稻壳生物炭对水中萘的吸附特性研究

Adsorption of naphthalene onto rice shell biochar in water

以稻壳为生物质原料,在管式炉中氮气氛围下分别于300,500,700℃及在马弗炉中限氧500℃下热解制备生物炭(生物炭依次表示为G300、G500、G700和M500),采用批量吸附实验研究四种生物炭对萘的吸附特性,并结合扫描电镜和傅里叶变换红外光谱分析等方法,探讨温度和气氛条件对生物炭吸附萘的影响。结果表明,稻壳生物炭对萘的吸附动力学曲线符合伪二级动力学模型,在24 h内皆达到吸附平衡,平衡吸附量分别为3.299,4.815,4.251,4.756 mg/g,等温吸附曲线可以用Freundlich模型较好地拟合,吸附容量从大到小为G500>M500>G700>G300。4种稻壳生物炭都具有不同程度的管道和表面隆起,管道形状和数量以及表面形态存在较大差异。红外光谱结果有较大的相似性,但是随着温度的升高,-OH、-CH2、CH3、C=C和C=O等官能团强度减弱或者逐渐消失,而另外一些官能团如芳烃化合物C-H、C-OH、C-O-C、COO-等官能团的强度则增加。

Waste rice shell was used to produce the biochar by pyrolysing at temperatures of 300,500,700℃under the protection of the nitrogen atmosphere of a tube furnace and at temperature of 500℃with limited oxygen in a muffle furnace(the biochar was labeled as G300,G500,G700 and M500 respectively).The adsorption characteristics of naphthalene onto four biochar were studied by a series of adsorption experiments.The effects of temperature and atmospheric conditions on the adsorption of naphthalene by biochar were investigated by means of scanning electron microscopy and Fourier transform infrared spectroscopy.The results showed that the adsorption kinetics curve of naphthalene onto biochar accorded with the pseudo second-order kinetics model.The adsorption reached equilibrium in 24 h,and the adsorption amounts was 3.299,4.815,4.251,4.756 mg/g,respectively.The isothermal adsorption curve could be well fitted by the freundlich model.The adsorption capacity were G500>M500>G700>G300.The four rice shell biochar had different pore structure and surface uplift,and the shape and number of pores and the surface form were quite different.There were significant similarities among the infrared spectra of the four rice shell biochar.With the increase of temperature,the functional groups such as-OH、-CH2、CH3、C=C and C=O gradually disappeared,while the intensity of other functional groups such as C-H、C-OH、C-O-C、COO-increased.