Adsorption of benzoic acid on sulphadimidine: suppressive effect of some hydrophilic polymers

The uptake of benzoic acid on sulphadimidine particles has been investigated. Depending on the concentration of sulphadimidine in the system, benzoic acid was adsorbed to the extent of 94%. Data from the adsorption experiments were shown to fit a Langmuir plot for systems containing up to 0.2 g 100 ml−1sulphadimidine. The suppressive effect of three hydrophilic polymers on adsorption was studied; the results followed the sequence: Polyvinylpyrrolidone (PVP) > methylcellulose > sodium carboxymethylcellulose. Dialysis experiments revealed that, within the range of concentrations used, neither PVP nor methylcellulose was significantly bound to benzoic acid.