Nitrogen-doped porous carbon derived from chitosan for the enhanced dehydrochlorination of lindane under mild conditions.

Dehydrochlorination of lindane is commonly conducted in homogeneous alkaline solutions, possessing a series of problems such as corrosion and poor recyclability. In order to overcome the pervasive problems concerning homogeneous catalysts, heterogeneous catalysts have been increasingly employed in the applications. In this study, nitrogen-doped porous carbons (NPCs) were developed by a simple way in which chitosan and ZnCl2 were employed as the precursor and activation agent, respectively. NPCs exhibited high surface area (1111-1497 m2/g) and large porosity (0.464-0.621 cm3/g), resulting in a great adsorption affinity to lindane and the by-products. As solid bases, NPCs displayed an enhanced catalytic activity on lindane dehydrochlorination. This was closely related to the amount of pyridinic nitrogen on the pore surface, which could be tuned by the synthesis temperature. The optimal removal efficiency of lindane was up to 99.9% in presence of A800 (a NPC catalyst) at moderate pH (9.0) and mild temperature (45 °C) after incubation for 24 h. The rate constant for A800 suspension was improved by 2-3 orders of magnitude in comparison with that obtained in homogeneous solution at moderate pH (9.0) and mild temperatures (25-45 °C). The reusability of the material was evaluated by cycling for three times without noticeably reduced catalytic activity. This study provides a novel strategy to achieve partial dechlorination of chlorinated organic pollutants.