Performance of Auramine Adsorption from Aqueous Solution on SDS-Modified Attapulgite
Attapulgite is a kind of natural inorganic mineral materials with good adsorption performance.As surface of attapulgite is negatively charged,cationic dyes exhibits positive charge,such as auramine,could be effectively adsorbed on it;in this way,the removal rate of auramine from water could reach 59.3%.Higher removal efficiencies can be even achieved by attapulgite modified with sodium dodecyl sulfate(SDS),an anionic surfactant,as the surface of modified attapulgite is more negatively charged.It has been showed from the image of scanning electron microscopy that attapulgite has a fibrous structure of parallel aggregates;and when attapulgite is modified with SDS,it could be seen the fibers are interknitted resembling a woven texture,so the structure of individual fibers become looser.Additionally,results of infrared spectrum analysis display a characteristic peak of SDS in the SDS-modified attapulgite,indicating a good modification effect on attapulgite by SDS.Furthermore,analysis of the laser granulometric instrument revealed that median diameter of SDSmodified attapulgite diminished to 3.758 μm compared with that(4.223 μm) of the raw attapulgite,thus enhancing its adsorption capacity.The adsorption equilibrium is attained within 30 minutes when the dosage of SDS-modified attapulgite is 0.45 g/L,and the removal rate and adsorption capacity reach to 80.2% and 296.3 mg/g respectively.Comparatively,the adsorption capacity of activated carbon is only 182 mg/g.The experiments conducted also prove that adsorption performance of SDS-modified attapulgite after being desorbed thermally is close to that of the raw attapulgite,which suggests that attapulgite may be reused.