Synthesis And Properties Of Iminodiacetic Acid Type Polymer Chelating Agent

With the rapid development of economy and society, sewagedischarges,especially polluted water by heavy metal, are increasing day by day.Notonly creat a large economic losses, but also cause serious damage to the health andsurvival of various kinds of organisms. Based on this, people developed manytraditional controlling methods, such as neutralization sedimentation method,electrochemical method, oxidation-reduction method and so on. But all thesetraditional methods expose a series of problems, like difficult recovery of heavy metal,the expensive processing, the unsatisfactory effect of sedimentation, and thesubstandard treated water. Relatively, chelating precipitation process with highefficiency, low cost, can also apply to the management of large-scale water pollution.The key factor lies in the property of the chelating agent itself. Therefore, accordingto the study of the principle of the coordination chemistry and sedimentation,designed and synthesized chelate polymer flocculant with similar structure of EDTA.A range of issues of the chelate,flocculating property and chelating mechanism arealso investigated.Begin with the iminodiacetonitrile and epichlorohydrin as raw materials, theintermediate products was obtained by the reaction in tetrahydrofuran, then evaporatethe solvent after reaction of adding diallylamine, add initiator azo diisopropylimidazole hydrochloride (AIBA) to realize9h of polymerization reaction,via whichwe can get pale yellow viscous liquid, then dilute with ethanol and purify withanhydrous acetone, after repeating purification3times, we can dry the product toconstant weight in a vacuum drying oven under60℃.At last a strong chelating heavymetal ion polymer flocculant diene propyl hydroxypropyl amine graft iminodiaceticacid sodium was produced. Using IR,1H NMR and elemental analysis to characterizethe structure of the product. All the results confirm the target polymer wassynthesized successfully. We prepare a certain concentration simulated wastewater ofcommon heavy metal ions（Cu2+、Ni2+、Zn2+、Pb2+、Cd2+and Hg2+） as the treatmentobject, investigates the polymer dosing quantity and the influence of pH on theremoval effect and survey the ion complexing state. The experimental results show that, when the mole ratio of the polymer and heavy metal ions are equal that is to saythe chelating groups-COO-are two times of heavy metal ions, we can achieve highestremoval efficiency, the measuring concentration of residual heavy metal ions andturbidity can meet the national integrated wastewater discharge standard (GB8978-1996) and the national electroplating pollutants emission standards(GB21900-2008). When process a variety of heavy metal ions selectively,we obtainedthe selectively order of the polymer for the four kinds of ion (Cu2+＞Pb2+＞Cd2+＞Zn2+). Qualitative research on the stability of chelate sediment, it can be concludedthat the chelate sediment in neutral or weak alkaline conditions is stable.Sedimentation performance study shows that the whole process of flocculation canfinish rapidly. Recycling research of heavy metal ions reveals that the copper residuecan be recycled in different varieties and different concentrations of acid. Therecovery of copper can be as high as82%in hydrochloric acid. We can realized thesecondary utilization of residue by recycle.Research on actual wastewater treatment: In the research on polymer, aluminumsulfate composite flocculant dosing quantity and the removal effects of Cu2+and Ni2+and COD in wastewater when forming the composite flocculant. We can conclude thatsingle cast cannot meet the national standard, and cast with composite the residual ionconcentration all meet the national electroplating pollutants emission standards. Onthe investigation of properties of the subsidence, sedimentation time is longer thantreating simulated wastewater but shorter than the prcessing the actual wastewater,the aluminum sulfate plays an important role during the process of larging the flocsand easing sedimentation. Study on the stability of the residue reveals that Cu2+andNi2+is relatively stable under the condition of natural environment and the processwon’t cause secondary pollution to the environment. Applying hydrochloric acid tosoak the residue, the biggest recovery of Cu2+can reach89.5%, Ni2+can reach higerthan90.5%.This train of thought of polymer structure design and the chelation mechanism ofheavy metal ion and chelating agent are fully illuminated. Mainly from the commontype of chelating agent, we analyzed the structure of EDTA chelation and on themechanism of cyclization growth of dialkyl diene propyl amine, construct the polymer with advantages of both the chelate structure and growth rings. We employedthe formation of the polymer and the floc residue, observing on the polarizationmicroscope, disproving combination pattern and action mechanism of the chelatingagent and heavy metal ions.All in all, we prepared of this polymer successfully and the polymer reatmentshows evident advantages on the effect of wastewater processing compared withtraditional processing methods.Taking this into account he polymer has broadapplication prospects. We also offered a theoretical basis and reference for thedevelopment of other new type of flocculant.