Optimization of Antimony Removal by Coagulation-Flocculation-Sedimentation Process Using Response Surface Methodology

Muhammad Waleed Inam,Muhammad Ali Inam,Abdul Salam Buller,Muhammad Akram,Ick Tae Yeom,Rizwan Khan

doi:10.3390/pr9010117

Muhammad Waleed Inam, Muhammad Ali Inam + Show 4 more

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https://doi.org/10.3390/pr9010117

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Abstract

Coprecipitation-adsorption plays a significant role during coagulation-flocculation-sedimentation (C/F/S) of antimony (Sb) in water. This work uses a Box–Behnken statistical experiment design (BBD) and response surface methodology (RSM) to investigate the effects of major operating variables such as initial Sb(III, V) concentration (100–1000 µg/L), ferric chloride (FC) dose (5–50 mg/L), and pH (4–10) on redox Sb species. Experimental data of Sb(III, V) removal were used to determine response function coefficients. The model response value (Sb removal) showed good agreement with the experimental results. FC showed promising coagulation behavior of both Sb species under optimum pH (6.5–7.5) due to its high affinity towards Sb species and low residual Fe concentration. However, a high dose of 50 mg/L of FC is required for the maximum (88–93%) removal of Sb(V), but also for the highest (92–98%) removal of low initial concentrations of Sb(III). Furthermore, BBD and RSM were found to be reliable and feasible for determining the optimum conditions for Sb removal from environmental water samples by a C/F/S process. This work may contribute to a better understanding and prediction of the C/F/S behavior of Sb(III, V) species in aqueous environments, to reduce potential risks to humans.

Highlights

Antimony (Sb) has been used extensively worldwide in various commercial applications, including the manufacture of chemicals, plastics, batteries, ceramics, semiconductor materials, and flame retardants [1,2]
The removal of Sb(III, V) from drinking water following the coprecipitation-adsorption mechanism was investigated by the C/F/S process using ferric chloride (FC) coagulant
The coprecipitation-adsorption method was employed to determine the effects of various parameters (i.e., Sb(III, V) concentration, FC dose, and pH) on Sb(III, V)

Summary

Introduction

Antimony (Sb) has been used extensively worldwide in various commercial applications, including the manufacture of chemicals, plastics, batteries, ceramics, semiconductor materials, and flame retardants [1,2]. Inorganic antimony (trivalent antimony (Sb[III]) and pentavalent antimony (Sb[V])) shows elevated concentrations in natural water bodies in different parts of the world. Sb concentrations of 239, 6384, and 157 μg/L have been found in Stampede and Slate Creek watersheds (Alaska, USA), rivers around antimony mines in the Xikuangshan area (Hunan Province, China), and lakes in the South East region (Sindh, Pakistan), respectively [3,4,5]. To protect human health and the environment, the USEPA (6 μg/L), EU (10 μg/L), World Health Organization (WHO) (5 μg/L), South Korea (20 μg/L), and Pakistan (5 μg/L) have set regulatory standards for Sb in drinking water [8,9,10]

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