生物炭对城乡多元有机固废蚯蚓堆肥产物应用于Cu(Ⅱ)吸附的研究

Application of biochar to the adsorption of Cu(Ⅱ)from vermicomposting products of urban and rural multiple organic solid waste

牛粪、椰糠、菌渣和菜叶等有机固废是典型的城乡固废,需要探究其资源化途径.本文通过添加不同质量比(0、1%、5%、10%和20%)的生物炭对牛粪、椰糠、菌渣和菜叶质量比为2∶1∶1∶1的多元城乡固废进行蚯蚓堆肥,探讨生物炭–蚯蚓堆肥产物作为吸附剂对Cu(Ⅱ)的吸附效果及作用条件.BET和FTIR显示,添加10%的生物炭使混合体系的孔隙发育优于生物炭,有利于提高堆肥产物的比表面积、孔隙结构,改变表面官能团的特性,增加羧基、羟基和羰基等含氧官能团的数量,形成更多的吸附位点.Langmuir等温线和准二级动力学模型能更好的描述5种堆肥产物的吸附过程,主要为近似单分子层化学吸附.其中投加10%生物炭的蚯蚓堆肥产物吸附效果最佳,准二级动力学系数为6.4462×10^(–4)g·mg^(–1)·min^(–2),Langmuir等温吸附常数为0.1067 L·mg^(–1),在pH 4.0,吸附时间8 h,吸附温度25℃,堆肥产物投加量为50.0 g·g^(–1)时,对Cu(Ⅱ)的最大吸附容量可达29.88 mg·g^(–1).结果表明添加10%生物炭的城乡多元有机固废蚯蚓堆肥产物,可作为一种良好的Cu(Ⅱ)吸附剂.

Organic solid wastes such as cow dung,coconut coir,fungus residue and vegetable leaves are typical urban and rural solid wastes,and their recycling pathways need to be explored.To investigate the adsorption of Cu(Ⅱ)by biochar-vermicompost products as an adsorbent,several typical urban and rural multi-organic solid wastes with a quality ratio of 2∶1∶1∶1 of cow dung,coir,fungus residue and vegetable leaves were vermicomposted by adding different mass ratios(0,1%,5%,10%and 20%)of biochar.BET and FTIR results showed that adding an appropriate amount of biochar could improve the specific surface area and pore structure of vermicompost products,change the surface functional groups,increase the number of oxygen-containing functional groups such as carboxyl,hydroxyl and carbonyl groups,and form more adsorption sites.Excessive addition of biochar may lead to better pore development than biochar in the mixed system,resulting in competitive adsorption between copper in compost and exogenous copper,thereby inhibiting the adsorption of exogenous copper.Langmuir isotherm and quasi-secondary kinetic models can better describe the adsorption process of five compost products,and the main adsorption process is approximately monolayer chemisorption.Among them,the adsorption performance of vermicompost products with 10% biochar was the best with the quasi-secondary kinetic coefficient at 6.4462×10^(-4) g·mg^(-1)·min^(‒2) and the Langmuir isothermal adsorption constant at 0.1067 L·mg^(-1).The maximum adsorption capacity of Cu(Ⅱ)is 29.88 mg·g^(-1) when pH is 4.0,adsorption time is 8 h,adsorption temperature is 25℃and the dosage of vermicompost product with 10% biochar is 50.0 g·g^(-1).The results showed that the vermicomposting product of urban and rural multi-organic solid waste with 10%biochar could be used as a good Cu(Ⅱ)adsorbent.