Preparation And Application Of PSAF+CTS Compound Flocculant

In this paper,a new type of organic-inorganic compound flocculant PSAF+CTS was recombinated by polysilicate aluminum ferric(PSAF) and chitosan(CTS).For PSAF+CTS joint the advantages of PASF and CTS together,it had stronger adaptability to treat waste waters with better treatment efficiency and lower cost.The optimal conditions of the combination condition,the differences of material structure of before and after the combination,the flocculent effect of water treatment,as well as the mechanisms,the flocculent ability of PSAF+CTS compared with single polyaluminium chloride(PAC),and the economic benefits were studied.The main results are summarized as follows:(1) The optimal combination conditions were:pH 1.4～1.8,reaction temperature at 70℃,the rate of raw material(PSAF:CTS) as 1:1,reaction time for 24h.(2) The infra-red spectrogram showed that:PSAF+CTS was a new polymerization polynuclear coordination compound,which was prepared through a series of reactions by PSAF and CTS.The results of scanning electron micrographs indicated that,the essential structure of PSAF and CTS in the compound flocculant PSAF+CTS changed toatally compared with their monomers,respectively. In addition,there were three kinds of structure existenced in PSAF+CTS:1) CTS was a kind of flake which was semitransparent and had no delaminations,but it didn't obvious after magnified by high power;2)PSAF showed the shape of continuous,no lashes and shaggy elevatio;3)the part which liked a cavernous honeycomb was the new structure generated from the reaction between PSAF and CTS.(3) PSAF+CTS can treat the turbidities of several kinds of waste water efficiently with highest removal rate above 99%.,and for the water with high turbidity and dark colour,it had well removal effect.As to domestic sewage,livestock waste water and papermaking waste water,it had as a high removal rate of COD as above 75%in general,and especially had a removal rate of 84.7%for the livestock waste water,which indicated that it had highe treatment ability for COD of livestock waste water.Though PSAF+CTS is strong acidic,it does not influence the pH of treated water for the apply dose of PSAF+CTS is low..But PSAF+CTS had low removal rate to heavy metal Cu²⁺,Zn²⁺,Cd²⁺,especially for Zn²⁺ of which the rate was only 45%,but had high removal rate to Cr⁶⁺ and Ni²⁺,which was 100%and 82.2%,respectively,As a kind of organic-inorganic compound flocculant,its flocculent mechanism was complex,the major of which was the association of several mechanisms such as mechanism of double different electronic shell compression, absorption-nuetralization electric,adsorption Bridging,precipitation net capture,and chelation.(4) As to livestock waste water,the removal effect of PSAF+CTS on turbidity,chromaticity and COD were better than that of single monomer of PSAF,CTS,the direct mixture of PSAF and CTS,or PAC which is applied on industry generously.Moreover,the residual dosage of Al³⁺ in the flocculent treated water was 0.11mg/L,which was lower than that in the PAC-treated water(0.69 mg/L),in addition,the residual dosage of SiO₂ was also low,which indicated that PSAF+CTS was high-performance and environmental protection flocculant.(5) The low cost to prepare the combination of PSAF+CTS in laboratory due to the low price of material which was 1.7225 yuan/L,the simplicity of wastewater treating methods,the suitability for the treatment of many kinds of industrial sewage and domestic sewage,the low treatment cost, and the fact that it could be put into the classic chemical precipitation equipment make PSAF+CTS has better treatment efficiency and good economic effectiveness.