氟硅酸废水制备白炭黑的改性研究

Study on hydrophobic silica from fluosilicic acid wastewater

以氟硅酸废水和氢氧化铝为原料通过化学沉淀法制得沉淀白炭黑;以月桂酸钠为改性剂对所制得的白炭黑进行了表面改性,考察了月桂酸钠添加量和改性时间对白炭黑疏水性和分散性的影响。采用场发射扫描电子显微镜(FE-SEM)、傅里叶变换红外光谱仪(FT-IR)、激光粒度分析仪、X射线衍射分析仪(XRD)等对改性前后的白炭黑样品的表面形貌、结构性能及分散性等进行了表征和分析。结果表明:当改性剂月桂酸钠添加量为2%,改性时间为40min时,可制得接触角为132.5°的疏水性白炭黑。改性后白炭黑样品的平均粒径(D50)从32.4μm减小至790nm,比表面积(BET值)从75m^2/g增加到165m^2/g,吸油值(DBP值)从2.25mL/g增加到3.12mL/g。改性后白炭黑样品的分散性和稳定性明显增加,团聚现象减少。

Precipitated SiO2 was produced via chemical precipitation method using fluosilicic acid wastewater and aluminum hydroxide as raw materials.Meanwhile,used sodium laurate as surface modifier,the in situ modification was carried out to investigate the effects of adding amount and modifying time on hydrophobicity of silica.The morphology,structure,property and dispersion of both non-modified and modified precipitated SiO2 were characterized and analyzed by field emission scanning electron microscope（FE-SEM）,fourier transform infrared spectrometer（FT-IR）,laser particle size analyzer and X-ray diffraction analyzer（XRD）.The results showed that：when the relative mass ratio of sodium laurate was2%and after 40 minutes of reaction,the contact angel of modified SiO2 film increased from 0°to 132.5°,the average particle size（D50）reduced from 32.4μm to 790 nm,the specific surface area value（BET）increased from 75m2/g to 165m2/g,and the oil absorbed value（DBP）increased from 2.25mL/g to 3.12mL/g.The modification enhanced the dispersity and stability of modified precipitated SiO2 while weakened the aggregation.