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Lignin removal from synthetic wastewater via Fenton-like reaction over Cu supported on MCM-41 derived from bagasse: Optimization and reaction intermediates
(2023-02-01)
Sriprom, Pongsert
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Neramittagapong, Sutasinee
;
Lin, Chitsan
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Neramittagapong, Arthit
;
Assawasaengrat, Pornsawan
Lignin degradation was performed using a Fenton-like oxidation reaction with Cu supported on MCM-41, derived from bagasse (Cu-BG-MCM-41), as the catalyst. The optimal degradation conditions required to remove a predetermined amount of lignin (95%) from an effluent were determined. Based on the literature review and preliminary tests, the critical parameters determining the operating conditions include temperature, catalyst loading, pH, H<inf>2</inf>O<inf>2</inf> concentration, and reaction time. The experimental design and working conditions were based on Box–Behnken design. The reaction products were analyzed via UV–vis and gas chromatography-mass spectrometry. Response surface methodology (RSM) was used to predict the optimum operating conditions for the Fenton-like reaction for 95% lignin degradation, which were a temperature of 80 °C, initial pH of 9, H<inf>2</inf>O<inf>2</inf> concentration of 1 mL/L, catalyst loading of 1.0 g/L, and reaction time of 30 min. These conditions were validated three times and the achieved percentage of lignin degradation was 95 ± 2%. This is close to the value of 95% used in the RSM to determine the optimum operating conditions, thus verifying the model. The catalyst was stable and functioned well under the optimum design conditions. Moreover, the reaction could be used to obtain high-value intermediate products if stopped after 5 min. Finally, lignin was degraded into vanillin, a higher-value product. As expected, the proposed Fenton-like approach expanded the pH working range from less than 4 to 5–9.
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Optimization of Vanillin Production from Lignin Using Catalytic Depolymerization over a CuO/Al2O3 Catalyst
(2023-01-01)
Sangnak, Sirawit
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Neramittagapong, Arthit
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Neramittagapong, Sutasinee
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Theerakulpisut, Somnuk
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Sriprom, Pongsert
The optimal conditions for vanillin production from lignin depolymerization using CuO/Al2O3 catalysts were determined by combining Box-Behnken design (BBD) and response surface methodology (RSM). Independent variables, including temperature (80–140 °C), NaOH loading (0.5–1.5 g), time (30–90 min), and catalyst weight (0.5–1.5 g), were investigated to determine the optimal conditions, with the concentration of vanillin being the dependent variable. A CuO/Al2O3 catalyst was prepared by impregnation method. The vanillin obtained from the reaction was analyzed using high-performance liquid chromatography (HPLC). The maximum obtained vanillin concentration of 59.14 mg·L<sup>-1</sup> was achieved with a temperature of 80 °C, a reaction time of 90 min, NaOH loading of 1.5 g, and 1.5 g of catalyst. The amount of NaOH was the most influential factor governing the obtained vanillin concentration. Regression analysis was performed to determine the formula describing the vanillin concentration in terms of the independent variables with a reasonable degree of accuracy (R<sup>2</sup> = 0.87). This study shows that the optimal conditions for the depolymerization of lignin to vanillin over a CuO/Al2O3 catalyst can be achieved under milder conditions than those reported previously.
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Optimization of Lignin Conversion by Hydrothermal Method for Recovery of Vanillin
(2020-10-20)
Sriprom, Pongsert
;
Leephisuth, Pornyamon
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Neramittagapong, Arthit
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Neramittagapong, Sutasinee
This work aimed to optimize lignin conversion to vanillin by hydrothermal method. An experiment was designed by Box-Benhken Design (BBD). Temperature, NaOH concentration, and reaction time were chosen as independent parameters for achieving the optimum reaction condition. The reaction products were analyzed by high-performance liquid chromatography. Based on the experimental results, the optimum condition for the hydrothermal process was predicted using the response surface method. The maximum vanillin production of 18.1 mg/L was predicted at the optimum condition given by the temperature of 142 °C, NaOH concentration of 9.2 g/L, and reaction time of 32 min. The conversion of lignin to vanillin was experimented using the predicted optimal condition to verify the prediction. It was found that the hydrothermal method at the optimum condition yielded 18.1 ± 2 mg/L of vanillin, which was in good agreement with the predicted value. It was also found that the yield of vanillin was influenced by temperature, NaOH concentration, and the interaction of both parameters, whereas the reaction time was much less influential.
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Partial oxidation of synthesized wastewater containing lignin to vanillin and phenol under mild conditions
(2020-02-01)
Sriprom, Pongsert
;
Leephisuth, Pornyamon
;
Neramittagapong, Arthit
;
Neramittagapong, Sutasinee
Partial oxidation of synthesized wastewater containing lignin to form phenol and vanillin was investigated. The reactions were carried out in a high-pressure reactor at various temperatures in the range of 140–200 ° C and under the air atmosphere with the initial air pressure of 2 bar for 75 min. The addition of NaOH has a strong effect on the formation of vanillin and phenol. The results showed that the highest vanillin concentration of 23.4 ppm and the highest phenol production of 30 ppm were obtained at a temperature of 140 °C and 200 °C, respectively. The vanillin and phenol can be produced from the partial oxidation of wastewater containing lignin at mild conditions.

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