A Novel Anion-exchange Resin Preparation And Adsorption Effect Of Nitrate From The Raw Drinking Water

Nitrate pollution in the raw drinking water has caused widespread concern in theworld. To develop cost-effective technology to remove the nitrate from raw drinking water,using1,4-Bis(chloromethoxy) butane and triethylamine, a strong basic anion-exchangeresin was prepared via chloromethylation and amination of the crosslinked polystyrenemicrosphere. The chemical structure of resin was characterized by Fourier InfraredSpectroscopy. Various influence factors on the chloromethylation reaction and aminationreaction were examined and the best synthesis process was obtained. The research ofsynthesised ion exchange resin adsorption behavior was studied, the conclusions are asfollows:(1) The optimal condition for chloromethylation reaction was:10ml g-1dichloromethane as the solvent,1.125ml g-1stannic chloride and1.798g g-1BCMB forwhite-spheres with the reaction time of6hours. The chloromethylated crosslinkingpolystyrene microsphere with chlorinity of16%was obtained in the condition as narrated(2) The best amination reaction conditions are as follows: formamide as theswelling agent, the amount of triethylamine dose is three times on the theory oftemperature control for60?, the reaction time is8h. Strongly basic anion exchange resincan be obtained under the reaction conditions with the all exchange capacity of2.4mmol g-1.(3) The equilibrium time of nitrate adsorption is40minutes. Temperature andsolution pH on the adsorption of nitrate had no significant effect. The adsorption process isin accordance with the pseudo secondary dynamics and Langmuir isotherm equation and itbelongs to the chemical adsorption, the diffusion is speed control steps. According to the calculation formula, the available adsorption quantity is18.34mg· g-1. Selectivecoefficient shows that the ion exchange resin has selective adsorption for nitrate. Thebehaviors of the resin regeneration results show that the best renewable NaCl liquidconcentration was8%and the regeneration time is30minutes. The regeneration rate afterthrowing10times can stay above98%, good performance shows that the ion exchangeresin regeneration temperature and solution ph have no obvious effect on adsorption ofnitrate. But can be seen from the trend, the adsorption reaction is exothermic reaction, andin a weak acid environment more can play the adsorption performance of ion exchangeresin.(4)Continuous flow experiment of ion exchange column shows that the through timeand leakage time were10hours and12hours respectively, and test curve was no obviouschange after three times in a row. It shows that the ion exchange column for nitrateremoval effective and of good regeneration performance. When sodium chloride with8%and4%respectively to r regenerate the ion exchange column, regeneration time were1hour and2hours respectively. To comprehensive industrial production needs, the bestregeneration fluid is8%sodium chloride. According to the formula, the dynamicadsorption of ion exchange resin was17.85mg·g-1, comparing with the static adsorptionexperiment income18.34mg·g-1, it is slightly down.