硫脲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

为同时去除农田地表径流中的重金属和农药，利用猪粪制备未改性猪粪生物质炭（简称"未改性生物质炭"）和硫脲改性猪粪生物质炭（简称"改性生物质炭"），分析比较硫脲改性对生物质炭的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，并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（Cd）和草甘膦效率的影响.结果表明:①与未改性生物质炭相比，改性生物质炭的pH、O/C（原子比）和H/C（原子比）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Cd和草甘膦的吸附能力增强，最大表观吸附量（Q_max）增加了近3倍；随着Cd和草甘膦初始浓度的增加，未改性和改性生物质炭对Cd和草甘膦的吸附量逐渐增加，增加量最高分别达18.52%和7.60%.③单一污染体系中两种生物质炭对Cd或草甘膦的吸附更符合Langmuir等温吸附模型，说明其对Cd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Cd的吸附能力分别增加了25.28%和21.26%，未改性生物质炭对Cd的最大表观吸附量增加了29.34%，但改性生物质炭对Cd的最大表观吸附量降低了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. 

Adsorption Characteristics of Thiourea-Modified Pig Manure Biochar to Cadmium and Glyphosate in Simulated Farmland Runoff

In order to simultaneously remove heavy metals and pesticides in farmland surface runoff, unmodified pig manure biochar and thiourea-modified pig manure biochar were prepared for sorption experiments in single- and binary solute aqueous solution. 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 effect of the initial concentrations on the sorption efficiency of cadmium and glyphosate on the unmodified biochar and the modified biochar was systematically investigated and compared. The results showed that:(1) Compared with the unmodified biochar, the pH values, the ratios of oxygen-carbon 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 (Q_max) 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 good fit to the Langmuir isothermal adsorption model, indicating that the sorption mechanism of cadmium or glyphosate was mainly monolayer adsorption. (4) Compared 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 by 2.63 and 3.45 times, respectively. The results indicate that the thiourea-modified pig manure biochar is a promising technique, which provides an economic and environmentally friendly way to solve the combined pollution problem in the actual environment.