Photocatalytic degradation of industrial pulp and paper mill effluent using synthesized magnetic Fe 2 O 3 -TiO 2 : Treatment efficiency and characterizations of reused photocatalyst

Abstract

In this work, heterogeneous photocatalysis was used to treat pulp and paper mill effluent (PPME). Magnetically retrievable FeO-TiO was fabricated by employing a solvent-free mechanochemical process under ambient conditions. Findings elucidated the successful incorporation of FeO into the TiO lattice. FeO-TiO was found to be an irregular and slightly agglomerated surface morphology. In comparison to commercial P25, FeO-TiO exhibited higher ferromagnetism and better catalyst properties with improvements in surface area (58.40 m/g), pore volume (0.29 cm/g), pore size (18.52 nm), and band gap (2.95 eV). Besides, reusability study revealed that FeO-TiO was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. Additionally, this study demonstrated the potential recovery of FeO-TiO from an aqueous suspension by using an applied magnetic field or sedimentation. Interactive effects of photocatalytic conditions (initial effluent pH, FeO-TiO dosage, and air flow-rate), reaction mechanism, and the presence of chemical oxidants (HO, BrO, and HOCl) during the treatment process of PPME were also investigated. Under optimal conditions (initial effluent pH = 3.88, [FeO-TiO] = 1.3 g/L, and air flow-rate = 2.28 L/min), the treatment efficiency of FeO-TiO was 98.5% higher than the P25. Based on Langmuir-Hinshelwood kinetic model, apparent rate constants of FeO-TiO and P25 were 9.2 × 10 and 2.7 × 10 min, respectively. The present study revealed not only the potential of using magnetic FeO-TiO in PPME treatment but also demonstrated high reusability and easy separation of FeO-TiO from the wastewater.

High photocatalytic activity of Fe2O3/TiO2nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

“…Since the CB edge energy level of Fe 2 O 3 (−4.78 eV relative to absolute vacuum scale (AVS)) is lower than that of TiO 2 (−4.21 eV relative to AVS) [43], Fe 2 O 3 could act as an electron trapper that captured the photogenerated electrons from the TiO 2 that were not used for reduction of oxygen, instead of recombination with holes. Such electron transfer could suppress charge recombination on TiO 2 [5,10,12,14–15], whereby the oxidation of 2,4-D still could occur in the VB of TiO 2 , and therefore, the photocatalytic degradation of 2,4-D could be improved. On the other hand, owing to the fast recombination of holes and electrons, the photocatalytic degradation of 2,4-D on bare Fe 2 O 3 was negligible (1%).…”

“…Another simple method to produce Fe 2 O 3 /TiO 2 is a mechano-chemical milling approach that can be carried out at ambient conditions [14]. Even though high activity was obtained, evidence of the formation of good contact between Fe 2 O 3 and TiO 2 nanoparticles was not provided.…”

Photocatalytic Treatment of An Actual Confectionery Wastewater Using Ag/TiO2/Fe2O3: Optimization of Photocatalytic Reactions Using Surface Response Methodology

“…The microparticles were irregular in shape and randomly organized with rough morphology. Rough particle morphology has been reported to contribute to the enhancement of the adsorption of target pollutants onto the photocatalyst surface during photocatalytic process of aqueous organic degradation [19,33]. Figure 2a is the scanning electron microscopy (SEM) image of Ag/TiO 2 /Fe 2 O 3 (0.5 wt% Ag/TiO 2 and 1.0 wt% Fe/TiO 2 ) showing heterogeneous shaped particles with variable particle sizes with the range of 0.5-5 µm.…”

“…Metal doping of TiO 2 can be accomplished through interstitial doping and substitutional doping. Interstitial doping involves metal dopants located on the surface of TiO 2 , and substitutional doping involves the substitution of Ti 4+ atoms by metal dopants [9,18,19]. Metal doping also introduces a mid-gap energy level in the band gap of TiO 2 [20,21].…”

Thermally-assisted photodegradation of lignin by TiO2/H2O2 under visible/near-infrared light irradiation

“…The hydroxyl radicals may be produced by means of various chemical, photochemical, sonochemical or electrochemical reactions [6]. Among these methods, the photochemical processes, especially heterogeneous photocatalytic process involving semiconductors and ultraviolet (UV) irradiation, such as TiO 2 /UV, Fe 2 O 3 -TiO 2 /UV, ZnO/UV, ZnO/O 2 /UV and TiO 2 /H 2 O 2 /UV, have attracted significant attention in the degradation of lignin [7][8][9][10]. Wide band gap semiconductors, such as TiO 2 and ZnO, are employed due to their high valence band potentials.…”