Turkan Kopac, Kadriye Bozgeyik, Julide Yener

Effect of pH and temperature on the adsorption of bovine serum albumin onto titanium dioxide

Colloids and Surfaces A 322 (2008) 19–28

The effects of pH and temperature on the equilibrium and the kinetics of bovine serum albumin (BSA) adsorption onto titanium dioxide (TiO₂) were investigated. Adsorption rate and equilibrium experiments were carried out at pH conditions of 4, 5, 10 and in a temperature range of 20-40 °C. Adsorption rate was increased with decreasing pH and increasing temperature. The Langmuir isotherm constants corresponding to adsorption capacity, Q(0), were 35.8, 40.0 and 42.6 mg/g for 20, 30 and 40 °C and pH 4; and 24.5, 29.1 and 33.4 mg/g for 20, 30, 40 °C and pH 5, respectively. The BSA adsorption capacities of TiO₂ were higher for pH 4 at 40 °C. Adsorption of BSA on TiO₂ at different pH and temperatures was found to be first order kinetics. At pH 4, k(1) has Values of 0.018 and 0.019 min^-1 at 20 and 40 °C, respectively. For pH 5, k(1) is 0.013 min^-1 at 20 °C and 0.019 min^-1 at 40 °C. The first order rate constants are higher at pH 4 than the values at pH 5. Higher values of the adsorption rate constants at pH 4, could be due to the change of pore structure of TiO₂ or denaturation by conformational change of BSA with increasing pH.

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