Research On Desalination Kinetics Of Vulcanized Paper And Methods To Improve The Desalination Efficiency

Vulcanized paper is manufactured by dipping several pieces of base paper into zincchloride solution. It is widely used in electrical industry and chemical industry by cutting itinto various gaskets owing to its wonderful characters of high mechanical intensity, highelectric insulativity and prefect mechanical processing characteristics. However, thedesalination phase in the manufacture process is very time consuming, which leads to the lowefficiency of the whole process. Thus, in order to make out the course of reaction ofvulcanized paper and improve the efficiency of desalination process, it is crucial to researchthe reaction mechanism and desalination kinetics.So firstly, this paper systematically discussed the fiber’s changes in the aspect of shapeand properties with modern analysis techniques before and after reaction with zinc chloridesolution. Next, combining with the structure of vulcanized paper we derived the desalinationkinetics model on the basis of Flick’s second law and established the kinetics function oncegetting the experimentaldata. Then, acid solution and chelating solution were applied in theprocess of desalination instead of pure water. At last, ultrasonicwavetechnology was appliedin the process of desalination and paper’s structure changes were discussed before and afterthe impact that ultrasonicwave caused. The main conclusions obtained are:1、Once the base paper getting in touch with the zinc chloride solution, fibers swelledswift, but as to the fibers whose primary wall were removed totally the swell ratio could reachto as high as2³. Zinc chloride solution was not the derivative solvents for fibers andcrystalline structure of the fiber didn’t show any change before and after treatment of zincchloride solution. However, the amorphous region of the fibers increased and base fiber’scrystallographic index decreased accompanied with the decrease of intermolecularhydrogenbond. The result of thermo gravimetric analysis showed that coincidental cohesionof cellulose was weakened and then the thermolysis temperature was reduced. Fibers bondedcompactly which lead to more join points and the paper’s structure became more compact anduniform after the fiber’s strong reaction of swelling and gelling.2、Linearrelation between zinc chloride concentration and conductivity was establishedafter experimental verification. On reasonable premise, the desalination kinetics model wasset up on the basis of Flick’s second law and then was amended inaccordance withexperimental data. After solving the parameters in the model, then the kinetics function wasobtained: c=[3.324×10^-3T+2.466exp（-R）-0.6522]-8/π²[3.324×10^-3T+2.466exp（-R）-0.6522]×[0.108exp(-π²t/L²×10^-6×e^-1913.5/T)+0.892exp(-4.08π²t/L²×10^-7×e^-3132/T]))On the fast washing stage and the slow diffusion. And then the overall rate constant andactivation energy for different phase could be estimated. In the final, errors between thevalueofcalculation and the experimental date was examined and the results showed that theestablished modes could describe the actual desalination process well.3、Acidic solution showed nothing effect on the desalting rate due to low content ofcarboxylgroup in the fibers so the total adsorption quantity of zinc ions was negligiblecompared with the total amount in the vulcanized paper. The chelating agent added in thedesalination liquid could chelae off the zinc ions swiftly while the chelating agent A didn’tshow any accelerated effect on the desalting process as a result of the clathrates’ overmuchadsorption to the vulcanized paper. On the other hand, clathratesgenerated by the chelatingagent EDTA and zinc ions displayed nothing adsorption to the paper body due to its electronegativity and as a result EDTA could accelerate the rate of desalination.4、Ultrasonicwave technology could have a sound effect to the desalting rate and if givena high power the effect was more obviously. While the zinc ions content decreased even morewhen we combined the two treatments of ultrasonicwave action and EDTA chelating.However, the structure of the vulcanized paper could have some changes after the treatmentof ultrasonicwave with a increase of the porosity from23.05%to25.43%.