Eggshell-supported Catalysts for the Advanced Oxidation Treatment of Humic Acid Polluted Wastewaters

Abstract

Metal nanoparticles have been reported as effective catalysts for the removal of refractory compounds from industrial wastewaters in advanced oxidation processes. Additionally, hundreds of thousands of tons of eggshells are discarded worldwide each year. In this work, this waste has been evaluated as support for the synthesis of nanomaterials by wet impregnation method. Four supported catalysts, with a load of iron or copper of 5% and 15%, were prepared and thoroughly characterized by means of different techniques (elemental analysis, XRF, XRD, FTIR, N2 adsorption-desorption, SEM, TEM and TGA). The catalysts performance was evaluated in wet oxidation tests to degrade humic acids, analyzing the evolution with time of COD, biodegradability index (BOD5/COD), color number and pH. The best results were achieved with 15% Cu and 5% Fe catalysts (COD reduction being 82.3% and 75.1%, respectively), whereas a COD reduction of 58% was obtained employing non-impregnated eggshell. This can be mainly attributed to the metal loading and the good metal distribution on the surface of the support. The BOD5 value of humic acids was initially null and, in all assays, the oxidation treatment enhanced the biodegradability. Therefore, eggshell has proved to be an interesting material to be employed as support in nanoparticles preparation.

State-of-the-Art of Eggshell Waste in Materials Science: Recent Advances in Catalysis, Pharmaceutical Applications, and Mechanochemistry

“…Eggshell-derived materials functionalized with copper and iron oxide at different concentrations have been also designed for the application in the catalytic wet oxidation of humic acid (a refractory compound present in industrial wastewaters) (Oulego et al, 2020 ). In this work, it was found that copper-modified eggshell showed enhanced catalytic activity in comparison with unmodified eggshell, most likely due to the better metal distribution on the eggshell support.…”

“…In this work, it was found that copper-modified eggshell showed enhanced catalytic activity in comparison with unmodified eggshell, most likely due to the better metal distribution on the eggshell support. Interestingly, eggshell by itself could also be employed to degrade humic acid and, even if less effectively, this option should be considered for future works due to the cost-efficiency of the catalyst design (Oulego et al, 2020 ). In another example, Asgari and coworkers have reported the preparation of carbon-doped magnesium oxide on eggshell powder as an efficient catalyst for the ozonation process to treat real wastewater from the textile industry, displaying improved results in comparison with commercially available activated carbon (Asgari et al, 2019 ).…”

Removal of Sulfadiazine Using 3D Interconnected Petal-Like Magnetic Reduced Graphene Oxide (MrGO) Nanocomposites

“…The nanocomposites mainly display two stages of weight loss. The first stage of the slight weight loss (about 2-6 wt %) is ascribed to the evaporation of surface-adsorbed water and solvent molecules under 200 • C. The second stage of the major weight loss is mainly resulted from the decomposition of the rGO skeleton and the removal of the oxygen-containing functional groups at 200-430 • C [30,31]. The residual mass percentages of the prepared MrGO-1, MrGO-2, and MrGO-3 nanocomposites are about 75.7%, 62.3%, and 52.9%, respectively.…”

Adsorption behavior of Congo red on a carbon material based on humic acid

“…Water is the source of human life, and the existence of water is vital to human survival. However, in recent years, water resources have gradually been in short supply, and at the same time the discharge of polluted wastewater has increased [1], [2] . Effective treatment of polluted wastewater is imperative.…”