Bio-Inspired Superhydrophilic Self-Assembled Coronavirus-Like Pt-WC/CNT for Hydrogen Evolution Reaction.

This study presents a novel approach to enhance the catalytic activity of composite materials by promoting active surface exposure and improving hydrogen transfer performance. Through a self-assembly route involving tailored gas-solid and galvanic replacement reactions, Pt-WC/CNT catalysts with superhydrophilicity and coronavirus-like structure are synthesized. These unique structural features contribute to a remarkable enhancement in the electrocatalytic performance of the hydrogen evolution reaction (HER). Notably, the Pt-WC/CNT catalyst exhibits an outstanding intrinsic activity and efficient bubble transfer properties, leading to a high turnover frequency of 34.97 H2·s-1 at an overpotential of 100 mV. This value is 4.8 times higher than that achieved by commercial Pt/C catalysts (7.30 H2·s-1), establishing Pt-WC/CNT as one of the most active catalysts reported to date. Moreover, the combination of gas-solid and galvanic replacement reactions in the synthesis process offers a scalable route for the production of Pt-loading controllable composite catalysts, thus challenging the dominance of commercial Pt/C catalysts.

Modulating Dominant Facets of Pt through Multistep Selective Anchored on WC for Enhanced Hydrogen Evolution Catalysis.

Facilitating the exposure of the active crystal facets on the surfaces of composite catalysts is a representative route to promote catalytic activity. Based on a tailored galvanic replacement reaction, herein, a self-assembly route is reported to prepare Pt-WC/CNT with Pt (200) preferential orientation and well-dispersed structure, which are capable of substantially boosting electrocatalysis in hydrogen evolution reaction (HER). Formation mechanism reveals that the (200)-dominated Pt-based catalysts form in galvanic replacement reaction through selective anchored on WC, and the multistep galvanic replacement process plays a critical role to realize the Pt (200)-dominated growth in higher Pt loading catalyst. These unique structural features endow the Pt-WC/CNT with a high turnover frequency of 94.18 H2·s-1 at 100 mV overpotential, 7-fold higher than that of commercial Pt/C (13.55 H2·s-1), ranking it among the most active catalysts. In addition, this method, which combines with gas-solid reaction and galvanic replacement reaction, paves the way to scalable synthesis as Pt facets-controllable composite catalysts to challenge commercial Pt/C.

Degradation of methyl tert-butyl ether (MTBE) in water by glow discharge plasma.

This study evaluated the ability of the glow discharge plasma (GDP) technique to degrade methyl tert-butyl ether (MTBE) in an aqueous solution. The results showed that a large amount of hydrogen peroxide and highly active *OH free radicals were produced during the treatment. Various experimental parameters including discharge current, initial MTBE concentration and initial pH played significant roles on MTBE degradation. In addition, Fe2+ had a catalytic effect on the degradation of MTBE, which is potentially attributable to the reaction between Fe3+ and the hydrated electron. It was also confirmed that GDP was comparable to electrocatalytic oxidation and high-density plasma and more efficient than photocatalytic degradation techniques. These results suggest that GDP may become a competitive MTBE wastewater treatment technology.

A kinetic model of ti(IV)-catalyzed H2O2/O3 process in aqueous solution.

To well describe the Ti(IV)-catalyzed H2O2/O3 reaction in aqueous solution, a kinetic model was established based on its mechanism. This model was then validated by the experiments of acetic acid degradation in aqueous solution. It was found that the correlation coefficient of fittings was higher than 0.970. Three key operating factors affecting organic degradation in the Ti(IV)-catalyzed H2O2/O3 process were studied, including Ti(IV) concentration, dissolved ozone concentration and initial H2O2 concentration. Furthermore, some experiments were conducted to determine the rate constant for dissolved ozone decomposition initiated by Ti2O5(2+). The rate constant measured is almost in accord with the data analyzed by this kinetic model. The goodness of fittings demonstrated that this model could well describe the kinetics of the Ti(IV)-catalyzed H2O2/O3 reaction mathematically and chemically. Therefore, this kinetic model can provide some useful information to optimize the parameters in ozonation of water containing certain pollutants.

Catalytic performance of Fe3O4-CoO/Al2O3 catalyst in ozonation of 2-(2,4-dichlorophenoxy)propionic acid, nitrobenzene and oxalic acid in water.

Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO3)3 x 9H2O and Co(NO3)2 x 6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-(2,4-dichlorophenoxy)propionic acid (2,4-DP), nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants (k) were determined to be 1.456 x 10(-2) min(-1) for ozonation alone and 4.740 x 10(-2) min(-1) for O3/Fe3O4-CoO/Al203. And O3/Fe3O4-CoO/Al2O3 had a larger R(ct) (6.614 x 10(-9)) calculated by the relative method than O3 did (1.800 x 10(-9)), showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree.

Solid base Mg-doped ZnO for heterogeneous catalytic ozonation of isoniazid: Performance and mechanism.

Magnesium-doped ZnO (denoted as x-MgZnO where x represented the molar ratio of Mg to the sum of Mg and Zn) powders synthesized by the traditional thermal decomposition were used as catalysts for ozonation of isoniazid (20 mg/L) at the initial pH of 7.2. Magnesium substituted zinc in wurtzite structure and the Zn-O-Mg bond was formed in Mg-doped ZnO on the basis of the results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. The removal efficiencies of isoniazid were enhanced in Mg-doped ZnO catalytic ozonation processes (57.7% by 0.05-MgZnO and 76.3% by 0.10-MgZnO in 9 min), compared with ozonation alone (50.5%) and ZnO catalytic ozonation (49.5%). The removal efficiencies of total organic carbon (TOC) were also improved in Mg-doped ZnO catalytic ozonation processes. When the initial pH of 7.2 was lower than the pHPZC (point of zero charge) of Mg-doped ZnO, surface hydroxyl groups of the catalysts were protonated and the solution pH gradually increased during Mg-doped ZnO catalytic ozonation. The increase in the solution pH value mainly induced ozone decomposition into superoxide radical (O2-). Furthermore, protonated surface hydroxyl groups (S-OH2+) on Mg-doped ZnO also contributed a little to ozone decomposition. The 0.10-MgZnO powder showed high stability after continuous use in the process. Additionally, we proposed a possible degradation pathway for the oxidation of isoniazid in Mg-doped ZnO catalytic ozonation on the basis of intermediates detected. This work provides an insight into the mechanism for basic sites of solid base in heterogeneous catalytic ozonation.

Coordination polymer-derived cobalt-embedded and N/S-doped carbon nanosheet with a hexagonal core-shell nanostructure as an efficient catalyst for activation of oxone in water.

As sulfate-radical (SR)-based advanced oxidation processes are increasingly implemented, Oxone has been frequently-used for generation of SR. While Co3O4 nanoparticle (NP) has been widely-accepted as a promising catalyst for activating Oxone, Co3O4 NPs tend to aggregate in water, losing their reactivity. Thus, many attempts have immobilized Co3O4 NPs on supports, especially carbonaceous substrates, because combination of Co NPs with carbon substrates offers synergistic effects for boosting catalytic activities. Moreover, carbon substrates doped with hetero-atoms (N and S) further increase electron transfer and reactivity. Therefore, it is even promising to immobilize Co NPs onto N/S-doped carbon (NSC) to form Co-embedded NSC (denoted as CoNSC) for enhancing Oxone activation. In this study, a convenient and facile technique is proposed to prepare such a CoNSC via a simple carbonization treatment of a coordination polymer of Co and trithiocyanuric acid (TTCA). The resulting CoNSC exhibits the sheet-like hexagonal morphology with the core-shell configuration, and Co NPs are well-embedded into the N/S-doped carbonaceous matrix, making it an advantageous heterogeneous catalyst for Oxone activation. As Azorubine S (ARS) decolorization is employed as a model reaction of Oxone activation, CoNSC exhibits a higher catalytic activity than pristine Co3O4 and NSC for Oxone activation to decolorize ARS. In comparison to the other reported catalysts, CoNSC also possesses a much lower Ea for ARS decolorization. CoNSC can be also reusable and stable for Oxone activation over multiple cycles without loss of catalytic activity. These features validate that CoNSC is a promising and useful Co-based catalyst for Oxone activation.

One-step prepared cobalt-based nanosheet as an efficient heterogeneous catalyst for activating peroxymonosulfate to degrade caffeine in water.

Two-dimensional (2D) planar cobalt-containing materials are promising catalysts for activating peroxymonosulfate (PMS) to degrade contaminants because 2D sheet-like morphology provides large reactive surfaces. However, preparation of these sheet-supported cobaltic materials typically involves multiple steps and complex reagents, making them less practical for PMS activation. In this study, a cobalt-based nanosheet (CoNS) is particularly developed using a one-step hydrothermal process with a single reagent in water. The resulting CoNS can exhibit a thickness as thin as a few nanometers and 2-D morphology. CoNS is also primarily comprised of cobalt species in a coordinated form of Prussian Blue analogue, which consists of both Co3+ and Co2+. These features make CoNS promising for activating PMS in aqueous systems. As degradation of an emerging contaminant, caffeine, is selected as a representative reaction, CoNS not only successfully activates PMS to fully degrade caffeine in 20 min but also exhibits a much higher catalytic activity than the most common PMS activator, Co3O4. Via studying inhibitive effects of radical scavengers, caffeine degradation by CoNS-activated PMS is primarily attributed to sulfate radicals and hydroxyl radicals to a lesser extent. The degradation products of caffeine by CoNS-activated PMS are also identified and a potential degradation pathway is proposed. Moreover, CoNS could be also re-used to activate PMS for caffeine degradation without activity loss. These results indicate that CoNS is a conveniently prepared and highly effective and stable 2-D catalyst for aqueous chemical oxidation reactions.

[Mechanism of MgO/GAC Catalyzed Ozonation of Organic Compounds].

MgO/granular activated carbon (MgO/GAC-1) was prepared via an impregnation method, and its activity in ozonation of diuron and acetic acid was investigated. MgO/GAC-1 was also compared in stability to the same catalyst prepared via precipitation according to the literature (MgO/GAC-2). The results showed that MgO/GAC-1 could increase efficiency of ozonation by 15%-35% in the process of degradation of diuron and acetic acid. When the pH of the solution was neutral or alkaline, MgO/GAC-1 could effectively retard the decrease in pH owing to formation of small molecular organic acids, thus ensuring the efficiency of ozone. When the pH of the solution was acidic, MgO/GAC-1 could increase the pH of the solution to a certain extent, thereby enhancing the efficiency of ozonation. The adjusting effect of pH value is the reason why MgO can significantly improve the efficiency of ozonation, a fact that was ignored in the relevant literature. Although MgO/GAC-1 had a larger specific surface area, MgO/GAC-1 had better activity in ozonation. A recycling test also indicated that MgO/GAC-1 had better stability, showing a good prospect for application.

Ferrocene-modified iron-based metal-organic frameworks as an enhanced catalyst for activating oxone to degrade pollutants in water.

Ferrocene (Fc) has been regarded as a useful catalyst for activating Oxone to generate sulfate radicals (SR) in degradation of organic pollutants. Nevertheless, direct usage of Fc molecules in aqueous solutions may lead to difficult recovery and aggregation. While a few attempts have immobilized Fc on several substrates, these substrates exhibit very low surface areas/porosities and, especially, do not offer significantly additional contributions to catalytic activities. In this study, a Fe-containing metal organic frameworks (MOFs), MIL-101, is particularly selected for the first time as a support to immobilize Fc chemically. Through the Schiff base reaction, ferrocenecarboxaldehyde can react with amine-functionalized MIL-101 (namely, MIL-101-NH2) to form Fc-modified MIL-101 (Fc-MIL). As Fc-MIL consists of both Fe from MIL-101 and Fc and also exhibits high surface areas, it appears as a promising catalyst for activating Oxone. Catalytic activities for Oxone activation by Fc-MIL are studied using batch-type experiments of amaranth dye degradation. Fc-MIL shows higher catalytic activities than its precursor MIL-101-NH2 owing to the modification of Fc, which equips with MIL-101 with more catalytic sites for activating Oxone. Besides, Fc-MIL also outperforms the benchmark catalyst of Oxone activation, Co3O4, to degrade amaranth. In comparison to the other reported catalysts, Fc-MIL shows the much smaller activation energy for amaranth degradation, proving its advantage over other catalysts. The synthesis technique proposed here can be also employed to develop other Fc-modified MOFs for other environmental catalysis applications.

Removal of terephthalic acid in alkalized wastewater by ferric chloride.

Terephthalic acid, which is a main component in alkali-decrement wastewater, is efficiently removed using ferric chloride in high pH solutions. About 90% removal of terephthalic acid is achieved at pH between 8 and 11. Especially, the removal reached 94.3% at pH 11. However, as the pH increased from pH 12 and 13, the low removal of terephthalic acid were found. The increasing ferric chloride dosage had a dramatic positive impact on the achieved removal of terephthalic acid. Further increase in the ferric chloride dosage did not produce better removal rate. The increase of terephthalic acid concentration also led to the increase of ferric chloride dosage in order to get the same removal of terephthalic acid. There was approximately a negative linear relationship between terephthalic acid concentration and removal of terephthalic acid. Compared with other coagulants, it can be seen that ferric chloride is more effective in a high pH solution and the amount of ferric chloride required is also less as compared with aluminum chloride, magnesium chloride and calcium chloride. Our results clearly showed that terephthalate anions strongly binds to positive Fe(OH)(3) flocs and forms insoluble complexes, probably through a mechanism involving electrostatic attraction. The electrostatic attraction may be particularly useful means of purifying wastewater in high pH solutions.

Characteristics of MnO2 catalytic ozonation of sulfosalicylic acid and propionic acid in water.

The characteristics of different types of MnO(2) catalytic ozonation of sulfosalicylic acid (SSal) and propionic acid (PPA) have been investigated in this paper. The experimental results show the dependence of catalytic activity of MnO(2) on organic compounds and the pH of solutions, but it is independent on the type of MnO(2). For example, three types of MnO(2) have not any catalytic activity when ozonation of PPA under the condition of this experiment. All MnO(2) catalytic ozonation of SSal at pH=1.0 have a greater total organic carbon removal than ozonation alone has, however, at pH=6.8 and 8.5, catalytic efficiency is not observed. Furthermore, the batch experimental results indicate that there are no direct relationship between the activity of metal oxide catalytic decomposition of ozone and that of its catalytic degradation of organic compounds.

Rapid treatment of atrazine-contaminated water by nickel/iron bimetallic system.

The utility of nickel/iron in the remediation of atrazine-contaminated water was investigated. The experimental results showed that nickel/iron had effective catalytic activity in dechlorinating atrazine under acidic conditions. The dechlorination reaction approximately followed the first-order kinetics under the experimental conditions (nickel/iron: 1.0 g/250 ml; C(atrazine) = 20.0 mg/L), the reaction rate increased with decreasing pH value of the reaction solution and increasing the proportion of Ni : Fe within 2.95%. For condition with 2.95% nickel/iron, the reaction rate constants were 0.07518 (R = 0.9927), 0.06212 (R = 0.9846) and 0.00131 min(-1) (R = 0.9565) at pH = 2.0, 3.0 and 4.0, respectively. HPLC analysis was used to monitor the decline of atrazine concentration.

[Degradation of dimethyl phthalate by Ti (IV)-catalyzed O3/H2O2 under acidic conditions].

The degradation efficiencies of dimethyl phthalate (DMP) by O3, O3/H2O2, Ti(IV)/O3 and Ti(IV)/O3/H2O2 were investigated under acidic conditions. The results indicated that Ti(IV)/O3/H2O2 was the best system with the highest degradation efficiency and mineralization rate of DMP, and the highest utilization rate of ozone at pH 2.8. The apparent rate constants of DMP degradation by O3, O3/H2O2, Ti(IV)/O3 and Ti(IV)/O3/H2O2 under the same conditions were 3.96 x 10(-4) s(-1), 9.54 x 10(-4) s(-1) 1.07 x 10(-3) s(-1) and 6.41 x 10(-3) s(-1), respectively. The ozone utilization rate of Ti(IV)/O3/H2O2 was improved by 6.51% compared with that of ozonation alone. The experimental results showed that the optimized concentrations of Ti(IV) and H2O2 were 1.4 mg x L(-1) and 10 mg x L(-1), respectively. According to the results of gas chromatography-mass spectrometry (GC/MS) and ion chromatography analysis, the possible reaction pathway of DMP degradation by Ti(IV)/O3/H2O2 was proposed and discussed.

Glow discharge plasma in water: a green approach to enhancing ability of chitosan for dye removal.

There is a need to explore effective and green approaches to enhancing the ability to use chitosan for contaminant removal for practical implementation of this technology. In the present study, glow discharge plasma (GDP), which has thus far been studied for degradation of contaminants, was used for the first time to pre-treat chitosan for dye removal in aqueous solution. The results show that the GDP treatment changed the morphology and crystallinity of chitosan particles, and the number of -CH(2) and -CH(3) groups in the chitosan samples increased. Various pretreatment parameters, including discharge current and time, played significant roles in the chitosan modification. It is observed that dye uptake in GDP-modified chitosan was faster than adsorption in untreated chitosan. The maximum adsorption by chitosan followed the order of untreated chitosan

Kinetics of Fe(3)O(4)-CoO/Al(2)O(3) catalytic ozonation of the herbicide 2-(2,4-dichlorophenoxy) propionic acid.

The presence of Fe(3)O(4)-CoO/Al(2)O(3) can improve degradation efficiency significantly during the ozonation of the herbicide 2-(2,4-dichlorophenoxy) propionic acid (2,4-DP). The main factors affecting degradation efficiency, such as pH, the catalyst concentration and addition of the scavenger, were investigated. The kinetics of the catalytic ozonation are also discussed. The results indicate that two factors, the oxidation after adsorption of 2,4-DP and the oxidation of hydroxyl radicals (OH), lead to a great enhancement in ozonation efficiency during the catalytic ozonation of 2,4-DP in the presence of Fe(3)O(4)-CoO/Al(2)O(3), in which the oxidation of the OH plays an important role. Under controlled conditions, the apparent reaction rate constants for the degradation of 2,4-DP were determined to be 2.567 × 10(-4)s(-1) for O(3) and 1.840 × 10(-3)s(-1) for O(3)/Fe(3)O(4)-CoO/Al(2)O(3). The results from the analysis of the reaction kinetics using the relative method showed that O(3)/Fe(3)O(4)-CoO/Al(2)O(3) possessed a larger R(ct) (R(ct) is defined as the ratio of the ·OH exposure to the O(3) exposure, R(ct) = ∫C(t)(OH) dt/C(t)O(3)dt) than O(3), indicating that O(3)/Fe(3)O(4)-CoO/Al(2)O(3) produced more hydroxyl radicals.

[Oxidative efficiency of the system of electrolysis coupled ozonation].

The oxidation system of electrolysis coupled ozonation (electrolysis-ozonation) was used to degrade 4-chlorophenol (4-CP), and its mechanism was discussed on the basis of kinetic analysis. The experimental results indicated the electrolysis-ozonation system had a significant synergistic effect during degradation of 4-CP. For example, the electrolysis-ozonation had the 4-CP removal rate of 92.7% and the COD removal rate of 64.9% in 900 s, respectively; while electrolysis alone plus ozonation alone only had the 4-CP removal rate of 69.7% and the COD removal rate of 30.1% under the same conditions. The results of H2O2 concentration analysis and photocurrent test showed that the synergistic mechanism of electrolysis-ozonation included two factors: (1) production of *03- at the cathode; (2) H2O2 generation resulting from reduction of dissolved oxygen. The above two factors led to generation of *OH in system effectively.

[CuO-Ru/Al2O3 catalytic ozonation of acetophenone in water].

Two-component CuO-Ru based on active Al2O3 (CuO-Ru/Al2O3) catalyst was prepared by incipient wetness impregnation and used to catalytic ozonation of acetophenone (AP). The results showed that doping Ru could significantly improve the catalytic activity of CuO/Al2O3. For example, the COD removal rates of AP solution after 30 min by ozonation alone, CuO/Al2O3/O3, and CuO-Ru/Al2O3/O3 were 6.3%, 20.0% and 54.0%, respectively. The change of pH almost had no affect on degradation efficiency of AP. However, a comparison of COD removal between ozonation alone and catalytic ozonation indicated that CuO-Ru/Al2O3 catalyst was more suitable for application in neutral or acidic condition. CuO-Ru/Al2O3 catalyst could accelerate decomposition rate of ozone in water, and its decomposition rate constant reached 2.58 x 10(-3) s(-1) while that of ozone alone in double-water was 1.19 x 10(-3) s(-1). The experimental result of t-butanol indicated that CuO-Ru/Al2O3 catalytic ozonation of AP followed a radical-type mechanism.

[Kinetic and mechanism of ozonation of terephthalic acid].

The effect of ozonation of terephthalic acid (TA) was evaluated, and the kinetic and mechanism of this process were also discussed. The rate constants of TA with ozone and OH radicals calculated by the relative method are (0.047 +/- 0.010) L x (mol x s)(-1) and 2.28 x 10(9) L x (mol x s)(-1), respectively. The above result was in accordance with the apparent reaction rate constant of ozonation of TA when the process was controlled by chemical reaction. Intermediates detected by high-performance liquid chromatography (HPLC) and ion chromatography (IC) included benzoic acid, tartaric acid, formic acid and oxalic acid, therefore the possible destruction pathway of ozonation of TA was proposed on the basis of above results.

[Deactivation mechanism of Pt anode in the process of electroxidation of p-chlorophenol].

Deactivation of Pt electrode in the process of electroxidation of p-chlorophenol (p-CP) was investigated using linear sweep voltammetry, LC/MS and spectrum analysis techniques. The experiment results indicated that Pt would lose its electro-catalytic activity soon because polymer formed at the electrode surface. The in-site IR spectra of Pt showed two weak absorption bands appeared at 1 200 and 1 800 cm(-1) during the oxidation of p-CP, which are characteristics of aromatic ether and carbonyl group, respectively. Increasing initial concentration of p-CP and pH value of solution would accelerate the deactivation speed of Pt. Acetonitrile lixivium for deactivated Pt was analyzed by LC/MS, and it was found that the polymers formed at the surface of Pt were some mixed compounds. The mechanism of polymerization includes the following ways: coupling reaction of organic radical each other; substituting reaction of organic radical with p-CP (or intermediates or small polymers).