Mild Hydrogenation of Urban Biowaste Hydrolysates to Biopolymers with Improved Properties

This work reports the hydrogenation of soluble biopolymers (SBP) obtained by hydrolysis of municipal biowaste anaerobic digestate (D) and compost (CP). The SBP are mix of heterogenous molecules with 5–750 kDa molecular weight constitued by aliphatic and aromatic C moieties substitued by acid and basic functional groups. They are mutipurpose products for use in the chemical industry as biosurfactants and plastics’ additives, in agriculture and in animal husbandry. Purpose of hydrogenation was to improve SBP properties, while keeping macromolecularity. Hydrogenation was carried out in 4–5% water solution at pH 10 at 100°C and 35 bar H2 pressure for 2– 30 min. Results show hydrogenation of up to 35% SBP C to products containing more aliphatic C and different molecular weight distribution. Relative to pristine SBP, the molecular weight of hydrogenated CP SBP and of D SBP are, respectively, higher and lower. Surfactants properties improve upon hydrogenation. Hydrogenated D SBP are better surfactants than hydrogenated CP SBP. Further improvement and uses of hydrogenated SBP are discussed