STUDY ON THE POSSIBILITY OF Zn2+ ADSORPTION USING HALLOYSITE CLAY MINERAL AND DESORPTION AND RECOVERY OF ZINC BY ELECTROCHEMICAL PRECIPITATION METHOD

Abstract

Halloysite in Thach Khoan area, Phu Tho has a nanotube shape, has the chemical formula when hydrated is Al2Si2O5(OH)4.2H2O and when dehydrated is Al2Si2O5(OH)4
with a specific surface area of 20.152m2
/g. In this paper, halloysite is used to study the ability to adsorb Zn2+ ions. The influence of some factors on Zn2+ adsorption
capacity and efficiency has been studied. Zn2+ adsorption efficiency and capacity reached 67.09% and 2.24mg/g under the following conditions: halloysite mass
0.6g/50mL solution, initial Zn2+ ion concentration 40mg/L, pH 5.6, exposure time 120 minutes at room temperature (25o
C). The process of desorption of Zn2+ from the
loaded adsorbent and recovery of metallic Zn was also studied. Zinc recovery efficiency reached 94.52% under appropriate conditions: applied current 7.5mA, electrolysis
time 5 hours, loaded halloysite mass of 0.3g, temperature 60o
C. The adsorption isotherm was studied based on two Langmuir and Freundlich models. The adsorption
kinetics were examined using two pseudo-first-order and pseudo-second-order kinetic models.