Continuous Fixed-Bed Column Study and Adsorption Modeling: Removal of Arsenate and Arsenite in Aqueous Solution by Organic Modified Spent Grains

Abstract

Arsenic is of environmental concern because of its toxicity to plants, animals, and humans. Arsenic in drinking water has the greatest impact on the general population and human health. In natural waters arsenic can be found in inorganic forms as oxidized pentavalent arsenate (As(V)) or trivalent arsenite (As(III)), mostly as H 2 AsO 4 -, HAsO 4 2-, H 3 AsO 3 , and H 2 AsO 3 - [1]. As(V) predominates in surface waters, while groundwater may also contain relevant concentrations of As(III) that are more mobile and toxic than As(V) [2]. Elevated concentrations of arsenic in groundwaters of China are the result of biogeochemical processes [3] or anthropogenic activities such as agriculture (the extensive use of herbicides and insecticides) and irregular disposal of hazardous waste from heavy industry [4][5].Long-term exposure through drinking water to even low concentrations of arsenic (≤50 μg/l) can cause Pol. J. Environ. Stud. Vol. 26, No. 4 (2017), 1847-1854 The adsorption of arsenate (As(V)) and arsenite (As(III)) was conducted in a continuous fixed-bed column by using organic modified spent grains (OSGs). The column performances were evaluated by varying the influent flow rate (0.91, 1.36, and 2.72 ml/min) and arsenic ions initial concentration (1.0, 2.0, and 6.0 mg/l for As(V); 0.5, 1.0, and 3.0 mg/l for As(III)) in order to obtain experimental breakthrough curves. The maximum adsorption capacity was at 6.0 mg/l for As(V) and 3.0 mg/l for As(III) influent concentration and 1.36 ml/min flow rate. The Thomas model, Adams-Bohart model, and Yoon-Nelson kinetic models were used to analyze column performance. The value of rate constant for Thomas and Adams-Bohart models decreased with increase of influent concentration, but increased with increasing flow rate. The rate constant for the Yoon-Nelson model decreased with increases in both initial influent arsenic ions concentration and flow rate.

Low-cost laterite-laden household filters for removing arsenic from groundwater in Vietnam and waste management

“…The breakthrough curve of NLTT for the initial As(V) concentration of 0.5 mg/L was steeper than that of initial As(V) concentration of 0.1 mg/L. This outcome is consistent with previous studies on As(V) removal by adsorbents in column experiments (Brion-Roby et al, 2018;Yunnen et al, 2017). Yunnen et al (2017) reported that the breakthrough curves for As(V) adsorption in columns containing organically modified plant grains at higher As(V) concentration were sharper due to a relatively smaller mass transfer zone and a more intraparticle diffusion-controlled process.…”

“…Yunnen et al (2017) reported that the breakthrough curves for As(V) adsorption in columns containing organically modified plant grains at higher As(V) concentration were sharper due to a relatively smaller mass transfer zone and a more intraparticle diffusion-controlled process. Moreover, at a higher initial concentration of As(V), the larger amount of As(V) passing through the column per unit time resulted in smaller mass transfer resistance, higher driving force, and an earlier saturation (Brion-Roby et al, 2018;Yunnen et al, 2017). The Thomas model (Thomas, 1944) was used to describe the breakthrough curves.…”

Studies on Adsorption Characteristics of Corn Cobs Activated Carbon for the Removal of Oil and Grease from Oil Refinery Desalter Effluent in a Downflow Fixed Bed Adsorption Equipment

“…The decrease in the KBA with increasing feed concentration suggests that the kinetics of the entire system is manipulated by the external mass transfer in the preliminary section of the adsorption column (De Franco et al, 2018;Gong et al, 2015). Similar pattern was observed by Yunnen et al (2017).…”

Modeling of the dynamics adsorption of some hazardous elements from aqueous solution onto bentonite-calcium-alginate beads

“…This behavior demonstrated that a change of concentration has significant affects the saturation rate and breakthrough time [23]. This could be because of that a possibility of a greater number metal ions number in solution and more adsorption sites of bentonite-Caalginate sorbents were being covered at higher impact concentration and lower concentration gradient between liquid and solid phases caused slower transport that a decreased coefficient of mass transfer [24].Breakthrough curves are sharper, steeper and shifted to an origin for metal ions with used sorbent with rising influent concentration because an active sites of bentonite-Ca-alginate fixed-bed system is saturated more rapidly at higher initial concentrations, time to reach both a breakthrough and exhaustion point is decreased [25][26]. Amount of Cs + , Sr 2+ , UO2 2+ and Co 2+ ions adsorbed in a multicomponent system was found to increase with rising an initial concentration of metal ions from 50 to 200 mg/L however, column performance decreased, as recorded in Table (1).…”