Research On Purification And Application Of The Attapulgite Clay

Jiangsu-Anhui areas possess huge reserves of attapulgite clay resource, but theminerals have complicated compositions, high amount of impurity and bigvariations of physical and chemical properties. Therefore, it is hard to process andraise the value-added of the attapulgite clay products. Study on the purificationtechnology of attapulgite clay to solve the above problems can not only obtainaffordable, high quality and high purity nano-mineral materials, but also promoterational applications of natural mineral resources and environmental protection. Itcan also provide information for enterprises which’s nano-processing attapulgiteclay to go a step further on high-tech and high value-added.In this dissertation, attapulgite clays from Chuzhou city, Anhui province, weretaken for the investigation. Scanning electron microscope (SEM) and field emissiontransmission electron microscope (FETEM) were used to observe the morphologyof the attapulgite clay particles. X-Ray diffraction (XRD) and infraredspectroscopy (IR) were employed to identify and analyze the composition of thephase and substances, and the chemical composition of the attapulgite clays wasanalyzed by X-Ray fluorescence spectrometer (XRF).In the third chapter, two physical methods, namely the direct centrifugationmethod and the wet ball milling and centrifugation method were used to purify theattapulgite clays, respectively, under the conditions of adding a certain amount ofdispersant and an ultrasonic dispersion. The experimental results show that thepurity of the attapulgite clays treated by the direct centrifugation and wetball-milling+centrifugation is82.4%and95.3%, respectively. After wet ballmilling and centrifugation, the attapulgite clay particles show needle rod shapeswith about20to50nm in diameter and50to600nm in length.In the fourth chapter, NXS-11A type rotary viscometer was employed to studythe rheological properties of the attapulgite clay slurry during centrifugalseparation, and to investigate the influence of ball milling, dispersant, slurrydilution and storage time on the viscosity variation with shear rate. When the shearrate exceeds200S-1, the viscosity reaches8mPa·s, the slurry not affected by shearrate is most easy to achieve low speed centrifugation. The slurry with high ratio ofliquid to solid shows good centrifugal separation effect after dilution, and it is suggested that the centrifugation separation was done in8hours after dilution. Thebest centrifugation separation effect was obtained with solid to liquid ratio of6:20diluted to1:10at low speed. Slurry with solid to liquid ratio of1:10wascentrifuged. After centrifugal separation at centrifugal force of198times,550times and078times, and centrifugal separation time of20min,30min and40min.,the mean particle size D(0.5) and the purity of resultant attapulgite clay particlesare3.520μm,1.759μm,0.194μm and82.7%,90.6%,95.3%, respectively.In the fifth chapter, using the purified attapulgite clay powders, six hydratedzinc nitrate and urea as raw materials, attapulgite loaded zinc oxide (ATP/ZnO")precursors were prepared by a homogeneous precipitation method. The precursorswere calcined to converted into ATP/ZnO composites, and the property ofphotocatalytic degradation of methyl orange was investigated. ATP/ZnOcomposites can be obtained by calcining the precursors at350℃and400℃for60min, and the average particle size of ZnO are42nm and85nm, respectively. Thephotocatalytic degradation rate of ATP/ZnO composites calcined at300℃,350℃and400℃for60min is37.31%,77.43%and71.12%, respectively.