负载方法对磁性生物炭特性的影响

Research on effects of loading methods on magnetic biochar properties

生物炭负载纳米Fe_(3)O_(4)颗粒(磁性生物炭)具有结构稳定、芳香化程度高、官能团丰富、孔隙发达、超顺磁性、导电性高等特点,其在堆肥、污水处理、厌氧消化、土壤修复等领域应用广泛。为探究不同负载方法对生物炭负载纳米Fe_(3)O_(4)颗粒性质的影响,本研究分别通过化学共沉淀法(MBC1)、溶胶凝胶法(MBC2)、球磨法(MBC3)制备了生物炭负载纳米Fe_(3)O_(4)颗粒。结果表明,纳米Fe_(3)O_(4)在MBC1表面呈现絮状,而在MBC2和MBC3表面呈现清晰球状。同时,生物炭负载纳米Fe_(3)O_(4)颗粒都出现了新的官能团(Fe—O—C和Fe—O),具有超顺磁性,磁饱和强度分别为8.619×10^(-2)、8.607×10^(-2)、8.960×10^(-2)A·m^(2)·g^(-1)。相比于生物炭,生物炭负载纳米Fe_(3)O_(4)颗粒的平均孔径增大了240%~330%,电导率提高了17%~26%,pH升至8~9。在3种方法制备的生物炭负载纳米Fe_(3)O_(4)中,MBC1的结晶度最差,MBC3的分散性最好。为生物炭负载纳米Fe_(3)O_(4)颗粒的制备及负载方法对其性质影响提供借鉴。

Nano-Fe_(3)O_(4)-loaded biochar(magnetic biochar)has the characteristics of rich surface functional groups,medium and large pores,superparamagnetism,high electrical conductivity and alkalinity.It is widely used in composting,sewage treatment,anaerobic digestion,soil remediation,and other fields.To explore the effect of loading methods on the properties of biochar loaded by nano-Fe_(3)O_(4),biochar loaded by nano-Fe_(3)O_(4)was prepared by chemical coprecipitation method(MBC1),sol-gel method(MBC2)and ball milling method(MBC3).The results showed that nano-Fe_(3)O_(4)was flocculent on the surface of MBC1,while it was clear and spherical on MBC2 and MBC3.Meanwhile,new functional groups(Fe—O—C and Fe—O)appeared in biochar loaded by nano-Fe_(3)O_(4),imparting magnetic properties.The magnetic saturation intensity of MBC1,MBC2 and MBC3 was 8.619×10^(-2),8.607×10^(-2),8.960×10^(-2)A·m^(2)·g^(-1),respectively.Compared with biochar,the average pore size of nano-Fe_(3)O_(4)loaded on biochar increased by 240%-330%,electrical conductivity increased by 17%-26%,and pH raised to 8-9.Among nano-Fe_(3)O_(4)loaded on biochar prepared by three methods,the crystallinity of MBC1-Fe_(3)O_(4)was the lowest,and the dispersion of MBC3-Fe_(3)O_(4)was the highest.This study provides a reference for the preparation of biochar loaded by nano-Fe_(3)O_(4)and the influence of loading methods.