In this paper, the synthesis of LaFeO 3 based on the gel combustion method has been improved by using citric acid (CA) as a secondary chelating agent on glucose. The synthesized samples were calcined at 600 °C and further characterized using X-ray diffraction (XRD), Fourier transform infrared, field-emission scanning electron microscopy (FESEM), scanning electron microscopy, energy-dispersive X-ray spectrophotometry, N 2 adsorption−desorption analyses, thermogravimetric analysis, and UV−vis−near-IR spectroscopy. The XRD data revealed that the pure orthorhombic perovskite phase LaFeO 3 was obtained when CA was added on glucose. From FESEM and Brunauer− Emmett−Teller analysis, LaFeO 3 synthesized using the addition of CA on glucose potentially showed well-uniform spherical particles and a high specific surface area of 40.77 m 2 /g with a particle size of 70 nm compared to glucose, which only showed 15.68 m 2 /g with a particle size of 100−300 nm. The photocatalytic activity of LaFeO 3 was evaluated by the degradation of diazo dyes, Reactive Black 5 (RB5) under visible-light irradiation, indicating that synthesized LaFeO 3 using the addition of CA on glucose exhibited excellent adsorption efficiency and remarkable photocatalytic activity with reaction rate constant K = 0.0680 min −1 , which was higher than that of the synthesized LaFeO 3 based on glucose only with reaction rate constant K = 0.0087 min −1 .
Humic Acid (HA) is considered as one of the major components that represents a major fraction of dissolved in natural water. Complex mixture of organic compounds on HA lead to the problematic issue for municipal wastewater treatment plants such as undesirable taste, colour to drinking water and fouling in pipe line. The reaction of HA with chlorine during disinfection processes would produce carcinogenic by-products like trihalomethanes. In this study, for the first time, LaFeO3 photocatalyst was successfully synthesized via gel-combustion method using combined glucose/citric acid as chelating agents and was further calcined at 400°C. The photocatalytic activity of samples was investigated by degradation of Humic Acid (HA) in water under visible light irradiation. Results proved that the photocatalytic degradation of HA is dependent on the catalyst dosage, initial concentration of HA, and oxygen availability in the aeration. The photocatalytic degradation also was enhanced by high surface area of synthesized LaFeO3 obtained by amorphous structure. Overall, the percentage removal of HA by varying the catalyst dosage are in the order of 88%, 90%, 98% and 97% for 0.6 g/L, 0.8 g/L, 1.0 g/L, and 1.2 g/L respectively for an irradiation period of 120 minutes. Next, the removal of HA by manipulating its initial concentration are 98%, 90%, 85% and 86% with respect to 10 g/L, 20 g/L, 30 g/L and 40 g/L taken for 120 minutes. Overall, the optimal operational parameters for the removal of HA of catalyst dosage is 1.0 g/L performing at 98%, for initial concentration of HA which was removed efficiently at 97% is 10 g/L and via aeration in this study was about 93%, after 120 min of irradiation times.
Focusing on the photocatalytic degradation of phenol under visible light, the synthesized lanthanum orthoferrites (LaFeO 3 ) by gel combustion method using citric acid as sacrificial agent were investigated. With the highest reaction temperature of 200 °C, the physicochemical properties of synthesized samples were characterized by X-Ray diffraction (XRD) analysis, Brunauer-Emmet-Teller (BET), and Energy Dispersive X-Ray spectroscopy (EDS). On the other hand, UV-Vis spectroscopy analysis was carried out to determine the phenol photodegradation activities and mechanism. The results suggested the well-defined LaFeO 3 nanocrystals with specific area of 28 m 2 g −1 were successfully synthesized. Besides that, variations in operating parameters such as pH, catalyst dosage and initial concentration of phenol in synthetic wastewater were also examined. In conclusion, LaFeO 3 nanocrystalline exhibited an exceptional photocatalytic activity for phenol degradation, thus providing a perfect alternative for pharmaceutical wastewater treatment.
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