New Insights on the Photodegradation of Caffeine in the Presence of Bio-Based Substances-Magnetic Iron Oxide Hybrid Nanomaterials

Abstract

The exploitation of organic waste as a source of bio-based substances to be used in environmental applications is gaining increasing interest. In the present research, compost-derived bio-based substances (BBS-Cs) were used to prepare hybrid magnetic nanoparticles (HMNPs) to be tested as an auxiliary in advanced oxidation processes. Hybrid magnetic nanoparticles can be indeed recovered at the end of the treatment and re-used in further water purification cycles. The research aimed to give new insights on the photodegradation of caffeine, chosen as marker of anthropogenic pollution in natural waters, and representative of the contaminants of emerging concern (CECs). Hybrid magnetic nanoparticles were synthetized starting from Fe(II) and Fe(III) salts and BBS-C aqueous solution, in alkali medium, via co-precipitation. Hybrid magnetic nanoparticles were characterized via X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The effect of pH, added hydrogen peroxide, and dissolved oxygen on caffeine photodegradation in the presence of HMNPs was assessed. The results allow for the hypothesis that caffeine abatement can be obtained in the presence of HMNPs and hydrogen peroxide through a heterogeneous photo-Fenton mechanism. The role of hydroxyl radicals in the process was assessed examining the effect of a selective hydroxyl radical scavenger on the caffeine degradation kinetic.

Thermal Conversion of Municipal Biowaste Anaerobic Digestate to Valuable Char

“…550 • C. The analysis of the derivative TG plot (DTG) evidenced that such a degradation phenomenon seems to be bimodal, and probably this is due to an initial weight loss due to the carbohydrate residue of the MWDF, followed by the degradation of the humic-like fraction at higher temperature values (ca. 430 • C), in accordance with the literature [14,15]. A second lower-weight loss of residual organic matter occurs above 550 • C. The results are consistent with previous TGA data for polysaccharides, such as chitosan [16] and humic-like substances isolated from composted biowaste [17].…”

PFAS Degradation in Ultrapure and Groundwater Using Non-Thermal Plasma

“…Advanced Oxidation Processes (AOPs) have been proposed to be implemented together with the conventional biological treatments to efficiently address the removal of CECs from wastewater [ 12 , 13 , 14 , 15 ]. These processes rely on chemical and/or physical processes generating highly reactive radical species (such as HO ● and SO 4 ●− ) able to react non selectively with the most organic compounds in solution, including, bio-recalcitrant compounds [ 16 , 17 ].…”

Activated-carbon/TiO2 composites preparation: An original grafting by milling approach for solar water treatment applications

“…For the multi functional properties, adsorption and photodegrada tion experiments were conducted using magnetically stirred beakers containing 100 mL of caffeine solutions prepared with ultrapure water (18 MΩ). Reagent Plus grade caffeine powder (> 99.0 % purity) from Sigma Aldrich USA, was chosen as a target pollutant molecule as it is recalcitrant to photodegradation [49] and safer to handle than most bio recalcitrants. Experiments were performed under a 40 W neon source radiating at 370 nm to activate the photocatalyst by exciting the bandgap energy value.…”