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The focus of this work is on Cr, which has two predominant oxidation states of the atmosphere: + ‏3, which is an essential nutrient in low doses, and +‏6, which is highly toxic and carcinogenic. We found that, the reduction of Cr6+ to Cr3+ was first order reaction and the rate controlling step is the diffusion of (Cr6+) from bulk to iron surface. Toxicity reduction method includes studding of 1-aryl-3-(1-phenylpyrazolo [3,4-b] quinoxalin-3-yl) -2-propenones derivatives or chalcone derivatives concentration, temperatures and rotation speeds effect, which exhibit a strong dependence and supported that the process is diffusion controlled. Thermodynamic parameter ΔG*, ΔH* and ΔS* are given. Mass transfer study of the process was correlated by the equation: Sh = 0.53Sc0.33Re0.38. The order of acceleration was confirmed by quantum calculations.