Dr. Muhammad Tahir Saddique
PhD supervisor at the National Textile University
Title: Comparison of different methods for the PZC determination of chitosan based novel biosorbents in textile waste water
Biography
Biography: Dr. Muhammad Tahir Saddique
Abstract
We used salt addition, mass and potentiometric fast titration to determine point of zero charge of chitosan, (chitosan + cellulose and chitosan + Algenite) biosorbents in presence of textile waste water. Comprehensive potentiometric experiments were conducted to find the surface acidity constants and the concentration of surface charged groups on the biosorbents. The PZC of chitosan based novel biosorbents is comparable in magnitude to the one obtained by salt addition and mass titration techniques at 303 K. However the slight differences in the PZC values obtained by different methods diminish at higher temperatures. We observed the fair agreement between experimental and calculated values of PZC. The influence of ionic strength and temperature on the acidity constant of biosorbents were investigated. The intrinsic acidity constants (pK1 and pK2) were found to decrease with increase in temperature, which shows endothermic nature of both biosorbent surfaces deprotonation reactions. The PZC and the concentration of surface groups were increased whre as concentration of pure biosorbent material decreased with decrease in temperature of medium. The changes in entropy (∆S) and enthalpy (∆H) connected with the surfaces deprotonation of the biosorbent composite materials/ electrolyte interface were measured. The loss in entropy indicated that potential determining ions were less hydrated at the interfacial regions. Themodynamic parameters showed that the positive values of enthalpy were the driving force for the depronation of the both biosorbents.