Amorphous iron hydroxide was fabricated in the laboratory by precipitation technique. Salt addition and fast titration methods were employed for the determination of zero point charge. The present study is mainly focused on the surface charge, PZC determination from the potentiometric titration data in the temperature range 293 – 323 K and to calculate the thermodynamic parameters during the exchange of surface H+/OH- ions. The PZC of the solid was decreased with increasing the temperature of electrolytic solution. The Standard thermodynamic parameters such as ΔHo and ΔSo were also determined from Berube and DeBruyn equation, which showed the endothermic nature of potential determining ion H+/OH- ions. Further, their freedom in the double layer has lost on account of the electrostatic force of interaction. The positive ΔGo values are suggesting the nonspontaneous transferring reactions of H+ and OH- from the bulk solution to the interfacial region.
Muhammad Irshad, Syed Mustafa, Muhammad Waseem, Khizar Hussain Shah and Umer Rashid
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