Abstract
Nanoparticles of iron precipitates produced by a microbial consortium are a suitable adsorbent for metal removal from electroplating industry wastewaters. Biogenic iron precipitates were utilized as adsorbents for chromate and zinc in batch conditions. Furthermore, the iron precipitates were embedded in alginate beads for metal removal in fixed-bed columns, and their performance was evaluated in a continuous system by varying different operational parameters such as flow rate, bed height, and feeding system (down- and up-flows). The influence of different adsorption variables in the saturation time, the amount of adsorbed potentially toxic metals, and the column performance was investigated, and the shape of the breakthrough curves was analyzed. The optimal column performance was achieved by increasing bed height and by decreasing feed flow rate and inlet metal concentration. The up-flow system significantly improved the metal uptake, avoiding the preferential flow channels.
Highlights
Industrial wastewaters from electroplating, mining, metal processing, or petroleum refineries contaminate the environment [1]
The adsorbent, iron oxide and siderite generated by a natural microbial consortium from an abandoned mine, was able to take up several potentially toxic metals from synthetic and dilute solutions
The biogenic iron precipitates were used as adsorbents with industrial wastewaters from a zincate process
Summary
Industrial wastewaters from electroplating, mining, metal processing, or petroleum refineries contaminate the environment [1]. The management, treatment, and disposal of industrial wastewater containing potentially toxic metals is a growing worldwide concern for governments, policymakers, industries, and researchers [2] Metals, such as chromium and zinc, are dangerous and toxic to the environment because they are non-biodegradable and accumulate in organisms through the food chain [3]. Nanomaterials provide high specific surfaces in comparison to the limited active sites in conventional adsorbents, which leads to high adsorption kinetics and efficiency [5] Metal oxide nanoparticles, such as alumina, titanium oxides, manganese, and iron oxides, exhibit interesting adsorptive properties and possess a potential application. Iron oxides are present in nature as different phases; the better-known adsorptive nanoparticles are the zero-valent iron (nZVI), Fe3 O4 and γ-Fe2 O3 [6,7] These materials present different physicochemical properties due to the difference in their iron oxidation states and their capacity for contaminant removal. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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