Dechlorination Of Lindane Over Biomass-Derived Catalysts

Lindane is an organochlorine pesticide and a persistent organic pollutant.On account of the chlorinated nature,lindane shows high toxicity and hydrophobicity.Generally,dechlorination makes the degradation products less toxic and better biodegradable.There are two principal types of dechlorination:nonreductive(i.e.,?-elimination)and reductive pathways for lindane.Traditionally,the elimination of lindane is performed in the strongly alkaline aqueous solution.In this work,multiwalled carbon nanotubes(MWCNTs)are tested as the solid bases in the mild pH range of 5.0-9.0.Pyridinic and amine nitrogen species are inferred as the main basic sites,which are responsible for the catalytic activity of nitrogen-containing MWCNTs.In presence of two nitrogen-containing MWCNTs,the rate constant are 4 and 46 times greater,respectively,compared with that obtained in homogenous solution at pH 9.0 and 25?.Nitrogen-doped porous carbons are developed by a simple way in which chitosan and ZnCl2 are employed as the precursor and activation agent,respectively.The materials exhibite high surface area(1111-1497 m2/g)and large porosity(0.464-0.621 cm3/g),resulting in a great adsorption affinity to lindane.The amount of pyridinic nitrogen can be tuned by the synthesis temperature.The materials display an enhanced catalytic activity on lindane elimination compared with nitrogen-containing MWCNTs.The rate constant for A800 suspension is improved by 2-3 order in comparison with that obtained in homogeneous solution at moderate pH(9.0)and mild temperature(25-45?).Then,hydrodechlorination of lindane with formic acid are conducted over N-doped porous carbon supported Pd catalyst at 25 ?.Formic acid decomposition and conversion of lindane can be improved due to the interaction of pyridine N with Pd.The catalyst developed in this work provides an edge over the commercial counterpart for lindane conversion.