Chromium is one of the most significant metals used in the industry. There are many techniques for treating different types of industrial waste water that include chromium ion. In this study, the authors successfully adsorbed the chromium ion from alkaline aqueous solutions using different prepared types of chitosan as adsorbent materials. For the simultaneous sorption behaviour, the adsorption potential of the produced adsorbent was investigated for Cr+6 in a batch system. Natural chitosan was extracted from shrimp shell as it contains about 8–10% chitin which is used in the production of chitosan. The removal percentage of Cr+6 reached 99% after grafting natural and commercial chitosan at specific conditions. Several isotherm models have been used for mechanistic studies. The results indicated that the adsorption data for commercial chitosan is well-fitted by the Freundlich isotherm, Langmuir for commercial grafted, natural and natural grafted chitosan. Kinetic and equilibrium studies showed that the experimental data of Cr+6 were better described by the pseudo-first-order model for commercial chitosan and fitted the pseudo-second-order model for different types of chitosan used. Significantly, in order to scale this effective strategy on an industrial scale, response surface methodology (RSM) was used as a modelling tool to optimise process parameters such as ion concentrations, utilising Statistica Software.