C. Tejada-Tovar ¹, A. D. Gonzalez-Delgado ¹, A. Villabona-Ortiz ¹

Affiliations
1 Department of Chemical Engineering, University of Cartagena, Cartagena, Bolivar, CO

Abstract

Background: Now-a-days, adsorption has been recognized as an effective method to remove heavy metals ions in water sources. Objectives: This work is focused on studying removal of chromium (VI) from aqueous solution by orange peel-based adsorbents (OP, OPAC, OP-CaCl₂ and OP-Chitosan). Effects of pH and adsorbent dosage on the adsorption of Cr (VI) were evaluated in order to determine suitable conditions for carrying out adsorption process. Methods/ Analysis: OP-CaCl₂ and OPAC biosorbents were obtained by chemical modification using CaCl₂ and H₃PO₄ acid solution, respectively, while OP-Chitosan was synthetized in acetic acid solution. FT-IR analysis was performed to OP and OP-Chitosan materials. The pH of heavy metal ions solutions was adjusted to3, 4 and 5 and adsorbent dosage was varied in 2, 4 and 6 g/L. Batch experiments were carried out in a magnetic stirrer plate at 30°C using 100 ppm Cr (VI) ions solution. Experimental data of equilibrium were used to calculate adsorption isotherms. Findings: The adsorption of Cr (VI) was found to be maximum for OPAC biosorbent and its highest removal yield (66.8%) was achieved at pH 3 and dosage of 6 g/L. Application of the Langmuir isotherm to OP biosorbent yielded a maximum adsorption capacity of 911.21 mmol/g and the data for OPAC and OP-Chitosan obeyed Freundlich isotherm with KL of 0.25 mmol/g and 8.17 mg/g, respectively. The heterogeneity factor (1/n) indicated that OPAC obeys to cooperative adsorption and OP-Chitosan to chemisorption. Application/Improvement: Compared to the various other adsorbents reported in the literature, the orange peel-based adsorbents in this study show very good promise for practical applicability.

Keywords

Adsorption, Biosorbent, Chromium, Heavy Metal, Removal

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A. Herrera-Barros ¹, C. Tejada-Tovar ¹, A. Villabona-Ortiz ¹, A. D. Gonzalez-Delgado ¹, J. Benitez-Monroy ¹

Affiliations
1 Department of Chemical Engineering, University of Cartagena, Cartagena, Bolivar, CO

Abstract

Background: The biosorption technology has been recognized as an attractive alternative for heavy metal ions uptake due to its several advantages as low cost and environmental friendly. Objectives: In this work, a biosorbent was synthesized from African oil palm bagasse biomass and alumina nanoparticles in order to use it for removing cadmium, nickel and chromium from aqueous solution. Methods/Analysis: The synthesis of Al₂O₃ was performed according to sol-gel methodology. The nanoparticles were loaded into biomass using an organic solvent. The resulting material was characterized by FT-IR, SEM and EDX analyses. The point of zero charges as well as ultimate analysis were also carried out for biomass. Findings: The FT-IR analysis revealed absorption bands characteristic of lignocellulosic biomass attributed to carboxyl, hydroxyl and amides functional groups. The presence of O-Al-O and Al-C=O suggested the successful synthesis of biosorbent. The morphology was identified as porous which enhances adsorption process. The EDX analysis confirms that carbon is the major constituent of biosorbent, similar to the results of ultimate analysis of African oil palm bagasse. In addition, removal yield values for cadmium, nickel and chromium of 92.02, 87.06 and 4%, respectively, were achieved at pH=6. Novelty/Improvement: This biosorbent exhibited excellent adsorption properties and could be used efficiently for removing cadmium and nickel water pollutants.

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A. Herrera-Barros ¹, C. Tejada-Tovar ², A. Villabona-Ortiz ², A. D. Gonzalez-Delgado ¹, J. Alvarez-Calderon ¹

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

Abstract

Background: In recent decades, agricultural residues have been widely applied in the development of novel materials in order to obtain high-value products and reduce disposal issues. Objectives: In this work, corn cob residual biomass was used to prepare a biosorbent chemically modified with alumina nanoparticles. Methods/Analysis: The alumina nanoparticles were synthesized by sol-gel methodology and loaded into biomass matrix using an organic solvent. The corn cob biomass was characterized by ultimate analysis, FT-IR technique, Boehm titration and point of zero charges method, which provide information related charge of biomass surface, diversification of functional groups and elemental composition. SEM and EDX analyses were also performed in order to study morphology and composition of the prepared biosorbent. Batch adsorption experiments were carried out to evaluate the effect of pH and particle size on adsorption efficiency and determine suitable conditions for further experimentation. Findings: The physicochemical characterization of corn cob biomass revealed the presence of carboxyl, hydroxyl and amine functional groups in FT-IR spectrum. After loading alumina nanoparticles, this spectrum exhibited characteristic peaks of aluminum bonds suggesting a successful synthesis. In addition, it was observed that pH played an important role in removal yield results, hence, pH=6 were selected as suitable value for performing further experiments. The removal yield for cadmium and nickel ions using chemically modified biomass were 91 and 86%, respectively, results higher than those obtained using biomass. Novelty/Improvement: The modification with Al2O3 nanoparticles enhances adsorption process and could be applied to other sources of biomass.

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