花生壳生物炭对铵态氮的吸附性能研究

为揭示生物炭对铵态氮的吸附性能,以花生壳为原料,低氧热解(300℃)制备生物炭,采用批量平衡吸附法,研究花生壳生物炭对铵态氮(NH4+-N)的吸附机制及影响因素。研究结果表明:生物炭吸附NH4+-N的量随溶液NH4+-N初始浓度增加而增加,当初始浓度接近100 mg/L时,吸附趋于饱和,最大吸附量达5.79 mg/g。Langmuir能较好地拟合花生壳生物炭对NH4+-N等温吸附数据,表明吸附是以单层吸附为主导。生物炭对NH4+-N的吸附约30 min达到平衡,伪二级动力学方程能较好地描述其吸附动态;随生物炭添加量的增加,其对NH4+-N的吸附量下降,而吸附率逐渐增加,100 mg/L吸附体系中,生物炭适宜添加量为0.6 g/50 m L,最大吸附率达40%。生物炭吸附NH4+-N的量随溶液p H升高而增加,当体系p H 9.0时,吸附量高达8.8 mg/g。可见,溶液NH4+-N初始浓度、生物炭添加量及p H是影响生物炭吸附性能的重要因素。

Study on Adsorption of Ammonium Nitrogen by Peanut Shell Biochar

In order to reveal the adsorption performance of biochar to ammonium nitrogen, peanut shell was used as raw material to prepare biochar through low-oxygen pyrolysis (300°C), and a batched equilibrium adsorption method was adopted to study the adsorption mechanism and influencing factors of peanut shell biochar (PSB) to ammonium nitrogen (NH4 -N). The results showed that the adsorption amount of NH4 -N by biochar increased with the increase of initial concentration of NH4 -N in solution, the adsorption tended to be saturated when the initial concentration was close to 100 mg/L, and the maximum adsorption amount was 5.79 mg/g. Langmuir could effectively fit the isothermal adsorption data of PSB to NH4 -N, which indicated that monolayer adsorption was dominant in the adsorption. The adsorption of NH4 - N by biochar reached equilibrium in about 30 min, and the pseudo second order kinetics equation could effectively describe its adsorption dynamic; the adsorption amount of NH4 -N decreased and the adsorption rate increased gradually with the increase of addition amount of biochar, the suitable addition amount of biochar was 0.6 g every per 50 mL in the adsorption system of 100 mg/L, and the maximal adsorption rate was 40%. The adsorption amount of NH4 -N by biochar increased with the increase of pH, the adsorption amount reached 8.8 mg/g when the pH was 9.0. Therefore, the initial concentration of NH4 -N in solution, the addition of biochar and the pH value were the important factors which could affect the adsorption performance of biochar.