Simultaneous Removal Of Cadmium And Phenol By Chelated Organic Bentonite From Mineral Processing Wastewater

Heavy metal and organic pollutants generally co-exist in industrial wastewater.Bentonite is a kind of widespread and cheap absorption material. But due to the limitsof its structure and property, the adsorption function of bentonite is unitary and cannot efficiently remove heavy metal and organic compounds simultaneously. Thus,bentonite would be widely used in actual waste water treatment after modification andadjustment of the layer structure.This paper modified bentonite by cationic surfactants and chelating agents andinvestigated the proportion of modifier and other conditions in preparing the modifiedbentonite. And then, simultaneous removal efficiency in adsorption of heavy metalcadmium and phenol in synthetical and actual mineral processing wastewater by themodified bentonite were stuied. Furthermore, the adsorption rule and mechanism bythe modified bentonite were explored by analyzing its structure and property withX-ray diffractometer and infrared spectrometer. The research results were as follows:（1） The bentonite was modified by benzyldimethylhexadecylammonium chloridea cationic ion surface active agent, and tetraethylenepentamine, an organic chelatingagent. The optimal preparing conditions were0.8CEC cationic surfactants and4mLchelating agent.（2） Cadmium and phenol in s synthetical wasterwater could be removedsimultaneously by the modified bentonite. Adsorption of cadmium and phenol by themodified bentonite met the Freundlich adsorption isotherm equation. And the optimalconditions of the adsorption time, pH value and temperature was60min,7and25℃respectively. The phenol in wastewater promoted the adsorption of Cd²⁺, howeverCd²⁺had miner effect on adsorption of phenol.（3） When the soil volume was0.04g, adsorption time was2h and pH valueranged in6⁸, the removal efficiency of phenolic compounds and Cd²⁺in actualmineral processing wastewater reached its maximum value88%and99%respectively.If pretreated with CaO before the adsorption by0.01g modified bentonite, Cadmiumand phenolic matter colud achieve Integrated wastewater discharge standard（GB8978-1996）.（4） It was shown that the organic carbon and nitrogen content were obviouslyincreased, the surface area was reduced and the level spacing was increased after modification by analyzing property and structure of the betonite, meanwhile the levelwas turned from water affinity to hydrophobic property.