Supported Nanosizedα-FeOOH Improves Efficiency of Photoelectro-Fenton Process with Reaction-Controlled pH Adjustment for Sustainable Water Treatment

Abstract

The overall photoelectro-Fenton (PE-Fenton) process for water treatment with neutral initial pH includes three steps of pH reduction, PE-Fenton reaction, and pH elevation. Reaction-controlled pH adjustment (RCpA), which utilizes the intrinsic electrochemical reactions instead of chemical addition, has been employed to lower the pH, maintain the lowered pH for the Fenton reaction, and recover the pH for final effluent discharge. This study demonstrated that the overall efficiency of this sustainable PE-Fenton process was improved by rapidly recycling the iron substance. Nanosized iron oxide was prepared and employed to ensure such rapid recycling. SEM and XRD results showed that the as-prepared iron oxide wasα-FeOOH with 20 nm in size. The experimental results of dimethyl phthalate (DMP) degradation showed that diatomite-supportedα-FeOOH (N-α-FeOOH/diatomite) could efficiently reduce the DMP concentration and total organic carbon. Furthermore, compared with Fe3+, the N-α-FeOOH/diatomite saved 160 min for iron settlement at 20 mg L−1DMP concentration. Also, with the increment in the initial DMP concentration, extra energy consumed by the individual step of PE-Fenton reaction using the N-α-FeOOH/diatomite became negligible compared with that using free iron ions with the increment in the initial DMP concentration. This development is expected to be a major step of the PE-Fenton process with RCpA towards actual water treatment.

Adsorption of Arsenic on Fe-Modified Biochar and Monitoring Using Spectral Induced Polarization

“…The broad reflection at 2θ = 20-25 • is indicative of amorphous biochar and is consistent with other unmodified biochars of poor crystallinity reported in the literature [61,62]. In the pattern corresponding to Fe-BC-500, the intense peak at 2θ = 23.3 • corresponds to the (110) plane of α-FeOOH, whereas the peak at 2θ = 25.5 • is attributed to the (012) plane of α-Fe 2 O 3 [63]. The major peak at 2θ = 35.45 • corresponds to the crystalline plane with a Miller index of (311).…”

“…α-Fe2O3 [63]. The major peak at 2θ = 35.45° corresponds to the crystalline plane with a Miller index of (311).…”

A Superior and Stable Electrocatalytic Oxygen Evolution Reaction by One-Dimensional FeCoP Colloidal Nanostructures

“…60,61 Furthermore, a comparison of the Raman spectra of fresh and postcatalytic FCP350 in Figure 6a shows the presence of a weak M−OOH peak at around 509 cm −1 and a broad M−OOH band at 950−1050 cm −1 in the postcycled catalyst. 62,63 Thus, the evolution of oxygen through eq 3 is concomitant with the validation of eq 2. 3 An extensive and active formation of in situ metal oxy-hydroxides as characteristics of our presented FeCoP nanorods leads to an excellent OER activity with an exceptionally high current density at a low overpotential, a low Tafel slope, and extended stability.…”

“…In addition to these, the in situ metal oxy-hydroxide formation is confirmed by conducting the slow-scan XRD measurement in the 13–43° 2θ range on the postcycled FCP350. The XRD patterns of the fresh and slow-scan postcatalytic catalysts are compared (Figure S11), and it is found that the slow-scan XRD pattern shows weak-intensity diffraction peaks of M­(Fe/Co)–OOH at 17–25 and 26.35°. , Furthermore, a comparison of the Raman spectra of fresh and postcatalytic FCP350 in Figure a shows the presence of a weak M–OOH peak at around 509 cm –1 and a broad M–OOH band at 950–1050 cm –1 in the postcycled catalyst. , Thus, the evolution of oxygen through eq is concomitant with the validation of eq . An extensive and active formation of in situ metal oxy-hydroxides as characteristics of our presented FeCoP nanorods leads to an excellent OER activity with an exceptionally high current density at a low overpotential, a low Tafel slope, and extended stability.…”

Natural diatomites: Efficient green catalyst for Fenton-like oxidation of Orange II

“…Diatomite has also been employed as a catalyst support for several reactions: oil hydrogenation [14], hydration of acrylonitrile [15], Fischer-Tropsch synthesis [16], hydrocarbons oxidation [1], photodegradation of industrial wastes [17,18], photoelectroFenton of industrial wastewaters [19], and phenol hydroxylation [20]. Nevertheless, the use of diatomite as a catalyst rather as catalyst support has not been extensively studied [21], although, the presence of a high percentage of iron would enable its use as a heterogeneous Fenton-like catalyst without requiring major modifications.…”