Adsorption study of Ni (II) and Pb (II) onto low-cost agricultural biomasses chemically modified with TiO2 nanoparticles

Background: Heavy metal pollution in wastewater is a rapidly growing global concern and great effort has been made for developing efficient and low-cost alternatives to mitigate it. Objectives: This work attempts to evaluate the adsorption capacity of residual biomass from lemon, cassava and yam peels chemically modified with TiO2 nanoparticles to remove Pb (II) and Ni (II) ions. Methods/Analysis: The TiO2 nanoparticles were synthesized following a green procedure with leaf extract of lemon grass. After loading these nanoparticles to prepared biomass, chemical characterization was performed by FT-IR and EDX analysis in order to identify functional groups and elemental composition. Findings: The FT-IR analysis revealed that hydroxyl and carboxyl groups most contribute to adsorption process and the elements O, Ti and C were identified as main components of biosorbents. It was calculated a maximum adsorption capacity of136.3, 125.4 and 161.2 mg/g; and 181.5, 193.4 and 199.5 mg/g for Ni (II) and Pb (II) ions using modified CP, YP and LP, respectively. In addition, experimental data for Ni (II) ions uptake using YP-TiO2 , LP-TiO2 and Pb (II) ions using YP-TiO2 biosorbent fitted to pseudo-second order. Meanwhile, Elovich model described accurately adsorption process overtime for Ni (II) using CP.TiO2 and Pb (II) using LP-TiO2 and CP-TiO2 biosorbent. The isotherm fitting revealed that Temkin and Freundlich best adjusted adsorption results for both heavy metal ions. Novelty/Improvement: These results suggested that modification with TiO2 improves adsorption capacity of residual biomass from fruit and vegetable peels and the resulting biosorbents can be efficiently applied for lead and nickel removal.