# Improving Sorbents for Glycerol Capture in Biodiesel Refinement
## 3 Materials and Methods  
Bis(trimethoxysilylethyl)benzene (DEB) and 1,2-bis(trimethoxysilyl)ethane (BTE) were obtained from Gelest, Inc. (Tullytown, PA, USA). Tetramethyl orthosilicate (98%), sodium hydroxide, methanol, hydrochloric acid, mesitylene (1,3,5-trimethylbenzene or TMB), Pluronic(r)P123, and glycerol (56-81-5) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Water was deionized to 18.2 M\(\Omega\) cm using a Millipore Milli Q UV-Plus water purification system. Biodiesel was produced (details in Section 3.7) in small batches using fresh canola oil purchased from a local supermarket. Figure 10: Glycerol binding from biodiesel from identical batch type experiments using 250 uM glycerol (10 mL) with 30 mg sorbent. Figure 9: Glycerol binding data for D13-Ph2(5) (**a**) and D13b(6) (**b**) from biodiesel. Isotherms (lines) are from data sets collected in aqueous solution (Table 2). Synthesis of E25-Ph(2) and E50-Ph(2) (Type 2, Ethane-Bridged Organosilicates, Ph Indicates Grafted Phenyl Groups)  
Scaffold materials were synthesized as described in previous reports [21; 26]. Pluronic P123 (3.8 g) and 0.5 g of mesitylene (E25) or 1.0 g of mesitylene (E50) were dissolved in 12.14 g of 0.1 M HNO\({}_{3}\) with heat (\(\sim\)65 \({}^{\circ}\)C) and magnetic stirring. The stirring mixture was allowed to cool to room temperature before drop-wise addition of 4.24 g of 1,2-bis(trimethoxysilyl)ethane. The mixture was stirred to homogenize (\(\sim\)1 min) and transferred to culture tubes. Tubes were tightly sealed and incubated in an oven at 60 \({}^{\circ}\)C overnight. The tubes were unsealed, and the white monolithic gels were heated for 2 d at 60 \({}^{\circ}\)C followed by 2 d at 80 \({}^{\circ}\)C. The block copolymer (Pluronic P123) was extracted from the dried materials by refluxing over-night in 1 M HCl in ethanol. The solid was collected by vacuum filtration. This process was repeated two more times. The collected solid was washed thoroughly with ethanol and water and dried at 110 \({}^{\circ}\)C.  
Grafting with phenyl groups followed a simple published procedure, beginning with an additional drying step at \(>\)100 \({}^{\circ}\)C in a vacuum [31]. Sorbent (1.0 g) was refluxed with 5 mL of phenyltriethoxysilane in 50 mL of toluene for 24 h. Grafted material was collected by gravity filtration, washed thoroughly with ethanol, and dried at 110 \({}^{\circ}\)C. Sulfonation was accomplished as described in the literature by magnetically stirring the phenyl-grafted material in 25 mL of H\({}_{2}\)SO\({}_{4}\) at 75 \({}^{\circ}\)C for 1 d [32]. The acidic mixture was then added to \(\geq\)200 mL of H\({}_{2}\)O. Solid was collected by gravity filtration, washed with H\({}_{2}\)O, and dried at 110 \({}^{\circ}\)C. Sulfonated material was magnetically stirred in 50 mL of 1 M NaCl solution at RT for 1 d followed by collection by gravity filtration, washing with H\({}_{2}\)O, and drying at 110 \({}^{\circ}\)C. The final sulfonated, phenyl grafted materials are referred to as E25-Ph(2) and E50-Ph(2), reflecting their base E25 or E50 scaffold, the phenyl group modification (Ph), and the sorbent type (2). Synthesis of ED11-Ph1(3), ED11-Ph2(3), and ED11a(4) (Types 3 and 4, Mixed Ethane and Diethylbenzene-Bridged Organosilicates, Ph Indicates Grafted Phenyl Groups)  
The base scaffold (ED11) was synthesized as previously reported [28]. Pluronic P123 (3.8 g) and mesitylene (1.0 g) were dissolved in 15.0 g of 0.1 M HNO\({}_{3}\) with heat (\(\sim\)65 \({}^{\circ}\)C) and magnetic stirring. The stirring mixture was then allowed to cool to room temperature. A silane mixture of 1,2-bis(trimethoxysilyl)ethane (2.12 g) and bis(trimethoxysilylethyl)benzene (2.94 g) was added drop-wise, and the mixture was stirred to homogenize (\(\sim\)1 min). The mixture was transferred to culture tubes that were tightly sealed and incubated in an oven at 60 \({}^{\circ}\)C overnight.