Activated carbons by zinc chloride activation for dye removal – a commentary

Hock, Pua Eng; Zaini, Muhammad Abbas Ahmad

doi:10.2478/acs-2018-0015

Cited by 64 publications

(32 citation statements)

References 32 publications

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“…A rapid degradation of imTRM2 produces a high residue of 23%, which consists of fixed carbon and zinc element. This is because, ZnCl 2 could inhibit the formation of tar, hence preserving the yield 10 . The evaporation of ZnCl 2 could occur at a temperature range of 400-600 °C 11 .…”

Section: Resultsmentioning

confidence: 99%

“…It comprises of networks of pores with channels constructed within a rigid skeleton of disordered layers of carbon atoms, connected by chemical bonds and stacked unevenly. ZnCl 2 also acts in pore drilling that enters the carbon matrix to form large pore volume and high surface area of activated carbon, while at the same time releasing some volatiles 10 .…”

Section: Resultsmentioning

confidence: 99%

“…The development of pores within the matrix of TAC2 is associated to the evaporation of volatiles in the presence of dehydrating agent, ZnCl 2 . Nevertheless, insoluble oxides can remain on TAC2 surface due to oxidation at activation temperature that is below the boiling point of ZnCl 2 of 732 °C, thus blocking some pathways 10 .

Figure 3 SEM images of TACs at different magnifications: ( a , b ) TAC2, ( c , d ) TAC3 and ( e , f ) TAC5.…”

Section: Resultsmentioning

confidence: 99%

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Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal

Zubir

Zaini

2020

Sci Rep

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this work is aimed at evaluating the conversion of Pterocarpus indicus twigs into activated carbon via composite chemical activation for methylene blue and congo red dyes adsorption. the activated carbons were prepared by single-step chemical activation using zinc chloride and/or phosphoric acid at different mass impregnation ratios at 600 °C for 90 min. The activated carbons were characterized for textural properties and surface chemistry. The batch adsorption was investigated at different concentrations (5-1,000 mg/L), contact times (2-540 min) and temperatures (30-60 °C). Phosphoric acid-activated twigs carbon showed a high surface area of 1,445 m 2 /g with maximum methylene blue adsorption capacity of 438 mg/g. On the other hand, a composite-activated carbon yields a 217 mg/g of congo red removal. The adsorption data for both dyes fitted well with Langmuir and pseudo-second-order kinetics models, indicating the predominance of chemical adsorption through monolayer coverage of dye molecules on the homogenous surface of activated carbon. the thermodynamics properties of dye adsorption onto twigs-derived activated carbons indicated that the process is endothermic, spontaneous and favourable at high temperature. Overall, activated carbons derived from Pterocarpus indicus twigs could be effectively used for dye wastewater treatment. In many developing countries worldwide, textile industry is among the vast economy-driven activities with 2.8% rise in demand every year 1. However, it becomes a main contributor to water pollution issue that brings about multiple negative impacts to aquatic environment, ecological balance, and human health 2. The fabric sector consumes nearly several hundred thousand gallons of water every day, hence generating a large quantity of wastewater 3. Typical textile wastewater consists of nutrients such as phosphate, nitrates, micronutrients, and sources of carbon for algae cultivation 4. Yet, it also primarily includes colorants and auxiliary chemicals which are toxic and harmful, hence creating negative implications to the water streams 5. Dyestuff components are toxic, carcinogenic, and mutagenic. Generally, dye is persistent for a long duration because the molecular structure is complex and can withstand degradation by sunlight and microorganism in water. Additionally, dye in water can impede the penetration of sunlight, thereby reducing the rate of photosynthesis and consequently results in oxygen deficiency for respiration 6. Dyes can be categorized into anionic, cationic, and non-ionic. For example, methylene blue (basic blue 9) is among the prevalent cationic dyes used in the fabric sector and can cause damaging effects, primarily to the aquatic ecosystem and human health. Wastewater treatment strategies have been introduced to mitigate water pollution. Among others, adsorption outweighs other removal techniques because the process is simple, economical, and feasible for dye wastewater decontamination even at low concentration depending on the physicochemical properties of adsorbent...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Figure 3 SEM images of TACs at different magnifications: ( a , b ) TAC2, ( c , d ) TAC3 and ( e , f ) TAC5.…”

Section: Resultsmentioning

confidence: 99%

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Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal

Zubir

Zaini

2020

Sci Rep

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“…The aqueous solutions of ZnCl2 present an acid character due to the Zn 2+ ions act as a Lewis acid, thus the ZnCl2 acts as a dehydration agent during the carbonization process, resulting in charring and aromatization reactions and development of the pore structure. Also, molecular hydrogen is evolved from the hydroaromatic structure of the precursor and leaves behind some sites for reaction [17][18][19].…”

Section: Chemical Characterizationmentioning

confidence: 99%

Adsorption of Lead (Ii) from Aqueous Solution Using Adsorbents Obtained from Nanche Stone (Byrsonima Crassifolia)

et al. 2020

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Abstract. The removal capacity of Pb(II) present in aqueous solution was evaluated, using as a sorbent the nanche stone (Byrsonima crassifolia) naturally (NS), modified with citric acid (MNS) and as activated carbon (AC). The point of zero charge (pHPZC) and the active sites (using the Boehm method and FTIR spectroscopy) were determined. The pHPZC of NS, MNS and AC were in an acid range. The concentration of active sites of NS, MNS and AC were 0.1037, 0.1123 y 0.1404 mol/g, respectively. The infrared spectra (FTIR) detected the formation of acid functional sites associated with the phenol group, carboxylic acids and lactones. The adsorption capacity of lead ions using NS, MNS and AC increases with the increment of the pH of the solution from 3 to 5; nevertheless, at pH 5, precipitation of lead ions is observed. Due to the above, the evaluation of the three materials was carried out at pH 4. Comparing the maximum capacity of adsorption of Pb(II) on NS with respect to MNS and AC at pH 4, it was increased in 2.2 and 10 times, respectively. The chemical modification applied to precursor, as well as its formation to AC, improved their adsorption capacity due to a greater generation of acid sites. The experimental data were represented with the models of Langmuir, Freundlich y Prausnitz-Radke and the parameter values of these isotherms were estimated using a least-squares method which utlilizes an optimization algorithm. Resumen. Se evaluó la capacidad de remoción de Pb(II) presente en solución acuosa, utilizando como adsorbente el hueso de nanche (Byrsonima crassifolia) de forma natural (HN), modificado con ácido cítrico (HNM) y como carbón activado CA. Se determinaron el punto de carga cero (pHPZC) y los sitios activos (utilizando el método Boehm y espectroscopía FTIR). El pHPZC del HN, HNM y CA estuvo en un rango ácido. La concentración de sitios ácidos del HN, HNM y CA fueron de 0.1037, 0.1123 y 0.1404 mol/g respectivamente. Los espectros infrarrojos (FTIR), detectaron la formación de sitios funcionales ácidos asociados al grupo fenol, ácidos carboxílicos y lactonas. La capacidad de adsorción del ion plomo con el HN, HNM y CA, aumentó al incrementarse el pH de la solución de 3 a 5; sin embargo, a pH 5, se observó precipitación de iones plomo. Debido a lo anterior, la evaluación de los tres materiales se realizó a pH 4. Comparando la máxima capacidad de adsorción de Pb(II) en el HN con respecto al HNM y al CA a pH 4, se incrementó en 2.2 y 10 veces, respectivamente. La modificación química aplicada al precursor, así como su formación a CA, amplió su poder de adsorción al desarrollarse una mayor cantidad de sitios activos ácidos. Los datos experimentales se representaron con los modelos de Langmuir, Freundlich y Prausnitz-Radke, y los valores de los parámetros de estas isotermas fueron estimados usando un método de mínimos cuadrados que utiliza un algoritmo de optimización.

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“…The reaction between the carbon atoms and dehydrating agent is promoted in the extended interlayer of carbons. Upon activation, the salt left in the pores are eliminated by acid wash17) . NaCl as a chemical activator is able to suppress the hydrocarbon impurities in the carbon pore that enlarge pore diameter size.…”

mentioning

confidence: 99%

Effect of Residence Time and Chemical Activation on Pyrolysis Product from Tires Waste

Putra

Amaliyah

Syam

et al. 2019

J. Jpn. Inst. Energy

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In this study, active carbon produced from tires waste using pyrolysis was investigated. As tires were made predominantly from the petroleum product rubber, they have a high heating value, as well as high volatile content and medium sulfur content. Those properties make them excellent candidates for pyrolysis, which can be used to recover energy and by-products. Pyrolysis has been conducted until the temperature of 750 °C and holds in residence time variation of 5, 60, and 120 min after oil and gas completely produced. Char was produced via pyrolysis then activated by chemical activation using NaCl solution for 24 hours followed by drying at the temperature of 100 °C for 1 hour. Activated carbon as pyrolysis product then analyzed using Scanning Electron Microscope, BET analysis and N2 adsorption analysis. It was observed that the pore size of the resulting carbon generally increases as increasing of residence time. In addition, increasing residence time also resulted in enhanced higher porosity development after chemical activation using NaCl as high as 2.19 nm with BET surface area of 28.19 m 2 /g. The formation of pores with an average diameter of pore 8 µm was observed on the carbon surface.

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Activated carbons by zinc chloride activation for dye removal – a commentary

Cited by 64 publications

References 32 publications

Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal

Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal

Adsorption of Lead (Ii) from Aqueous Solution Using Adsorbents Obtained from Nanche Stone (Byrsonima Crassifolia)

Effect of Residence Time and Chemical Activation on Pyrolysis Product from Tires Waste

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