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.

Using nano zero valent iron supported on diatomite to remove acid blue dye: 46 synthesis, characterization and toxicology test 47 48 49 50 Abstract 51The aim of this work was to synthesize and characterize nanoscale zero-valent iron 52 (NZVI) supported on diatomaceous earth (DE) at two different molar concentration 3 M 53 and 4M (nZVI-DE-1 nZVI-DE-2), to test the decolorization treatment of acid blue dye 54 (AB) and perform a toxicological test using zebrafish. The synthesis of the nanoparticles 55 was obtained using the chemical reduction method and the material was characterized by 56 X-ray diffraction, Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray 57 (EDX), and transmission electron microscopy and Specific Surface Area (BET). The 58 results showed spherical forms in clusters between 20 to 40 nm of zero valent iron 59 supported on diatomaceous earth. The removal of 1 g/l of AB from water treated with 60 NZVI-DE-1 and NZVI-DE-2 reached the decolorization of 90% and 98% of all dye. 61While controls like NZVI and DE-1 and DE-2 achieved the removal of 40, 37 and 24 % 62 of the dye. Toxicological analysis using zebrafish showed that AB causes a severe defect 63 in development and embryos die after exposure. However, the water samples treated with 64 NZVI-DE-1 and NZVI-DE-2 are not harmful for the zebrafish embryos during the first 65 24 hours. We conclude that the use of NZVI-DE-1 and NZVI-DE-2 is a promising 66 treatment for dye pollution. 67 68 69 Keywords: nanoparticles, water treatment, dyes, zero-valent iron, acid blue 70 71 72The concentration of dyes in industrial effluents can reach 500 mg/L and pollute local 73 freshwater, reducing the efficiency of sunlight and thereby impeding the process of 74 photosynthesis. (Jung et al., 2016). As a result, the water temperature of the stream 75 decreased, and photoautotrophs organism like algae, euglena, and cyanobacteria could no 76 longer survive (Bide, 2007). The death of these organisms is an ecological loss because 77 they play an essential role in the cycle of nutrients and are capable of absorbing organic 78 matter present in the stream. They can also remove carbon dioxide from the atmosphere, 79 are an indispensable source of food and oxygen for several organisms (Callieri, 2014). 80Pollution due to synthetic dyes also affects the health of aquatic and terrestrial organisms 81 (Samchetshabam et al., 2017). 82Acid blue (AB) was selected for this study because it is used widely by the industrial 83 sector, including for cosmetics, food coloring or for dyeing different fibers, and is 84 commonly mixed with sulfuric acid to make it more soluble before industrial application 85 thereby increasing the toxicity (Ammar et al., 2006). AB is not only toxic for aquatic life 86 but can also cause skin irritation, cornea damage, and promote the development of tumors 87 and cancer (Khelifi et al., 2008). 88 Several kinds of research have been carried out with the aim of removing dyes from water 89 using aerobic or anaerobic degradation, filtration, adsorption,...