Removal of Selenium Species from Waters Using Various Surface‐Modified Natural Particles and Waste Materials

Abstract

Waste red mud and natural pumice/volcanic slag particles were surface modified and their selenium adsorption from waters was investigated. Acid activation/heat treatment of original red mud (ORM) particles significantly increased their micropore and external surface area and cumulative volume of pores. Iron oxide coating of pumice/ slags and acid activation of ORM decreased their pH pzc values and increased surface acidity. Selenite/selenate adsorption on iron oxide surfaces and acid activated red mud (AARM) was very fast with approximately first-order adsorption kinetics. Iron oxide coating of pumice/slag and acid activation of ORM particles significantly enhanced their selenite and selenate uptakes. Maximum Se adsorption capacities as high as 6.3 (mg Se/g adsorbent) were obtained by AARM. The extent of selenate uptakes by the surface modified particles was generally lower than those of selenite. Due to competition among Se species and other background water matrix for iron oxide adsorption sites, reduced selenite/selenate uptakes were found in natural water compared to single solute tests. Higher Se uptakes by iron oxide surfaces were found at pH 7.5 compared to pH 8.9, due to increased electrostatic repulsion among iron oxides and Se species at higher pH. The most effective adsorbents among the tested 17 different particles for Se uptake were AARM and iron oxide coated pumice. Se concentrations less than drinking water standards (5-10 mg/L) can be achieved by these particles. These low-cost, natural, or recyclable waste particles appear to be promising adsorbents for Se removal after their surface modification.Abbreviations: AARM, acid activated red mud; BET, Brunauer-Emmett-Teller; DDW, distilled and deionized water; DOC, dissolved organic carbon; IC, iron oxide coated; ICP/MS, inductively coupled plasma/MS; Isp, Isparta pumice; Kula, Kula-Salihli volcanic slag; NOM, natural organic matter; ORM, original red mud; pH pzc , pH of point of zero charge; SEM, scanning electron microscope; SEM-EDX, scanning electron microscope-energy dispersive X-ray spectrometer; SS, steel slag; XRF, X-ray fluorescence Clean -Soil, Air, Water 2012, 40 (7), 735-745 735

Preparation of titanate nanoflower for sorption of 75Se(IV) radioisotope from aqueous solution: Equilibrium, kinetic and thermodynamic studies

“…The surface of sorbent carries positive charges at pH value lower than IEP, which enhances electrostatic force of attraction with biselenite and selenate ions. At high pH values (8)(9)(10)(11)(12), drastically decrease in the percentage of adsorption was observed. At this pH range, the surface sites of the used adsorbent are deprotonated at- taining a negative charge and the high negatively charged selenite (SeO 2− 3 ) species prevail in this range.…”

“…In order to investigate the adsorption mechanism and adsorption characteristics, the kinetics data of 75 Se(IV) ions sorbed onto the prepared TNF sorbent (Figs. 8,9) were analyzed using pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion kinetic models, respectively. The conformity between experimental data and each model predicted values that were expressed by the correlation coefficient ( 2 ).…”

“…Brought to you by | Western University Authenticated Download Date | 10/11/15 11:47 PM Traditional adsorbents such as zeolite [8], red mud [9], clay [10] and activated carbons [11] have been applied for assessing the adsorption potential of arsenic removal, but indicate low adsorption capacity and slow kinetics. So, it is important to develop efficient and reusable adsorbent materials for Se(IV) removal from wastewater with high efficiency and low cost.…”

Adsorption studies for the simultaneous removal of arsenic and selenium using naturally prepared adsorbent materials

“…Arsenic and selenium adsorption has been well studied (Jain and Ali 2000;Ladeira and Ciminelli 2004;Bleiman and Mishael 2010;Liu et al 2012;González et al 2011;Tian et al 2011;Yigit et al 2012;Chen and An 2012); however, the use of low-cost materials in these studies has been minimal, thus making the treatment procedures too expensive or inapplicable to environmental water treatment systems, especially in the developing communities (Zhang et al 2010). The adsorbents that have been used include activated alumina (Hung et al 2004), hydrous cerium oxide nanoparticles , magnetic wheat straw (Tian et al 2011), granular ferric hydroxide (Banerjee et al 2008) and hydrous stannic oxide (Manna and Ghosh 2007).…”

“…Adsorbents such as peanut husks (Ngah and Hanafiah 2008), orange peels (Feng et al 2009;Dhakal et al 2005;Lasheen et al 2012;Yigit et al 2012) and eggshell membranes (Cheng et al 2011;Zhang et al 2010) can be used for the adsorption of toxic materials from water, such as copper, cadmium, lead, nickel and zinc, amongst others. Eggshell membranes and orange peels are abundantly available with the eggshell membranes being available throughout the year whilst the orange peels are seasonal, yet the output when in season is too high to ignore.…”