An Eco-Friendly Modification of a Walnut Shell Biosorbent for Increased Efficiency in Wastewater Treatment

Andra-Cristina Enache, Petrisor Samoila (), Corneliu Cojocaru (), Roxana Apolzan, Georgeta Predeanu and Valeria Harabagiu
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Andra-Cristina Enache: Laboratory of Inorganic Polymers, “Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
Petrisor Samoila: Laboratory of Inorganic Polymers, “Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
Corneliu Cojocaru: Laboratory of Inorganic Polymers, “Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
Roxana Apolzan: SC Cosfel Actual SRL, 95-97 Grivitei Street, 010705 Bucharest, Romania
Georgeta Predeanu: Research Center for Environmental Protection and Eco-Friendly Technologies (CPMTE), University Politehnica of Bucharest, 1 Polizu Street, 011061 Bucharest, Romania
Valeria Harabagiu: Laboratory of Inorganic Polymers, “Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania

Sustainability, 2023, vol. 15, issue 3, 1-17

Abstract: Herein, we report the performance of some low-cost biosorbents developed by environment-friendly modification of walnut shells. Two types of biosorbents were prepared by ecological modification of walnut shell surfaces: (1) biosorbents obtained by hot water treatment (WS H2O ) and (2) biosorbents produced by mercerization (WS NaOH ). Different techniques were used to evaluate the morphological, elemental, and structural modification of the biosorbents, by comparison with raw materials. These characterization techniques involved scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis, and Fourier-transform infrared spectroscopy (FTIR). The biosorbents were employed for the removal of methylene blue (MB) and crystal violet (CV) cationic dyes (as model organic pollutants) from aqueous solutions. The kinetic adsorption data mainly followed the pseudo-first-order model. The maximum adsorption capacities of the produced biosorbents ranged from 102 to 110 mg/g and were observed at 330 K. Equilibrium data for adsorption were fitted to Langmuir and Freundlich isotherm models. The calculated values of thermodynamic parameters suggested that the investigated adsorption processes were exergonic (Δ G < 0) and exothermic (Δ H < 0). In addition, a possible valorization of the cost-effective and eco-friendly spent biosorbents was tested by performing secondary adsorption of the anionic dyes.

Keywords: biomass; green technologies; sustainable development; biosorbents; eco-friendly modification; cationic dyes (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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