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

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.

Coagulation Behavior of Antimony Oxyanions in Water: Influence of pH, Inorganic and Organic Matter on the Physicochemical Characteristics of Iron Precipitates

“…A recent study [ 7 ] attempts to explain the influence of pH and HA on pentavalent [Sb(V)] and trivalent [Sb(III)] removal with particular emphasis on the physicochemical properties of Fe precipitates. The significant effect of pH on Sb(V) removal has been evidenced, particularly at alkaline conditions [ 6 , 9 , 16 ]. The presence of hydrophobic organic compounds such as HA may alter the surface properties of Fe flocs, thereby affecting the overall performance of the coagulation process [ 7 , 17 ].…”

Competitive Removal of Antimony and Humic Acid by Ferric Chloride: Optimization of Coagulation Process Using Response Surface Methodology

“…While the cubic model showed aliasing owing to lack of data points availability for model coefficients estimation. Therefore, further analysis was performed using the quadratic model [33].…”

“…An earlier study [32] also showed applicability of RSM for simultaneous removal of arsenic (As) and DOC during the chemical coagulation process. Our previous study [33] investigated Sb removal by varying initial Sb concentration, FC dosage, and pH values using RSM and the Box-Behnken design (BBD) model. However, the developed model did not account for the interaction of organic species, and up to 12% of total variation in Sb removal response was not described by the model.…”

Mn–Ce oxide-modified activated carbon composites as efficient adsorbents for removing As(iii) from water: adsorption performance and mechanisms

“…To minimize the possible health risks associated with arsenic exposure, the World Health Organization (WHO) has recommended a more stringent limit of 10 μg L −1 as the maximum permissible arsenic level in drinking water. 2 Many strategies like oxidation, 3 ion exchange, 4 reverse osmosis, adsorption, 5,6 extraction 7,8 and biosorption 9 have been employed for remediating arsenic polluted water. Among such techniques, adsorption is considered as a practical approach owing to its simple operation, cost-effective nature and efficient capture of metal ions even at low concentrations.…”