Hydrophobic Modification And Application Of Cationic Polyacrylamide

The removal of dye and dissolved organic matter by flocculation is one of important research areas in textile wastewater treatments.The color removal efficiency mainly depends on the properties of flocculants.In recent year,flocculants develop rapidly along with the development of the flocculants' theory and chemical industry.Various flocculants categories have been developed including inorganic flocculants,organic flocculants,low molecular weight flocculants,organic polymer flocculants and composite flocculants.Wide attention has been drawn in science research and water-treatment industry.Due to positive charge in molecular chain,cationic organic-polymer flocculants can remove organics with negative charge efficiently from waste-water,especially,dye wastewater,which is toxical and hard to remove from water.It has been found that cationic flocculants have the advantages that high decolorization efficiency,wide application areas, small pH effect,low dosage and quick flocculation speed,etc.Therefore,cationic organic-polymer flocculants have been extensively studied and applied to waste-water treatment in the world.Cationic polycarylamide is one of most popular flocculants.At present, cationic monomers used to polymerize mainly depend on import,so that cost is high.In order to solve the contradiction between cost and flocculability,popular cationic-polymer flocculants were hydrophobically modified by introducing functional groups into flocculants molecular chain in this paper.This enhanced the intermolecular interaction between flocculant and dye,reduced water-solubility of floccutant and floes.And so floes dye molecules were removed from water quickly and flocculation efficiency rose.Firstly,P(AM-DADMAC) was synthesized in inverse emulsion.The effects of composite emulsifier,disperse medium,kind of initiator,volume ratio of oil and water,concentration of initiator and monomer on stability of inverse emulsion and intrinsic viscosity of copolymer.The suitable polymeric system was chosen by studying the polymerization of AM and DADMAC in inverse emulsion.On the basis,a flocculant of P(AM-DADMAC-VTMS) was synthesized in inverse emulsion,with kerosene as disperse phase,Va-044 as an initiator,Span80/Tween80 as composite emulsifier,VTMS as a hydrophobically modified monomer,AM and DADMAC as main comonomers,overcoming the shortage of aqueous solution polymerization.The effects of feed ratio of VTMS and DADMAC on characteristics of polymer were investigated.The structure of terpolymer is confirmed by FT-IR.Particles in inverse emulsion and polymer powders were investigated by the scanning electronic microscopy(SEM).The color removal of reactive brilliant red X-3B (X-3B) by P(AM-DADMAC-VTMS) has been studied.The results showed that removal ratio of X-3B increased largely with increasing the content of VMS,and when AM/DADMAC/VTMS=79.2/19.8/1.0,the largest removal ratio is 94.28%;optimal dose and removal ratio decrease with DADMAC increase;modified flocculant has better flocculability when pH is 2-5;the addition of NaCI to waste-water shield the function of charge neutralization between flocculant and dye,but the more the content of VTMS is,the less the effects ofpH and NaC1 on color removal are.Methacryloxyethyltrimethyl ammonium chloride(DMC) is also a typical cationic monomer used to synthesize cationic flocculant.Therefore,the paper synthesized a novel flocculant P(AM-DMC-VTMS),with DMC,AM and VTMS as comonomerso The color removal of X-3B and dispersion orange 30 were investigated by P(AM-DMC-VTMS).It is found that the decolorization efficiency of P(AM-DMC-VTMS) is better than that of P (AM-DMC).With the content of VTMS increase,removal ratio of reactive dye and dispersion dye increase.With the content of DMC,removal ratio of reactive dye increase. Optimal pH ranges is 2-5.When molar ratio of trepolymer is AM/DMC/VTMS=79.2/19.8/1.0, maximum decolorization of X—3B is 89.3%and that of dispersion organe 30 is 98.1%. While P(AM-DMC) with similar molar ratio,maximum decolorization is only 41.7%and 46.9%for X-3B and dispersion organe 30,respectively.In order to further study the effect of hydrophobically modified monomer on decolorization,the paper choose another monomer-methacryloxypropyltrimethoxy silane (MPMS) as a modified agent and synthesized a novel flocculation P(AM-DMC-MPMS). Water-solubility of P(AM-DMC-MPMS) is lower than that of P(AM-DMC-VTMS).when molar ratio of terpolymer is AM/DMC/MPMS=79.2/19.8/1.0,optimal dose is 180mg/L and M-8B was removed completely.With the content of DMC increase,optimal dose decreases. P(AM-DMC-VTMS) is better efficiency than P(AM-DMC) as flocculant to treat waste-water of dispersion dye and suspension of kaolin.The study on the decolorization of printing and dyeing wastewater showed that decolorizing performance of P(AM-DMC-MPMS) is better than that of PFS.Decolorization mechanism showed that dye molecules removal of M-8B depend on the cooperation of charge neutralization,hydrophobic interaction and intermolecular hydrogen bond.Intermolecular hydrogen bond and hydrophobic interaction are key factors of decolorization when their cationicity are low.P(AM-DMC-MPMS)/PFS is compatible system and can form network structure.The color removal of M-8B and dispersion organ 30 by composite flocculant was investigated. Removal ratio of M-8B by P(AM-DMC-MPMS)/PFS and P(AM-DMC)/PFS is 99.8%and 99.39%,respectively,and for dispersion organ 30,removal ratios are both above 98%when pH is 3-6.P(AM-DMC-MPMS)/PFS have more efficiency than PFS when as flocculation for printing and dyeing waste-water.Optimal dose and removal ratio of the former are 55.68mg/L and 82.57%,respectively.However,for the latter,when dose is 74.24mg/L,removal ratio only is 59.29%.