Synergistic process using Fe hydrolytic flocs and ultrafiltration membrane for enhanced antimony(V) removal

Abstract

A B S T R A C TAntimony (Sb) is harmful to human health, and Sb(V) is much more difficult to remove from water than other toxic elements such as arsenic (As). Theoretical studies have suggested that in situ flocs have stronger adsorption ability toward heavy metals than pre-made adsorbents. We believe that rational design of in situ flocs and the associated device structure will enable a floc-based device to be utilized in the removal of heavy metals. Based on this concept, we developed an integrated process taking advantage of the strong adsorption abilities of in-situ Al or Fe hydrolytic flocs and excellent separation properties of ultrafiltration (UF) membranes. We found that flocs could be well dispersed in a membrane tank with aeration from the bottom, and Fe-based flocs performed better in removing Sb(V) and alleviating membrane fouling than Al-based flocs. We also demonstrated that higher Sb (V) removal efficiency was induced with continuous injection, and lower solution pH. By controlling the aeration rate, injection frequency and the solution pH, membrane fouling was alleviated, especially under weakly acidic conditions. Additionally, owing to the higher rejection efficiency of the UF membrane, the effluent quality was improved, including the iron concentration, turbidity, and chromaticity. This innovative separation method shows promising potential for application in removing heavy metals in water treatment.

Multiple dynamic Al-based floc layers on ultrafiltration membrane surfaces for humic acid and reservoir water fouling reduction

“…However, the removal efficiency and peak value variation were influenced little under different aeration rates (Fig. 3b), as reported previously (Ma et al, 2017).…”

“…Due to its better UF membrane performance (Sections 3.1 and 3.2), continuous injection was further investigated. As aeration rate plays an important role in floc characteristics, including particle size and membrane attachment ability (Ma et al, 2017), UF membrane performance was tested with different aeration rates (Fig. 3).…”

Frontier Materials for Adsorption of Antimony and Arsenic in Aqueous Environments: A Review

“…Reverse osmosis can therefore be used to remove Sb(V) and produce a superior result than Sb(III) regardless of the pH value [ 11 ]. Sb(V) can also be removed by the strengthening ultrafiltration membrane method, and its process is simple to operate [ 37 ].…”

Antimonate Removal from Polluted Mining Water by Calcined Layered Double Hydroxides

“…In aqueous solution, Sb(III) and Sb(V) prevail, respectively, under reducing and oxidizing conditions as antimonous acid H 3 SbO 3 and antimonic acid H 3 SbO 4 and their dissociation products, with the Sb(OH) 6 − anion being the most common and stable aqueous species in a wide range of natural pH values [1,9]. Among the techniques suitable for the abatement of Sb concentration in the solution, such as coagulation-flocculation [10], electrochemical methods [11,12] and membrane separation [13,14], the adsorption is considered a low cost and effective method [9]. Several studies reported that metal hydroxides and oxohydroxides (e.g., MnOOH, Al(OH) 3 , FeOOH) are good Sb removers, however they result more efficient for Sb(III) than Sb(V) under slightly acid to acid conditions [15][16][17][18].…”