Vanillin production from chemical oxidation of Pinus spp. Kraft lignin is investigated. At a temperature of 130 °C, an oxygen partial pressure of 3 bar, a total pressure of 9 bar, and a lignin concentration of 60 g/L in an alkaline medium of 2 N NaOH, a maximum vanillin yield of 10% is obtained. On the basis of experimental results in a batch reactor operated under various conditions of temperature, oxygen partial pressure, total pressure, initial lignin concentration and pH, a kinetic model is proposed to simulate vanillin production from oxidation of Kraft lignin. The reaction rate of vanillin production is, for pH > 11.5, r C = k NC[O2]1.75[L] − k CI[O2][C] and, for pH < 11.5, r C = k NC[O2]1.75[L] − Af(pH)[C]2. An attempt to predict pH variation during the reaction is also made. The overall flowsheet of the process is briefly addressed, and the recovery of vanillin by adsorption is discussed.

Vanillin can be produced by oxidation of kraft lignin, with air, in alkaline medium. The optimal conditions for vanillin production strongly depend on pH and temperature. This paper addresses the effect of temperature and pH on vanillin degradation by oxidation. Experiments were carried out in a wide range of vanillin concentration, oxygen partial pressure, temperature and pH. Simple models are proposed to explain the observed rate of vanillin consumption under conditions of high alkalinity (pH>12) and lower alkalinity (pH<12). At pH>12,the reaction rate of vanillin oxidation is first order in dissolved oxygen concentration [O2] and in vanillin concentration [C], i.e., (−rC) ∝[O2][C]; at pH<12, the rate is zero order in oxygen concentration and second order in vanillin concentration, i.e., (−rC)∝f(pH)[C]2.

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Batch isotherm experiments were carried out to select the best chromatographic supports for the purification of beet distillery condensates with the aim of recovering fermentable water. Adsorption parameters of four inhibitory solutes of the condensates chosen as targets were obtained, leading to the selection of a weak anion-exchanger and a polystyrenic resin. These results were further used for the chromatographic scaleup. Dynamic adsorption experiments run on both resins with a synthetic mixture of the four target solutes showed the presence of competition for the adsorption. The extended Langmuir model was then found to be applicable for a first estimation of the solute breakthrough. The treatment efficiencies of the two supports were confirmed with an industrial condensate, indicating components in the effluent that were not considered did not significantly affect the adsorption of the main compounds. Eventually, a combination of the two complementary resins was proposed for complete effluent detoxification.