Microstructure Of Hollow Microspheres And Its Effect On Adsorption Properties

Dye wastewater is one of the important pollution sources in water pollution.It has the characteristics of complex composition,high chroma and concentration,large variation in water quality,and difficulty in biodegradation.Coal gangue and fly ash are the solid wastes emerging from coal production and coal-fired power plants,respectively.lt has many excellent properties as an adsorbent and it is inexpensive.Treatment of sewage with coal gangue and fly ash can achieve the purpose of waste treatment.Due to the unique structure,attapulgite is also widely used in the treatment of various types of wastewater.In this paper,coal gangue,fly ash and attapulgite microspheres bodies were prepared by spray drying,and after the calcination treatment,a good microspheres adsorbing material is obtained which applied to the treatment of dye wastewater.Effects of calcining temperature,microspheres dosage,concentration of dye and contact time on the adsorption properties on dye of microspheres were investigated.The adsorption kinetics and adsorption isotherm model were studied.The microstructure of microbeads was characterized by XRD,SEM,TG/DTA and other methods,and the adsorption mechanism was elucidated.Static adsorption experimental study shows that,coal gangue microspheres have the best adsorption effect on methyl violet and malachite green when the calcination temperature is 800? and the dosage is 6 g/L,the adsorption capacity and removal efficiency are 16.2 mg/g and 97.2%,9.5 mg/g,and 94.6%,respectively;fly ash microspheres have the best adsorption effect on methyl viole when the calcination temperature is 800?and the dosage is 4 g/L,the adsorption capacity and removal efficiency are 24.09 mg/g and 96.4%,respectively;attapulgite microspheres have the best adsorption effect on methylene blue when the calcination temperature is 600? and the dosage is 1 g/L,the adsorption capacity and removal efficiency are 96.62 mg/g and 96.6%,respectively.The adsorption processes of coal gangue,fly ash and attapulgite microspheres all conform to the pseudo-second-order kinetics model.The adsorption process of methyl violet by coal gangue and fly ash microspheres conformed to the Langmuir model,the adsorption of methylene blue by attapulgite microspheres and the adsorption of malachite green by coal gangue microspheres is in accordance with the Freundlich model.After the calcining process,coal gangue,fly ash and attapulgite microspheres can maintain a complete spherical structure.After suitable calcination temperature,adsorption capacity of microspheres are increased.With the increase of the calcining temperature,thechange of the phase of several kinds of microspheres occurred at different temperatures,the specific surface area showed a decreasing trend,and the adsorption capacity of microspheres was reduced.