Biofuel production, hydrogen production and water remediation by photocatalysis, biocatalysis and electrocatalysis

Abstract

The energy crisis and environmental pollution have recently fostered research on efficient methods such as environmental catalysis to produce biofuel and to clean water. Environmental catalysis refers to green catalysts used to breakdown pollutants or produce chemicals without generating undesirable by-products. For example, catalysts derived from waste or inexpensive materials are promising for the circular economy. Here we review environmental photocatalysis, biocatalysis, and electrocatalysis, with focus on catalyst synthesis, structure, and applications. Common catalysts include biomass-derived materials, metal–organic frameworks, non-noble metals nanoparticles, nanocomposites and enzymes. Structure characterization is done by Brunauer–Emmett–Teller isotherm, thermogravimetry, X-ray diffraction and photoelectron spectroscopy. We found that water pollutants can be degraded with an efficiency ranging from 71.7 to 100%, notably by heterogeneous Fenton catalysis. Photocatalysis produced dihydrogen (H2) with generation rate higher than 100 μmol h−1. Dihydrogen yields ranged from 27 to 88% by methane cracking. Biodiesel production reached 48.6 to 99%.

Enhanced removal of Ce(iii) and Sr(ii) ions from aqueous solution using ultrasonication-assisted sawdust-TiO2 sorbent

“…To understand the sono-sorption behavior and the sonosorption capacity for Sr(II) and Ce(III) metal ions on the ST sorbent, the Langmuir (eqn (10) and ( 11)), 108 Freundlich (eqn ( 12)), 109 and Dubinin-Radushkevich (D-R) 110 isotherm models (eqn ( 13)-( 15)) were used to fit the experimental data. These models are expressed as follows: Langmuir:…”

“…They found that the best method is the adsorption process, which is due to its unique properties in terms of reducing time and obtaining a high removal rate of metal ions and radioactive isotopes using different adsorbents. [5][6][7][8][9][10] Lately, biomass materials like coconut shell activated carbon, 11,12 sawdust, [13][14][15] activated carbon, [16][17][18][19] natural materials, 20,21 activated carbon derived from pine sawdust, 22 magnetic plastic waste-biomass char composite (MPBC), 23 activated carbon and carbon nanotubes that synthesized from biomass, [24][25][26][27][28][29] .....etc., have been used as adsorbents to isolate heavy metal ions, organics, dyes and radioactive isotopes from contaminated water. Where, these biomass materials include numerous function groups as -COOH, -OH, and CO and these groups are associated with the element through ion-exchange, van der Waals interactions, complexation or co-precipitation.…”

“…They found that the best method is the adsorption process, which is due to its unique properties in terms of reducing time and obtaining a high removal rate of metal ions and radioactive isotopes using different adsorbents. 5–10…”

The Promise of Metal-Doped Iron Oxide Nanoparticles as Antimicrobial Agent

“…This process can be modulated through modification of their fundamental structure . However, their effectiveness as biocatalysts in the biomedical field remains uncertain since of their modest conductivity and larger band gap. , Enhancement of the electronic configuration and number of biologically active sites is an efficient approach for boosting their electrical conductivity as well as chemical–physical aspects enabling biocatalysis since these factors play a significant influence on catalytic performances. , Numerous techniques are aimed at improving a material’s catalytic effectiveness by offering a greater abundance of catalytic sites with an expanded surface area, such as the inclusion of additional substances or doping defect technology, the architecture of composite materials, and so on. , Among these, doping is a practical approach to augmenting the efficiency of biocatalytic processes through the incorporation of additional atoms within the mother metal oxide lattice structure. After successfully doping, the dopant can regulate the electronic configuration of the biocatalyst by boosting the electric charge carrier density and conductivity and further improving the active sites .…”

“…62,63 Enhancement of the electronic configuration and number of biologically active sites is an efficient approach for boosting their electrical conductivity as well as chemical− physical aspects enabling biocatalysis since these factors play a significant influence on catalytic performances. 64,65 Numerous techniques are aimed at improving a material's catalytic effectiveness by offering a greater abundance of catalytic sites with an expanded surface area, such as the inclusion of additional substances or doping defect technology, the architecture of composite materials, and so on. 66,67 Among these, doping is a practical approach to augmenting the efficiency of biocatalytic processes through the incorporation of additional atoms within the mother metal oxide lattice structure.…”