In the present work, nitrogen-doped three-dimensional (3D) hierarchical ordered mesoporous carbon supported palladium (Pd 20 wt%/N-3D) electrocatalyst was successfully synthesized with the ...nanocasting method. The as-prepared material was physicochemically and electrochemically characterized. It is found that the as-prepared electrocatalyst exhibits a hierarchically porous structure with interconnected walls, which permits the exposure of more active sites to the respective reactant. Due to its special structure, the electrocatalyst (i) is highly poison-tolerant to the intermediates of glucose electrooxidation reaction, (ii) presents high activity for ascorbic acid electrooxidation, and (iii) exhibits a moderate activity to dopamine electrooxidation reaction. The as-prepared electrocatalyst displayed a relatively good stability behavior. Its sensitivity range is reported to be 0.990 μA μM
−1
cm
−2
, 0.38 μA μM
−1
cm
−2
, and 0.09 μA μM
−1
cm
−2
for ascorbic acid, dopamine, and glucose, respectively.
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•Electrocoagulation for swine wastewater pretreatment was systematically studied.•Fe anode and neutral matrix were better than Al anode and more acid/alkali matrix.•Removal of 98.5%, ...99.5%, 50.6% was achieved for SS, TP, COD by electrocoagulation.•Electrooxidation occurred during electrocoagulation improved the biodegradability.
Characterized by the high concentration suspended solids (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), ammonium nitrogen and total phosphorus (TP), a solid–liquid separation as a pretreatment is mandatory for swine wastewater before biological treatment. In this study, batch tests of electrocoagulation were investigated under different structural parameters (anode material, inter-electrode distance) and operational parameters (current density, stirring speed, initial pH and reaction time). The results showed that the optimal conditions were the Fe anode, inter-electrode distance of 2.0 cm, current density of 30 mA/cm2, no stirring, initial pH of 6.3 without control and reaction time of 35 min in this study. By comparing with chemical coagulation, satisfactory performance was achieved under optimal electrocoagulation: supernatant recovery of 60%, SS, TP, COD and BOD removal efficiencies of 98.5%, 99.5%, 50.6% and 10%. In addition, fluorescent substances formation was observed under electrocoagulation and thus increased the BOD/COD ratio from 0.36 to 0.66. The enhanced biodegradability would facilitate the subsequent biological removal and the overall swine wastewater treatment. Conclusively, the iron electrocoagulation technology is a promising process for high-strength swine wastewater pretreatment.
Constructing monodispersed metal sites in heterocatalysis is an efficient strategy to boost their catalytic performance. Herein, a new strategy using monodispersed metal sites to tailor Pt‐based ...nanocatalysts is addressed by engineering unconventional p–d orbital hybridization. Thus, monodispersed Ga on Pt3Mn nanocrystals (Ga‐O‐Pt3Mn) with high‐indexed facets was constructed for the first time to drive ethanol electrooxidation reaction (EOR). Strikingly, the Ga‐O‐Pt3Mn nanocatalyst shows an enhanced EOR performance with achieving 8.41 times of specific activity than that of Pt/C. The electrochemical in situ Fourier transform infrared spectroscopy results and theoretical calculations disclose that the Ga‐O‐Pt3Mn nanocatalyst featuring an unconventional p–d orbital hybridization not only promote the C−C bond‐breaking and rapid oxidation of ‐OH of ethanol, but also inhibit the generation of poisonous CO intermediate species. This work discloses a promising strategy to construct a novel nanocatalysts tailored by monodispersed metal site as efficient fuel cell catalysts.
The monodispersed Ga site tailored Pt3Mn nanocatalyst based on high‐indexed facets was constructed and shows excellent EOR performance with high activity and selectivity towards the C2 reaction pathway, which was attributed to the unconventional p–d orbital hybridization and atomic‐level interface synergy.
Simultaneous highly efficient production of hydrogen and conversion of biomass into value‐added products is meaningful but challenging. Herein, a porous nanospindle composed of carbon‐encapsulated ...MoO2‐FeP heterojunction (MoO2‐FeP@C) is proposed as a robust bifunctional electrocatalyst for hydrogen evolution reaction (HER) and biomass electrooxidation reaction (BEOR). X‐ray photoelectron spectroscopy analysis and theoretical calculations confirm the electron transfer from MoO2 to FeP at the interfaces, where electron accumulation on FeP favors the optimization of H2O and H* absorption energies for HER, whereas hole accumulation on MoO2 is responsible for improving the BEOR activity. Thanks to its interfacial electronic structure, MoO2‐FeP@C exhibits excellent HER activity with an overpotential of 103 mV at 10 mA cm−2 and a Tafel slope of 48 mV dec−1. Meanwhile, when 5‐hydroxymethylfurfural is chosen as the biomass for BEOR, the conversion is almost 100%, and 2,5‐furandicarboxylic acid (FDCA) is obtained with the selectivity of 98.6%. The electrolyzer employing MoO2‐FeP@C for cathodic H2 and anodic FDCA production requires only a low voltage of 1.486 V at 10 mA cm−2 and can be powered by a solar cell (output voltage: 1.45 V). Additionally, other BEORs coupled with HER catalyzed by MoO2‐FeP@C also have excellent catalytic performance, implying their good versatility.
A porous MoO2‐FeP@C nanospindle is proposed as a robust bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and biomass electrooxidation reaction. The MoO2‐FeP@C not only exhibits excellent HER activity, but also catalyzes the electrooxidation of biomass into value‐added products. The electrolyzer assembled by MoO2‐FeP@C for cathodic H2 and anodic 2,5‐furandicarboxylic acid production requires a low voltage of 1.486 V at 10 mA cm−2.
PdRh/C catalyst and electrodeposited Pd, Rh and PdRh particles on glassy carbon electrode were studied in methanol and ethanol oxidation reactions in comparison with Pt-containing catalysts. Some ...features of this process have been described: (1) the appearance of oxidation peak in acidic and neutral media is possible only when polarization on CV is prolonged to hydrogen adsorption region where the surface OH-group formation occurred and surface oxides are reduced; (2) the CV-responses of model systems (electrodeposited Pd, Rh, PdRh) corresponding to alcohol oxidation increase and deform even during relaxation period when polarization is switched off; (3) experiments with addition of corresponding aldehydes (formaldehyde, acetaldehyde) to alcohol solution with stabilized CV responses showed that only increase in currents but not deformation of CV occurred. The addition of acid residue did not change the response noticeably. The formation of the same electroactive species, gem-diolate, for both alcohol and aldehyde electrooxidation mechanisms was supposed.
Abstract Dairy industry effluent is characterized by high chemical oxygen demand (COD) and other pollution load. This study addresses the elimination of organic compounds in dairy wastewater using ...electrocoagulation (EC), electrooxidation (EO) and a synergistic combination of EC and EO. The removal of COD, color and turbidity was investigated at various current intensities by using different electrodes and at various electrolysis times. Results show that EC is a relatively quick process (6 min), which is very effective in removing colloidal and suspended particles, as seen in changes in turbidity and color, but it is effective to eliminate only half of the COD. However, EO reduces 40% of COD in a practical time of about 30 min. To improve the removal of COD we proceeded to combine the two processes. Thus, the coupled process eliminates 60% of COD in a practical amount of time (21 min), removes the colloidal and suspended particles and eliminates color, turbidity, phosphorus, K+ and NTK. The use of the seed toxicity test allows evaluating the quality and effectiveness of the studied effluent treatment system. Seed irrigated with raw waste or treated dairy effluent show no phytotoxicity.
Platinum is often used as a catalyst in ethanol electrooxidation. Still, it has many disadvantages being expensive and its active site can be poisoned by CO. Transition metal of Co and Ni can become ...a catalyst in alcohol electrooxidation at a lower cost to synthesize. In this work, bimetallic CoNi were successfully prepared by electrodeposition method with different Co/Ni ratios to enhance ethanol electrooxidation. Samples of CoNi are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and electrochemical impedance spectroscopy (EIS). XRD diffractogram confirmed the formation of CoNi. Morphology of CoNi in SEM characterization showed that CoNi with ratio 5:1 has the more dispersed particle and the greatest surface area. EDX characterization indicated that the relative weight of different Co/Ni ratios, the composition wt.% Co is 81.15% and wt.% Ni is 18.85% in CoNi 5:1, wt.% Co is 60.96% and wt.% Ni is 30.94% in CoNi 2:5, while wt.% Co is 50.19%, and wt.% Ni is 49.81% in CoNi 5:5. EIS characterization showed that CoNi with ratio of 5:1 has faster electron kinetics. Electrooxidation of ethanol used cyclic voltammetry (CV) method. The best results from the ethanol electrooxidation reaction were obtained for CoNi with a ratio of 5:1 because of the greatest surface area that showed in scanning electron microscopy and fast electron transfer kinetics compared to others ratio of CoxNiy.
•Both fluoroquinolones are totally removed regardless of supporting electrolyte (SE).•Use of NaCl leads to a significantly faster removal of the fluoroquinolones (FQs).•The SE nature affects the TOC ...removal rate, much more markedly for NaCl.•Solution antimicrobial activity vs. electrolysis time is affected by SE and FQ nature.•LC-MS/MS analyses show that both SE and FQ nature determine occurring oxidation steps.
The effects of the supporting electrolytes (SEs) Na2SO4, NaCl, Na2CO3, NaNO3, and Na3PO4 on the anodic oxidation of norfloxacin (NOR) and ciprofloxacin (CIPRO), assessed by the respective degradation kinetics and byproducts and electrolyzed solution antimicrobial activity, are compared. Galvanostatic anodic oxidations were performed in a filter-press flow cell fitted with a boron-doped diamond anode. Removal rates higher than the theoretical one for a process purely controlled by mass transfer were found for all SEs, indicative of contribution by indirect oxidation processes. However, the removal rates for NaCl were about tenfold higher, with the lowest energy consumption per order (ECO) of targeted pollutant removal rate (ca. 0.7 kW h m–3 order–1), a very competitive performance. The TOC removal rates were also affected by the SE, but not as markedly. The antimicrobial activity of the electrolyzed solutions against Escherichia coli showed distinct temporal profiles, depending on the fluoroquinolone and SE. For instance, when Na3PO4 was used, the antimicrobial activity was completely removed for NOR, but none for CIPRO; conversely, when NaCl was used, complete removal was attained only for CIPRO. From LC-MS/MS analyses of Na3PO4 electrolyzed solutions, rupture of the fluoroquinolone ring leading to byproducts with no toxicity against E. coli occurred only for NOR, whereas exactly the opposite occurred for the NaCl solutions. Clearly, the nature of both the SE and the fluoroquinolone influence the oxidation steps of the respective molecule; this was also evidenced by the distinct short-chain carboxylic acids identified in the degradation of NOR and CIPRO.
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