Continuous Heterogeneous Fenton-Type Process for Dye Pollution Abatement Intensified by Hydrodynamic Cavitation

Abstract

The heterogeneous Fenton-type process was investigated in a continuous upflow fixed-bed reactor (UFBR) of a nano Prussian Blue catalyst supported on γ-alumina beads. Temperature and oxidant concentration strongly increased dye discoloration and total organic carbon (TOC) conversion. The long-term stability of the catalyst was confirmed. The best performance was found with a residence time of 2 min at 353 K and an inlet hydrogen peroxide concentration twice the stoichiometric one required for mineralization, attaining complete discoloration and 45% TOC conversion. The formed reactive species continued the reaction after leaving the UFBR. Hydrodynamic cavitation (HC) of the collected outlet stream led immediately to complete discoloration and doubled the TOC conversion in 40 min. Short-chain carboxylic acids accounted for about 70% of the remaining TOC. The UFBR in-series with the HC reactor led to complete discoloration and intensified the TOC conversion. The subsequent HC step thoroughly consumed the remnant oxidant, increasing its efficiency.

Hydrodynamic Cavitation Effects on Advanced Oxidation Processes and Mass Transfer: A Conceptual Model

“…In the last decade, there has been a research focus on process intensification through the combination of HC and AOPs in hybrid processes, as well as the coupling of an HC device to an AOP reactor in series [3,5,10,21,30,38,41,43]. The improvements found when using HC have been attributed mainly to the enhancement of the radical generation rate and mass transfer improvements.…”

Degradation of Organic Dyes by the UCNP/h-BN/TiO2 Ternary Photocatalyst

“…9 Chemical methods, including electrochemical methods and advanced oxidation methods, involve reactions induced between reactive substances and dyes by light, electricity, and magnetism, which result in the oxidation and decomposition of dyes into nontoxic or weakly toxic small molecules. 10,11 Photocatalysis refers to the degradation of toxic macromolecular pollutants into nontoxic or weakly toxic small molecular substances under ultraviolet (UV) light. 1 Titanium oxide (TiO 2 ) is a semiconductor photocatalyst that is widely used because of its biocompatibility, stable chemical properties, low cost, and favorable photocatalytic activity.…”

“…Physical methods, including physical adsorption and membrane separation, are simple but result in the incomplete treatment of dye wastewater. ,, Biological methods involve the separation or degradation of organic dyes into inorganic products and intermediates through the adsorption, flocculation, and degradation of bacteria . Chemical methods, including electrochemical methods and advanced oxidation methods, involve reactions induced between reactive substances and dyes by light, electricity, and magnetism, which result in the oxidation and decomposition of dyes into nontoxic or weakly toxic small molecules. , …”

“… 9 Chemical methods, including electrochemical methods and advanced oxidation methods, involve reactions induced between reactive substances and dyes by light, electricity, and magnetism, which result in the oxidation and decomposition of dyes into nontoxic or weakly toxic small molecules. 10 , 11 …”

CoO, Cu, and Ag Nanoparticles on Silicon Nanowires with Photocatalytic Activity for the Degradation of Dyes

“…Therefore, the treatment of colored effluents becomes an issue of environmental concern. The techniques used to treat dyes in wastewater are the Fenton processes [2,3], ozonation [4], adsorption [4][5][6][7][8], membrane technology [4,9,10], electrochemical techniques [10], photocatalysis [11][12][13], and others [14][15][16].…”