Fe^(2+)改性菖蒲生物炭制备及对水中磷的吸附特性

Preparation of Fe^(2+) modified calamus biochar and its adsorption characteristics towards phosphorus from aqueous solutions

为实现湿地植物(菖蒲)的资源化利用,以NaOH进行预处理,以FeSO_(4)为改性剂,通过热解制备了改性菖蒲生物炭(MBC),探究热解温度、改性剂浓度、添加量、溶液初始pH和共存离子对生物炭吸附磷的影响,并通过SEM-EDS、FT-IR、XRD和元素组成等手段对生物炭进行表征。结果表明,相较于未改性的菖蒲生物炭(BC),MBC对磷的吸附效果明显增强,在热解温度为673 K、改性剂浓度为1.0 mol·L^(−1)时制得的MBC吸附除磷效果最好,磷去除率和平衡吸附容量分别为98.48%、24.62 mg·g^(−1)。改性后,生物炭材料的亲水性和极性得到提高,总比表面积、微孔比表面积和微孔孔容大幅增加。材料表面成功负载了铁氧化合物,主要以Fe_(3)O_(4)和-Fe_(2)O_(3)晶体形式存在。MBC最佳投加量为0.2 g·L^(−1),其对磷酸盐的吸附行为良好符合准二级动力学模型,且Langmuir等温吸附模型能更准确的描述MBC对磷酸盐的吸附特征。MBC对污水水质pH具有较宽的适应范围并对磷酸根离子具有较强的选择吸附性。

In order to realize the resource utilization of the wetland plant(calamus),calamus biochar(MBC)was prepared with FeSO_(4) modifier by pyrolysis of NaOH pretreated calamus.The effects of pyrolysis temperature,modifier concentration,additive amount,initial solution pH and coexisting ions on phosphorus adsorption by biochar were investigated.Biochar was characterized by SEM-EDS,FT-IR,XRD and elemental composition analysis.The results showed that,compared with unmodified calamus biochar(BC),the adsorption effect of phosphorus on MBC was significantly enhanced.the MBC prepared at pyrolysis temperature of 673 K and 1.0 mol·L^(−1) modifier concentration had the best phosphorus removal effect,the removal rate and equilibrium adsorption capacity were 98.48%and 24.62 mg·g^(−1),respectively.After modification,the hydrophilicity and polarity of biochar materials increased,and the total specific surface area,specific surface area and micropore volume increased significantly.Iron oxides were successfully loaded on the surface of the material,which mainly existed in the form of Fe_(3)O_(4) and-Fe_(2)O_(3) crystals.The optimal dosage of MBC was 0.2 g·L^(−1),and the adsorption behavior of MBC was in good agreement with the pseudo-second order model.Langmuir isothermal adsorption model could more accurately describe the phosphate adsorption characteristics on MBC.MBC had a wide range of pH adaptability and strong selective adsorption to phosphate anions.