Modification Of Zhidan Bentonite And Its Adsorption Of Organic Pollutants In Water

As an important energy and chemical industry base in China,northern Shaanxi region is rich in energy resources but lacks water resources,which plays an essential role in energy and chemical production.The energy and chemical enterprises occupy the limited water resources to sustain production while discharge plenty of industrial wastewater containing refractory,toxic organic pollutant,which means that if the industrial wastewater can not be treated and recycled in northern Shaanxi region,it will lead to serious ecological pollution and even bring about negative effect on the sustainable development of the energy and chemical industry base.In this dissertation,from the point of view of adjust measures to local conditions,the absorption performance and mechanism of bentonite in Zhidan has been system investigated basing on the experimental result of activating and modification and absorption performance of organic pollutants in wastewater by adsorption experiment.The aim of this research is to develop bentonite materials which can be used to adsorb the organic pollutant.The main original conclusions of this work are as follows:After purification and sodium,the absorption performance of Zhidan bentonite on mlachite green,methylene blue,alizarin red and phenol organic pollutants was investigated by adsorption thermodynamics,adsorption kinetics and packed column adsorption.The adsorption capacity and adsorption effect and adsorption mechanism of bentonite on different kinds of organic pollutants was also investigated.The experimental results showed that the purification and sodium Zhidan bentonite exhibit good adsorption effect on cationic organic matter(malachite green and methylene blue)while the adsorption capacity on the anionic organic pollutants(Alizarin Red)and phenolic organic pollutants(phenol)is weak.The reason is that the bentonite lack of anion exchange site and surface hydrophilic and the dominating adsorption mechanism is the cation exchange interaction between bentonite interlayer.Bentonite adsorption capacity and adsorption of organic contaminants with charge and molecular structure are closely related.In order to overcome the insufficiency of low surface area of traditional modified natural clay and expand the adsorption range of bentonite,hydrochloric acid,sulfuric acid,nitric acid and phosphoric acid was employed to activate the purification and sodium Zhidan bentonite.The effect of acid concentration,ratio of solid and liquid,activation temperature and activation time properties of activated clay was investigated through the single factor and orthogonal experimental design.The as-prepared activated bentonite was characterized,the acid activation mechanism and the comparison of acid activation of bentonite kaolin and illite was also investigated.The results indicated that sulfuric acid in the activation process has the better application effect.Under the optimal technical condition synthesized high activated clay using the Zhidan bentonite as the raw materials was 18%of sulfuric acid,95?,1:2.5 of solid-liquid ratio,4h.Under this technical condition,the specific surface area of activated clay reached 162.6 m2/g.The essence of bentonite activation is that the montmorillonite interlayer cation and eight anthropometric cation was constantly exchange and dissolution process,activation in the same conditions,bentonite ratio surface area was significantly higher than that of illite and kaolin,the main reason is that the bentonite with relatively low silica content and high iron content.Iron oxides were employed to modify the activated inorganic pillared clay.The structure,chemical property of pillared clay and its absorption performance and mechanism of anionic organic compounds,cationic organic compounds and phenol organic matter was investigated.The experimental results indicated that under pillared modification of iron oxide,the inter-lamellar spacing and specific surface area of as-prepared pillared activated clay increased.Compare to the sodium bentonite,the pillared activated blenching clay show the good treatment effect of anion alizarin red and easy to be recycled.The absorption performance of pillared activated blenching ability to malachite green is significantly decreased while slight increase to the hydrophobic phenolic compounds(phenol).The reason is that Fe2O3 pillared modifications don't change the surface hydrophilic while increase the adsorption of anionic sites and reduce the cationic sites.Trimethylchlorosilane(TMCS)and cetyltrimetylammonium bromide(CTMAB)was employed to surface organic modification and cationic surfactant pillared modification of activated clay and sodium bentionite.The as-prepared organic grafting activated clay and organic pillared bentonite was characterized and the mechanism was also investigated.The adsorption performance of as-prepared series modified was used to treat the Lan-Carbon wastewater via comparison to activated carbon,bentonite,and activated clay.The results indicated organic modifier chlorotrimethylsilane(TMCS)can graft to SiOH group of activated clay surface through covalent bond.After modification,the surface of activated clay changed from hydrophilic to hydrophobic,specific surface area decrease slightly.While after pillared modification by long carbon chain surfactant,cation exchange has occurred between cation surfactant and cation of bentonite layer.Which result in the long alkyl group was induced to bentonite layers structure,and blocked most duct of bentonite are duct between layer,specific surface area reduced significantly.The adsorption performance of modified activated clay and sodium bentonite on hydrophobic phenol increased significantly,and the former was higher than the latter,which is related to the capacity of organic modification clay and Specific surface area.The organic grafted activated clay has good performance on hydrophobic organic of Lan-Carbon wastewater,which further expand the bentonite in organic wastewater treatment of applications.