Preparation Of Dithiocarboxyl Polyacrylamide Derivatives And Its Performance For Removing Copper

Amide is high activity function group in the molecular structure of polyacrylamide,and can be easily trasfomed to hydroxymethy-polyacrylamide and sulfomethy-polyacrylamide to prepare new type of water treatment agents.In this paper,a coordinating ligand dithiocarboxy of heavy metal ions is introduced to the molecular chains of polyacrylamide successfully to prepare two kinds of model flocculant.This two novel flocculants,called dithiocarboxyl hydroxymethy-polyacrylamide?DTMPAM?and dithiocarboxyl sulfomethy-polyacrylamide?DTSPAM?,can be directly applied to the treatment of heavy metal waste water for the dual functions of chelating and flocculation.On the basis of the single factor and orthogonal experiment in our previous work.Polyacrylamide was chosed as start material to explore response surface analysis and optimize the preparation conditions of DTMPAM and DTSPAM.Thus,the structures of DTMPAM and DTSPAM were initially synthesised and characterized by infrared analysis,scanning electron microscope and elemental analysis.Subsequently,we choosed Cu?II?water as the object samples to study,the performances of DTMPAM and DTSPAM for removal of Cu?II?and turbidity are mainly investigated by flocculation experiments,and the influencing factors,such as Cu?II?initial concentration,pH value of water sample,organic complexing agents,coexisting turbidity,etc.,were discussed in this paper.Finally,the stability of the chelating floc DTMPAM-Cu?II?,DTSPAM-Cu?II?and the recovery of Cu?II?in the floc was investigated.The main research results are summarized as follows:?1?The optimized conditions for the preparation of DTMPAM were as follows:the concentration of MPAM was 0.5%,the molar ratio of MPAM,CS₂ and NaOH was1:1.43:1.43,pre-reaction temperature was 25?,pre-reaction time was 60min,main-reaction temperature was 45?,and main-reaction time was 70min.The optimized conditions for the preparation of DTSPAM were as follows:the concentration of SPAM was 1.5%,the molar ratio of SPAM,CS₂ and NaOH was 1:2:2.3,the pre-reaction temperature was 20?,the pre-reaction time was 15 min,the main-reaction temperature was 51?,and the main-reaction time was 120 min.?2?DTMPAM and DTSPAM are soluble in ether and distilled water,insoluble in acetone and anhydrous ethanol.Both infrared analysis and elemental analysis show that DTMPAM and DTSPAM molecular chains have successfully connected to dithiocarboxyl.The Zeta potential of DTMPAM and DTSPAM in distilled water and tap water is negative and the absolute value of Zeta potential in tap water is less than the absolute value of Zeta potential in distilled water.DTMPAM has good stability and can be kept stable for 25 days at low temperature.And DTSPAM storage stability is relatively better,can be stored for about30 days.?3?DTMPAM trap single heavy metal ion effluent showed as follows,when the pH value of water sample was 6.0,The removal rate of Cu?II?was the best,and rate was upto98.63%.The removal rate of DTMPAM to Cu?II?has decreased slightly with the increase of the initial concentration of Cu?II?in the system.The removal of Cu?II?in the water samples was the optimal dosage of DTMPAM,and the removal rate of Cu?II?was decreased with excessive DTMPAM.The presence of organic ligand EDTA has a significant inhibitory effect on DTMPAM removal of Cu?II?.Moreover,with the increase of EDTA concentration,the inhibitory effect is more significant.When turbidity is present in the water sample,the low turbidity can promote the removal of Cu?II?by DTMPAM,while the turbidity will inhibit its removal.?4?The Zeta potential of DTMPAM solution was negative under different pH values,and Zeta potential decreased with the increase of pH value of the solution,indicating that DTMPAM was an anionic polymer chelate-flocculant.The recovery rates of chelated flocculent DTMPAM-Cu in HCl,HNO₃ and H₂SO₄ immersion fluid were 95.62%,99.21%and 90.35%respectively.?5?DTSPAM trap single heavy metal ion effluent showed that,when the pH value of water sample was 6.0,the effect of Cu?II?was the best,and the removal rate was 93.52%.The removal rate of DTSPAM on Cu?II?increases with the initial concentration of Cu?II?in the system.The removal rate of Cu?II?in the water sample was reduced by DTSPAM,and the removal rate of Cu?II?was decreased.The presence of organic ligand EDTA and sodium pyrophosphate has a significant inhibitory effect on DTSPAM removal of Cu?II?.Moreover,with the increase of the concentration of EDTA and pyrophosphate,the inhibitory effect is more significant.Coexisting turbidity has a small effect on the removal of Cu²⁺from DTSPAM,and DTSPAM can also effectively remove turbidity in water samples at the same time.?6?The Zeta potential of DTSPAM solution was negative under different p H values,and Zeta potential decreased with the increase of pH value of the solution,indicating that DTSPAM was an anionic polymer chelate-flocculant.The recovery rates of chelated floc in HCl,HNO₃ and H₂SO₄ immersion fluid were 84.65%,98.51%and 83.26%respectively.