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研究了由氧化铁、氧化铝、聚丙烯酸 (PAA)和聚乙烯吡咯烷酮 (PVP)构成的胶体体系中的聚合絮凝机理。用沉降试验、Zeta电位和吸附量测定多种方法研究了聚合物 -颗粒相互作用的机理。试验结果表明 ,低分子量PAA存在时 ,氧化铁处于分散状态 ;10 6 g/molPAA使氧化铁较好地絮凝。相反 ,氧化铝悬浮液能被广泛分子量的PAA聚合物絮凝 ,而且在某些情况下能在比常规浓度 ( 10 - 6 )低得多的超低浓度 ( 10 - 9)下实现絮凝。常规的低分子量PAA分散剂 (分子量为5 0 0 0 0g/mol)所呈现的絮凝 /分散特性取决于他们的浓度。即使界面的Zeta电位是负值时这两种氧化物仍发生絮凝 ,说明在产生絮凝时除了静电作用外 ,还有其他力如桥联作用存在。在酸性pH条件下 ,氧化铝与低分子量PAA的良好絮凝归因于电荷中和及聚合物分子的桥联作用。低分子量PAA在 pH～ 3 5能絮凝氧化铝但不能絮凝氧化铁 ,因为氧化铝表面的羟基物质有利于氢键键合。氧化铁絮凝需要能提供桥联支持的更大聚合物分子。非离子聚合物PVP ,不能絮凝氧化铝而氧化铁能被大分子量PVP聚合物絮凝 ,主要是由于表面羟基和PVP -PAA络合物之间有利的成键作用
The mechanism of polymerization flocculation in a colloidal system composed of iron oxide, aluminum oxide, polyacrylic acid (PAA) and polyvinylpyrrolidone (PVP) was investigated. The mechanism of polymer-particle interaction was studied by various methods, such as sedimentation test, Zeta potential and adsorption capacity. The experimental results show that iron oxide is in a dispersed state when low molecular weight PAA is present, and 10 6 g / mol PAA makes the iron oxide better flocculate. In contrast, alumina suspensions can be flocculated with a broad range of molecular weight PAA polymers and, in some cases, flocculate at very low concentrations (10 - 9) much lower than conventional concentrations (10 - 6). The flocculation / dispersion characteristics exhibited by conventional low molecular weight PAA dispersants (molecular weight of 50000g / mol) depend on their concentration. Even if the Zeta potential of the interface is negative, the two oxides still flocculate, indicating that in addition to the electrostatic effect of flocculation, there are other forces such as the bridging effect exists. The good flocculation of alumina with low molecular weight PAA is due to charge neutralization and bridging of polymer molecules at acidic pH. Low molecular weight PAA flocculates alumina at pH ~ 35 but does not flocculate iron oxide because the hydroxyl groups on the alumina surface favor hydrogen bonding. Iron oxide flocculation requires larger polymer molecules that can provide bridging support. The nonionic polymer PVP, which can not flocculate alumina while the iron oxide can be flocculated by the high molecular weight PVP polymer, is mainly due to the favorable bonding between the surface hydroxyl groups and the PVP-PAA complex