Preparation Of Coal Based Sorbent And Its Application For The Removal Of Heavy Metal From Wastewater

As the rapidly development of industry in our country,the water resource is facing grim situation such as the shortage of water and the seriously water pollution.A large number of heavy metals and organics in the wastewater would do great harm to the ecological environment without any treatment.Therefore,the economic and effective treatment of water pollution is the key issue at home and abroad.Lignite is a kind of natural mineral,which is rich in resources and cheap in price.Besides,lignite shows excellent adsorption,exchange and complexation properties due to its large quanlity humic acid,great surface area,abundant pores and oxygen functional groups.Therefore,the using of sorbent from lignite can not only save the sources of energy,but also achieve the purpose of waste treatment.The sorbent from lignite was prepared by acid and alkaline modification.The sorption performance of the prepared sorbent on phenol,methylene blue,copper ion and lead ion in aqueous solution was also investigated.The adsorbents were characterized by Scanning Electron Microscope and infrared spectroscopy.The effect of the modified method on chemical properties of the adsorbent was also studied.The possible adsorption mechanisms of wastewater were discussed on the basis of the characterization results.And the experimental parameters on adsorption reaction time,liquid ratio,pH value and reaction temperature were studied,respectively.The results are as follows:1.The adsorption experiment of phenol aqueous solution shows that: on the best adsorption conditions,phenol adsorption capacity of original lignite can reach 18.86mg/g.Phenol adsorption capacity of KOH modified lignite is 29.04 mg/g.Phenol adsorption capacity of H₃PO₄ modified lignite is 26.97 mg/g.The Methylene blue adsorption experiment shows that: on the best adsorption conditions,Methylene blue adsorption capacity of original lignite can reach 15.77 mg/g.Methylene blue adsorption capacity of H₃PO₄ modified lignite is 264.64 mg/g.And the possible adsorption mechanisms of organic pollutants were discussed according to the kinetic data,thermodynamic data and the characterization results.It indicated that thespecific surface area of adsorbent show great influence in adsorption capacity of organic in solution:the more acidic groups?-OH?existing on the higher surface area surface lead to higher adsorption capacity of organic pollutant.2.The copper ion adsorption experiment shows that: on the best adsorption conditions,copper ion adsorption capacity of original lignite can reach 3.41 mg/g.Copper ion adsorption capacity of KOH modified lignite is 23.30 mg/g.Copper ion adsorption capacity of H₂SO₄ modified lignite is 13.01 mg/g.The lead ion adsorption experimental shows that: on the best adsorption conditions,lead ion adsorption capacity of original lignite can reach 10.41 mg/g.Lead ion adsorption capacity of KOH modified lignite is 67.98 mg/g.And the possible adsorption mechanisms of heavy metal pollutants were discussed according to the kinetic data,thermodynamic data and the characterization results.Various chemical groups exist on the adsorbent surface by modification,the metal ions in the wastewater were fixed on the adsorbent via ion exchange reaction with the acidic functional groups such as-COOH on the surface of the adsorbent.The resourceful lignite were used as the adsorbent for removal of organic and metal pollutant from wastewater in this paper.The adsorption capacity of lignite can be improved by chemical activation.Due to its easy operation and low cost,this method can provide a new way for improving the value of lignite.