Adsorption Of Cd²⁺ By Different Kinds Of LDHs

Heavy metal pollution is one of the water pollution, and metal cadmium is themost dangerous substance in the environmental water pollution. Cadmium (Cd) in theenvironment mainly comes from smelting non-ferrous metal,the cadmium ore miningdepositing, electroplating, paint, pharmacy, glass, ceramics, and other chemicalindustrial emissions of "three wastes" material. Long-term drinking cadmiumpollution by the food and water or inhaled cadmium smoke can lead to "bone paindisease", cadmium going into bone can cause bone deformation, bone softening,evennatural fracturing, then people die.So Removing the cadmium ions of the waterenvironment is a very urgent task, the method of heavy metal cadmium ions removalis of the important practical significance. This experiment by using three kinds ofconventional LDH preparation methods (precipitation, ion exchange chromatography,restructuring method), EDDS for the modification source, which is prepared threekinds of LDH, and then research the theoretical and practical application of adsorptionto the metal cadmium.Through two commonly method of the X-ray diffraction analysis, Fourierinfrared spectrum characterize all kinds of LDHs. The XRD map shows that the layerstructure of LDHs is complete and the crystallinity is very good. By the FT-IR map,it is known that EDDS exists obviously in the layers of A and B LDHs, because of thecarboxylic acid vibrating peaks in the map.The scavenging kinetic curves were modeled using the level to level2dynamicmodel,theC and D LDHs accord with level1dynamic model, AandB according tolevel2. The correlation coefficient can reach above0.99. The key is, through the dataof adsorption dynamics test, electing to the best modification LDH which goes on theisothermal adsorption test, the obtained data uses Langmuir model fitting, at the sametime the unmodified LDH (D) and activated carbon of200to300microns particlesize are compared.LDH(B)is found a quite big application prospect.Then through the blank of LDHs for desorption test, from the microcosmicunilateral explain the reason why LDH(B) is better than A and C in the adsorption test.The further reality application in sediments of dongting lake and xia bay port suggestthat the LDH(B) can reduce biological availablity of cadmium,which control thecadmium in water environmental through the food chain entering to human body,reduce the harm to human.