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2 results on '"Cruz, G. (G.J.F.)"'

1. Evaluation and selection of biochars and hydrochars derived from agricultural wastes for the use as adsorbent and energy storage materials

Author

Lang, J. (J.), Matějová, L. (L.), Cuentas-Gallegos, A. (A.K.), Lobato-Peralta, D. (D.R.), Ainassaari, K. (K.), Gómez, M. (M.M.), Solís, J. (J.L.), Mondal, D. (D.), Keiski, R. (R.L.), Cruz, G. (G.J.F.), Lang, J. (J.), Matějová, L. (L.), Cuentas-Gallegos, A. (A.K.), Lobato-Peralta, D. (D.R.), Ainassaari, K. (K.), Gómez, M. (M.M.), Solís, J. (J.L.), Mondal, D. (D.), Keiski, R. (R.L.), and Cruz, G. (G.J.F.)

Abstract

The utilization of unconventional agricultural wastes to obtain new porous carbonaceous materials, at mild pyrolysis temperatures and without complex procedures, for either water treatment and energy storage applications is important from the economic and environmental perspective. In this study, biochars and hydrochars were prepared from banana rachis, cocoa pod husks, and rice husks at 600 °C-2 h, under nitrogen flux. The prepared materials were characterized to better understand how their morphological, textural, physical-chemical and/or structural properties correlate with their methylene blue (MB) adsorption capacities. The material with the best properties (mainly SBET > 800 m²/g) and MB adsorption capacity was a novel biochar prepared from banana rachis (BW-BC). This novel material was selected for additional kinetics and equilibrium adsorption tests for lead (Pb) along with its energy storage capacity. In equilibrium test, the novel biochar reached a maximum adsorption capacity for methylene blue of 243.4 mg/g and the highest adsorption capacity for Pb(II) of 179.7 mg/g. In the kinetic adsorption test, the equilibrium adsorption value for methylene blue was 150.4 mg/g and that for Pb(II) was 159.6 mg/g. Most importantly, the performance of the BW-BC material for energy storage in supercapacitors surpassed that of the commercial activated carbon YP50F, reaching specific energy values of 6.66 and 8.52 Wh/kg in acidic and neutral electrolytes, respectively. Among the evaluated hydrochar and biochars derived of agrowastes, the biochar prepared from banana rachis showed the best properties, being potentially useful as adsorbent or as an electrode material for energy storage.

Published
2021

2. Microporous activation carbon made of sawdust from two forestry species for adsorption of methylene blue and heavy metals in aqueous system:case of real polluted water

Author

Cruz, J. (J.F.), Cruz, G. (G.J.F.), Ainassaari, K. (K.), Gómez, M. (M.M.), Solís, J. (J.L.), and Keiski, R. (R.L.)

Subjects
sawdust, adsorption, methylene blue, metales pesados, adsorción, aserrín, heavy metals, azul de metileno, aqueous system, sistemas acuosos
Abstract

Activated carbon samples were prepared and characterized from two novel forestry precursors by one-step chemical activation with ZnCl₂. The adsorption capacities of the adsorbents were tested with methylene blue in monocomponent synthetic solution and with heavy metals from polluted river water. The specific surface areas (S BET ) of the produced activated carbons were 1278 and 1404 m²/g. Further characterization was carried out by FTIR, RAMAN spectroscopy, XRD and FESEM analysis. The pore structure of both activated carbons was predominantly microporous with presence of mesopores. The maximum methylene blue (MB) adsorption capacities for both activated carbons were 250 mg/g and 357 mg/g. MB kinetic experiments were carried out and the influence of the initial MB concentration and the activated carbon dosage was evaluated. The samples reached removal levels close to 100% during the first 5 min of experiments with dissolved As(V) and Pb(II) in the polluted river water, reducing the concentration of these elements until levels below the local water quality standards. Resumen Se prepararon carbones activados a partir de dos precursores de la actividad forestal utilizando activación química en un solo paso con ZnCl₂. Las capacidades de adsorción se determinaron con azul de metileno en soluciones sintéticas y con metales pesados de agua de un río contaminado. Las áreas superficiales específicas de los carbones activados se calcularon entre 1278 y 1404 m²/g. Una caracterización de los materiales se realizó mediante FTIR, espectroscopía RAMAN, difracción de rayos X y microscopía electrónica de barrido. La estructura porosa de ambos carbones activados fue predominantemente microporosa con presencia de mesoporos. La máxima adsorción de azul de metileno por ambos carbones fue de entre 250 mg/g y 357 mg/g. La cinética de adsorción de azul de metileno con diferentes concentraciones iniciales del colorante y diferentes dosis de carbón activado, también fue evaluada. Las muestras alcanzaron una capacidad de remoción de As(V) y Pb(II) disueltos en agua de un río contaminado cercanas 100 % durante los primeros 5 min, reduciendo los valores de estos contaminantes a niveles por debajo de los estándares de calidad de agua locales.

Published
2018

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