Preparation And Modification Of Sheep Bone Char And Its Adsorption Capacity For Phenols

In Recent dacades, with the achievement of activated carbon research, thre is a increasing tendency in researching available, renewable, environmentally friendly materials as an raw material like as solid dust, agricultural by products and animal bone. Xinjiang Uyghur Autonomous region is one of the developed animal husbandry area in china, mutton has a close relationship with local diet culture.A great amount of sheep bone has been discharged into invironment as solid waste.In this study, firstly, using sheep bone as raw material, ZnCl2 as chemical activation agent, preparation conditions such as ZnCl2 concentration, soaking time,activation temperature and activation time were optimized by orthogonal and single factor experiment.Further sheep bone char modified with nitric acid. BET, SEM, EDS and FTIR analyses were used to compare surface morphology and characters of sheep bone charcoal(SBC) and modified sheep bone charcoal(MSBC).Secondly, both SBC and MSBC were used to adsorption of phenol and 4-chlorophenol(4-cp).To evaluate the adsorption capacity of SBC and MSBC, the effects of temperature,contact time, initial adsorbate concentration and adsorbent dosage on the adsorption process were observed and the experimental data fitted with Langmiur, Fruendlich and Temkin isotherm models. The pseudo first-order, pseudo second-order, and intra particle diffusion models were fitted to estimate adsorption mechanism.Thirdly, SBC and MSBC were used for adsorptive removal of COD from petrochemical waste water.pseudo first-order, pseudo second order kinetic models and intraparticle diffusion model were used to analyze the adsorption mechanism.The result showed that: optimum preparation conditions for sheep bone char were the concentration of ZnCl2 is 30%, impregnation time is 36 h, activation temperature is 850℃, activation time is 60 min.BET surface area of SBC and MSBC were 149.8 and 413.4 m2/g, total pore volume were0.29 and 0.46 cm3/g respectively.It can be observed from nitrogen adsorption-desorption isotherms of SBC and MSBC at77 k that the isotherms for SBC and MSBC fit type IV based on IUPAC classification.Duo to the existence of mesoporous appear hysteresis loops, and MSBC has relative higher adsorption capacity and wider pore distribution compared to SBC.It can be conculde from bath adsorption studies that MSBC showed grater adsorption capacity to both phenol and 4-cp. Under the condution temperature was25 ℃,contact time was 60 min,initial concentration were 100mg/L for phenol and200mg/L for 4-cp, the adsorption capacity reached 25.66 and 74.50mg/g for MSBC respectively. While adsorption capacity of SBC reached 13.67,32.37mg/g at the condition of temperature was 25 ℃,contact time were60 min and 300 min,initial concentration were 100mg/L and 200mg/L for phenol and 4-cp.The adsorption isotherm study showed that Freundlich adsorption model gives the good agreement with the adsorption process of phenol and 4-cp on SBC, and 4-cp adsorption on MSBC, indicated that adsorption on heterogeneous surface with active sites which have different adsorption energy. Comparatively 4-cp adsorption process on SBC fitted the Temkin isotherm model implying that which process conducted via the indirect adsorbent/adsorbate interaction. From intraparticle diffusion model it could be known that during all these adsorption process there are other mechanisms affect to rate controlling step such as boundary layer control except the intra particle diffusion.Among SBC, MSBC and coal based activated carbonCAC, MSBC gives better adsorption capacity for petrochemical waste water COD. Increasing of contact time and adsorbent dosage lead to increase the removal of COD, reached 89.17,87.48and79.19%for MSBC, SBC, CAC respectively. Pseudo second-order model contribute good fitting for all three adsorption processes, and the intraparticle diffusion plot present multilinearity, at the first step, intraparticle diffusion was not the only ratecontrolling step, but at the second step boundary layer control and other mechanisms may affect the rate of adsorption.