Degradation of Azo Dyes with Different Functional Groups in Simulated Wastewater by Electrocoagulation

Increasing attention has been paid to the widespread contamination of azo dyes in water bodies globally. These chemicals can present high toxicity, possibly causing severe irritation of the respiratory tract and even carcinogenic effects. The present study focuses on the periodically reverse electrocoagulation (PREC) treatment of two typical azo dyes with different functional groups, involving methyl orange (MO) and alizarin yellow (AY), using Fe-Fe electrodes. Based upon the comparative analysis of three main parameters, including current intensity, pH, and electrolyte, the optimal color removal rates for MO and AY could be achieved at a rate of up to 98.7% and 98.6%, respectively, when the current intensity is set to 0.6 A, the pH is set at 6.0, and the electrolyte is selected as NaCl. An accurate predicted method of response surface methodology (RSM) was established to optimize the PREC process involving the three parameters above. The reaction time was the main influence for both azo dyes, while the condition of PREC treatment for AY simulated wastewater was time-saving and energy conserving. According to the further UV–Vis spectrophotometry analysis throughout the procedure of the PREC process, the removal efficiency for AY was better than that of MO, potentially because hydroxyl groups might donate electrons to iron flocs or electrolyze out hydroxyl free radicals. The present study revealed that the functional groups might pose a vital influence on the removal efficiencies of the PREC treatment for those two azo dyes.

Hybrid materials precursor to natural bentonite in the decontamination of Alizarin Yellow from aqueous solutions

The present study aims to investigate the insights of Alizarin Yellow removal by hybrid materials precursor to natural bentonite. The hybrid materials employed are bentonite modified with hexadecyltrimethylammonium bromide (HDTMA) (BnH) and aluminium pillared HDTMA bentonite (BnAH). Surface morphology of materials are obtained with scanning electron microscopy-Energy dispersive X-ray analysis (SEM-EDX). The batch reactor operations conducted in the removal of Alizarin Yellow by these solids for various parametric studies which enabled to deduce the mechanism involved at solid/solution interface. Sorption capacity and selectivity was increased significantly using hybrid materials in the removal of AY. Hybrid materials showed very high removal capacity of AY and apparently unaffected at varied pH (4.0−10.0) and sorptive concentrations 1.0 to 25.0 mgL^-1. Kinetic studies indicated that an apparent equilibrium occurred within 5–10 min of contact and the kinetic data was better fitted to the pseudo-second-order kinetic model. The percent removal of AY was not affected by increasing the background electrolyte (NaCl) concentration to 0.1 molL^-1 and in presence of several co-existing ions. It is revealed that the hybrid materials are found more organophilic and AY molecule bound with strong forces at the surface of hybrid materials.

Pb-0.6%Sb/α-PbO2/β-PbO2-MnO2 Electrode Electrodeposited In Methanesulfonic Acid With Application To The Electrocatalytic Degradation of AYR Wastewater

In the present work, a novel Pb-0.6%Sb/α-PbO2/β-PbO2-MnO2 composite electrode with high electrocatalytic activity was obtained by electrodeposition in methanesulfonic acid and further investigated in the electrochemical degradation of alizarin yellow R(AYR) wastewater. The selection of temperature ranges was found to cause a quantitative difference in the formation of α/β-PbO2 phases. In this way, both phases were simultaneously electrodeposited in the same methanesulfonic acid, and electrodes with corresponding proportions of phases were fabricated. Furthermore, performance tests indicated that composite electrodes with the most appropriate corresponding proportions of phases co-deposited with proper amount of MnO2 could obviously improve the COD removal efficiency and degradation efficiency of AYR to 78.1% and 80.3%. They also showed commendable recyclability and fine economic applicability. Ultimately, the paper proposed a proper electrocatalytic degradation pathway of AYR based on the identification of the major intermediate products. The results proved that MnO2-co-doped composite electrodes had more promising application potential in the electrocatalytic degradation of AYR wastewater.

Decreasing Formaldehyde Emission from Particleboard Panels Fabricated by Adding Newly Phenolic Compounds as a Scavenger to Urea Formaldehyde Resin

This study focused on the influence of some novel scavengers on the physical, mechanical, and formaldehyde emission of particleboard produced with urea-formaldehyde resin. Three different scavengers, alizarin red sulfonate, alizarin yellow-GG, and chromotropic acid, were incorporated to the UF resin at 1, 3, 5, and 7% (by weight) loading levels based on the oven-dried weight of the resin. Other manufacturing parameters were kept constant in the producrion of particleboards. The results indicated that the formaldehyde emission of the particleboards significantly reduced with increasing amount of the scavengers. The lowest formaldehyde emission was found in the specimens containing alizarin red sulfonate (0.38 mg/l), followed by chromotropic acid (0.43 mg/l), and alizarin yellow-GG (0.49 mg/l), respectively, at 7 wt% loading level of the scavengers. Although the physical and mechanical properties of the particleboards decreased with the increasing content of the scavengers, they met the requirements of particleboards for interior fitments (including furniture) for use in dry conditions (P2 grade) of EN 312 standard. According to the results of technological properties and formaldehyde emission of the particleboards, it can be said that alizarin red sulfonate is the best scavenger among the investigated scavengers.