Preparation Of Doped Ferrites Via Sol-gel-hydrothermal Method With Spent Batteries

With the popularization of IT, digital and AV equipment, dry cells have become necessary portablepower source. The types of the batteries emerge in endlessly because of the increase of portable electronicdevices. One-shot battery and rechargeable batteries are very popular at present. Since entering the21stcentury, alkaline zinc manganese battery and nickel-metal hydride batteries get rapid development, andthey have occupies a large share of the market. In China, the production of alkaline zinc manganese batteryand nickel-metal hydride battery is more than2billion in2005. And it grows in rate of20%per year. Thesame as other batteries, these two batteries also have their life. It costs about240000tons of zinc,280000tons of manganese dioxide and20000tons of copper to produce alkaline zinc manganese per year. Thereare a lot of zinc, manganese, copper, nickel, chromium and other heavy metals in the spent alkaline zincmanganese batteries. Each year the quality of the spent nickel-metal hydride battery which contain4700tcobalt and800t nickel is about2.95×104t. If we don’t recycle and discard them into the living garbage, theywill not only cause serious waste of resources, but also will cause environmental pollution and the harm tohealth of human. So the recovery of spent alkaline zinc manganese batteries and nickel-metal hydridebatteries is significant.This study which used spent nickel-metal hydride battery dissolved by the sulfuric acid and hydrogenperoxide solution and spent alkaline zinc manganese battery dissolved by nitric acid and hydrogen peroxidesolution as raw materials prepared Ni-Co ferrite with sol-gel method and Mn-Zn ferrite and doped Mn-Znferrite with sol-gel-hydrothermal method. Microwave digestion method was also used to synthesize Mn-Znferrite, trying to improve the magnetic properties of the products. In the experimental process, the sampleswere characterized by means of XRD, IR, SEM, TEM, TG-DSC and VSM techniques.Past research has shown that the optimal conditions of synthesizing Ni-Co ferrite using sol-gel method:the molar ratio of citric acid to the total metal ions is1:1, the pH value of the solution is7, the calcinedtemperature is850℃, and the calcined time is3h. The optimal conditions of synthesizing Mn-Zn ferriteusing sol-gel-hydrothermal method is that: the molar ratio of citric acid and metal ions0.6:1, the pH valueof sol7, the hydrothermal reaction temperature is240℃. The dopant of Cu2+, Ni2+, Cr3+, Pb2+not only didn’t change the spinel structure of the Mn-Zn ferrite, but also increase the magnetic properties of theMn-Zn ferrite. The improvement of its magnetic properties is most obvious when Cu2+was doped.In this paper, the innovation is: the sol-gel-hydrothermal method has been improved, and the Mn-Znferrites which have better magnetic properties are prepared. The influence of the different preparationconditions and the dopant which contained in the spent batteries just like Cu2+, Ni2+, Cr3+, Pb2+has beendiscussed.Based on the research of recycling spent batteries, we consider using copper, nickel, chrome, leadwhich are contained a little in the spent battery to dop at the same time. It not only reduces recyclingprocessing of the heavy metals in spent battery, but also reform the magnetic properties of Mn-Zn ferrite. Itprovides a new ideal for recycling the spent batteries and has high theoretical significance and goodapplication prospect.