Activation of clay surface sites of Bambouto's Andosol (Cameroon) with phosphate ions: Application for copper fixation in aqueous solution

• H2O2 was used to remove organic matter with the aim of liberating surface sites.
• The effect of competitive ions such as: K+, Ca2+, NO3-, CO32-, SO42- and Cl- was investigated.
• The allophone functionalized with phosphate acts as new adsorbent for Cu2+ remediation.

The andosol collected from the mount Bambouto contains high ratio of amorphous mineral, especially an allophane which is known for its phosphate adsorption affinity. This andosol material also contains organic-matter which limits the phosphate adsorption. In the present work, H2O2 was used to remove organic matter with the aim of liberating the surface site as well as to increase the adsorption capacity of the sample. The effect of competitive ions such as: K+, Ca2 +, NO3−, CO32 −, SO42 − and Cl− on the adsorption of phosphate ions in our andosol's sample were investigated. In addition, the desorption of phosphate after saturation of andosol was also carried out in order to reuse the samples. The desorption study was done using a solution of NaOH with concentrations ranging from 1 to 10 mmol/L and the effect of the dissolution of andosol's material under basic solution was also studied. The sample after adsorption of phosphate ions shows great affinity for copper ions removal in aqueous solution.