Sorption of micropollutant estrone to a water treatment ion exchange resin

Abstract

Micropollutants occur in natural waters from a range of sources. Estrogenic compounds are naturally excreted by humans and hence stem predominantly from wastewater effluents. Due to their small molecular weight and concentration their effective control is a challenge. In this study magnetic ion exchange (MIEX), which was developed to remove natural organic matter (NOM) from surface water, was investigated for such a micropollutant, estrone. The interaction of estrone with the resin occurs as a side effect when NOM is removed. This interaction results in some degree of removal. However, the accumulation of those hazardous materials on the resin, which can be associated with accidental release, as well as the concentration in the regeneration brine of the process, is environmentally more significant. For this reason a thorough investigation of interaction phenomena was undertaken. Estrone and polymeric materials (such as ion exchange resins or membranes) interact through a number of mechanisms including specific and non-specific interactions. Sorption and desorption of estrone were studied as a function of pH, temperature, natural organic matter concentration, sulfate concentration and ionic strength to elucidate possible mechanisms. The results demonstrated that the resin removed around 70% estrone at high pH conditions (>10.4) when estrone was predominantly negatively charged. However, below pH 10.4, when estrone was neutral, approximately 40% of estrone still sorbed due to hydrogen bonding. The optimum temperature for estrone sorption was observed to be in the 15 to 35 degrees C range, while the presence of other anions, including natural organic matter reduced estrone removal due to competition for anion exchange sites. Desorption of estrone was most effective with 2 M NaCl regeneration brine concentration when estrone was negatively charged (98% desorption). However, when estrone was neutral there was no significant difference between 1 M and 2 M NaCl. The results presented in this study indicate that polar non-ionic micropollutants were removed by magnetic ion exchange resin due to sorption to the resin polymer. This has implications for treatment, however, the accumulation of micropollutants on polymeric materials in water treatment as well as the abundance of such micropollutants in the regeneration brine are risks that warrant monitoring.

Effect of resin charged functional group, porosity, and chemical matrix on the long-term pharmaceutical removal mechanism by conventional ion exchange resins

“…Previous investigations have demonstrated the efficient adsorption of estrone (Zhang and Zhou, 2005;Neale et al, 2010), SMX (Choi et al, 2007;Huang et al, 2011;Fern andez et al, 2014), TC (Choi et al, 2007), and NPX (Landry et al, 2015) onto AERs in batch tests, which was also demonstrated during the first cycle in this study. In fact, AER treatment removed almost all of the microconstituents, regardless of their predominant existing forms, during short-term cyclical operation (i.e., the 1st adsorptionregeneration cycle) in this study.…”

“…This is in agreement with previous observations by Huang et al (2011), who found that the compounds with substantial removal by AER treatment at pH 8.0 had a broad pK a range of 1.7e10.1. Neale et al (2010) also found that AER treatment removed around 70% of estrone (pK a 10.4) at pH > 10.4 or approximately 40% of estrone at pH < 10.4. In this study, the presence of complex non-electrostatic interactions ensured the effective adsorption of all 12 pharmaceuticals onto AER during short-term cyclical operation.…”

“…Many studies have highlighted the strong potential of commercial anion exchange resins (AERs) to remove pharmaceuticals from various water matrices (Michael-Kordatou et al, 2015) (e.g., MIEX ® resins for seven sulfonamide antibiotics, seven tetracyclic antibiotics (Choi et al, 2007), estrone (Neale et al, 2010), triclosan, and sulfamethoxazole (SMX) (Huang et al, 2011); Lewatit MP500 resins for SMX and sulfamethazine (Fern andez et al, 2014); Purolite A520E resins for diclofenac (DCF) (Landry and Boyer, 2013); Dowex 22 resins for DCF, ketoprofen, and naproxen (NPX), ibuprofen, paracetamol (Landry et al, 2015); IRA938, IRA958, IRA458, and IRA402 resins for nalidixic acid (Robberson et al, 2006); and Oasis MAX resin for caffeine and metformin (B€ auerlein et al, 2012)). Due to the presence of various functional groups (e.g., eOH, eCOONa, eSO 3 Na, eN]Ne, and phenolic hydroxyl groups), many pharmaceutical molecules can simultaneously participate in both electrostatic interactions (i.e., Coulombic forces between the positively charged quaternary ammonium functional groups of AERs and the anionic moieties of pharmaceuticals) and various non-electrostatic interactions (B€ auerlein et al, 2012).…”

Micropollutant sorption to membrane polymers: A review of mechanisms for estrogens

“…For example, magnetic ion exchange resin (MIEX) developed for enhanced natural organics removal, sorbs significant amounts of uncharged micropollutants such as estrogens [161]. The resin has a macroporous polyacrylate shell with quaternary ammonium functional groups for ion exchange.…”

Removal of Dissolved Organic Matter by Magnetic Ion Exchange Resin

“…For anionic chemicals, such as bentazone and 2,4-dichlorophenoxyacetic acid [74][75][76], MIEX resin shows high removal up to 99 %, whereas for non-ionic chemicals, such as atrazine and isoproturon, MIEX resin shows negligible removal [33]. MIEX resin removed approximately 40 % of estrone at pH 8 (neutral molecule) and removal increased to approximately 70 % at pH 12 where estrone is negatively charged [77]. MIEX resin showed 0-48 % removal of 15 commonly detected pharmaceuticals and personal care products with higher removal observed for negatively charged species [78].…”