This paper focuses on the development and characterization of activated carbons to agro-food waste by activation with ortho phosphoric acid, and its application in the elimination of chromium in solution. The functions were determined by Bohem's method. The thermal analysis was carried out on the hulls of waste. The specific surface area and the pore volume are determined according to the method of Brunauer, Emmet and Teller and the method of Barret, Joyner and Halenda respectively. The Lagergren and Ho and McKay models were used for the kinetic study of chromium removal. Those of Langmuir and Freundlich have to do with the study of isotherms and the law of Van't Hoff and Gibbs in relation to the determination of thermodynamic parameters. The results obtained show that the surface functions are acidic in nature. Activated carbon from balanites aegyptiaca has developed a specific surface (1560.7401 m2 g -1 ) that exceeds that of Hyphaene thebaica (722.1510 m2 g -1 ). The pseudo-order 2 kinetics (Ho and McKay) better describe the adsorption with correlation coefficients close to unity. Adsorption capacities and rate constants prove rapid adsorption at the early stages. For the isotherms, the calculated parameter values are much more consistent with those of the Langmuir isotherm. ∆Gads 0 < 0 ; the adsorption process is spontaneous. Moreover, the values are in the range of a physisorption.

Agriculture and livestock are the main socio-economic activities of the population of the Zinder region (Niger). However, these activities have negative impacts on groundwater quality, which is the main source of water supply for this population. In this work, the physicochemical quality of the waters of the Socle of the Zinder region was studied during the rainy and dry seasons. Twenty-four samples were the subject of a physico-chemical analysis. The data obtained were processed by the hydrochemical method by the Diagram software and the principal component analysis by the XLSTAT software. Of the waters analyzed, 83% have normal pH values (6.5 - 8.5) and 17% acid pH <6.5 during both seasons. The nitrate levels of Yekoua (62.04 and 63.36 mg.L-1), Dan Ladi (123.64 and 146.96 mg.L-1), Bourbourwa (64.65 and 80.08 mg.L -1) and Kazoé (130.68 and 124.52 mg.L-1) and fluoride of Kazoé (1.5 mg.L-1), Midik (1.6 mg.L-1) and Bourbourwa (2.98 mg.L-1) during both seasons are abnormal. Four facies characterize the analyzed waters, with a predominance of bicarbonated calci-magnesian(42%) during the rainy season, calci-magnesian bicarbonate (41.7%) and calci-magnesium chloride (41.7%) during the dry season. The residence time by hydrolysis and alteration of silicate rocks and the pluviolessivage of soils are the main mechanisms that govern the mineralization of these waters. These grades, call for remediation treatments. Clays could be promoters for this treatment because they are very available and less expensive.