Utilization of Waste Biomass (Kitchen Waste) Hydrolysis Residue as Adsorbent for Dye Removal: Kinetic, Equilibrium, and Thermodynamic Studies

Valorization of food waste as adsorbents for toxic dye removal from contaminated waters: A review

Industrial contaminants such as dyes and intermediates are released into water bodies, making the water unfit for human use. At the same time large amounts of food wastes accumulate near the work places, residential complexes etc. polluting the air due to putrefaction. The need of the hour lies in finding innovative solutions for dye removal from wastewater streams. In this context, the article emphasizes adoption or conversion of food waste materials, an ecological nuisance, as adsorbents for the removal of dyes from wastewaters. Adsorption, being a well-established technique, the review critically examines the specific potential of food waste constituents as dye adsorbents. The efficacy of food waste-based adsorbents is examined, besides addressing the possible adsorption mechanisms and the factors affecting phenomenon such as pH, temperature, contact time, adsorbent dosage, particle size, and ionic strength. Integration of information and communication technology approaches with adsorption isotherms and kinetic models are emphasized to bring out their role in improving overall modeling performance. Additionally, the reusability of adsorbents has been highlighted for effective substrate utilization. The review makes an attempt to stress the valorization of food waste materials to remove dyes from contaminated waters thereby ensuring long-term sustainability.

Flame synthesis of carbon nanoparticles from corn oil as a highly effective cationic dye adsorbent

Carbon nanoparticles (CNP) were synthesized through flame deposition method from a sustainable corn oil precursor. The morphology, particle size, surface chemistry, thermal stability, and zeta potential of the CNP were characterized. The batch adsorption of a cationic dye, methylene blue (MB), by the CNP at various concentrations, pH, and temperatures was evaluated to investigate the CNP's efficacy in industrial wastewater treatment applications. Results revealed the excellent adsorption of MB onto the CNP. The experimental data were then fitted into isotherm models, kinetic models, and thermodynamic models, and the model parameters, constants, Gibb free energy, enthalpy, and entropy were calculated and discussed. Hydrogen bonding and strong electrostatic interaction were the main adsorption mechanism for MB adsorption by the CNP. The CNP exhibited a maximum adsorption capacity of 138.89 mg/g, indicating superior adsorption of MB dye without the need for any further purification and activation steps. The adsorption efficiency did not compromise as the solution temperature increased up to 60 °C, and it can further be enhanced under alkaline conditions. To simulate the practical and industrial use of the developed CNP in textile effluent treatment, successful experiments were conducted in continuous flow adsorption by allowing concentrated MB solution to flow through a designed fixed bed purification system with a CNP filter bed.

Fabrication of mechanical robust keratin film by mesoscopic molecular network reconstruction and its performance for dye removal

Regenerated keratin-based adsorbents have attracted much attention in environmental pollution remediation. However, fabricating keratin-based adsorbents with excellent adsorption performance is still a challenging issue due to its weak mechanical property. In this study, mechanical robust keratin composite films were designed and engineered at mesoscopic scale by molecular network reconstruction strategy. It was found that the β-crystallites structure of silk fibroin template could induce the transformation of free unfolded molecular chains of keratin to β-sheet conformation and further resulted in the controllable manipulating of the mechanical properties of keratin films. This mechanical reinforced composite film showed high adsorption efficiency and capacity for dyes as well as ideal regeneration and recycling performance. Adsorption behavior of reactive brilliant blue KN-R by keratin composite films was comprehensively studied. The adsorption capacity (q_e) and removal efficiency for KN-R by the adsorbent could reach as high as 190.84 mg/g and 98.52%, respectively. The adsorbent exhibited excellent regeneration and recycling performance due to its mechanical robustness. The molecular network reconstruction strategy is both straightforward and effective for fabricating mechanical robust adsorbent for pollutant remediation.