alpha-FeOOH was prepared by two different methods and were designated as sample-1 and sample-2. Point of zero charge (PZC) and surface ionization and complexation constants of both the samples were calculated from the potentiometric titration data of their suspensions in aqueous electrolyte solutions. PZC values of the sample-1 and sample-2 were found to be at pH similar or equal to 8.4 and 8.2 respectively, which demonstrated a negligible difference. However, the absolute values of their surface charge at the given pH and electrolyte concentration was significantly high for sample-1 as compared with sample-2. This was attributed to the high Ns values (total number of surface sites) of former sample. Moreover, the numerical values Delta pK(a)(int) and Delta p*K-complex(int) suggested the fad that ionization and complexation reactions were weak in sample-2 as compared with sample-1.
H U REHMAN ,M SHAKIRULLAH ,I U HAQ ,
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