Catalytic Oxidation of Ponceau 4R in Aqueous Solution using Iron-impregnated Al-pillared Bentonite: Optimization of the Process

Abstract

The application of the Fenton-like process for the oxidation of an aqueous solution of Ponceau 4R dye, using an aluminum pillared clay impregnated with iron (Fe(wt%)/Al-PILC) as catalyst, was investigated. The Response Surface Methodology (RSM), based on a Central Composite Design (CCD) was used to evaluate and optimize the oxidation process of a Ponceau 4R solution. Three independent variables were studied in the experimental design: the amount of H2O2 expressed in multiples of times of stoichiometry dose, iron concentration incorporated by impregnation onto aluminum pillared clay (Fe(wt%)), and amount of catalyst (Fe(wt%)/Al-PILC). The response variables were decolorization and total organic carbon (TOC) removal. The significance of independent variables and their interactions were tested by means of analysis of variance (ANOVA), with a 95% confidence level. With low stoichiometric dose of H2O2 (0.96 and 1.54 times), medium amount of catalyst (374.4 and 391.3 mg) and high Fe concentration impregnated in pillared clay (9.3 and 7.7 wt%), the total decolorization and high TOC removal were achieved. Under multi-objective optimization conditions (3.0 times the stoichiometric dose of H2O2, 420 mg Fe(wt%)/Al-PILC and 5.5 wt% Fe impregnated in Al-PILC), it was possible to achieve 86.18% decolorization and 66.81% TOC removal after 5 h of reaction at 25 °C, with the additional advantage of showing an iron leaching of less than 0.10 mg/L. The established models' soundness is confirmed by a good fit between predictive models and experimental results. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Research Trends on Pillared Interlayered Clays (PILCs) Used as Catalysts in Environmental and Chemical Processes: Bibliometric Analysis

“…In the case of dyes, these compounds are of particular interest because they inhibit photosynthetic processes in water bodies, are toxic to some aquatic species, and may even affect human health. This is why several authors have reported the removal of azo dyes using PILCs in CWPO processes [ 50 , 67 , 68 ]. Between 1980 and 2019, the most commonly used dyes as model molecules in scientific publications for the treatment of colored wastewater, using AOP/PILC systems, are methylene blue (23%), methyl orange (12%), orange II (12%), rhodamine B (10%), malachite green (7), among others (36%).…”

“…is is why several authors have reported the removal of azo dyes using PILCs in CWPO processes [50,67,68]. Between 1980 and 2019, the most commonly used dyes as model molecules in scientific publications for the treatment of colored wastewater, using AOP/PILC systems, are methylene blue (23%), methyl orange (12%), orange II (12%), rhodamine B (10%), malachite green (7), among others (36%).…”

Pillared Bentonite Materials as Potential Solid Acid Catalyst for Diethyl Ether Synthesis: A Brief Review

“…Metal polyhydroxy cation-pillared bentonites, such as Al, Ti, and Fe, show higher thermal stability than organic cation-pillared bentonites. 26) Several metals have been investigated for their potential as pillar agents, such as Al-PILC, 28,31,49) Zr-PILC, 14,26,34,46,[51][52][53][54] Ti-PILC, 45,49,56) Mo-PILC, 57) and Cr-PILC. 30,58) In current developments, researchers are beginning to explore the use of combined metal oxide pillars to enhance surface properties and acidity in bentonite, including Al/Zr-PILC, 19,45) Al/Fe-PILC, 47,59) Al/ Co-PILC, 22) Al/Cr-PILC, 30) Al/Fe/Ni-PILC, 60) Fe/Cr-PILC, 58) Ni/Zr-PILC, 61) Mg/Al-PILC.…”

“…They found that the low surface area and low acidity of bentonite limited the active sites available for catalysis, resulting in lower conversion rates than Al-pillared bentonite. Research by AlSawalha et al 46) focused on the acidic properties of various Jordanian clays, including bentonite, kaolinite, and diatomite, for conversion 2-methyl-3-butyn-2-ol (MBOH). The maximum NH 3 desorption rate from the zeolite surface is the highest and decreases from bentonite to kaolinite and diatomite.…”