Biofuel consists of non-fossil fuel derived from the organic biomass of renewable resources, including plants, animals, microorganisms, and waste. Energy derived from biofuel is known as bioenergy. The reserve of fossil fuels is now limited and continuing to decrease, while at the same time demand for energy is increasing. In order to overcome this scarcity, it is vital for human beings to transfer their dependency on fossil fuels to alternative types of fuel, including biofuels, which are effective methods of fulfilling present and future demands. The current review therefore focusses on second-generation lignocellulosic biofuels obtained from non-edible plant biomass (i.e., cellulose, lignin, hemi-celluloses, non-food material) in a more sustainable manner. The conversion of lignocellulosic feedstock is an important step during biofuel production. It is, however, important to note that, as a result of various technical restrictions, biofuel production is not presently cost efficient, thus leading to the need for improvement in the methods employed. There remain a number of challenges for the process of biofuel production, including cost effectiveness and the limitations of various technologies employed. This leads to a vital need for ongoing and enhanced research and development, to ensure market level availability of lignocellulosic biofuel.

Integrated wastewater treatment processes are needed due to the inefficient removal of emerging pharmaceuticals by single methods. Herein, an adsorbent-photocatalyst integrated material was fabricated by coupling calcium alginate with sulfur-doped TiO₂/tungsten disulfide (S-TiO₂/WS₂/alginate beads) for the removal of oxytetracycline (OTC) from aqueous solution by an integrated adsorption-photocatalysis process. The semiconductor S-TiO₂/WS₂ hybrid photocatalyst was synthesized with a hydrothermal method, while the integrated adsorbent-photocatalyst S-TiO₂/WS₂/alginate beads were synthesized by blending S-TiO₂/WS₂ with sodium alginate using calcium chloride as a precipitating agent. The physicochemical characteristics of S-TiO₂/WS₂/alginate beads were analyzed using X-ray diffraction , scanning electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The integrated adsorption-photocatalysis process showed enhanced removal from 92.5 to 72%, with a rise in the OTC concentration from 10 to 75 mg/L respectively. The results demonstrated that the adsorption of OTC onto S-TiO₂/WS₂/alginate beads followed the Elovich kinetic model and Redlich–Peterson isotherm models. The formations of H-bonds, cation bridge bonding, and n-π electron donor-acceptor forces were involved in the adsorption of OCT onto S-TiO₂/WS₂/alginate beads. In the integrated adsorption-photocatalysis, surface-adsorbed OTC molecules were readily decomposed by the photogenerated active radical species (h⁺, O₂^•−, and HO^•). The persulfate addition to the OTC solution further increased the photocatalysis efficacy due to the formation of additional oxidizing species (SO₄^•⁻, SO₄⁻). Moreover, S-TiO₂/WS₂/alginate beads showed favorable efficiency and sustainability in OTC removal, approaching 78.6% after five cycles. This integrated adsorption-photocatalysis process offered significant insight into improving efficiency and reusability in water treatment.

The ubiquitous presence of pharmaceutical drugs and microbes in the water is leading to the development of drug resistant microbes. Therefore, efficient materials that can remove or inactivate the drug and microbe contaminants are required. In this work, nickel sulfide/calcium alginate (Ni₃S₄/CA), silver sulfide/calcium alginate (Ag₂S/CA), modified titanium dioxide/calcium alginate (TiO₂/CA), and Ni₃S₄/Ag₂S/TiO₂/calcium alginate (Ni₃S₄/Ag₂S/TiO₂/CA) aerogels have been synthesized for the removal of the oxytetracycline (OTC) drug and microbial contaminants from real beverage industry wastewater. The results revealed that Ni₃S₄/Ag₂S/TiO₂/CA aerogel is highly efficient for OTC adsorption and inactivation of microbes compared to Ni₃S₄/CA, Ag₂S/CA and TiO₂/CA aerogels. The OTC adsorption depends greatly on the solution pH, and optimum OTC removal was observed at pH 6 in its zwitterionic (OTC^±) form. The formation of H-bonding and n-π electron donor-acceptors is possible to a considerable extent due to the presence of the double bond benzene ring, oxygen and nitrogen, sulfur-containing functional groups on the OTC molecules, and the Ni₃S₄/Ag₂S/TiO₂/CA aerogel. Based on the statistical analysis, root-mean-square deviation (RMSD), chi square (χ²) values, and higher correlation coefficient (R²) values, the Redlich–Peterson isotherm model and Elovich kinetic model are most suited to modelling the OTC adsorption onto Ni₃S₄/Ag₂S/TiO₂/CA. The prepared aerogels’ excellent antimicrobial activity is observed in the dark and with solar light irradiation. The zone of inhibition analysis revealed that the antimicrobial activity of the aerogels is in the following order: Ni₃S₄/Ag₂S/TiO₂/CA > TiO₂/CA > Ag₂S/CA > Ni₃S₄/CA, respectively. Moreover, the antimicrobial results demonstrated that reactive oxygen species, electrons, and active radical species are responsible for growth inhibition and killing of the microbes. These results indicated that Ni₃S₄/Ag₂S/TiO₂/CA aerogel is highly efficient in decontaminating pollutants from wastewater.

Fouling and biofouling remain significant challenges in seawater desalination plants. One practical approach to address these issues is to develop anti-biofouling membranes. Therefore, novel hybrid zinc phthalocyanine/polyvinylidene fluoride-co-hexafluoropropylene (Zn(4-PPOx)₄Pc/PVDF-HFP) membranes were prepared by electrospinning to evaluate their properties against biofouling. The hybrid nanofiber membrane was characterized by atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle measurements. The theoretical calculations of PVDF-HFP, Zn(4-PPOx)₄Pc), and Zn(4-PPOx)₄Pc/PVDF-HFP nanofibers were performed using a hybrid functional RB3LYP and the 6-31 G (d,p) basis set, employing Gaussian 09. DFT calculations illustrated that the calculated physical and electronic parameters ensured the feasibility of the interaction of PVDF-HFP with Zn(4-PPOx)₄Pc via a halogen–hydrogen bond, resulting in a highly stable and remarkably reactive structure. Moreover, molecular electrostatic potential (MEP) maps were drawn to identify the reactive regions of the Zn(4-PPOx)4Pc and PVDF-HFP/Zn(4-PPOx)4Pc nanofibers. Molecular docking analysis revealed that Zn(4-PPOx)₄Pc has highest binding affinity (−8.56 kcal/mol) with protein from S. aureus (1N67) mainly with ten amino acids (ASP405, LYS374, GLU446, ASN406, ALA441, TYR372, LYS371, TYR448, LYS374, and ALA442). These findings highlight the promising potential of Zn(4-PPOx) ₄Pc/PVDF-HFP nanocomposite membranes in improving the efficiency of water desalination by reducing biofouling and providing antibacterial properties.