Common operational issues and possible solutions for sustainable biosurfactant production from lignocellulosic feedstock.

Surfactants are compounds with high surface activity and emulsifying property. These compounds find application in food, medical, pharmaceutical, and petroleum industries, as well as in agriculture, bioremediation, cleaning, cosmetics, and personal care product formulations. Due to their widespread use and environmental persistence, ensuring biodegradability and sustainability is necessary so as not to harm the environment. Biosurfactants, i.e., surfactants of plant or microbial origin produced from lignocellulosic feedstock, perform better than their petrochemically derived counterparts on the scale of net-carbon-negativity. Although many biosurfactants are commercially available, their high cost of production justifies their application only in expensive pharmaceuticals and cosmetics. Besides, the annual number of new biosurfactant compounds reported is less, compared to that of chemical surfactants. Multiple operational issues persist in the biosurfactant value chain. In this review, we have categorized some of these issues based on their relative position in the value chain - hurdles occurring during planning, upstream processes, production stage, and downstream processes - alongside plausible solutions. Moreover, we have presented the available paths forward for this industry in terms of process development and integrated pretreatment, combining conventional tried-and-tested strategies, such as reactor designing and statistical optimization with cutting-edge technologies including metabolic modeling and artificial intelligence. The development of techno-economically feasible biosurfactant production processes would be instrumental in the complete substitution of petrochemical surfactants, rather than mere supplementation.

Photocatalytic degradation of congo red dye using nickel-titanium dioxide nanoflakes synthesized by Mukia madrasapatna leaf extract.

Semiconductor photocatalysts are efficient degraders of organic and inorganic waste water pollutants. Herein, we synthesized nickel-titanium dioxide (Ni-TiO2) nanoflakes using Mukia maderaspatana leafs with the aim of analyzing their photocatalytic degradation potential. Morphological analyses revealed that the nanoflakes were highly agglomerated with an average size of 100 nm. Further, elemental analysis confirmed the presence of Ti, O, and Ni, whereas Fourier transform infrared spectroscopy and X-ray diffraction established the presence of TiO2 and NiO. We found that photocatalytic degradation of congo red under UV illumination increased with increasing incubation period, demonstrating that Ni-TiO2 nanoflakes can be used as optimal photocatalysts for the degradation of dyes in waste water.

Bi-model cationic dye adsorption by native and surface-modified Trichoderma asperellum BPL MBT1 biomass: From fermentation waste to value-added biosorbent.

In this study, we aimed to assess the possible reusability of native and surface-modified waste biomass of a novel ascomycetes fungi Trichoderma asperellum BPL MBT1 for the adsorption of triphenylmethane dyes. Spent biomass obtained from fermentation medium has been applied in the uptake of model cationic dyes viz., crystal violet and malachite green. Optimization of experimental parameters by batch mode studies revealed that dye adsorption is influenced by medium pH time, initial concentration of dyes, and adsorbent dosage. It was observed that pH 10 was optimum for cationic dye adsorption. Further, the adsorption process obeyed the bi-model (Langmuir-Freundlich model) isotherm and adhered to pseudo-second-order kinetics. The involvement of ion exchange as the dominant mechanism of dye adsorption was indicated by the mean free energy obtained from Dubinin-Radushkevich isotherm. Cellular morphology and the involved functional groups were studied by scanning electron microscopy and Fourier transform infrared spectroscopy that revealed the presence of carbon and oxygen containing groups on the surface. Maximum desorption efficiency was achieved using a 0.1 M solution of HCl and the stability of the biosorbent was confirmed through reusability analysis. Our results confirm the applicability of both native and surface-modified T. asperellum BPL MBT1 biomass as a potential biosorbent for the sustainable wastewater treatment and safe dye disposal.