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The occurrence of chlorine dioxide (ClO 2 ) disinfection by-products (DBPs) in drinking water, namely, chlorite, chlorate, and trihalomethanes (THMs), was investigated. Two-hundred-ninety-four drinking water samples were collected from seven desalination plants (DPs), four reservoirs (R), and eight mosques (M) distributed within various locations in southern and northern Qatar. The ClO 2 concentration levels ranged from 0.38 to <0.02 mg L −1 , with mean values of 0.17, 0.12, and 0.04 mg L −1 for the DPs, Rs, and Ms, respectively. The chlorite levels varied from 13 μg L −1 to 440 μg L −1 , with median values varying from 13 to 230 μg L −1 , 77–320 μg L −1 , and 85–440 μg L −1 for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 μg L −1 to 280 μg L −1 , with mean values varying from 36 to 280 μg L −1 , 11–200 μg L −1 , and 11–150 μg L −1 in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 μg L −1 , and the maximum value reached 77 μg L −1 However, all of the DBP concentrations fell within the range of the regulatory limits set by GSO 149/2009, the World Health Organization (WHO), and Kahramaa (KM). [ABSTRACT FROM AUTHOR]

Pesticides are used in agriculture to protect crops from pathogens, insects, fungi and weeds, but the release of pesticides into surface/groundwater by agriculture runoff and rain has raised serious concerns not only for the environment but also for human health. This study aimed to investigate the impact of surface properties on the performance of seven distinct membrane types utilized in nanofiltration (NF), reverse osmosis (RO) and forward osmosis (FO) processes in eliminating multiple pesticides from spiked water. Out of the membranes tested, two are self-fabricated RO membranes while the rest are commercially available membranes. Our results revealed that the self-fabricated RO membranes performed better than other commercial membranes (e.g., SW30XLE, NF270, Duracid and FO) in rejecting the targeted pesticides by achieving at least 99% rejections regardless of the size of pesticides and their log K ow value. Despite the marginally lower water flux exhibited by the self-fabricated membrane compared to the commercial BW30 membrane, its exceptional ability to reject both mono- and divalent salts renders it more apt for treating water sources containing not only pesticides but also various dissolved ions. The enhanced performance of the self-fabricated RO membrane is mainly attributed to the presence of a hydrophilic interlayer (between the polyamide layer and substrate) and the incorporation of hydrophilic nanosheets in tuning its surface characteristics. The findings of the work provide insight into the importance of membrane surface modification for the application of not only the desalination process but also for the removal of contaminants of emerging concern. [Display omitted] • Membrane rejection against pesticides varied depending on its physiochemical properties. • RO membranes showed the highest pesticides rejection followed by NF and FO membranes. • Improving surface properties of RO membranes using GO further enhanced pesticides removal. • GO-modified RO membrane achieved >99% rejections regardless of pesticide size and log K ow. [ABSTRACT FROM AUTHOR]

In this study, three types of adsorbents were used to remove and recover strontium ions (Sr2+) from aqueous and brine solution of seawater reverse osmosis (SWRO), namely roasted date pits (RDP) and RDP modified using copper and nickel salts of potassium hexacyanoferrates to obtain RDP–FC–Cu, and RDP–FC–Ni, respectively. Additionally, the influence of various parameters, including pH, temperature, initial concentration, and co-existing ions was also evaluated. The results revealed that pH 10 was the optimum pH in which the maximum Sr2+ ions were adsorbed. Additionally, all adsorbents had a high adsorption capacity (99.9 mg/g) for removing Sr2+ ions at the highest concentration (100 mg/L) and a temperature of 45 °C was found to be the optimum temperature. A scanning electron microscopy for the adsorbents before and after the adsorption of strontium showed the remarkable pore filling onto the active sites of all adsorbents. The thermodynamics parameter demonstrated that the adsorption occurred in an endothermic environment, and that, the reaction was spontaneous, and favorable at all the temperatures investigated. According to isotherm studies, the Langmuir model was the best-fit isotherm model; indicating that strontium adsorption involved the formation of monolayers and multilayers at higher temperatures (45 °C). Furthermore, high desorption percentages (above 90%) were achieved for all the adsorbents when an HCl concentration of 0.5 M was used. This showed the high reusability of the adsorbents. Lastly, the adsorption of strontium from the SWRO brine containing a number of metal ions was extremely sufficient as all the adsorbents were efficient to adsorb a high amount of Sr2+ despite the presence of other competing ions. [Display omitted] • Three adsorbents were investigated to remove and recover strontium ions (Sr2+) from brine solution. • PH 6 was the optimum pH in which the maximum Sr2+ was adsorbed. • 99.9 mg/g adsorption capacity was achieved for all adsorbents at the concentration of 100 mg Sr2+/L and 45 °C. • >90% desorption percentages were achieved for all the adsorbents at 0.5 M HCl. [ABSTRACT FROM AUTHOR]