The purpose of this study is to produce powdered activated carbon under optimized conditions from a novel precursor, carob (Ceratonia siliqua L.) industrial processing residues, by zinc chloride (ZnCl2) chemical activation. The production influences of impregnation ratio (ZnCl2/precursor, g g(-1)), carbonization temperature, and carbonization duration on the some textural properties of produced carbons have been investigated and the best production conditions were determined. The optimum conditions resulted in an activated carbon with a carbon content of 58.95% and a yield of 48.83%, while the surface area of 1693 m(2) g(-1), with the total pore volume of 2.655 cm(3) g(-1), mesoporosity of 98.95% and average pore diameter of 6.70 nm. Its adsorptive performance was tested using methylene blue and metanil yellow dyes. The adsorption behaviors for both dyes were well described by the Langmuir isotherm model, showing a monolayer adsorption capacity of 597 mg g(-1) and 568 mg g(-1), respectively. The results indicate that optimal activated carbon could be employed as an efficient adsorbent for the removal of the basic and acidic dyes from effluents. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.