The objective of this study is the removal of some environmental hazards from aqueous solutions using six nickel on two supports prepared by impregnation and sol-gel methods. The first support was rice husk ash (SiR) and the other was silica-gel SiG by different loading weight percent of nickel 4.80, 9.60, 14.80, 4.90, 9.80 and 14.70% respectively, which were produced, Ni/SiRI, Ni/SiRII, Ni/SiRIII, Ni/SiGI, Ni/SiGII  and  Ni/SiGIII, respectively. The solids were described by TGA, DTA, DSC, XRD, TEM and BET measurements.The surface analyses show that for the bare SiR support is a common amorphous structure and in Ni/SiR catalyst precursors after calcination at 773 K, nickel is presented as NiO species. TEM images depict that nickel crystallites are spherical in shape, its size is in nano-scale and much lower than 14 nm and distributed uniformly. The adsorption of hazard material likeCr⁺⁶ is maximal at the lowest values of pH and increases with temperature for the prepared solids. Optimum conditions for Cr⁺⁶ removal were found to be pH =3.00, adsorbent dosage 0.05 g/L of solution and equilibrium time 2.00 h. The experimental data were analyzed using Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherm models. It was found that Freundlich and D–R models fitted well. The value of the adsorption energy calculated using D–R isotherm, was 1.20±0.10 kJ /mol for Ni/SiR and Ni/SiG solids and it indicated that the adsorption process was physical in nature. The Ni/SiG solids shows higher capacity for adsorption of Cr(VI) than Ni/SiR solids.