Study On Preparation Of Nano-silver, Nano-divalent Silver Powder And Their Antibacterial Properties

Health is one of the most talked about recent years, however the outbreak and spread ofSARS and other infectious diseases further to make people recognize that bacteria areubiquitous, all-pervasive, and their propagation and spread is a serious threat to human health.The use of antibacterial materials to kill and inhibit the growth and reproduction of harmfulbacteria is an important means to improve our health level. Study of antibacterial agent and itspreparation technology and antibacterial properties have an important meaning to humanhealth and life.In this paper，the nano-silver was prepared by the method of chemical reduction and thenanometer bivalent silver oxide powders were synthesized by the method of liquid phaseoxidizing sedimentation. Then their surface morphology and crystal structure werecharacterized by transmission electron microscopy（TEM） and X-ray diffraction（XRD）. Foundwith glucose or hydrogen peroxide as reducing agent, configuration low concentration ofreactants in the ice bath conditions, stationary agitation, the reaction continued half an hour,and then quiet place to no bubble, then vacuum drying, generating particle size 30 to 60 nm,good dispersion, high purity of the nanosize silver particles.Nitric acid silver as the rawmaterial, sodium hydroxide for precipitation agent, potassium sulfate as the oxidant, thecontrol pH value in 11 or so, reaction temperature 80℃, 70℃vacuum drying 3 h. Then getthe nano-divalent silver particles which are good dispersion and no obvious reunionphenomenon, their particle size is 10 to 20 nm.Prepared nanometer silver, nano-oxidation of siliver and nano-oxide high-silver complexas antibacterial agent, with inhibition zone method and the dilution plate method sterilizationtest to the water, escherichia coli and bacillus subtilis, and analysis the antibacterialmechanism of the antibacterial agent, We attain the results as follows: （1） Bactericidal effectof nano oxidation high silver is of all the best, then nano oxidation high silver complex , nanosilver is the worst. （2） It is decided by proportion of oxidative high silver that the bactericidal effect of nano oxidation high silver. （3） Nano silver and nano-divalent silver mainly containstwo sterilization mechanism, the first kind is by the metal dissolution function andelectrostatic adsorption sterilization mechanism into the internal bacteria, combined with thethiol of the bacterial enzyme protein molecules, destruction of the enzyme activity andelectronic transmission systems, resulting in bacterial death; The second is that lightcatalyzing produce hydroxyl radicals （·OH） and active oxygen ion （·O₂^-）which can damageproliferation ability of the microbial cell, restrain or kill bacteria.