Ozonization to Upgrade Waste‐Derived Soluble Lignin‐Like Substances to Higher Value Products

Abstract

Soluble biobased lignin‐like polymeric substances (SBO) isolated from the alkaline hydrolysates of composted biowastes are promising chemical auxiliaries for multiple uses. They have good surfactant properties. Their black color spoils their performance in detergency and dyeing. Ozonization of SBO is reported now to yield bleached biosurfactants with improved performance. The work was performed, with SBO obtained from composted gardening residues, alone or mixed with kitchen wastes. They were dissolved in water at 3.3 % concentration. Oxygen containing 4 mol/mol % ozone was flown at 60 L h−1 for 48 h through the SBO solution. The crude ozonized products in ca. 80 % yield were filtered through different molecular cut off membranes and characterized for chemical features, molecular weight, and surface tension in water. The ozonized fractions with 200–500 kDa molecular weights accounted for 12–29 % of the total ozonized fractions's organic matter. They lowered water surface tension to 48–52 mN m−1. The lower molecular weight ozonized fractions had no surfactant activity, but their molecular features suggest other potentially valuable uses.

High Molecular Weight Biosurfactants from Mild Chemical Reactions of Fermented Municipal Biowastes

“…The results obtained in the authors’ previous and present work show that mild chemical hydrolysis and oxidation at room or 60 °C temperature may be well integrated with biochemical processes to valorise biomass as renewable alternative to fossil feedstock more than incineration or high temperature hydrothermal hydrolysis, oxidation and pyrolysis. In the present work, focusing on fermented MBW, it is shown that room temperature oxidation allows improving the performance and value of biopolymers obtained by 60 °C hydrolysis.…”

“…The present paper reports further work addressing the following aspects, which were not covered before. In the previous work, ozonisation of CP SBP was carried in alkaline water solution only at 48 h gas‐liquid contact time while ozonisation of D SBP was not investigated. The comparison of the ozonisation substrates was particularly important as D SBP was expected to yield better surfactants.…”

“…Ozonisation of SBP gave a water‐soluble and a water insoluble product. The formation of the insoluble product was observed also in the preliminary ozonation work and from authors studying the ozonisation of pine kraft lignin in alkaline solution. This fact was attributed to the dehydrogenative coupling of phenolic degraded fragments by active oxygen radicals and to the extensive cross‐linking between ozonised molecules.…”

“…This fact was attributed to the dehydrogenative coupling of phenolic degraded fragments by active oxygen radicals and to the extensive cross‐linking between ozonised molecules. This mechanism could also explain the formation of the insoluble product in our preliminary work …”

“…In comparison with the bacterial surfactants, the R150 D SBP exhibits colour, cmc, and γ cmc values, competitive with glycolipids for performance. However, the D SBP production cost has been estimated 0.1–0.5 € kg −1 , much below the bacterial surfactant cost. With this in mind, even if the ozonised SBP was produced in low yields, its high potential value could make the ozonisation process worthy of further development.…”