Effect of hydrothermal carbonization temperature on pH, dissociation constants, and acidic functional groups on hydrochar from cellulose and wood

Saha, Nepu; Saba, A.E.; Reza, Mehedi

doi:10.1016/j.jaap.2018.11.018

Cited by 151 publications

(78 citation statements)

References 41 publications

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“…The washed dried hydrochar was finally used to measure the pH. Details of this measurement technique are discussed elsewhere [18].…”

Section: Characterization Of Solid Productsmentioning

confidence: 99%

“…There are several techniques, such as mass titration, potentiometric titration, immersion technique, and pH drift method to measure the pH PZC on a solid surface [33]. Among those techniques, pH drift method was used to measure the pH PZC in this study because it was found to be the most commonly used and reliable method in our earlier studies [18,34]. According to this method, around 0.25 g of dried hydrochar sample was placed in six Erlenmeyer flasks.…”

Section: Characterization Of Solid Productsmentioning

confidence: 99%

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Cationic Dye Adsorption on Hydrochars of Winery and Citrus Juice Industries Residues: Performance, Mechanism, and Thermodynamics

et al. 2020

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With the increasing needs of clean water supplies, the use of biomass wastes and residues for environmental remediation is essential for environmental sustainability. In this study, the residues from winery and citrus juice industries, namely grape skin and orange peel, respectively, were first converted to hydrochars by hydrothermal carbonization (HTC) and then a cationic dye (methylene blue) adsorption was studied on hydrochars. Hydrochars from both feedstocks were produced at three different temperatures (180, 220, and 250 °C) and a fixed residence time (1 h) to evaluate the hydrochar’s performance on the dye adsorption. The hydrochars were characterized in terms of their pH, pH at point of zero charge (pHPZC), surface functionalities, and surface area. A batch adsorption study of the dye was carried out with variable adsorbate concentration, pH, and temperature. Two adsorption isotherms namely Langmuir and Freundlich models were fitted at 4, 20, and 36 °C. The thermodynamic properties of adsorption (Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS)) were evaluated from the isotherms fittings. Results showed that the dye adsorption on both hydrochars was significant and followed Langmuir isotherm. The maximum adsorption capacity on citrus waste hydrochar was higher than the winery waste hydrochar at any corresponding HTC temperature. Although hydrochars showed the lowest surface area (46.16 ± 0.11 and 34.08 ± 1.23 m2/g for citrus and winery wastes, respectively) at 180 °C, their adsorption was the highest, owing to their maximum density of total oxygen functional groups (23.24 ± 0.22 and 32.69 ± 1.39 µmol/m2 for citrus and winery wastes, respectively), which decreased with the increase in HTC temperature. This research shows a sustainable route for the production of highly effective adsorbent materials at lower HTC temperatures from citrus and winery wastes.

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“…The washed dried hydrochar was finally used to measure the pH. Details of this measurement technique are discussed elsewhere [18].…”

Section: Characterization Of Solid Productsmentioning

confidence: 99%

Section: Characterization Of Solid Productsmentioning

confidence: 99%

Cationic Dye Adsorption on Hydrochars of Winery and Citrus Juice Industries Residues: Performance, Mechanism, and Thermodynamics

et al. 2020

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“…The FTIR spectra of the corncob hydrochar presented in Figure 1 are conducted to determine the functional groups on sample surface. The broad and strong band in the range of 3000 -3600 cm −1 is assigned to the -OH stretching vibration in hydroxyl or carboxyl groups [28] [29] [30]. Additionally, the band at 1700 cm −1 in the FTIR spectra of the prepared hydrochars is denoted as the stretching vibration of -C = O in carboxyl, carbonyl, quinonyl or ester groups [31].…”

Section: Characterizationmentioning

confidence: 99%

Experimental, Thermodynamic and Kinetic Studies for the Adsorption of Phenolic Compounds Derived from Oilfield Wastewater by the Corncob Hydrochar

Xie¹,

Ding²,

Liu³

et al. 2019

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The corncob hydrochar is prepared by using a stainless autoclave at 230˚C for 8 h. The products are characterized by elemental analyzer, Fourier Transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of hydrochar dosage, pH, adsorption time and phenol concentration on the adsorption performance of hydrochar are investigated by means of single-factor experimental analysis. Based on the experiments the adsorption thermodynamic and kinetics are tentatively discussed. The results show that abundant oxygen-containing functional groups are scattered on the surface of the corncob hydrochar. The adsorption kinetics of phenol on the hydrochar corresponds well with pseudo-second-order kinetic model. Thermodynamic studies indicate that Freundlich adsorption isotherm model is much better than Langmuir model in describing the adsorption of phenol on the corncob hydrochar at 25˚C-45˚C. This study provides scientific basis for the development of cheap and efficient adsorbents for the removal of phenols derived from oilfield wastewater.

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“…HTC is a wet thermochemical process carried out at relatively mild conditions: temperatures between 180 and 280 • C, autogenous saturated vapour pressure between 10 and 80 bars, and residence time ranging from a few minutes up to several hours. Under these process conditions, water acts similarly to an organic solvent due to the tremendous changes in its polarity and dielectric constant, and as a catalyst for biomass conversion via hydrolysis, dehydration, and decarboxylation reactions [7][8][9][10][11]. The main product of HTC is a carbon-rich solid material referred to as hydrochar, which finds application as high energy bio-fuel [12][13][14][15][16][17][18][19][20][21], as a pre-treated material for anaerobic digestion enhancement [15,22], as a soil amendment [14,23,24], and as an advanced carbonaceous material [25,26].…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Carbonization Kinetics of Lignocellulosic Agro-Wastes: Experimental Data and Modeling

2019

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Olive trimmings (OT) were used as feedstock for an in-depth experimental study on the reaction kinetics controlling hydrothermal carbonization (HTC). OT were hydrothermally carbonized for a residence time τ of up to 8 h at temperatures between 180 and 250 °C to systematically investigate the chemical and energy properties changes of hydrochars during HTC. Additional experiments at 120 and 150 °C at τ = 0 h were carried out to analyze the heat-up transient phase required to reach the HTC set-point temperature. Furthermore, an original HTC reaction kinetics model was developed. The HTC reaction pathway was described through a lumped model, in which biomass is converted into solid (distinguished between primary and secondary char), liquid, and gaseous products. The kinetics model, written in MATLABTM, was used in best fitting routines with HTC experimental data obtained using OT and two other agro-wastes previously tested: grape marc and Opuntia Ficus Indica. The HTC kinetics model effectively predicts carbon distribution among HTC products versus time with the thermal transient phase included; it represents an effective tool for R&D in the HTC field. Importantly, both modeling and experimental data suggest that already during the heat-up phase, biomass greatly carbonizes, in particular at the highest temperature tested of 250 °C.

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Effect of hydrothermal carbonization temperature on pH, dissociation constants, and acidic functional groups on hydrochar from cellulose and wood

Cited by 151 publications

References 41 publications

Cationic Dye Adsorption on Hydrochars of Winery and Citrus Juice Industries Residues: Performance, Mechanism, and Thermodynamics

Cationic Dye Adsorption on Hydrochars of Winery and Citrus Juice Industries Residues: Performance, Mechanism, and Thermodynamics

Experimental, Thermodynamic and Kinetic Studies for the Adsorption of Phenolic Compounds Derived from Oilfield Wastewater by the Corncob Hydrochar

Hydrothermal Carbonization Kinetics of Lignocellulosic Agro-Wastes: Experimental Data and Modeling

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