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ABSTRACT:The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1 % for chromium (VI) at pH 2, exposure time of 1h at 25 ºC. Maximum capacity of cadmium of 88 % was obtained in the pH range of 5-6 at 25 ºC after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater.

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There has been increasing concern about the impacts of exposure to chemical compounds with endocrine disrupting activities in the environment, especially aquatic environments, to wildlife and humans. South Africa is known to have used and abused most chemicals listed by developed and developing countries as endocrine-disrupting chemicals. Endocrinedisrupting chemicals have been reported in water, sediment and serum, as well as in fish tissue samples, at a level that could trigger endocrine disruption in humans and wildlife. Although some monitoring has been reported, particularly in water systems within the country, information on EDCs in other environmental matrices is scanty. The water systems monitored so far are very few. The strongest economy in Africa, and an emerging world economy depending on agriculture, mining, manufacturing and industry, needs to focus more on monitoring and to strengthen government organs and institutions to monitor and ensure environmental safety.

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This study examined the prevalence of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in river water samples (n = 56) and suspended solids (n = 5) from three major Western Cape rivers, in South Africa. Solid phase extraction (SPE) followed by liquid chromatography combined with electrospray tandem mass spectrometry (LC-MS/MS) using an analytical method developed in ISO 25101 (2009), PFOS and PFOA concentration in river water and in suspended solids from the rivers was investigated and quantified. From the results, PFOA and PFOS were detected in all the river water samples and were found in concentrations up to 314 and 182 ng/L for Diep River; 390 and 47 ng/L for Salt River; and 146 and 23 ng/L for Eerste River, respectively. In suspended solids, concentrations for PFOS and PFOA were 28 and 26 ng/g for Diep River; 16 and less than limit of detection for Eerste River; and 14 and 5 ng/g for Salt River, respectively. Some of these concentrations are higher than those previously reported in similar studies in various countries, and this suggests there is a cause for concern, in the Western Cape, South Africa, particularly in catchments where river and ground water is drawn for agricultural purposes in the province.

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