Preparation And Properties Of New Organic And Inorganic Flocculants

Inorganic-organic composite polymer flocculants can make full use of the advantages of both inorganic and organic flocculants, and thus improves the flocculation efficiency enlarges the range of application. Wastewater often contains all kinds of heavy metal ions which threat human health. And color in wastewater increases the difficulty of processing.Thus, in this paper, two inorganic polymer flocculants, poly ferric sulfate zinc (PFSZ) and poly iron zinc silicate (PSZF), one organic polymer flocculant, polydiallyldimethylammonium chloride(PDADMAC), and their composite were developed. The performances of the organic polymer flocculant and inorganic-organic composite polymer flocculant in removing heavy metal ions and color were investigated.Inorganic polymer flocculants poly ferric sulfate zinc (PFSZ) and poly iron zinc silicate (PSZF) were prepared. The effect of different preparation conditions, such as molar ratio of iron and zinc, reaction temperature and time on the flocculation performance was investigated. The optimum preparation conditions were explored by the orthogonal experiments. From the experimental results, the optimal dosing quantity for PFSZ is 350.4 mg/L, and 330.21mg/L for PSZF. The flocculation efficiency of the flocculants prepared were compared, and the results show that lower dosing and better flocculation performance of the composite flocculants, PFSZ and PZSF, were obtained. The pH range used for the composite flocculants is more wider.A two-step preparation method for the organic flocculant dimethyl diallyl ammonium chloride (PDMDAAC) was employed. The effect of operation parameters, such as initiator dosage, reaction time and temperature, etc on the flocculant molecular weight was studied. Reacting PDMDAAC with PFSZ and PSZF, a composite flocculant was prepared. The performance, such as turbidity and heavy metal Cu2+ removal rate, decolorization rate of the composite flocculant was evaluated for different operating parameters. The results showed that the optimal dosing amount for poly ferric sulfate zinc-poly dimethyl diallyl base ammonium chloride (PPFSZ) is 307.74 mg/L, and 98.61%,98.61% and 96.47% removal rate for the turbidity, Cu2+, and color respectively is attained. And for Poly iron zinc silicate- poly dimethyl diallyl base ammonium chloride (PPSZF), the optimal dosing quantity of 429.5 mg/L, the maximum removal rate of 99.01%,82.0%,83.7% for turbidity, Cu2+ and color respectively was found. Compared the composite flocculant with the single organic or inorganic flocculant, the organic flocculant shows some decolourization ability, but the turbidity and Cu2+ removal perfomance is weak. And the inorganic polymer flocculant is good at turbidity removing and color removing, however the color removal rate is low. The composite flocculant makes full use of the advantage of both organic and inorganic flocculant, and indicates excellent performance in all aspects, turbidity, color and Cu2+ removal compared with the single inorganic or organic flocculant.