Application of emerging ion exchange resin for boron removal from saline groundwater

Abstract

Saline groundwater is presently used, when feasible, for hydraulic fracturing operations of unconventional shale resources. In certain geographies, the saline groundwater possesses high boron concentration which is incompatible with the field fracking chemicals; hence, a low boron concentration is desired. The present investigation evaluated a novel chelating ion exchange resin that has potential to remove boron at neutral pH.Bench scale isotherm experiments at various pH revealed negligible difference in removal efficiency between pH 7 and 10. Experiments conducted at 25 °C and 70 °C showed higher sorption of boron removal at lower temperature. Flow through bench column test using deep well saline groundwater (25 mg/L boron and 2.5% TDS) from south Texas showed boron effluent concentration of < 0.1 mg/L and a resin capacity of 5.0 mg/g. Experimental data from pilot study using same saline groundwater showed the resin was very effective in removing boron to low concentrations (<0.5 mg/L). The resin capacity was in the range of 4.4 to 3.1 mg/g operated under different flowrates, which agreed with Thomas model predicted capacity of 3.8 mg/g. The resin was successfully regenerated multiple times by using 7% HCl and 4% NaOH solutions consecutively.Overall the study elucidated that this emerging resin can be applied for large-scale applications for selective boron removal from saline groundwater sources.