污泥-稻壳混烧灰对Pb(Ⅱ)吸附性能的研究

Adsorptive Characteristics of Pb(Ⅱ) by Sludge and Rice Hull Co-combustion Ash

稻壳与污泥协同焚烧是一种富有前景的污泥能源化措施,污泥稻壳混烧灰是一种被忽视的资源。该文旨在探究污泥稻壳混烧灰在高浓度含铅废水处理中的应用潜力,分析了不同污泥和稻壳配比混烧灰的基本理化性质,研究了不同p H和不同Pb^(2+)初始浓度下混烧灰对Pb^(2+)的吸附特性,并初步探究该吸附过程的动力学和吸附机理。结果表明混烧灰对Pb^(2+)的吸附容量可媲美其它经过复杂改性处理的灰渣;在燃烧温度900℃时,污泥掺量60%、稻壳掺量40%制备的混烧灰吸附性能最好,在p H为5,初始Pb^(2+)浓度低于400 mg/L时混烧灰对Pb^(2+)的去除率高于90%;相较于Freundlich等温吸附模型,Langmuir等温吸附模型的拟合结果更好,拟合最大吸附量为108.7mg/g;动力学研究发现混烧灰对Pb^(2+)的吸附行为主要发生在5 h以内。混烧灰对Pb^(2+)去除的主要原因是混烧灰中无定形二氧化硅微水解形成硅醇对Pb^(2+)的作用,无定形二氧化硅表面存在孤立羟基和成对羟基导致了2种吸附产物Pb_2SiO_4和PbSiO_3·xH_2O存在。

Husk and municipal sludge co-combustion is a promising municipal sludge disposal method for energy, the cocombustion ash produced from the process is a neglected resource. This article researched the pretreated co-combustion ash applied in the lead polluted wastewater disposal, physical and chemical characteristics of the co-combustion ash was studied with different sludge mixing ratio. The adsorption characteristics was discussed in different p H and initial Pb2＋concentration,following by the kinetics research, and finanally the adsorption mechanism was explored. The result showed that the Pb2＋adsorption capacity of co-combustion ash is equal to those ashes modified by complicated process. The raw material mixing ratio to the highest adsorption efficiency was 60% for sludge and 40% for rice husk, when the fuel temperature is 900 ℃. The adsorption efficiency is over 90%, when the p H value is 5 and the initial Pb2＋concentration is below 400 mg/L. Langmuir was better than Freundlich model to fit the adsorption process. The maximal adsorption capacity fitted by Langmuir isothermal adsorption model was 108.7 mg/g. Kinetics show the adsorption process mainly happened in the first 5 h. In the adsorption process, the silanol hydrolyzed by amorphous silicon dioxide plays the most important role. The adsorption products can be Pb2SiO4 or PbSiO3·x H2O, which is decided by isolated hydroxy and coupled hydroxy in the surface of amorphous SiO2.