Sustainable valorization of Aloe vera processing waste into functional cellulose and lignin for environmental and industrial applications

Biomass valorization offers a sustainable route to address environmental challenges while providing renewable alternatives to petrochemical-based and wood-derived materials. Valorization of Aloe vera processing residues, particularly leaf skin waste, offers a sustainable pathway for producing high-value biopolymers. In this study, Aloe vera (Aloe sabaea) processing residues were converted into high-value biopolymers through an integrated biorefinery approach. Microcrystalline cellulose (MCC) was extracted from leaf skin waste with a yield of 36.03%, high purity (≈ 95% α-cellulose), enhanced crystallinity (72%), and good thermal stability (DTG peak ≈ 338 °C), indicating its potential use in industrial applications such as bionanocomposites and pharmaceutical excipients. In parallel, the black liquor, a by-product of the above delignification process, was used to isolate lignin by acid precipitation, yielding 9.15% and a molecular weight of 5931 ± 241 g/mol. The isolated lignin was used to demulsify a water-in-oil emulsion, achieving a separation efficiency above 98.5%. Demulsification was achieved under acidic conditions, highlighting the potential of lignin as a demulsifying agent under harsh conditions. The recyclability of lignin as a demulsifier was confirmed, with 93% lignin recovery after the first purification and retained demulsification efficiency (≈ 98.8%), demonstrating its stable reusability without loss of interfacial activity. This work demonstrates an efficient biorefinery approach for the dual valorization of Aloe vera waste into functional biopolymers for environmental remediation and industrial applications.