A Study On The Modification Condition Of Attapulgite And The Removal Of Heavy Metal Ions In Wastewater

With the advance of modern industry,people's living standard has been continuously improved,and the problem of water pollution is becoming more and more serious.It is found that heavy metal ions pollution is different from organic pollutants by researching various pollutants in sewage samples.For example,the pollution of heavy metal ions is not biodegradable and can deposite in organisms.So,it is necessary to develop a new technology to effectively remove heavy metal ions in wastewater and to explore its removal mechanism.Attapulgite,as a kind of natural ore with abundant yield,is selected as the adsorption material.The component analysis of attapulgite samples was carried out by usingXRFuncalibratedtotalquantitativeanalysisandmicrowave digestion/inductively coupled plasma mass spectrometry?ICP-MS?.The morphology of attapulgite was characterized by scanning electron microscopy?SEM?.In this experiment,the removal of Cu²⁺,Ni²⁺,Pb²⁺and Cd²⁺in wastewater was systematically studied.The simulated wastewater containing Cu²⁺,Ni²⁺,Pb²⁺and Cd²⁺are used.The optimum experimental conditions of disposing wastewater applying gattapulgite were found by orthogonal experiment.The content of heavy metal ions in simulated wastewater were determined by ICP-AES.The removal ratio of Cu²⁺was 65.01%,Ni²⁺was 61.02%,Pb²⁺was 80.00%and Cd²⁺was 58.00%when natural attapulgite was used.Beyond that,it was found that Attapulgite can be used for many times.The removal efficiency of heavy metal improved applying the Acid modified attapulgite and the best absorption results were achieved when the concentration of sulphuric acid was 4 mol/L,nitric acid was 2 mol/L and hydrochloric acid reached 2mol/L with a ratio of attapulgite to acid of 10.The optimum ratio of surfactant cetyl trimethyl ammonium bromide?CTAB?,a surfactant,to attapulgite was 1:20 if CTAB was used to modify attapulgite.The surface morphologies of attapulgite and modified attapulgite was observed utilizing SEM.In addition,the infrared spectra of different attapulgite were analyzed by means of FT-IR.The studies showed that the surface morphologies of acid modified attapulgite obviously changed and the internal space and channel sharply increased.Meantime,the hydrophobicity of attapulgite clearly reinforced as a result of the organic modified reagent grafted at the surface of attapulgite,which is proved by FT-IR.The experimental results showed that the organic modified attapulgite?O-ATP?was best at removing heavy metal ions in sewage(the removal ratio of Cu²⁺was 100.00%,Ni²⁺was 93.91%,Pb²⁺was 100.00%and Cd²⁺was 97.10%)The adsorption experiment was conducted on the actual coal wastewater by using the original soil and modified attapulgite.The results show that the adsorption effect of heavy metal ions using O-ATP is the best.The removal rates of four heavy metal ions were Cu²⁺?76.50%?,Ni²⁺?66.70%?,Pb²⁺?49.90%?,and Cd²⁺?100.00%?.Due to the complexity of the actual sewage system,the removal rate of actual wastewater was slightly lower than that of simulated wastewater.