Study On The Preparation And Its Properties Of Cow Dung Activated Carbon

In this paper, cow dung was selected as raw material for the production of activated carbon, and the activated carbon’s producing conditions, the characterization of activated carbon including the adsorption thermodynamics and kinetics characteristics was studied, and then heavy metals wastewater was treated by activated carbon and tested their adsorption properties.ZnCl2, KOH, H3PO4,CaCl2,(NH4)2HPO4five activating agent dipping cow dung for the production of activated carbon were studied first According to the yield and iodine adsorption value comparison, selected (NH4)2HPO4as the most suitable activator for the production of activated carbon finally.after the Determination of (NH4)2HPO4is the most suitable activator, based on the yield, the adsorption of iodine and methylene blue value as the evaluation index, further investigated the concentration of activator, solid-liquid ratio, activation temperature and activation time on the adsorption performance of the activated carbon. After orthogonal test, the best producing condition was obtained:the concentration of (NH4)2HPO4was30%; solid-liquid ratio was1:3; activation temperature was700℃; activation time was60min. Under the optimum conditions, the activated carbon’s average rate of47.18%, the iodine adsorption average value of673.39mg/g and the methylene blue adsorption average value of8.12mL/0.1g.Used specific surface area and pore size distribution analyzer, N2adsorption-desorption isotherms, and according to the BJH method and the BET theory to analyze the pore size distribution, pore volume and the specific surface area of cow dung activated carbon. The results indicated that under the optimum conditions, the activated carbon’s surface area was730.8m2/g; the total pore volume was0.443cm3/g; the mesoporous volume and micropore volume were0.285m3/g and0.149m3/g, the ratio of mesoporous was64.4%and the average pore size was2.422nm. Surface morpHology of the activated carbon were observed by the scan electron microscope, results showed that the activated carbon surface was rough, appears convexo-concave and honeycomb structure, and the surface of the activated carbon have developed and different size pore structure, and have diversity of pore shape. Fourier transform infrared spectroscopy (FT-IR) and XRD ray diffraction were employed to analyse the surface chemical functional groups and micro structure of the activated carbon. The results showed that the surface of the activated carbon may contain some functional groups, such as hydroxyl, carboxyl, pHenolic hydroxyl, amino and pHospHorus-containing functional groups etc, part of the carbon atom formed relatively stable lamellar grapHite structure after activated. Crystal violet was used to assess the adsorption performance, and investigated the effects of the adsorption thermodynamics and kinetics of adsorption. Then, the results showed that both Langmuir adsorption isotherm equation and Freundlich adsorption isotherm equation could be used to well describe the adsorption process of methyl violet, Langmuir model is more suitable to describe the crystal violet adsorption process of activated carbon; adsorption kinetics of crystal violet on the activated carbon is more consistent with the two order kinetic model.Finally, the self-made cow dung activated carbon was employed to absorb Cu2+and Cr (VI) heavy metal wastewater, and compared with commercial activated carbon. Main investigated the affection of the dosage, adsorption time, adsorption temperature and pH on the Cu2+and Cr (VI) adsorption by activated carbon. The results indicated that for the initial concentration of1.2mmol/L Cu2+wastewater and0.6mmol/L Cr (VI) wastewater, the best dosage of self-made activated carbon were0.1g/Land1.1g/L, and the adsorption equilibrium time were60min and40min, low temperature and low pH value are all beneficial for the adsorption of two kinds of metal wastewater by activated carbon. Analysis results showed that the self-made activated carbon adsorb effection is better than commercial activated carbon for the two metal wastewater, cow dung activated carbon is more suitable for Cu2+wastewater’adsorption.