Adriana Herrera-Barros ¹, Candelaria Tejada-Tovar ², Angel Villabona-Ortiz ², Angel Gonzalez-Delgado ¹, Ana Reyes-Ramos ²

Affiliations
1 Chemical Engineering Department, Nanomaterials and Computer Aided Process Engineering Research Group (NIPAC), University of Cartagena, Cartagena, Bolívar, CO
2 Chemical Engineering Department, Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Cartagena, Bolivar, CO

Abstract

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-TiO₂biosorbent. 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.

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Adriana Herrera-Barros ¹, Candelaria Tejada-Tovar ², Angel Villabona-Ortiz ², Angel Gonzalez-Delgado ¹, Luis Fornaris-Lozada ²

Affiliations
1 Chemical Engineering Department, Nanomaterials and Computer Aided Process Engineering Research Group (NIPAC), University of Cartagena, Cartagena, Bolivar, CO
2 Chemical Engineering Department, Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Cartagena, Bolivar, CO

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-TiO₂biosorbents. 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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Adriana Herrera-Barros ¹, Candelaria Tejada-Tovar ², Angel Villabona-Ortiz ², Angel Dario Gonzalez-Delgado ¹, Erika Ruiz-Paternina ²

Affiliations
1 Nanomaterials and Computer Aided Process Engineering Research Group (NIPAC), University of Cartagena, Chemical Engineering Department, Cartagena, Colombia, Avenida del Consulado Calle, 30 No. 48 – 152,, CO
2 Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Chemical Engineering Department, Cartagena, Colombia, Avenida del Consulado Calle 30 No. 48 – 152,, CO

Abstract

Background: Agricultural wastes have attached great attention for developing novel materials with physico-chemical properties favorable for several applications as heavy metal ions uptake from aqueous solution. Objectives: In this work, Lemon Peels (LP) residual biomass was successfully modified into a novel biosorbent using alumina (Al₂O₃) nanoparticles and applied to remove cadmium ions. Methods/Analysis: Characterizations of LP-Al₂O₃biosorbent by FT-IR and SEM were performed to identify morphology and main functional groups. Batch adsorption experiments were carried out under different pH values (2, 4, 6) and particle sizes (0.355, 0.5, 1 mm). The removal yields were calculated using LP and LP-Al₂O₃ in order to compare these results and determine the effect of alumina nanoparticles on adsorption process. Finding: The FT-IR analysis revealed the presence of covalent binding of aluminum with carboxyl and carbonyl groups of this biomass. The porous surface of LP-Al₂O₃biosorbent observed in SEM micrograph suggested a high surface available to metal ions binding. The removal yields were increased from 90.35 to 93.3% after loading alumina nanoparticles into lemon peels biomass due to the larger surface given by nano-scale particle size. Novelty/Improvement: These results suggested that lemon peels-based biosorbents can be efficiently used for cadmium ions uptake from aqueous solution.

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