Influence of AlCl _3 on aggregation stability of aqueous dispersions of kraft lignin according to filtration through track membranes

摘要

The influence of AlCl _3 (0-10 ~(-3) M) and pH (9.5-2.0) on the aggregation of dilute (10 mg/l) aqueous dispersions of kraft lignin is studied by filtration through several track membranes with pore diameters of 50-2500 nm. AlCl _3 is shown to have markedly higher coagulating ability than NaCl and CaCl _2. In a pH range of 4.1-7.0, which corresponds to the significant hydrolysis of AlCl _3, the concentration inversion of AlCl _3 coagulating ability is observed when passing from 10 ~(-4) to 10 ~(-3) M, which is caused by the charge reversal of negatively charged kraft lignin particles under the action of AlCl _3 hydrolysis products.