Search

The present work investigates the properties and oxidation stabilities of biodiesel derived from catfish oil (B100 CFO) generated by the fish processing plants in Vietnam. The composition and physicochemical properties of the B100 CFO were measured, including oxygen content (∼11 wt%), viscosity (4.5306 mm 2 s −1 ), density (0.8772 g cm −3 ), peroxide value (28.13 mg kg −1 ), heat of combustion (39.18 MJ kg −1 ), and acid number (0.12 mg KOH g −1 ). Methyl oleate (46.44 wt%) was the dominant fatty acid methyl ester. B100 CFO was found to have poorer low-temperature quality than most vegetable oil derived biodiesels as determined by its fusion and crystallization properties. Novel modified ASTM D5304 and D2274 tests were employed to study the oxidation process of B100 CFO and the impact of oxidation time on its stability. Under ASTM 5304 test conditions, rapid O 2 consumption by B100 CFO occurred after 8 h, behavior similar to commercial biodiesel stabilized with antioxidant additives. The influence of oxidation condition and time on the B100 CFO physicochemical properties and low-temperature qualities was also investigated according to ASTM methods. Three oxidation stages were identified in B100 CFO based on the peroxide value change during the modified ASTM D5304 and D2274 tests. B100 CFO was also found have superior oxidation stability in comparison with B100 derived from waste cooking oil. This is the first report on oxidation stability of B100 derived from catfish oil. [ABSTRACT FROM AUTHOR]

A multi-stimuli responsive pseudo [3]rotaxane NI-DBC/RB-DBA was composed of a green-emissive (λ em = 530 nm) naphthalimide-based macrocyclic host and a turn-on red-emissive (λ em = 595 nm) rhodamine-based guest towards Fe3+ ion, which illustrated interesting photo-physical properties in dioxane/H 2 O (4:6, v/v) solutions. Due to the chelation-induced ring unfolded form of red-emissive rhodamine unit upon the addition of Fe3+ ion, mono-fluorophoric pseudo [3]rotaxane NI-DBC/RB-DBA could be transformed into bi-fluorophoric pseudo [3]rotaxane NI-DBC/RB-DBA-Fe3+ to reveal the Förster resonance energy transfer (FRET) process, which could be further identified by time-resolved photoluminescence (TRPL) measurements to obtain a higher energy transfer efficiency of 45.4% than that (21.1%) of its analogous mixture without host-guest interactions. Regarding pH effects, both pseudo [3]rotaxane systems NI-DBC/RB-DBA and NI-DBC/RB-DBA-Fe3+ could also be employed as pH sensors in acidic (pH = 1–6) and basic (pH = 8–12) conditions, respectively. Moreover, the pH range of 6–8 could be appropriate to maintain excellent sensing capabilities of pseudo [3]rotaxane NI-DBC/RB-DBA to detect Fe3+ ion. Accordingly, pseudo [3]rotaxane NI-DBC/RB-DBA could show the FRET-ON sensing behaviour towards Fe3+ ion, which was attributed to the turn-on red-emissive rhodamine-functionalized RB-DBA acceptor. Owing to the best FRET process and ratiometric fluorescence of bi-fluorophoric pseudo [3]rotaxane NI-DBC/RB-DBA-Fe3+ after Fe3+ ion detection, pseudo [3]rotaxane NI-DBC/RB-DBA provided a prominent limit of detection (LOD) value of 39.01 nM, which was further proceeded as simple test strips towards Fe3+ ion recognition and applied to the detection of Fe3+ ion in various pristine water samples. Therefore, the developed pseudo [3]rotaxane with host-guest interactions has been well designed and constructed to utilize FRET-ON processes as a novel Fe3+ ion sensor. [Display omitted] • A novel FRET-based pseudo[3]rotaxane involving the naphthalimide host donor and rhodamine guest acceptor was fabricated. • Multi-stimuli responsive properties of the pseudo[3]rotaxane were investigated under various pH values and metal ions. • After Fe3+ ion coordination, the pseudo[3]rotaxane revealed a FRET-ON process with a high energy transfer efficiency. • The designed pseudo[3]rotaxane could be employed to detect Fe3+ ion in various pristine water samples by simple test strips. [ABSTRACT FROM AUTHOR]