m/V also 20g/L
original equation in the study: »FeO<1-> + SrNO3<1+> = »FeOSrNO3 with log K = 5.68 ± 0.89 (»FeO<1-> + H<1+> = »FeOH with log K = 9.70 ± 0.02; Sr<2+> + NO3<1-> = SrNO3<1+> with log K = 0.60 (Falck, W. E., Read, D., & Thomas, J. B. (1996). Chemval 2: thermodynamic database. EUR(Luxembourg).(from ThermoChimie)))
combination of surface complexation and ion exchange model