Preparation Of Diatomite-based Adsorbents And Their Adsorption Properties

In this paper,two kinds of diatomite modified materials were prepared.The modified materials were characterized by scanning electron microscope(SEM)and energy dispersive spectrdmeter(EDS).Two kinds of diatomite-based modified materials were prepared for the removal of direct dyes and anionic dyes in wastewater.(1)Due to its unique physical properties,diatomite has been widely used to treat heavy metals and organic pollutants.However,because of its inherent defects,its adsorption performance still has some limitations.Firstly,diatomite is pickled,then magnetic diatomite is prepared by hydrothermal synthesis,and finally,hexadecylpyridinium chloride(CPC)is compounded with magnetic diatomite.Preparation of CPC-Magnetic Diatomite Composites using diatomite as matrix.It is used as an adsorbent for adsorbing direct red 4BS,direct freeze yellow G,and methyl orange in wastewater.The load of CPC makes a large amount of ammonium ions on the surface of the adsorbent,change the charge properties on the surface of diatomite to make its surface positively charged.The three dyes exist in the form of anions in the water.Due to the attraction of the opposite charges,the three dyes are effectively removed by the adsorbent.In the experiment,the influence of adsorption time,reaction temperature and solution p H on the adsorption performance of CPC-magnetic diatomaceous earth adsorbent was investigated.The results showed that the adsorption balance time of adsorbents for direct red 4BS,direct freeze yellow G and methyl orange was 8 h,8 h and 10 h.Adsorption capacity will increase as reaction temperature increases.Adsorption of three dyes by CPC-magnetic diatomite conformed to the quasi-second order kinetic model,and the adsorption isotherms of the three dyes conformed to the Langmuir model.(2)The diatomite was pretreated with acid washing and high-temperature calcination,and then modified with Mg(OH)2 to prepare Mg(OH)2 modified diatomite by three methods: water phase,dual solvent and grinding.The modified adsorbents prepared by different methods were applied to the adsorption of dye Congo red,and the effects of different modified conditions on the adsorption performance were investigated.The optimal modification method was selected,and the adsorption performance of Congo red was further examined by time,temperature and solution p H conditions.The results showed that the diatomite was calcined at first,then theadsorbent modified by grinding method had the best adsorption effect on Congo red.The adsorption equilibrium time was 3 h,and the temperature increase was conducive to the adsorption.Adsorption of Congo Red by Mg(OH)2 modified diatomite conformed to the quasi-second-order kinetic model,and the adsorption isotherm conformed to the Langmuir model.