Adsorption of Mn (II) Ions from Aqueous Solution: A 2⁴ Factorial Design Approach

Abstract

Adsorption involves the accrual of a substance near an interface in relation to its concentration in the bulk solution. The effects of interaction time,  adsorbent dosage, solution concentration and pH of solution on adsorption of Mn²⁺ were studied using the 24 factorial experimental design. Optimum  adsorption of Mn²⁺ was 95.97 % with a predicted response of 97.64 % and a residual value of -1.67 obtained at 150 mins of interaction time, 1.00 g  adsorbent dosage, 10.00 mg/dm3 solution concentration and pH 4.00. Estimated effects and coefficients of response with main and interaction effects of  the four adsorption factors revealed that adsorbent dosage, concentration and pH of solution had P-values of 0.040, 0.000 and 0.001 respectively; and  had significant effect on adsorption of Mn²⁺. The interaction of adsorbent dosage with solution pH, adsorption time with adsorbent dosage also had  significant influence on the removal of Mn²⁺ from aqueous solution. Analysis of variance used to validate the model showed that there is no lack of fit at  95 % confidence level. Correlation coefficient of the experiment and predicted values indicate a good performance of the model. Hence, factorial  experimental design can be used to predict the extent of different adsorption conditions of the variables and optimum adsorption.