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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C. Tejada-Tovar ¹, A. Villabona-Ortíz ¹, A. Herrera-Barros ¹, Á. D. González-Delgado ¹, L. Garcés ¹

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

Abstract

Background: The increasing concentration of heavy metal pollutants as hexavalent chromium ions has gained attention due to its effect on the environment. Hence, different methods have been applied for removing Cr (VI) in aqueous solution and bioadsorption seems to be a cost-effective alternative due to the use of lignocellulosic materials as biosorbents. Objectives: This paper is focused on a comparative study of adsorption capacity of Cassava Peel (CP), Lemon Peel (LP) and its chemical modification with citric acid (CP-CA and LP-CA). Methods/Analysis: The adsorption process was carried out in batch and continuous systems in order to determine the effects of biosorbent particle size and pH on Cr (VI) removal yield. Findings: It was obtained that removal yield of 54% and 56% were obtained for unmodified cassava peel and citric acid-modified cassava peel, respectively. In addition, LP-CA showed higher removal yield (48%) than LP (43%), which suggested that chemical modification, improves biosorbent performance. The Cr (VI) ions were desorbed using a solution of HCl, and then the biomass was used in three adsorption cycles to determine its reusability. The kinetic model was adjusted to the pseudo-second order model and Elovich’s model for both modified and unmodified biomasses regarding adsorption isotherms. Freundlich model is the one that best describes the adsorption process. Novelty/Improvement: The good performance of these biosorbents in aqueous solution of Cr (VI) ions make them promising candidate for removing of heavy metals water pollutants.

Keywords

Adsorption, Biomass, Biosorbent, Chromium, Heavy Metal

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C. Tejada-Tovar ¹, A. Herrera-Barros ², A. Villabona-Ortíz ¹, Á. González-Delgado ², J. Núñez-Zarur ¹

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

Abstract

Background: Adsorption technology using residual biomass has gained attention as a low-cost alternative for removing Cr (VI) ions from aqueous solutions. Objectives: This work attempts to study the effect of orange peel modification with CaCl2 on Cr (VI) ions uptake in batch and continuous system. In addition, pH and particle size were evaluated to determine suitable values for carrying out adsorption process. Methods/Analysis: OP-CaCl2and OP biosorbents were characterized by FT-IR analysis in order to identify their functional groups. The pH of heavy metal ions solutions was adjusted to 2, 3, 4 and 6 and adsorbent particle size was varied in 0.355, 0.5 and 1 mm. Experimental data for batch experiments were used to calculate adsorption isotherms and kinetic. The results of adsorption on packed-bed columns were fitted to dynamic models. Desorption process was also studied to determine reusability of biomass. Findings: It was found that hydroxyl, carboxyl and aliphatic groups are the main contributors to adsorption process. The highest removal yield (86%) was achieved at pH of 2 and particle size of 0.355 mm. The chemical reticulation with CaCl2 did not improve adsorption capacity of orange peel biosorbent. Kinetic and isotherm models that best fit experimental data were Elovich´s and Freundlich´s, respectively. Regarding continuous systems, data obeyed Yoon-Nelson and Dose-response models with R2 =0.99. Desorption study with HCl reported a removal yield of 43.7% for second cycle of biosorbent use. Novelty/Improvement: These results suggested that orange peel is a suitable biosorbent alternative for removing Cr (VI).

Keywords

Adsorption Kinetics, Biosorption, Chromium Hexavalent, Isotherms, 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-Ortíz ², A. D. Gonzalez-Delgado ¹, Y. Villabona- Duran 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, Bolívar, CO

Abstract

Background: The presence of toxic pollutants in water sources has become a major issue worldwide and different technologies have been applied for water treatment such as chemical precipitation, ionic interchange, adsorption, membrane filtration, flocculation, among others. In the last decades, nanotechnology has gain attention in the development of nanomaterials for removing these pollutants. Objectives: In this work, Hg (II) and Cr (II) adsorption process was studied using residual biomass (orange peels, corn cob and oil palm bagasse) modified with Al2O3 nanoparticles. Methods/ Analysis: The biomasses before and after modification were characterized by FT-IR analysis in order to determine main functional groups. In addition, XRD technique was used to calculate average crystallite size and identify both γ and δ alumina. Findings: It was found that suitable conditions for further experiments were particle size of 0.355 mm and pH values of 2 and 6 for Cr (VI) and Hg (II), respectively. For Hg (II) ions, the highest removal yields were 70.89, 34.18 and 54.9 % using OPB-Al₂O₃, CC-Al₂O₃ and OP-Al₂O₃, respectively. For Cr (VI) ions, these values were 48.2, 39.8 and 30.5 % using OPB-Al₂O₃, CC-Al₂O₃ and OP-Al₂O₃, respectively. Novelty/Improvement: These results suggested that OPB-Al₂O₃ can be successfully used in removing Cr (VI) and Hg (II) with higher efficiency than the others synthesized biosorbents.

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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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