Some types of inactive biomass have been studied in terms of their adsorption properties as alternatives to the commonly used Activated Carbon (AC) such as orange peel. The present study evaluates a physical-chemical treatment for enhancing the adsorption capacity of raw orange peel for two model organic pollutants (azo dye and phenol). Instant Controlled Pressure Drop, (“DIC” by its abbreviations in french), a vacuum drying technology, was applied as a first treatment, prior to chemical surface modification ― either basic, using NaOH or acid, using Citric acid―. The use of DIC modifies and improves the structural properties of the material. Consequently, the combination of this technique followed by a chemical treatment shows an enhancement in the adsorption capacity of orange peels. The results showed that R-OH, R-COOH and R-COOCH3 groups were present on the orange peel surface according to the treatment used. DIC treatment increases the adsorption capacity of raw orange peels 285% for the azo dye and 632% for phenol; DIC treatment plus adding the chemical surface modification, increase the adsorption 640% and 1812% for azo dye and phenol, accordingly. The presented research work showed a novel technique for orange peels preparation as an adsorbent material.