower removal for these compounds compared to hydrophilic compounds

A robust X-ray fluorescence technique for multielemental analysis of solid samples

X-ray fluorescence (XRF) quantitation software programs are widely used for analyzing environmental samples due to their versatility but at the expense of accuracy. In this work, we propose an accurate, robust, and versatile technique for multielemental X-ray fluorescence analytical applications, by spiking solid matrices with standard solutions. National Institute of Standards and Technology (NIST)-certified soil standards were spiked with standard solutions, mixed well, desiccated, and analyzed by an energy dispersive XRF. Homogenous targets were produced and low error calibration curves, for the added and not added, neighboring, elements, were obtained. With the addition of few elements, the technique provides reliable multielemental analysis, even for concentrations of the order of milligram per kilogram (ppm). When results were compared to the ones obtained from XRF commercial quantitation software programs, which are widely used in environmental monitoring and assessment applications, they were found to fit certified values better. Moreover, in all examined cases, results were reliable. Hence, this technique can also be used to overcome difficulties associated with interlaboratory consistency and for cross-validating results. The technique was applied to samples with an environmental interest, collected from a ship/boat repainting area. Increased copper, zinc, and lead loads were observed (284, 270, and 688 mg/kg maximum concentrations in soil, respectively), due to vessels being paint stripped and repainted