Equilibrium and thermodynamic studies on adsorption of BSA using PVDF microfiltration membrane

It was the aim of this work to investigate equilibrium and thermodynamic aspects for static adsorption of bovine serum albumin (BSA) as model protein of extracellular polymer substances (EPS) from membrane bioreactor (MBR) on hydrophilic polyvinylidene fluoride (PVDF) microfiltration membrane. In present paper, the influences of temperature, pH and ionic strength were studied and eight different isotherm models were used to fit equilibrium data by nonlinear regression method. The obtained results showed that the best-fitted adsorption isotherm models were in the order of: Langmuir and Freundlich > BET > Langmuir ≈ Redlich–Peterson ≈ Temkin > Freundlich > Fowler and Guggenheim (Hill–De Boer), of which, Langmuir–Freundlich isotherm is the best suitable. Thermodynamic investigation indicated that this process was not spontaneous and endothermic and maybe attributed to physicosorption, and the distribution of BSA adsorbed on PVDF membrane was more chaotic than that in the aqueous solution. The results from the static adsorption of BSA on PVDF membrane can be a useful tool to evaluate the behavior of membrane biofouling in MBR and also provide basis for performance comparison among different membranes.

► The static adsorption of BSA on PVDF microfiltration membrane was investigated.
► Equilibrium and thermodynamic aspects for static adsorption were examined.
► Langmuir–Freundlich isotherm is the best suitable by nonlinear regression method.
► The process is non-spontaneous, endothermic and maybe attributed to physicosorption.