Using Nano Zero-Valent Iron Supported on Diatomite to Remove Acid Blue Dye: Synthesis, Characterization, and Toxicology Test

Ernesto Flores-Rojas,Omar Solorza-Feria,Luz Breton-Deval,Erick Justo-Cabrera,Héctor M Poggi-Varaldo,Denhi Schnabel

doi:10.3390/su132413899

Abstract

This work aimed to synthesize and characterize nanoscale zero-valent iron (nZVI), supported on diatomaceous earth (DE) at two different molar concentrations, 3 and 4 M (nZVI-DE-1 nZVI-DE-2), to test the decolorization treatment of acid blue dye (AB) and perform a toxicological test using zebrafish. The synthesis of the nanoparticles was obtained using the chemical reduction method. The material was fully characterized by X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy and specific surface area (BET). The results showed spherical forms in clusters between 20 and 40 nm of zero-valent iron supported on diatomaceous earth. The removal of 1 g/L of AB from water treated with nZVI-DE-1 and nZVI-DE-2 reached the decolorization of 90% and 98% of all dye. By contrast, controls such as nZVI and DE-1 and DE-2 removed 40%, 37%, and 24% of the dye. Toxicological analysis using zebrafish showed that AB causes a severe defect in development, and embryos die after exposure. However, the water samples treated with nZVI-DE-1 and nZVI-DE-2 are not harmful to the zebrafish embryos during the first 24 h. However, all embryos exposed to the new material for more than 48 hpf had cardiac edema, smaller eyes, and curved and smaller bodies with less pigmentation.

Highlights

Textile industries discharge into wastewater without any treatment around 100 tons of dyes worldwide [1]
The objective of this research was to characterize and synthesize nanoscale zero-valent iron supported on diatomaceous earth and test if treated water had a negative effect on the viability of zebrafish embryos
The first identified as nanoscale zero-valent iron (nZVI)-diatomaceous earth (DE)-1 was prepared from 0.3 M FeCl2 .4H2 O at a 40/60 proportion of FeCl2 .4H2 O/DE, while the second type identified as nZVI-DE-2 was made at a 50/50 ratio of FeCl2 .4H2 O/DE. nZVI and nZVI-DE-1 and -2 were obtained using the chemical reduction method of FeCl2 .4H2 O in an aqueous solution using NaBH4 as a reducing agent, due to its simplicity and efficiency in securing nZVI [29]

Summary

Introduction

Textile industries discharge into wastewater without any treatment around 100 tons of dyes worldwide [1]. The stream’s water temperature decreases, and photoautotrophic organisms such as algae, euglena, and cyanobacteria can no longer survive [3] The death of these organisms is an ecological loss because they play an essential role in the cycle of nutrients and can absorb organic matter present in the stream. Other parameter levels affected by the dye pollution are the biochemical oxygen demand (DBO), chemical oxygen demand (COD), and total suspended solids (TSS). These changes in the water quality composition could promote the death of fish and amphibians and change the microbial community [5].

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