An adsorbent, volcanic rocks coated with α-Fe2O3 nanoparticles, was prepared and utilized for the removal of Cu(II) and Ni(II) ions from an aqueous solution. Characterization of the coated volcanic rocks indicated that the α-Fe2O3 nanoparticles were successfully and homogeneously distributed on the volcanic rocks, including penetration into rock pores. Batch experiments were conducted to investigate adsorption performance. The adsorption behavior of both ions was found to best fit a pseudo second-order model and Langmuir isotherm. The maximum adsorption capacities of Cu(II) and Ni(II) ions were 58.14 mg g−1 and 56.50 mg g−1 at 293 K, respectively, and increased with rising temperature. The loaded α-Fe2O3 nanoparticles onto volcanic rock significantly increased removal of Cu(II) and Ni(II) ions. The adsorption process was combined control of film diffusion and intra-particle diffusion. Adsorption thermodynamics indicated the adsorption process was spontaneous and occurred mainly through chemisorption. The results confirmed that the volcanic rocks coated with α-Fe2O3 nanoparticles acted as a high-efficiency and low-cost absorbent, and effectively removed Cu(II) and Ni(II) from wastewater.

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