Preparation Of Sorbents From Two Kinds Of Solid Wastes For Lead,Cadmium And Silver Contaminated Water Treatment

Rapid industrialization has contributed to the massive release of wastewater containing heavy metals from many industries,which is the main source of water heavy metals pollution.Heavy metal ions are toxic and non-biodegradable,and can accumulate in living organism.Therefore,the harmful ions must be removed before wastewater discharge.Among all the heavy metals removal approaches,adsorption is widely considered as operation simple,economical and high efficient.The focus of the adsorption method is low-cost and high efficient adsorbents.The industrial and agriculture solid wastes are wide range of sources,low-cost and abundant,nonetheless they are humal to the enviroment.It will be of great importance to select suitable raw material from the wastes and transforming it into adsorbent for heavy metals wastewater treatment,as it can significantly reduce the costs of adsorbents and resource utilization of the wastes simultaneously.In this study,two kinds of high efficient adsorbents were preparation from waste Li-ion batteries?LIBs?and pomelo peel respectively for lead,cadmium and silver contaminated water treatment.The raw material recovery from spent LIBs is artificial graphite?AG?powder.Firstly,the AG was modified by acid potassium permanganate solution to synthesize MnO₂-AG which surface was covered by MnO₂ particles.Secondly,pore structure parameters,Elemental composition analysis,XRD analysis,TGA,and SEM-EDX analyses of AG and MnO₂-AG indicate that the cladding of MnO₂ particles on AG.And sorption experiments shows that the MnO₂-AG exhibited a markedly improved removal capability toward Pb?II?,Cd?II?and Ag?I?than the raw AG.Secondly,The influences of intial metal concentration,contact time and intial pH on adsorption capacity of MnO₂-AG was investigated by batch adsorption experiments.The maxium adsorption capacities of Pb?II?,Cd?II?and Ag?I?on MnO₂-AG were 99.88,29.49 and 67.80 mg/g,respectively.Thirdly,XRD analysis and FTIR analyses of MnO₂-AG after Pb?II?,Cd?II?and Ag?I?adsorption showed that the removal of the heavy metals by MnO₂-AG was mainly through ion exchange of hydroxyl group.As a renewable agriculture solid wastes,the white spongelike part of pomelo peel was was usd as precursor of adsorbent for Pb?II?and Ag?I?contaminated water treatment.Firstly,the pomelo peel carbon?PP?was prepared by mixing the raw material and phosphoric acid and activating under air atmosphere at 250?.Secondly,a batch adsorption experiments was carry out for investigating the influences of intial metal concentraion,contact time and intial pH on adsorption capacity of PP.And the results showed that the PP had strong sorption ability to Pb?II?and Ag?I?with maximum sorption capacities of 88.74 and 137.4 mg/g.Thirdly,FTIR,XRD,SEM and EDX analyses of PP before and after Pb?II?and Ag?I?sorption indicated that the Pb?II?adsorption is mainly controlled by the precipition of Pb to form Pb₅?PO₄?₃OH on the surface of adsorbent,wheraes the main adsorption mechanism of Ag?I?was that oxygen-containing function groups on the surface of PP adsorbing and reducing the silver ions to form silver crystal,which is beneficial to recycle silver further.