Treatment of yellow dye 23 by heterogeneous Fenton-like process was studied using iron rich soil as an iron source. The iron rich soil sample was characterized by XRD, SEM and BET analysis. XRD pattern indicates that the iron rich soil is made of goethite and hematite. The reaction was systematically investigated under various experimental conditions such as pH, iron rich soil dosage, oxidant and dye concentrations. The result revealed that using iron rich soil as catalyst led to high discoloration efficiency (97.71% for 140 min of treatment) at pH = 2.5, 2 g/L iron rich soil and 16 m•mol/L H 2 O 2. The degradation kinetics of acid yellow 23 can be described by a pseudo-first-order reaction following the Langmuir-Hinshelwood mechanism. The main roles of hydroxyl radicals in degradation process were investigated by adding of various radical scavengers.

The present paper reports on the kinetic and equilibrium studies of the adsorption of Nickel(II) ions from aqueous solution onto modified natural iron oxide (NAT) from Mbalam (East Region of Cameroon) and synthetic iron oxide (SYNTH). The parameters investigated using batch techniques include, the contact time, adsorbent mass, pH and initial metal ion concentration. The experimental results obtained showed that, the optimum pH of 6 for bothadsorbents with an equilibrium time of 30 minutes was sufficient. The kinetic data correlated well with the pseudo-first-order and pseudo-second-order kinetic models for both the adsorbents based on the correlation coefficients (R 2 ) obtained. The adsorption processes followed both the Langmuir and the Tempkin adsorption models for the natural iron oxide, whereas the Freundlich and Tempkin adsorption models fitted well the adsorption data for the synthetic iron oxide. The maximum quantity of Nickel(II) ions adsorbed was 250 mg/g for the two adsorbents. These results revealed a high adsorption capacity of natural iron oxide which is comparable to that of synthetic iron oxide.

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