Enzymatic valorization of cellulosic and hemicellulosic-based biomasses via the production of antioxidant water-soluble hydrolyzate of maize stalks and the green bio-deinking of mixed office waste paper

Abstract

AbstractBio-valorization of various biomasses provides a sustainable promising approach for the eco-friendly production of variable value-added products. Herein, the current study devoted to the enzymatic valorization of two widely available biomasses, namely, maize stalks and waste paper. The cellulytic and hemicellulytic-rich cocktail was produced through the fermentation of rice straw by a locally isolated fungal strain Aspergillus terreus. The potential applicability of the produced cocktail for the enzymatic hydrolysis of the polysaccharide constituents of maize stalks was evaluated under various strategies. The reported results indicated that the microwave pretreatment of the biomass yielding a water-soluble hydrolyzate rich in cellobiose and xylobiose, sustained by thin layer (TLC) and high-performance liquid chromatographic (HPLC) measurements, in addition to phenolic compounds. Moreover, the enzymatic hydrolysis of the extracted hemicellulosic fraction from maize stalks was rich in xylooligosaccharides and phenolic compounds higher than that released from the hydrolysis of commercial xylan. The estimated antioxidant activity of the resulted hydrolyzate was also monitored by the scavenging of 1,1-diphenyl-2-picrylhydrazyl free radical spectrophotometrically at 515 nm. Moreover, the potential applicability of the produced enzymatic cocktail was examined for the bio-deinking of waste paper. The physical, chemical, and surface morphological characteristics of the treated paper sample was compared to a blank one regarding the whiteness index, ash content, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Fourier transform infrared spectroscopy (FTIR). On the base of the estimated results, the produced enzymatic cocktail possessed efficient dislodgement ability for the printed ink from the paper surface.