Study On The Performance, Adsorbing Properties Of Attapulgite-humic Acid Composite Adsorbent

Wastewater still causes great harm to the environment and human health with the rapiddevelopment of industry, increasingly stringent emission standards. Therefore, recycling ofwater is widely attention, the role of adsorption method in wastewater treatment will becomeincreasingly important. Seeking and developing efficient low-cost adsorbents become the keyissue of the study.In this paper, modified attapulgite clay was prepared through purification, acidificationand thermal activation of attapulgite clay minerals from Baiyin city in Gansu province, andwas added to the humic acid from lignite in Tianzhu, with this method attapulgite-humic acidcomposite adsorbent was prepared. Compared the adsorption properties of the compositeadsorbent with another two separate adsorbents, and adsorption conditions were optimizedthrough the combination of a single factor and orthogonal experiments, such as the effect ofadsorbent proportion, the dosage, temperature, pH value, adsorption time and theconcentration of the adsorbate to adsorption efficiency. The adsorbent were characterized andanalyzed by Infrared Spectroscopy (FTIR), Scanning Electron Microscopy, XRD and anotherdetection technologies. Found that the particle size of the composite adsorbent is small anduniform, specific surface area and surface active groups have been greatly improved.By optimizing the experimental conditions, the composite adsorbent has a goodadsorption performance to Ni2+, Mn2+, phosphate and methylene blue. The best adsorptionconditions of Ni2+are the concentration of150mg/L, adsorbent dosage of0.8g, adsorptiontime of4h, the temperature of40℃, pH of6, the adsorption rate reaches97.5%with theadsorption capacity of9.14mg/g. The best adsorption conditions of Mn2+are theconcentration of100mg/L, adsorbent dosage of0.8g, adsorption time of2h, the temperatureof40℃, pH of7, the adsorption rate reaches92.5%with the adsorption capacity of5.78mg/g.The best adsorption conditions of phosphate are the concentration of100mg/L, adsorbentdosage of0.8g, adsorption time of4h, the temperature of80℃, pH of5, the adsorption ratereaches91.5%with the adsorption capacity of5.72mg/g. The best adsorption conditions ofmethylene blue are the concentration of300mg/L, adsorbent dosage of0.3g, adsorption timeof4h, the temperature of50℃, pH of1, the adsorption rate reaches97.2%with the adsorptioncapacity of48.6mg/g. The adsorption performance of the composite adsorbent to Cr6+is notas good as the adsorption effect of humic acid, but the adsorption effect is improvedobviously after the experimental conditions are optimized.Finally, the adsorption thermodynamics and kinetics of composite adsorbent are studied.The result indicates that in most cases the composite adsorbent is priority to chemical adsorption, physical adsorption is auxiliary adsorption mode, with the combination of themonolayer and multilayer adsorption.