Composite adsorbents including oxidized graphene: effect of composition on mechanical durability and adsorption of pesticides

Abstract

A number of multifunctional composite adsorbents based on hydrated zirconium dioxide has been synthesized. The inorganic ion exchanger contained nanosheets of oxidized graphene (GO), the modifier amount was 0.5-7 mass. %. The composites were investigated with methods of transmission electron microscopy and nitrogen adsorption-desorption, macropores were determined using water as a working liquid. It has been found that increasing of GO content depresses microporosity, but meso-and macroporosity grow. Crushing strength reduces exponentially with increase of total pore volume from 0.49 to 0.62 cm 3 g -1 . Removal of phenol from water containing also inorganic ions was investigated. Adsorption capacity reaches 0.15-0.85 (phenol), 0.5-0.85 (Ca 2+ and Mg 2+ ), 0.005-0.045 (SO 4 2-) mmol g -1 . When the GO content in the composites is 0.5-2 %, this carbon addition improves adsorption of cations and organic molecules comparing with hydrated zirconium dioxide. Further increase in GO amount causes no sufficient effect on adsorption due to decline of specific surface area of the composites. It has been suggested that the optimal content of the modifier, which provides the maximal growth of adsorption capacity, is 2 %. This composite is obtained in a form of large granules (0.3-0.5 mm), their crushing strength is 9 bar. The material was applied to removal of pesticides (acetomipride, carboxine, epoxyconazole and thiamethoxam) from aqueous multicomponent solution under batch conditions. The residual content of carboxine and epoxyconazole, molecules of which contain benzene rings, is lower than the maximal allowable concentration. No deterioration of pesticide uptake has been found after five cycles of adsorption-regeneration.

Development of Sorption Materials of Wide Functional Purpose in the V.I. Vernadskii Institute of General and Inorganic Chemistry of the Nas of Ukraine

“…Значення, отримані методом еталонної Регенерацію неорганічних композитів доцільно проводити лужними розчинами (десорбція іонів) для запобігання дегра дації оксидів [59,63] або киплячою водою (десорбція молекулярних сполук) [56].…”

“…Проте композит містить і агломеровані наночастинки ОГ, а також частинки ГДЦ, поверхня яких не вкрита ОГ. Оскільки вуглецеве покриття послаблює взаємодію між частинками неорганічної матриці, то необхідно регулювати кількість модифікатора у композиті для запобіган ня погіршення механічної міцності гранул[56]. Їхній розмір зменшується зі збільшен ням вмісту модифікатора[56,58,59].…”