Abstract
Background: Heavy metal water pollutants have received great attention due to its toxic effects on the environmental and health of human beings. Different techniques have been applied to remove heavy metal ions from aqueous solution including ion exchange, chemical precipitation and adsorption. Objectives: In this work, biosorption process was studied for nickel and lead ions uptake onto agricultural residual biomasses chemically modified with TiO2 . Methods/Analysis: The titanium dioxide nanoparticles were synthesized based on a green procedure using a leaf extract of lemongrass. Cassava and yam peels biomasses (CP and YP) were prepared and loaded with these nanoparticles through an organic solvent. The resulting biosorbents (CP-TiO2 and YP-TiO2 ) were characterized by FT-IR and SEM analysis in order to identify functional groups and morphology. The effect of pH and particle size on removal yield was evaluated by carrying out batch adsorption experiments at room temperature and fixed biosorbent dosage. Findings: It was observed characteristic peaks of titanium dioxide in FT-IR spectra of biosorbents confirming its successful synthesis. The carboxyl and hydroxyl groups were also identified, which can easily bind with metal ions to remove them from the solution. The surface of biosorbents showed a non-porous and heterogeneous morphology. The solution pH=6 was selected as suitable value according to adsorption result and point of zero net charge. The particle size did not significantly affect adsorption performance of biomaterials. The removal yields were 99.84% and 99.85% for Pb (II) using CP-TiO2 and YP-TiO2 , respectively. For Ni (II), the removal yields were 81.51% and 86.66% using CP-TiO2 and YP-TiO2 biosorbents. Novelty/Improvement: These results suggested that agricultural wastes, such as cassava and lemon peels, can be used to prepare biosorbents with high adsorption efficiency and its modification with nanoparticles allowsattracting greater amount of heavy metal ions increasing removal yields. Keywords: Biotechnology, Biomass, Biosorption, Nanomaterials
Highlights
Heavy metals water pollutants are considered a severe environmental concern worldwide due to their nonbioaccumulation nature, high toxicity, carcinogenicity, prevalence, existence and persistence in the environment[1,2]
It has been reported that carboxyl and hydroxyl groups can bind with metal ions to remove them from the solution[15,28], which are observed in all biosorbents spectrum
The Fourier Transform Infrared Spectroscopy (FT-IR) analysis revealed the presence of hydroxyl, carboxyl and R-COO-Ti groups
Summary
Heavy metals water pollutants are considered a severe environmental concern worldwide due to their nonbioaccumulation nature, high toxicity, carcinogenicity, prevalence, existence and persistence in the environment[1,2]. Conventional methods for nickel and lead uptake exhibit disadvantages such as high operational cost, energy requirements and generation of toxic wastes[7]. Biosorption seems to be a promising new technique due to its low costs, easy operation, high efficiency and affinity of biomaterials for heavy metals[9]. Different techniques have been applied to remove heavy metal ions from aqueous solution including ion exchange, chemical precipitation and adsorption. The effect of pH and particle size on removal yield was evaluated by carrying out batch adsorption experiments at room temperature and fixed biosorbent dosage. Novelty/Improvement: These results suggested that agricultural wastes, such as cassava and lemon peels, can be used to prepare biosorbents with high adsorption efficiency and its modification with nanoparticles allowsattracting greater amount of heavy metal ions increasing removal yields
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