Synthesis and characterization of pecan nutshell-based adsorbent with high specific area and high methylene blue adsorption capacity

• Published in: Journal of molecular liquids Vol. 276; pp. 570 - 576
• Main Authors: Lima, Hugo H.C., Maniezzo, Rogério S., Llop, Maria E.G., Kupfer, Vincente L., Arroyo, Pedro A., Guilherme, Marcos R., Rubira, Adley F., Girotto, Emerson M., Rinaldi, Andrelson W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2019
• Subjects: Adsorption; Chemical activation; Hydrochar; Pecan nutshell; Water treatment; Pecan nutshell; Water treatment; Hydrochar; Chemical activation; Adsorption
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2018.12.010

In this work, a pecan nutshell was used as a precursor to prepare activated hydrochar (HPN-ATV) with a high specific area. HPN-ATV was engineered as an adsorbent for the removal of methylene blue (MB) from aqueous environments. The obtained materials were characterized using textural, morphological, and chemical analysis techniques. HPN-ATV showed a BET specific area of 2342 m2 g−1 and an average pore diameter of 2.24 nm. Boehm titration and FTIR spectral analysis indicated the presence of acidic and basic functional groups on the surface of HPN-ATV, which rendered the removal of cationic molecules more favorable. The kinetic experimental data better correlated with the pseudo-second-order kinetic and Elovich equations, and the Langmuir model showed a better fit for the data of MB adsorption. The adjusting parameters indicated a monolayer with an adsorption capacity of 1190.62 mg g−1, which is higher than that of the other adsorbents reported in literature. In addition, the thermodynamic data suggested a spontaneous adsorption process with endothermic characteristics. •Hydrobiochar with a specific area of 2342 m2 g−1 was obtained from Pecan nutshell.•The results indicated a monolayer with an adsorption capacity of 1190.62 mg g−1•Methylene blue was absorbed predominantly via chemisorption.•The adsorption process is spontaneous with endothermic characteristics.