Simazine removal from waters by adsorption on porous silicas tailored by sol–gel technique

• Synthesis of sol–gel highly porous silica for adsorption of simazine from water.
• Bringing agrochemical concentration below the law limit allowed in wastewaters.
• Regenerating the adsorbent which can be used again in the iterative process.

Two porous silica samples were synthesized through the sol–gel technique and characterized in terms of surface area and pore size distribution. The ability of such samples in removing simazine from polluted waters by adsorption was evaluated by investigating the main process parameters (pH, time, initial simazine concentration and solid/liquid ratio). An iterative process of simazine removal from waters by adsorption on the more suitable of the two silica samples is proposed, featuring: (i) final simazine concentration well below 0.05 mg/dm3, the maximum concentration allowed by Italian laws in wastewaters; (ii) regeneration of the adsorbent by a few minutes thermal treatment at 500 °C, which results in the removal of simazine without markedly damaging the adsorbent; (iii) thorough oxidation of simazine by combustion.

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