Biomass valorization of liquid whey into carbon quantum dots via hydrothermal process for food pathogenic bactericidal activity and photocatalytic degradation of brilliant red dye

• Published in: Food bioscience 2024-04, Vol.58, p.103764, Article 103764
• Main Authors: Thakur, Sweezee, Bains, Aarti, Kumar, Anil, Goksen, Gulden, Yaqoob, Mudasir, Parvez, Mohammad Khalid, Al-Dosari, Mohammed S., Chawla, Prince
• Format: Article
• Language: English
• Subjects: antibacterial properties; Antimicrobial; biomass; carbon; Circular economy; Dye reduction; dyes; fluorescence; fluorescence emission spectroscopy; liquids; milk; minimum inhibitory concentration; oxygen; photocatalysis; Photoluminescence; Sensors; Spectroscopy; Staphylococcus aureus; thermal stability; wavelengths; whey
• ISSN: 2212-4292; 2212-4306
• DOI: 10.1016/j.fbio.2024.103764

Whey is the primary waste material of the dairy industries; therefore, the present study focuses on the valorization of milk processing industry-originated liquid whey into valuable products, specifically liquid whey carbon quantum dots (LW-CQDs) for pathogenic bactericidal and photocatalytic dye reduction efficacy. Facile synthesis of fluorescent LW-CQDs was carried out by employing a green hydrothermal approach at 200 °C for 12 h. Several analytical techniques were used to confirm the thermally stable spherical particles, measuring 9.04 ± 0.76 nm size in diameter, primarily composed of carbon and oxygen LW-CQDs. The presence of diverse functional groups (hydroxyl, carboxyl, carbonyl, and methyl groups) of LW-CQDs contributed to overall optical properties, which manifested a blue emission peak at 418 nm with 240 nm excitation wavelength in fluorescence spectroscopy. UV–Visible spectra featured two peaks (π → π ∗ transition of C = C bonds and n → π ∗ transition of C = O bonds) at around 249 and 293 nm, respectively. Moreover, the synthesized LW-CQDs exhibited a significantly higher zone of inhibition (25.98 ± 0.17 mm) and significantly lower minimum inhibitory concentration (4.47 ± 0.01 μl/ml) against the Staphylococcus aureus. In addition, LW-CQDs revealed a higher killing rate of reaction for S. aureus as compared to K. pneumoniae, P. aeruginosa, and S. typhi and remarkably degraded 92.95 % of brilliant red dye under visible light (2000 lux). Hence, these facile LW-CQDs hold potential for applications in the effectiveness of antimicrobial and photocatalytic dye reduction activity, which show valuable contributions to both waste valorization and sustainable material development. [Display omitted] •A hydrothermal approach was employed for the synthesis of liquid whey-derived carbon quantum dots.•LW-CQDs exhibited blue fluorescence with an average size of 9.04 nm and spherical morphology.•Potential bactericidal activity was observed against Gram-positive Staphylococcus aureus.•Under visible light, LW-CQDs effectively degraded brilliant red dye up to 92.95 %.