Role of Polymerized Micelles on the Calcium Carbonate Mineralization of Nanofibers Yaewon Park, † Preeti Rawat, ‡ and Ericka Ford* Department of Textile Engineering, Chemistry and Science, The Nonwovens Institute, North Carolina State University, 1020 Main Campus Drive, Raleigh, North Carolina 27606, United States * S Supporting Information ABSTRACT: Calcium carbonate (CaCO 3 ) is a well-known chemical adsorbent. In this study, anthraquinone dye adsorption by CaCO 3 -mineralized nanofibers was evaluated with respect to the chemistry and structure of ionic particles that were seeded into the fibers. Reacted and unreacted surfmers of polyoxyethylene-1-(alkyloxylmethyl) alkyl ether sulfuric ester ammonium salt (PAMS) and polyoxyethylene alkylphenyl ether ammonium sulfate (PAPS) were added to aqueous poly(vinyl alcohol) (PVA) solutions at concentrations above their critical micelle concentration prior to electrospinning. The roles of these polymerized micelles on CaCO 3 mineralization (produced by dipping PVA nanofibers into alternating solutions of aqueous CaCl 2 and NaCO 3 ) were compared to the roles of calcium chloride (CaCl 2 ) and unseeded PVA nanofibers. Seeding nanofibers with reacted PAMS and PAPS resulted in higher degrees of CaCO 3 mineralization than those with unreacted surfmers. PAPS caused even greater degrees of CaCO 3 mineralization than other seeds, including PAMS. Likewise, dye absorption was greatest among the vaterite CaCO 3 containing surfaces that were along nanofibers seeded with PAPS. Complexation between the PAMS and PVA hydroxyl groups had reduced their ability to attract calcium ions to the surfaces of nanofibers for mineralization, which also suppressed dye adsorption. ■ INTRODUCTION Calcium carbonate (CaCO 3 ) is a naturally abundant, low-cost adsorbent 1 that is widely used in environmental remediation, as in the case of oil spills, 2 heavy-metal removal, 3 and dye extraction 4 from water. When applied to high-surface-area nanofibers, 5 CaCO 3 coatings could enhance their performance in chemical separation. 6,7 Several techniques have been used to mineralize polymeric surfaces with CaCO 3 : hydrothermal mineralization and the cyclical dipping of materials into salt solutions. Calcite, vaterite, and aragonite are crystalline forms of CaCO 3 . Their formation during the process of CaCO 3 mineralization depends on each technique’s unique set of process parameters. 8 Common among these techniques is the use of seed particles that can successfully nucleate CaCO 3 growth along surfaces. Calcination, which transforms precursors into crystals, 9 requires elevated temper- atures for crystal formation and can degrade the polymer. The hydrothermal approach most resembles natural methods of mineralization. It involves the prolonged exposure of surfaces to a salt solution. Yang et al. 10 immersed chitosan/poly(vinyl alcohol) (PVA) nanofibers, seeded with calcium chloride (CaCl 2 ) or CaCO 3 nanoparticles, in aqueous CaCl 2 /sodium carbonate (Na 2 CO 3 ) for up to 40 days at 25 °C. Suslu et al. 11 similarly immersed poly(3-hydroxybutyrate-co-3-hydroxyvaler- ate) (PHBV) nanofibers that were embedded with hydrox- yapatite (HAp) nanoparticles and surfactant into a saline solution for 5 weeks at 37 °C. Nanofibers in those studies were seeded with salts and polyelectrolytes to induce mineralization hydrothermally. Carboxylic acids, hydroxyl groups, ether linkages, 12 and sulfate moieties 13,14 can adsorb calcium cations (Ca 2+ ) for mineralization to occur. When different polymers were blended with poly(acrylic acid) (PAA), PAA carboxylic acid groups attracted Ca 2+ for CaCO 3 formation. 15,16 Also, PVA hydroxyl groups, coating the surface of commercial polyamide Received: March 2, 2017 Revised: May 26, 2017 Accepted: June 22, 2017 Published: June 22, 2017 Article pubs.acs.org/IECR © XXXX American Chemical Society A DOI: 10.1021/acs.iecr.7b00902 Ind. Eng. Chem. Res. XXXX, XXX, XXX-XXX