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改性猪粪生物质炭对模拟农田径流中镉和草甘膦吸附特征
宋佳颖, 刘君, 宗海英, 宋宁宁, 苏宝坤, 王芳丽
青岛农业大学
摘要:
为了同时去除农田地表径流中重金属和农药,利用猪粪制备生物质炭和硫脲改性生物质炭,系统地研究了单一和复合污染体系中初始浓度对两种生物质炭吸附水溶液中镉和草甘膦效率的影响,并分析比较了硫脲改性对生物炭的pH、元素组成、表面含氧官能团和巯基含量等理化性质的影响。结果表明:①与未改性生物质炭相比,改性生物质炭的pH、氧碳比和氢碳比降低,比表面积增大,含氧官能团和巯基含量增加。②与未改性生物质炭相比,改性生物质炭对镉和草甘膦的吸附能力增强,最大表观吸附量增加了近3倍;随着镉和草甘膦初始浓度的增加,未改性和改性生物质炭对其吸附量逐渐增加,最高分别约为18.52%和7.60%。③单一污染体系中两种生物质炭对镉或草甘膦的吸附更符合Langmuir等温吸附模型,说明其对镉或草甘膦的吸附机理是单分子层的吸附起主导作用。④复合污染体系中,未改性和改性生物质炭对镉的吸附能力分别增加了25.28%和21.26%,未改性生物质炭对镉的最大表观吸附量增加了29.34%,但改性后降低了47.28%;未改性和改性生物质炭对草甘膦的吸附能力减弱,但最大表观吸附量分别增加了2.63和3.45倍。研究显示,硫脲改性猪粪生物质炭作为一项有前景的新技术,为解决实际环境中的复合污染问题提供了经济环保的技术手段。
关键词:  硫脲改性猪粪生物质炭    草甘膦  农业面源污染  吸附  复合污染
DOI:
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基金项目:国家自然科学基金(41701562;41701356);青岛农业大学大学生创新创业训练计划项目(662)
Adsorption Characteristics of Cadmium and Glyphosate in Aqueous Solution by Modified Pig Manure Biochar
宋佳颖, LIU Jun, ZONG Haiying, SONG Ningning, 苏宝坤, 王芳丽
Qingdao Rural Environmental Engineering Research Center,School of Resources and Environment,Qingdao Agricultural University
Abstract:
To simultaneously remove heavy metals and pesticides in the farmland surface runoff, pig manure biochar and thiourea-modified pig manure biochar were prepared for the sorption experiments in the single- and binary solute aqueous solution. The effect of the initial concentrations on the sorption efficiency of cadmium and glyphosate on the biochar and the modified biochar was systematically investigated and compared. The effects of thiourea modification on the physicochemical properties of biochar such as pH value, elemental composition and the contents of the surface oxygen-containing functional groups and sulfhydryl groups were analyzed and compared. The results showed that: (1) Compared with the unmodified biochar, the pH values, the ratios of oxygen- and hydrogen-carbon of the modified biochar decreased, whereas the specific surface area and the content of oxygen-containing functional groups and sulfhydryl groups increased. (2) Compared with the unmodified biochar, the adsorption capacity of the modified biochar for cadmium and glyphosate was enhanced, and the maximum apparent adsorption capacity increased nearly 3-fold. With the increase of initial concentrations of cadmium and glyphosate, the adsorption of cadmium and glyphosate by the unmodified and modified biochars gradually increased, with the maximum increase of 18.52% and 7.60%, respectively. (3) The adsorption of cadmium or glyphosate in the single solute aqueous solution exhibited a better fit on the Langmuir isothermal adsorption model, indicating that the sorption mechanism of cadmium or glyphosate was dominated by monolayer adsorption. (4) Compare with those in the single solute system, in the binary solute system, the adsorption capacities of cadmium by the unmodified and modified biochars increased by 25.28% and 21.26%, respectively, with an increase of 29.34% on the unmodified biochar but a decrease of 47.28% in the maximum apparent sorption capacity. The adsorption capacities of glyphosate on the unmodified and modified biochars were weakened, whereas the maximum apparent adsorption capacities of glyphosate increased 2.63 and 3.45 times, respectively. The results indicate that the thiourea-modified pig manure biochar is a promising technique, providing an economic and environmental way to solve the combined pollution problem in the actual environment.
Key words:  Thiourea-modified pig manure biochar  Cadmium  Glyphosate  Agricultural diffuse pollution  Sorption  Combined pollution