Removal Of Cr(?) From Water By Typical Pharmaceutical Residues And Derived Carbon

With the rapid developments of urbanization and industrialization,a large amount of industrial wastewater with toxic heavy metals is discharged,which poses health harm and heavy ecological risks.Chromium has been considered as one of the top 16th toxic pollutants,which exists in aqueous medium in Cr(III)and Cr(VI)oxidation states.The demands for chromium arise in a series of industries:Metallurgy,chemical industry,papermaking,electroplating and anodizing baths.These industries can produce large amounts of wastewater containing Cr(VI)and Cr(III),especially in electroplating industry.Moreover,Cr(VI)is more toxic and lower stable than Cr(III)in terms of eco-toxicological effects,which is considered a priority pollutant.Therefore,it is very important to remove the low concentration of Cr(VI)ions from the waste water.Typical pharmaceutical residues come from traditional Chinese medicine extraction and antibiotic production.The traditional Chinese medicine residue was mainly landfill,and the antibiotic residues were mainly incineration.However,these disposal methods will not only pollute the environment,but also a waste of resources.The thesis is concern about removal of Cr(VI)from Water by Typical Residue and Derived Carbon,and further characterized by SEM,XRD,FI-IR,BET andTG.The results are summarized as follows.(1)This study investigated the use of CHER to adsorb Cr(VI)from aqueous solution.Results indicated that adsorption was maximum at solution pH of 2.0 while the Cr(VI)removal efficiencies for chuanxiong rhizome residue(CRR)and Chinese wolfberry residue(CWR)were 86.56%and 99.93%,respectively.Isotherm data were modeled by using Freundlich,Langmuir and Temkin isotherm.The maximum monolayer adsorption capacities for CWR and CRR were 79.60 mg·g-1 and 36.21 mg·g-1,while their corresponding adsorption capacities obtained from experimental data were 37.30 mg·g-1 and 32.42 mg·g-1,respectively.However,Freundlich isotherm fitted the data well.Both adsorption and reduction of Cr(VI)to Cr(III)forms followed by complexation onto the adsorbent surfaces favored removing Cr(VI).The results also suggested that the abundant and cheaply available CRR and CWR can be used as efficient adsorbent materials for Cr(VI)removal from wastewater.(2)Cephalosporin residue(CR)was used to produce biochar(BC)and activated carbon(AC)at 600?(BC600 and AC600).To compare the removal Cr(VI)behaviors and mechanisms of the CR and derived chars,batch adsorption experiments were performed in micro-environment,which combined with the characteristics of adsorbents before and after adsorption.Results showed that the adsorptions of Cr(VI)by CR and CR-chars were obeyed Freundlich and Langmuir models.Based on the Langmuir model,the maximum adsorption capacities of Cr(VI)onto CR,BC600 and AC600 were 107.41 mg·g-1,88.19 mg·g-1 and 74.07 mg·g-1,respectively.The Cr(VI)removal behavior was complex and associated with adsorbent properties and solution micro-environment,whose main mechanisms were adsorption and reduction.The study developed a new way to reutilize CR and lower the toxicities of CR and Cr(VI),and showed a great potential for treating hazardous waste,reflecting sustainable waste management.