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Activated carbon (AC) from coal, coconut and palm kernel shell was regenerated after adsorbing chlorate from chlor-alkali plant brine solutions. Hydrochloric acid (HCl) of 17% w/w concentration showed the ability to regenerate AC, with some chlorine gas being released. Regeneration with HCl yielded enhanced adsorption of chlorate. AC from coconut shell adsorbed chlorate better than coal and palm kernel shell AC. Higher chlorate concentration in the influent and lower influent pH resulted in better adsorption. Regeneration of the AC with 17% w/ w HCl reduced chlorate to chlorine derivatives. The AC released 107 mg/g of chlorine during the first regeneration and 160-178 mg/g after the second regeneration. During regeneration, coal AC released the highest amount of chlorine at 0.51-0.59 mg/g of chlorate adsorbed followed by palm kernel shell with 0.34-0.36 mg/g, while coconut shell AC released 0.18 mg/g. Scanning electron micrograph of the coconut shell AC carried out after each regeneration showed the structure of AC remained intact, with active sites surfacing on the regenerated AC. Using AC for chlorate adsorption followed by regeneration with 17% w/w HCl may reduce the release of brine and chlorate to the environment from chlor-alkali plants.This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for non-commercial purposes with no derivatives, provided the original work is properly cited (http:// creativecommons.org/licenses/by-nc-nd/4.0/) chlorine (Brinkmann et al. 2014). However, the disadvantage of this process is that it requires high quality brine. In order to maintain the quality of the brine being fed to the electrolyser, some brine is purged to the environment. Chlorate is released to the environment when plant operators purge their brine. This affects the quality of the receiving water bodies. With the call for sustainability, and greener processes, these releases must be reduced. The researchers looked for methods to reuse these streams so that there is reduced effluent released from such plants. There are legislations in some countries that limit the release of chlorate from pulp and paper mills, however there is a lack of legislation limiting their release from chlor-alkali plants. Many plant operators may be unaware of the harm caused by the release of chlorate to the environment from their plants. In work done previously, the authors studied the adsorption of chlorate from the brine stream of chlor-alkali plants using activated carbon (AC) (Lakshmanan & Murugesan 2016). ACs are used in pollution mitigation studies as they exhibit the ability to remove substances and pollutants from aqueous solutions (Arena et al. 2016). The present research studies how AC that is used for chlorate adsorption from a multi-component effluent stream and achieves selective adsorption of one component (Yang et al. 2016) can be effectively regenerated and minimise environmental pollution.Three types of commonly ava...

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