盐度对疏水改性聚丙烯酰胺吸附行为的影响

选择性絮凝分选是微细粒矿物高效分选的重要手段之一.为了强化絮凝剂在亲水、疏水矿物表面的絮凝选择性,将疏水基团十六烷基二甲基烯丙基氯化铵(C₁₆DMAAC)引入聚丙烯酰胺(PAM)分子链中合成了疏水改性聚丙烯酰胺(HMPAM),采用耗散型石英晶体微天平(QCM-D)研究了不同浓度K⁺和Ca²⁺对分散剂六偏磷酸钠(SHMP)和HMPAM在亲水和疏水化表面原位吸附行为的影响,并使用激光粒度分析仪分析了不同盐度下SHMP和HMPAM对硅微粉及疏水改性硅微粉粒径分布的影响.结果表明,不同盐度环境下HMP AM均呈现了较好的絮凝选择性.背景溶液分别为10 mmol·L^-1、100 mmol·L^-1KCl及1 mmol·L^-1 CaCl₂时,QCM-D结果表明SHMP在疏水化表面均未形成吸附层,随后HMPAM在疏水化表面发生吸附,且随着盐度的增加,HMPAM的吸附量增大且吸附层的耗散性降低;背景溶液为10 mmol·L^-1 C...

Effect of salinity on the adsorption behavior of hydrophobically modified polyacrylamide

Selective flocculation separation is one of the most efficient methods for fine mineral separation. To enhance the flocculation selectivity on the surfaces of hydrophilic and hydrophobic minerals, a hydrophobic group such as cetyldimethyl allyl ammonium chloride (C₁₆DMAAC) was introduced within the molecular chain of polyacrylamide (PAM) to synthesize hydrophobically modified polyacrylamide (HMPAM). The effects of different K+ and Ca2+ concentrations on the in situ adsorption behavior of dispersants such as sodium hexametaphosphate (SHMP) and HMPAM and their effect on hydrophilic and hydrophobic surfaces were studied using dissipative quartz crystal microbalance (QCM-D). The effects of SHMP and HMPAM on the particle size distribution of silicon powder and hydrophobically modified silicon powder with different salinity were analyzed using a laser particle size analyzer. Results indicated that HMPAM exhibited good flocculation selectivity at varying salinity concentrations. When the background solutions were 10 mmol?L?1, 100 mmol?L?1 KCl, and 1 mmol?L?1 CaCl₂, the QCM-D results indicated that no adsorption layer of SHMP was formed on the hydrophobic surface; moreover, the HMPAM was adsorbed on the hydrophobic surface in sequence. With an increase in salinity, the adsorption of HMPAM increased, and the dissipation of the adsorption layer decreased. Moreover, in the background solution of 10 mmol?L?1 CaCl₂, SHMP did not inhibit the adsorption of HMPAM on hydrophobic surfaces, and an adsorption layer with the change of resonant frequency (Δf) of ?18.3 Hz was formed. Conversely, a thin and dense adsorption layer of SHMP was generated on the surface of SiO₂ in 100 mmol?L?1 KCl, which inhibited the adsorption of HMPAM. In 10 mmol?L?1 CaCl₂, a dissipative adsorption layer of SHMP was detected on the surface of SiO₂. Furthermore, a relatively dense adsorption layer was deposited after the injection of 10 mmol?L?1 CaCl₂ solution, which also inhibited the adsorption of HMPAM. The results of floc size measurements revealed that the position and shape of the floc size distribution peak of the silica powder did not change with the effect of SHMP and HMPAM in the background solutions of 100 mmol?L?1 KCl and 10 mmol?L?1 CaCl₂, thus indicating that the SHMP inhibited the flocculation of silica powder by HMPAM. The floc size of the hydrophobically modified silica powder increased with the effect of SHMP and HMPAM. Summarily, the effects of SHMP and HMPAM on the particle size distribution of silicon micro powder and hydrophobic silicon micro powder under different salinity were consistent with the results of QCM-D measurements. This study is an important research basis for selecting and developing flocculants for selective flocculation separation.