聚硅酸制备的数学建模及聚铁混凝剂性能

为使科研活动与产品工业化接轨,对聚硅酸(PS)的合成过程进行数学建模,同时采用PS作为半成品制备聚硅酸铁(PSF)混凝剂.以水玻璃及H2SO4合成PS,针对PS的成冻时间(t)与聚合pH值、初始SiO2质量分数(w(SiO2))及聚合温度的关系进行数学建模,并研究pH对具有一定聚合度PS形态的影响.采用共聚法用PS、FeSO4·7H2O及NaClO3制备PSF,对比研究PSF、聚合硫酸铁(PFS)及复合铝铁(PFA)对低温低浊水的混凝性能及其微观品质.结果表明,将具有一定聚合度的PS的pH调低后,部分PS解聚,解聚后的状态完全不同于初始同样低pH时的状态.PSF的混凝效果优于PFS、PFA.对PS制备过程进行数学建模是工业制备优质PSF的基础条件.PSF独特的微观特征正是其具有优异混凝性能的根本原因.PSF对低温低浊水的混凝机理是以电中和/脱稳为前提条件,以架桥为必要条件.

Mathematical modeling of preparation of polysilicic acid and coagulation performance of poly iron coagulants

A mathematical model on the preparation process of polysilicic acid (PS) was established to joint the bench-scale study with industrialization.Poly-silicic-ferric (PSF) coagulant was prepared using PS as semi-manufactured goods.PS was prepared using water glass and H2SO4 solution,and mathematical modeling concerning the relationship between gelation time (t) and such factors as pH value,initial w (SiO2) and temperature was presented.The influence of pH value on the species of PS with certain polymerization degree was explored.PSF coagulant was prepared using PS,FeSO4·7H2O and NaClO3 by co-polymerization.Both coagulation performance in treating lower temperature and lower turbidity water by PSF and characteristics of PSF were investigated compared with those of polyferric sulfate (PFS) and poly ferric aluminum (PFA).Results show that some PS is depolymerized after decreasing pH value when PS reaches a certain degree of polymerization,but the species after depolymerization differs from that at the same original pH value.PSF has higher coagulation efficiency than PFS and PFA.The mathematical modeling on the preparation of PS is the basic condition for preparing high quality PSF in industrial scale.The particular characteristics of PSF are just the essential reason for its superior coagulation performance.In the coagulation mechanism of treating low temperature and low turbidity water by PSF,charge-neutralization/destabilization is the precondition and the bridging is the necessary condition.