title: Preparation of acidic and alkaline macrocapsules for pH control.
abstract: A series of experiments was performed to prepare acidic macroencapsulated buffers composed of 20% Ca(H2PO4)(2) and 80% Eudragit S 100 polymer and alkaline macrocapsules composed of 65% K2HPO4 and 35% Eudragit E PO polymer (the powdered form of Eudragit E 100). Eudragit S 100 was shown to be soluble at a pH greater than 7.0, while Eudragit E 100 was soluble at a pH less than 7.0. Both polymers did not impart significant biochemical oxygen demand. The Eudragit E PO polymer solution showed low toxicity (EC50=91%) based on the Microtox Acute Toxicity Test compared to the 0.1mM background phosphate buffer solution (EC50=100%) while the Eudragit S 100 polymer solution showed higher toxicity (EC50=53%). Batch tests showed that the acidic macrocapsules reduced the pH of a 0.1mM phosphate solution from 11 to neutral, while the alkaline macrocapsules increased the pH of a 0.1mM phosphate solution from 3 to neutral. The macrocapsules could potentially be used as an in situ proportional pH controller for groundwater remediation.
authors.affiliation: Department of Civil and Environmental Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208, USA. flora-joseph@sc.edu
authors.forename: Joseph R V
authors.initials: JR
authors.lastname: Flora
authors.forename: Benjamin
authors.initials: B
authors.lastname: Baker
authors.forename: Daniel
authors.initials: D
authors.lastname: Wybenga
authors.forename: Huiying
authors.initials: H
authors.lastname: Zhu
authors.forename: C Marjorie
authors.initials: CM
authors.lastname: Aelion
mesh_terms: D002021:Buffers; D052918:Environmental Restoration and Remediation / Q000295:instrumentation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D010710:Phosphates / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D012995:Solubility; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D002021:Buffers; D010710:Phosphates; D011109:Polymethacrylic Acids; D017680:Potassium Compounds; C518398:Eudragit E PO; C013216:potassium phosphate