TURNING TAR-DERIVED PHENOLIC OILS INTO POROUS CARBON GELS FOR WATER POLLUTANTS REMOVAL - Archive ouverte HAL Access content directly
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TURNING TAR-DERIVED PHENOLIC OILS INTO POROUS CARBON GELS FOR WATER POLLUTANTS REMOVAL

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Sébastien Schaefer
Vanessa Fierro
Alain Celzard
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Abstract

Separation of coal tar into different fractions by distillation affords high-value products but also phenolic oils (POs). If phenol and cresols are the main reactive chemical species in POs, other chemicals such as coumarone and indene may also be found in large or significant amounts. On the other hand, coumarone-indene-phenol resins, and phenol-or cresol-derived gels are well-known materials. Thus, the driving idea of the present research was to propose an easy synthetic way of turning POs into high added-value carbon materials for water remediation. A one-pot synthesis in a monophasic organic medium was explored to produce solvogels. After drying the latter, the as-produced aero-, cryo-and xerogels were pyrolized to obtain the final carbon gels. Liquid phase adsorption assays of methylene blue (MB) were then carried out on one selected material. MB is indeed a commonly used molecule for such early stage of water pollutant removal studies. Materials and Methods 15 g of PO and a variable amount of isopropanol (7.5, 10, 12.5, 15 or 17.5 g of solvent) were first mixed in a 50 mL beaker under vigorous stirring during 2 min. Then, 0.64 g of para-toluenesulfonic acid (PTSA) was solubilized under stirring (2-5 min) in the initial mixture. Next, 3.12 g of paraformaldehyde (crosslinker) were added and solubilized under stirring. The mixture was then poured in hermetically sealed sample tubes, which were subsequently placed in a previously heated (85°C) oven during 5 days. The solvogels were then extracted from the sample tubes and washed for 3 days with absolute ethanol. Finally, aerogels were produced using supercritical drying (CO2), cryogels were produced using a lyophilisation step (after exchange with appropriate solvent, i.e., ultrapure water or tert-butanol), whereas xerogels were produced using convective drying (85°C in air). At last, the dried gels were pyrolized under N2 stream (100 cm 3 STP min-1) at 900 °C (5°C min-1 , 2h dwell time). The resultant carbon gels were named mA, mC or mX, depending on their way of drying, and "m" standing for the amount of isopropanol in the initial mixture. The texture of the final carbon gels was obtained from N2 and CO2 adsorption studies. The adsorption isotherms were then treated using SAIEUS® software (two-dimension non-local density functional theory: 2D-NLDFT) in order to obtain pore size distributions, pore volumes and specific surface areas. The MB adsorption experiments (kinetics and equilibrium studies) were carried out at 3 different temperatures (15, 25 and 45 °C).
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Dates and versions

hal-02907627 , version 1 (05-01-2021)

Identifiers

  • HAL Id : hal-02907627 , version 1

Cite

Sébastien Schaefer, Vanessa Fierro, Alain Celzard. TURNING TAR-DERIVED PHENOLIC OILS INTO POROUS CARBON GELS FOR WATER POLLUTANTS REMOVAL. Carbon 2018, Jul 2018, Madrid, Spain. ⟨hal-02907627⟩
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