Adsorption of methyl orange from aqueous solution by aminated pumpkin seed powder: Kinetics, isotherms, and thermodynamic studies

• Published in: Ecotoxicology and environmental safety Vol. 128; pp. 109 - 117
• Main Authors: Subbaiah, Munagapati Venkata, Kim, Dong-Su
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.06.2016
• Subjects: adsorbents; Adsorption; aqueous solutions; Azo Compounds - analysis; Cucurbita - chemistry; desorption; equations; Ethanolamine - chemistry; Fourier transform infrared spectroscopy; Hydrogen-Ion Concentration; Isotherms; Kinetics; Methyl orange; Microscopy, Electron, Scanning; Models, Theoretical; Powders; pumpkins; scanning electron microscopy; Seeds - chemistry; sodium hydroxide; Solutions; sorption isotherms; Spectroscopy, Fourier Transform Infrared; Surface Properties; Temperature; Thermodynamics; Water Pollutants, Chemical - analysis; Thermodynamics; Kinetics; Adsorption; Methyl orange; Isotherms
• ISSN: 0147-6513; 1090-2414; 1090-2414
• DOI: 10.1016/j.ecoenv.2016.02.016

Present research discussed the utilization of aminated pumpkin seed powder (APSP) as an adsorbent for methyl orange (MO) removal from aqueous solution. Batch sorption experiments were carried to evaluate the influence of pH, initial dye concentration, contact time, and temperature. The APSP was characterized by using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The experimental equilibrium adsorption data were fitted using two two-parameter models (Langmuir and Freundlich) and two three-parameter models (Sips and Toth). Langmuir and Sips isotherms provided the best model for MO adsorption data. The maximum monolayer sorption capacity was found to be 200.3mg/g based on the Langmuir isotherm model. The pseudo-first-order and pseudo-second-order model equations were used to analyze the kinetic data of the adsorption process and the data was fitted well with the pseudo-second-order kinetic model (R2>0.97). The calculated thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 from experimental data showed that the sorption of MO onto APSP was feasible, spontaneous and endothermic in the temperature range 298–318K. The FTIR results revealed that amine and carboxyl functional groups present on the surface of APSP. The SEM results show that APSP has an irregular and porous surface which is adequate morphology for dye adsorption. Desorption experiments were carried to explore the feasibility of adsorbent regeneration and the adsorbed MO from APSP was desorbed using 0.1M NaOH with an efficiency of 93.5%. Findings of the present study indicated that APSP can be successfully used for removal of MO from aqueous solution. [Display omitted] •Adsorption of MO onto APSP was studied at various operating conditions.•The APSP is an efficient adsorbent for the removal of MO.•The APSP was characterized by using FTIR and SEM analysis.•Equilibrium, kinetics and thermodynamic studies were carried out for the sorption process.•The APSP showed excellent regeneration performance and reusability.