Removal of Antimony Species, Sb(III)/Sb(V), from Water by Using Iron Coagulants

Abstract

Antimony (Sb) is classified as a toxic pollutant of high priority, because its effects on human health (toxicity) are similar to those of arsenic. However, unlike arsenic, the removal of antimony from polluted waters is still not well understood. In the present study the removal of common antimony species in water, namely, Sb(III) and Sb(V), was investigated by the addition of iron-based coagulants. The applied coagulants were Fe(II), Fe(III), and equimolar mixed Fe(II)/Fe(III) salts and the experiments were performed with realistic antimony concentrations in the range 10–100 μg/L, by using artificially polluted tap water solutions. Sb(III) removal by Fe(III) provided better adsorption capacity at a residual concentration equal to the drinking water regulation limit of 5 μg/L, that is, Q5 = 4.7 μg Sb(III)/mg Fe(III) at pH 7, which was much higher than the value achieved by the addition of Fe(II) salts, that is, Q5 = 0.45 μg Sb(III)/mg Fe(II), at the same pH value. Similarly, Sb(V) was more efficiently removed by Fe(III) addition, than by the other examined coagulants. However, Fe(III) uptake capacity for Sb(V) was found to be significantly lower, that is, Q5 = 1.82 μg Sb(V)/mg Fe(III), than the corresponding value for Sb(III). The obtained results can give a realistic overview of the efficiency of conventionally used iron-based coagulants and of their mixture for achieving Sb concentrations below the respective drinking water regulation limit and therefore, they can be subsequently applied for the designing of real-scale water treatment units.

An Effective Method to Remove Antimony in Water by Using Iron-Based Coagulants

“…In the coagulation process with FeSO 4 , flocs formed by the hydrolysis of Fe 2+ ions were simple mononuclear complex, and their adsorption capacity was poorer than that of flocs formed by the hydrolysis of PFS and FC. In addition, the electrostatic interaction between the positive HFO flocs and negative Sb(OH) 6 − facilitated the removal of Sb(V).…”

“…As a result, the HFO colloid became unstable and larger HFO flocculates were formed, precipitated, and separated from water, achieving the removal of antimony. The electrostatic interaction between the positively charged flocs and negatively charged Sb(OH) 6 − promoted the removal of Sb(V). However, when the pH value was below 3, the hydrolysis of iron-based coagulants decreased, which inhibited the removal of Sb.…”

“…Given the high toxicity and severe pollution of Sb, many technologies have been developed to remove Sb from water in recent years, such as coagulation [6,7], adsorption [8,9], membrane [10], and electro-coagulation [11] related technologies. For example, many adsorbents were applied to remove Sb, such as goethite, diatomite, and Fe-Mn binary oxide [12].…”

Orange Peels as a Sustainable Material for Treating Water Polluted with Antimony

“…Antimony has many industrial applications, for example, in the manufacture of lead alloys for the transportation industry. Other applications are the production of industrial materials, such as plastic, diodes, semi-conductors, as well as glass and ceramics (Mantha et al, 2018). The use of antimony in the industry is one of the reasons why its concentration in the natural environment has increased; in some cases, pollution is caused when it is discharged into the environment without being treated (Saeidnia et al, 2016).…”

La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico. Parte IX: Antimonio(III))/H⁺/Ionac SR7

“…Recent investigation included: coagulation/ flotation, membrane processes, etc. (Ungureanu et al, 2015), liquid-liquid extraction with ionic liquids (Dupont and Binnemans, 2016), precipitation or adsorption with iron based compounds (Multani et al, 2016;Qi and Pichler, 2016;Deng et al, 2017;Yang et al, 2017;Mitrakas et al, 2018), bacterial treatment (Zhu et al, 2018), and various adsorbents, i.e. chitosan-modifies pumice, calcined hydrotalcite (Sari et al, 2017;Constantino et al, 2018).…”