Preparation And Properties On Heavy Metals Adsorption Of Modified Bentonite

Industrialization has caused a large number of environmental pollution problems in modern times,and its environmental influence has gradually become prominent.The pollution of water by heavy metals is of particularly concern to the public.Adsorption is a widely applied technology in treatment methods of heavy metal waste water.Bentonite is a clay mineral material and montmorillonite is the main mineral,which can be applied in the wastewater treatment.In order to separate and extract heavy metals from waste water,it is necessary to increase the adsorption and regeneration efficiency of bentonite to heavy metals.In this paper,sodium bentonite was modified and the modified bentonite was characterized by XRD,FT-IR,SEM and BET.The adsorption properties of modified bentonite on heavy metal ions and the removal and regeneration of heavy metal ions were investigated and the adsorption mechanism of modified bentonite was discussed.The main results are as follows:（1）Cetyltrimethy lammonium bromide（CTMAB）was chosen as the modifier to modify sodium bentonite and was used to prepare organic modified bentonite.Through the characterization,it was found that the interlayer spacing of the organically modified bentonite was obviously increased and the original structure of the bentonite was maintained.The morphology was not significantly curled and the layered structure was looser.It can be found that under different experimental conditions,organic modified bentonite has better adsorption and degradation effect on Cd²⁺.The regeneration rate of Cu²⁺was stronger than that of Cd²⁺for ammonia but the regeneration rate was not high.The degradation rate of citric acid on Cu²⁺was stronger than that of Cd²⁺.When the concentration of citric acid was 0.5mg/L,the degradation rate of Cu²⁺reached 79.1%.The organically modified bentonite for degradation Cd²⁺ was well described by Langmuir adsorption model.（2）The layer spacing of bentonite modified with cetyltrimethy lammonium bromide and sodium dodecyl sulfate increased to 1.998 nm.The lamellar structure was loose,dilated and has high porosity.The degradation rate of Cd²⁺reached the maximum at 120min,and the effect of Cd²⁺was best when the amount of adsorbent was 0.2g.The magnetically modified bentonite was modified by using FeCl3·6H2O as the magnetic source.Through the characterization,it was found that the interlayer distance increased to 1.402 nm and there were diffraction peaks of bentonite and Fe3O4.The magnetically modified bentonite has a faster degradation rate of Cd²⁺ and Cu²⁺ and has a stronger degradation.The effect of magnetically modified bentonite on the degradation of Cd²⁺and Cu²⁺was different under different pH conditions,and the degradation is the best when the pH is 6.（3）The film phase of the dispersion of trioctylamine in sulfonated kerosene was coated on the organically modified bentonite to obtain a coated organic bentonite.Through the characterization,it was found that the interlayer spacing of the organic bentonite film was up to 2.107 nm.The morphology showed a smooth layered structure with loose,bright surface and there are obvious oily film on the surface.Adsorption properties of Cd²⁺ and Cu²⁺ on the organic bentonite coating have been studied.It is found that under the different experimental conditions,the organic bentonite coating has good effect on the degradation of Cd²⁺.The regeneration performance of Cd²⁺and Cu²⁺adsorbed on organic bentonite has been found that the degradation rate of Cu²⁺ by ammonia water reaches a maximum of 50.2%at 2min.When the concentration of citric acid was 0.05mg/L,the regeneration rate of Cu²⁺was 75.5%.However,the regeneration rate of Cd²⁺was not more than 20%.Coated organic bentonite is more consistent with Langmuir adsorption model for Cd²⁺.