Efficient metal ion adsorption and photodegradation of Rhodamine-B by hierarchical porous Fe-Ni@SiO2 monolith

Abstract The presence of toxic contaminants (like heavy metal ions and dyestuffs) in water causes an environmental threat and are challenging to discrete out from the water. Now a days, to overcome the challenge of the conventional process as well as for removal of these contaminants from water, mesoporous materials are used as an adsorbent or degradant. In this work, porous rock like bimetal-oxide monolith (Fe-Ni@SiO 2 ) was synthesized via sol-gel method. Adsorption of heavy metal ions and photocatalytic degradation of Rhodamine B (RhB) dye by using Fe-Ni@SiO 2 monolith was carried out. Adsorption experiments were performed in different batches by varying several parameters. The equilibrium between Fe-Ni@SiO 2 and metal ion solution was achieved in approximately 70 min time at pH 6. The equilibrium data found to be well fitted using Freundlich and Langmuir adsorption isotherms. The maximum adsorption efficacy for Pb(II) and Cd(II) ions was 1018 mg/g and 974 mg/g, respectively. The adsorption process was found to be spontaneous and exothermic in nature. Also, for the RhB dye, the photocatalytic efficiency of the Fe-Ni@SiO 2 monolith (using different amount) has been calculated under visible light source. We acquired the best results using 0.10 g/L Fe-Ni@SiO 2 monolith and a further increase in the amount of photocatalyst result in an increase in opacity of the solution inside the reactor. The findings from this study suggests that the Fe-Ni@SiO 2 monolith shows promising results for water treatment and could be employed as an alternative adsorbent/photocatalyst for toxic metal ion adsorption and dye degradation.