Determination of surface-accessible acidic hydroxyls and surface area of lignin by cationic dye adsorption

Abstract The surface carboxyl and sulfate groups on cellulose nanowhiskers were quantified via the adsorption of toluidine blue O (TBO), a cationic dye. Here, simple and rapid protocols, such as mixing the nanowhisker suspensions with a dye solution, separating the supernatants via centrifugation, and determining the excess dye concentration via visible light absorbance techniques, were used to obtain reproducible results comparable with those obtained via titration. In addition to facilitating the discrete quantification of the sulfate and carboxyl groups, the TBO adsorption method enabled carboxyl quantification in the presence of mercapto groups, which was difficult to achieve via titration. The adsorption of TBO onto the carboxyl groups was completed within 30 min, enabling the rapid treatment of many samples within a short period.

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Studies in Adsorption: Determination of Specific Surface Area Of Lanthanum, Mercury and Molybdenum Ferrocyanides by a Cationic Organic Dye Adsorption

Reviews in Inorganic Chemistry ◽

10.1515/revic.2008.28.1.77 ◽

2008 ◽

Vol 28 (1) ◽

Author(s):

S.N. Singh ◽

N. Ramchurjee ◽

B.B. Tewari

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Dye Adsorption ◽

Organic Dye

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Determination of the specific surface area of FORUM fluoroplastic powder by the dye adsorption from solutions

Colloid Journal ◽

10.1134/s1061933x0605019x ◽

2006 ◽

Vol 68 (5) ◽

pp. 651-653 ◽

Cited By ~ 4

Author(s):

O. V. Shangareeva ◽

V. I. Fedoseeva ◽

N. F. Fedoseev

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Dye Adsorption ◽

Adsorption From Solutions

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

Energies ◽

10.3390/en13184686 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4686

Author(s):

Nepu Saha ◽

Maurizio Volpe ◽

Luca Fiori ◽

Roberto Volpe ◽

Antonio Messineo ◽

...

Keyword(s):

Surface Area ◽

Environmental Sustainability ◽

Environmental Remediation ◽

Dye Adsorption ◽

Point Of Zero Charge ◽

Batch Adsorption ◽

Maximum Adsorption Capacity ◽

Cationic Dye ◽

Grape Skin ◽

Citrus Juice

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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