Abstract
The influence of phosphate as acid Na3PO4 solution in tap water was investigated using gravimetric and potentiostatic techniques. It was found that the phosphates are adsorbed in the form of positively charged colloidal particles on the cathodic areas of the metal. The degree of coverage, θ, vs log concentration of PO4 3− shows good agreement with Frumkin's isotherm in the form:
θ/1−θ exp (−2.55θ) = 2530.CpO3− 4
The calculated standard free energy of adsorption was found to be ∆ Gads° = −28·8 kJ.mol−1 (or −6·9 kcal.mol−1).
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