Preparation Of Thiol Acetylation Polyacrylamide Derivatives And Their Properties Of Copper Removal

The heavy metal wastewater is a kind of industrial wastewater containing persistent pollutants,which is harmful to human health and environment.There are some defects in traditional chemical precipitation for heavy metal wastewater treatment,such as unstable removal effect,large amount of sludge production and high treatment cost.Polyacrylamide?PAM?and its derivatives are used in wastewater treatment to remove colloidal pollutants in water,such as turbidity,chromaticity,fungus and so on.It can not effectively remove dissolved heavy metal ions and it often used as coagulants in the treatment of heavy metal wastewater.Introducing the strong coordination groups of heavy metal ions into the existing polymer flocculants,and a new heavy metal treatment agent that has good effect on heavy metal capture is captured.Inspired by this,The sulfur containing group sulfhydryl group is introduced into the molecular chain of the polymer flocculant PAM derivative,on the one hand,heavy metal ions in the wastewater chelated with the introduced thiols what can be transformed into sediment,on the other hand,On the other hand,the sedimentation and separation of precipitates can be accelerated by the strong flocculation property of the parent PAM derivatives,thus the application range of PAM derivatives is broadened in water treatment.In order to improve the treatment efficiency of wastewater containing copper ions as well as to simplify the treatment process.In this paper,the two novel heavy metal flocculant,called mercaptoacetyl aminomethy-polyacrylamide?MAAPAM?and mercaptoacetyl hydroxymethy-polyacrylamide?MAMPAM?,the intermediate product amethylamine methyl polyacrylamide?APAM?and hydroxymethyl polyacrylamide?MPAM?are prepared by using Macromolecule flocculant polyacrylamide?PAM?are first synthesized respectively throughaminomethylation and hydroxymethylation reaction,and then sulfydryl groups are grafted ontoAPAM and MPAM by amidation reaction.The use of new heavy metal flocculants MAAPAM and MAMPAM can make the treatment of heavy metal wastewater easy to use by using the existing processing units of traditional chemical precipitation and reducing the cost of treatment.The optimal synthesized conditions of MAAPAMand MAMPAM through Plackett-Burman experiment,as well as steepest ascent experiment and central composite design?CCD?of response surface methodology?RSM?.MAAPAM and MAMPAM were characterized by elemental analysis,IR and EDS.The removal of Cu?II?in wastewater as the research object,The removal performance of MAAPAM and MAMPAM on Cu?II?in wastewater was investigated by flocculation test;The solution characteristics,storage stability of MAAPAM and MAMPAM as well as the structure of MAAPAM-Cu and MAMPAM-Cu,stability properties and Cu?II?recovery performance of chelate floc were discussed.The main results are as follows:?1?On the basis of the previous single factor experiment,5 factors affecting the preparation conditions of MAAPAM were screened.that is,the concentration of APAM,the proportion of reactant?APAM and the ratio of TGA material?,the pH value of the reaction medium,the reaction time and the reaction temperature.main factors affecting the preparation conditions of MAAPAM were selected as reactant ratio,reaction medium pH and reaction temperature by Plackett-Burman experiment;factors in the preparation conditions of MAMPAM were selected:the concentration of MPAM,the proportion of reactants?the ratio of MPAM and TGA?,the pH value of the reaction medium,the reaction time and the reaction temperature.The main influencing factors in the preparation conditions of MAMPAM were MPAM concentration,reactant ratio,and the pH value of the reaction medium by Plackett-Burman experiment.?2?The optimum preparation conditions of MAMPAM is as follows:the concentration of MPAM is 0.31%;the molar ratio of MPAM and TGA is 1:3.2;pH value in reaction medium was 4.76;the reaction temperature was 25?;and the reaction time is 2h.Under the optimum conditions,the removal rate of Cu?II?could reach 95.30%,which is close to the predicted value 94.47%of the model.The relative deviation between experimental and predicted value is only 0.83%.The result prove that the model established by RSM is reasonable and feasible;The optimum preparation conditions of MAAPAM is as follows:the concentration of APAM is 1.0%;the molar ratio of APAM and TGA is 1:4;pH value in reaction medium is 4.9;the reaction temperature is 20?;and the reaction time is 3.0h.Under the optimum conditions,the removal rate of Cu?II?can reach 99.61%,which is close to the predicted value 99.08%of the model.The relative deviation between experimental and predicted value is only-0.53%.The result prove that the model established by RSM is reasonable and feasible.?3?By means of infrared analysis,elemental analysis and energy spectrum analysis,it is indicated that sulfhydryl groups are successfully connected on APAM and MPAM molecular chains.The Zeta potential results show that MAAPAM belongs to the amphoteric heavy metal flocculant,its isoelectric point pHiep is 8.2 in tap water and 8.8 in distilled water;MAMPAM belongs to anionic heavy metal flocculant,and its Zeta potential value is negative in tap water and distilled water.MAAPAM and MAMPAM have good stability under the condition of standing at normal temperature without avoiding light and refrigerators?4Centigrade?,and under the condition of refrigerator?4 Centigrade?is a little better than normal temperature.?4?Compared with other types of heavy metal trapping agents,the new heavy metal flocculant MAAPAM and MAMPAM treated the simulated Cu?II?wastewater with the characteristics of Cu?II?,large and easy settling,good water quality,and colorless clarification of effluent;MAAPAM and MAMPAM have a certain selectivity for removing heavy metal ions in waste water,and the highest removal rate of Cu?II?is 99.59%,97.92%;MAAPAM and MAMPAM also have some removal effects on Cd?II?,and the maximum removal rates are 90.26%and 85.08%respectively.MAAPAM and MAMPAM have no removal effect on Ni?II?,Pb?II?,Zn?II?.?5?When MAAPAM and MAMPAM are used to treat wastewater containing Cu?II?separately,the treatment effect is good,and the effluent could meet the emission standard specified by the state.When the simulated sodium citrate,sodium pyrophosphate,humic acid and turbidity exist in the simulated wastewater containing Cu?II?,the coexisting sodium citrate and sodium pyrophosphate have a certain inhibitory effect on MAAPAM and MAMPAM except Cu?II?,but the inhibition can be reduced or eliminated by increasing the dosage of the dosage.The coexisting EDTA has a greater inhibitory effect on MAAPAM and MAMPAM except Cu?II?,and the higher the EDTA concentration,the stronger the inhibition effect.When MAAPAM and MAMPAM remove Cu?II?and turbidity coexistence system or Cu?II?and the coexistence system,both the turbidity and the turbidity can be well removed.?6?The chelating floc produced by the capture of Cu?II?by MAAPAM and MAMPAM is more stable and difficult to produce two times.The recovery of chelate MAAPAM-Cu and MAMPAM-Cu by soaking 15d days with HNO₃ recovery solution is 90.05%and 92.28%,respectively,by the recovery of Cu?II?in the chelating floc by strong acid.?7?The chelating floc MAAPAM-Cu and MAMPAM-Cu are characterized by energy infrared spectroscopy and energy spectrum analysis.The chelating effect of the sulfhydryl group with Cu?II?is demonstrated,and the main mechanism of the interaction of Cu?II?and organic coordination complexes is chelating chelation.In summary,the new type of heavy metal flocculant MAAPAM and MAMPAM prepared by this type,respectively,treat the simulated Cu?II?wastewater and the actual heavy metal wastewater respectively.It has the advantages of good treatment effect,simple process,easy operation control,good stability of the chelate,and no two pollution dyeing.Therefore,the new type of heavy metal flocculant has broad prospects for popularization and application,at the same time,it can provide reference and reference for the development of other new flocculants.