The performance of polyvinylidene fluoride (PVDF) ultrafiltration membranes is often restricted by hydrophobicity, biofouling, and limited selectivity. In this work, a chemically stabilized, dual-modified PVDF ultrafiltration membrane incorporating functionalized multi-walled carbon nanotubes (MWCNTs-COOH) and the first use of triclosan (TCS) was developed to enhance separation efficiency and antifouling performance. Epichlorohydrin (ECH)–mediated crosslinking enabled stable chemical integration of the functional additives, thereby improving structural integrity and performance durability. FTIR spectra confirmed successful incorporation of ECH and TCS, while TGA revealed enhanced thermal stability of M4 (up to ~ 700 °C) due to the aromatic nature of triclosan. SEM–EDX and AFM analyses showed increased surface roughness (Ra = 34.27 nm for M4 vs. 22.63 nm for unmodified PVDF), indicating effective surface modification. Contact angle measurements showed improved hydrophilicity (84.71° to 52.3°), attributed to enhanced surface polarity and cohesive polymeric interactions. The synergistic effects of MWCNTs-COOH, ECH crosslinking, and surface-immobilized triclosan translated into excellent ultrafiltration performance, with a stable permeability of 23.26 L m⁻2 h⁻1 and bovine serum albumin rejection exceeding 99%. Overall, the combined chemical stabilization and surface functionalization strategy yields a multifunctional PVDF membrane with enhanced selectivity, antifouling resistance, and operational stability, highlighting its potential for advanced ultrafiltration and wastewater treatment applications.

The importance of this work lies in the application of a combined electrocoagulation/electro-Fenton (EC/EF) treatment for carwash wastewater, offering a cost-effective and efficient remediation approach. During electro-coagulation (EC), experiments were carried out in a cylindrical cell containing 450 mL of carwash wastewater. This process promotes the formation of $$Fe\left( {OH} \right)_{n}$$ (n = 2 or 3) as coagulants, along with $${\text{Fe}}^{3 + } {\text{/Fe}}^{2 + }$$ ions acting as catalysts. The effects of key operating parameters, including applied current, electrode material (Fe and Al), and initial pH, were evaluated, and both COD removal and energy consumption were assessed. In the EF stage, comparative trials were performed in stirred reactors equipped with a Pt anode and a carbon-felt cathode under O₂ bubbling to generate H₂O₂ at the cathode. The hydroxyl radicals produced at the anode surface through water oxidation and in the bulk solution via Fenton’s reagent (Fe2⁺/H₂O₂) promote the oxidative degradation of organic contaminants. The effects of the supporting electrolyte, applied current and the catalytic activity were investigated to optimize electro-Fenton efficiency. Under optimal EC conditions (I = 1 A, Fe electrode, pH = 5.7), 76.58% COD removal was achieved with an energy consumption of 0.987 kWh·m⁻3. Nearly complete COD removal (97.8%) was obtained using the combined process, where residual organics after EC were removed during electro-Fenton treatment at 0.3 A for 360 min.

In this work, a series of metal-exchanged silicotungstic acid salts was synthesized and assessed as catalysts on the oxidative esterification of benzaldehyde with hydrogen peroxide in a one-pot reaction in homogeneous phase. Initially, the three commercial heteropolyacids (H3PW12O40, H3PMo12O40, and H4SiW12O40) were tested at the same concentration of Brønsted acid sites. Since the silicotungstic acid was the most active, their metal salts were prepared and evaluated as catalysts. Among the salts synthesized (M4(SiW12O40)x, Mx+ = Al3+, Fe3+, Cr3+, In3+, Co2+, Cu2+, Zn2+, Ni2+, and Mn2+), the Cu4(SiW12O40)2 (divalent) and Fe4(SiW12O40)3 (trivalent) were the most efficient catalysts toward the formation of the goal product (i.e., benzoate methyl). The highest activity of the catalyst was attributed to the stronger Lewis acid character of Cu2+ and Fe3+ cations if compared to the other metal cations evaluated. The influence of the main reaction parameters, like catalyst load, temperature, and reactant stoichiometry, was investigated. A probable reaction pathway was proposed based on the acidity measurements and reaction selectivity, where the Lewis and Brønsted acidity sites of the catalyst are responsible by the activating of the substrate (benzaldehyde) and reactant (hydrogen peroxide). The catalyst load and the reactant’s proportion are key aspects to achieve a high benzaldehyde conversion and ester selectivity. The copper(II) silicotungstate was also evaluated in the esterification of other aldehydes and alcohols.