U.S. patent application number 15/472925 was filed with the patent office on 2017-10-05 for sorbent design for improved glycerol adsorption.
The applicant listed for this patent is The Government of the United States of America, as represented by the Secretary of the Navy, The Government of the United States of America, as represented by the Secretary of the Navy. Invention is credited to Brian Melde, Martin H. Moore, Brandy J. White.
Application Number | 20170283722 15/472925 |
Document ID | / |
Family ID | 59929146 |
Filed Date | 2017-10-05 |
United States Patent
Application |
20170283722 |
Kind Code |
A1 |
Melde; Brian ; et
al. |
October 5, 2017 |
Sorbent Design for Improved Glycerol Adsorption
Abstract
Mesoporous organosilica sorbents are effective to remove
contaminants (such as glycerol or detergent) from biodiesel.
Contacting biodiesel with various a mesoporous organosilica
sorbents comprising phenyl and sulfonate moieties resulted in the
contaminants being absorbed by the sorbent and thus removed from
the biodiesel.
Inventors: |
Melde; Brian; (Alexandria,
VA) ; White; Brandy J.; (Washington, DC) ;
Moore; Martin H.; (Woodbridge, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Government of the United States of America, as represented by
the Secretary of the Navy |
Arlington |
VA |
US |
|
|
Family ID: |
59929146 |
Appl. No.: |
15/472925 |
Filed: |
March 29, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62314577 |
Mar 29, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10L 2290/542 20130101;
B01J 20/262 20130101; C10L 2200/0476 20130101; Y02E 50/13 20130101;
Y02E 50/10 20130101; C10L 1/19 20130101; C10L 2270/026
20130101 |
International
Class: |
C10L 1/02 20060101
C10L001/02; B01J 20/26 20060101 B01J020/26 |
Claims
1. A method of removing a contaminant from biodiesel, comprising:
contacting a mesoporous organosilica sorbent comprising phenyl and
sulfonate moieties with a biodiesel containing a contaminant; then
separating the biodiesel from the sorbent, whereby a fraction of
the contaminant in the biodiesel is absorbed by the sorbent and
thus removed from the biodiesel.
2. The method of claim 1, wherein said contaminant is glycerol.
3. The method of claim 2, wherein the sorbent is effective to
absorb at least 50% of the glycerol.
4. The method of claim 1, wherein said contaminant is a
detergent.
5. The method of claim 4, wherein the sorbent is effective to
absorb at least 50% of the detergent.
6. The method of claim 1, wherein the sorbent is selected from the
group consisting of ED11-Ph1, D13b, and D13-Ph2.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application claims the benefit of U.S. Provisional
Application 62/314,577 filed on Mar. 29, 2017, the entirety of
which is incorporated herein by reference.
BACKGROUND
[0002] Biodiesel is produced by transesterification of animal fat,
vegetable oil, or waste cooking oil with an alcohol, producing the
desired biodiesel fuel along with glycerol as a byproduct. A number
of studies have focused on the evaluation of the economic viability
of biodiesel..sup.2-5 Production costs are approximately 0.5 USD/L,
1.5 times that of petroleum-based diesel, with virgin feedstocks
comprising 50 to 70% of costs..sup.3,4 The feedstock costs can be
reduced through the use of waste cooking oils and similar products,
but these materials increase the complexity of synthesis and,
often, the presence of contaminants..sup.5 In addition to providing
a renewable source of energy, biodiesel is attractive as an
alternative fuel due to related reduced environmental impact; use
of these fuels decreases emission of atmospheric pollutants..sup.6
Procuring water together with liquid and solid waste disposal
comprise up to 10% of manufacturing costs,.sup.3,4 while also
influencing the environmental impact of this alternative fuel
source. As an example, multiple wash steps for biodiesel
purification can generate gallons of waste water for each gallon of
usable biofuel. Biodiesel contaminants include glycerol, alcohols,
free fatty acids, surfactants, and residual catalyst. Glycerol,
while a contaminant in biodiesel, can be recovered and purified to
aid in offsetting the costs of biodiesel production..sup.4
[0003] Contaminants (including glycerol) can be removed from
biodiesel via the use of dry wash media as an alternative or
partial replacement for water washing. Currently, use of dry wash
media for cleaning biodiesel is largely limited to small operations
and hobbyists. Using dry wash media avoids excessive waste water
production while reducing production time and requiring less space
when compared to water washing. BD ZorbX and DudaLite (DW-R10.RTM.)
ion exchange resin are commercial examples of types of materials
used for this purpose. BD ZorbX is a mixture of cellulose fibers
from hardwood intended to absorb a variety of contaminants
including surfactants, glycerol, and catalyst; Eco2Pure.TM. is a
similar material. DW-R10 is intended as a polishing step following
bulk glycerol removal, and it is claimed to remove surfactants,
glycerol, catalyst, and water. Drionex, Purolite.RTM. PD206, and
Magnesol D-Sol are intended for similar applications.
[0004] A need exists for alternative sorbent materials.
BRIEF SUMMARY
[0005] Sulfonated sorbents can capture targets from complex
mixtures. Described herein are sorbents directed at removal of
undesirable contaminates in fuel preparations. In particular, the
sorbents developed under this effort are intended for use in the
removal of glycerol and surfactants from fuel preparations. Their
application may be (for example) (1) as dry wash polishing media,
(2) for purification processes, or (3) as part of an analytical
process for evaluation of fuel quality.
[0006] In one embodiment, a method of removing a contaminant (such
as glycerol and/or detergent) from biodiesel includes contacting a
mesoporous organosilica sorbent comprising phenyl and sulfonate
moieties with a biodiesel containing a contaminant; then separating
the biodiesel from the sorbent, whereby a fraction of the
contaminant in the biodiesel is absorbed by the sorbent and thus
removed from the biodiesel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows various structures related to sorbent
compositions. The material variants are presented here showing both
the sorbent scaffold (boxed area) and the groups added during
post-synthesis processing.
[0008] FIG. 2A shows nitrogen sorption analysis for several
sulfonated sorbents and FIG. 2B shows pore size distributions for
the same sorbents. In each FIG. 2A, the curves appear in the
following order from bottom to top: S65-Ph, S85-Ph, E25-Ph, and
E50-Ph. In FIG. 2B, S65-Ph is represented by a line with two long
dashes and a short dash, S85-Ph is represented by a line with one
long dash and two short dashes, E25-Ph is represented by a line
with widely-spaced medium dashes, and E50-Ph is represented by a
line with closely-spaced smaller dashes.
[0009] FIG. 3A shows nitrogen sorption analysis for additional
sulfonated sorbents: top panel ED11-Ph1; lower panel top curve ED11
and lower curve ED11-Ph2. FIG. 3B shows pore size distributions for
the same sorbents, labeled as follows: ED11 (two long dashes and a
short dash), ED11-Ph1 (two short dashes and a long dash), and
ED11-Ph2 (medium dashes).
[0010] FIGS. 4A, 4B, 4C, and 4D show nitrogen sorption analysis (A
and B) and pore size distribution (C and D), for further sulfonated
sorbents. In FIGS. 4A and 4C, the curves represent, from top to
bottom, D13a, D13c, and D13-Ph. In FIG. 4B the top curve is D13-Ph2
and the lower curve is D13-Ph. In FIG. 4D, D13-Ph2 has two long
dashes and a short dash (heavier weight) while D13-Ph has two long
dashes and a short dash (lighter weight).
[0011] FIGS. 5A and 5B show nitrogen sorption analysis and pore
size distribution, respectively, for sulfonated resins. In each of
these, the top curve is PDVB-2 and the lower curve is PDVB-3.
[0012] FIG. 6 shows glycerol binding by sorbents. Experiment used a
solution consisting of 271 .mu.M glycerol in water (10 mL) with 30
mg sorbent.
[0013] FIGS. 7A and 7B show glycerol binding isotherms for E25-Ph
(closely-spaced short dashes), S85-Ph (two long dashes and a short
dash), ED11-Ph1 (widely-spaced medium dashes), D13-Ph (triplets of
a long dash between two shorter dashes with spaces between), PDVB-2
(alternating long and short dashes) presented for use of equivalent
sorbent mass (A) and calculated for equivalent sorbent surface area
(B).
[0014] FIG. 8 shows binding of glycerol from spiked biodiesel by
the sorbents. Experiment used a solution consisting of 250 .mu.M
glycerol in biodiesel (10 mL) with 30 mg sorbent.
[0015] FIG. 9 shows binding of Triton X-100 (250 .mu.M) from water
(dotted bars) and spiked biodiesel (gridded bars) by ED11-Ph1
(varied sorbent mass).
[0016] Regarding the above identification of lines and curves by
relative position, this relates to their relative position at the
mid-point of the X axis.
DETAILED DESCRIPTION
[0017] Definitions
[0018] Before describing the present invention in detail, it is to
be understood that the terminology used in the specification is for
the purpose of describing particular embodiments, and is not
necessarily intended to be limiting. Although many methods,
structures and materials similar, modified, or equivalent to those
described herein can be used in the practice of the present
invention without undue experimentation, the preferred methods,
structures and materials are described herein. In describing and
claiming the present invention, the following terminology will be
used in accordance with the definitions set out below.
[0019] As used in this specification and the appended claims, the
singular forms "a", "an," and "the" do not preclude plural
referents, unless the content clearly dictates otherwise.
[0020] As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0021] As used herein, the term "about" when used in conjunction
with a stated numerical value or range denotes somewhat more or
somewhat less than the stated value or range, to within a range of
.+-.10% of that stated.
[0022] Overview
[0023] The sorbents developed under this effort are intended for
use in the removal of glycerol and surfactants from fuel
preparations. Their application may be (for example) (1) as dry
wash polishing media, (2) for purification processes, or (3) as
part of an analytical process for evaluation of fuel quality.
[0024] Hierarchical nanoporous scaffolds offer an alternative to
currently available commercial dry wash media. The materials under
consideration are hybrid inorganic-organic materials.sup.7-17 in
which inorganic and organic moieties are mixed on the molecular
scale through the use of bridged polysilsesquioxane
precursors..sup.18 The materials offer large macropores with a
templated mesopore structure..sup.7,12,17,19 While a number of
applications have been reported for mesoporous sorbents, additional
applications can be facilitated through the use of these
hierarchical structures; the macroscale features reduce diffusion
limitations and increase access to the mesopore volumes..sup.20,21
Materials of this type have been used for the capture of
nitroenergetic and organophosphate targets..sup.20,22 The materials
of the current study were developed for adsorption of glycerol,
which can result in fuel tank deposits, injector corrosion, and
higher emissions of aldehydes. The materials are synthesized with
varying composition of the pore walls then sulfonated to promote
hydrogen bonding interactions with glycerol. While this sulfonation
of the material provides a similar functionality to that present in
several of the dry wash media mentioned above, incorporation of the
sulfonate groups on and within the scaffold and adjacent to varying
structures provides an avenue for significant improvements in
performance through scaffold tailoring.
[0025] Description and Operation
[0026] Synthesis of Sorbent Materials
[0027] E25-Ph and E50-Ph: Scaffold materials were synthesized as
described in previous reports..sup.21,23 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.sub.3 with heat
(.about.65.degree. 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 (.about.1 min) and transferred to culture
tubes. Tubes were tightly sealed and incubated in an oven at
60.degree. C. overnight. The tubes were unsealed, and the white
monolithic gels were heated for 2 d at 60.degree. C. followed by 2
d at 80.degree. 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 2 more times. The collected solid was washed
thoroughly with ethanol and water and dried at 110.degree. C.
[0028] Grafting with phenyl groups followed a simple published
procedure, beginning with an additional drying step at
>100.degree. C. in a vacuum..sup.24 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.degree. C. Sulfonation
was accomplished as described previously by magnetically stirring
the phenyl-grafted material in 25 mL of H.sub.2SO.sub.4 at
75.degree. C. for 1 d..sup.25 The acidic mixture was then added to
.gtoreq.200 mL of H.sub.2O. Solid was collected by gravity
filtration, washed with H.sub.2O, and dried at 110.degree. 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.sub.2O, and drying at 110.degree. C.
[0029] ED11-Ph1, ED11-Ph2, and ED11: The base scaffold was
synthesized as described previously..sup.26 Pluronic P123 (3.8 g)
and mesitylene (1.0 g) were dissolved in 15.0 g of 0.1 M HNO.sub.3
with heat (.about.65.degree. 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 (.about.1 min). The mixture
was transferred to culture tubes that were tightly sealed and
incubated in an oven at 60.degree. C. overnight. The tubes were
unsealed, and the white monolithic gels were heated for 2 d at
60.degree. C. followed by 2 d at 80.degree. C. The block copolymer
was extracted from the dried materials by refluxing overnight in 1
M HCl in ethanol; the solid was collected by vacuum filtration.
This process was repeated 2 more times. The collected solid was
washed thoroughly with ethanol and water, then dried at 110.degree.
C. Grafting, sulfonation, and sodium exchange for ED11-Ph1 and
ED11-Ph2 were completed using the protocols described above;
ED11-Ph1 and ED11-Ph2 refer to similarly but separately synthesized
materials. The sulfonation step produces the variation in materials
characteristics. ED11 was not grafted with phenyl groups prior to
sulfonation and sodium exchange.
[0030] S65-Ph and S85-Ph:Scaffold materials were synthesized based
on a previously published procedure..sup.27,28 Pluronic P123 (4.0
g) and 0.65 g (S65) or 0.85 g (S85) mesitylene were dissolved in
12.0 g of 1.0 M HNO.sub.3 with heat (.about.65.degree. C.) and
magnetic stirring. The mixture was allowed to cool to room
temperature before drop-wise addition of 5.15 g tetramethyl
orthosilicate, and the mixture was stirred to homogenize (.about.1
min). The mixture was transferred to culture tubes that were
tightly sealed and incubated at 60.degree. C. overnight. The tubes
were unsealed, and the white monolithic gels were heated at
60.degree. C. for 6 d. The material was calcined under ambient
atmosphere: temperature was ramped 1.degree. C./min to 650.degree.
C. and held for 5 h. Material was refluxed in 1 M HCl for 1 d,
similar to the solvent extraction process for other materials, to
condition the surface similarly for grafting. It was then collected
by vacuum filtration, washed with ethanol and H.sub.2O, and dried
at 110.degree. C. Grafting, sulfonation, and sodium exchange for
these sorbents were completed using the protocols described
above.
[0031] D13-Ph, D13a, D13b, D13c, and D13-Ph2: Scaffold materials
were synthesized by dissolving Pluronic P123 (3.8 g) and mesitylene
(1.8 g) in 16.0 g of 0.1 M HNO.sub.3 with heat (.about.65.degree.
C.) and magnetic stirring. The mixture was allowed to cool to room
temperature prior to drop-wise addition of
bis(trimethoxysilylethyl)benzene (5.87 g), and the mixture was
stirred to homogenize it (.about.1 min). The mixture was
transferred to culture tubes that were tightly sealed and incubated
in an oven at 60.degree. C. overnight. The tubes were unsealed, and
the white monolithic gels were heated for 2 d at 60.degree. C. and
2 d at 80.degree. C. Block copolymer was extracted from the dried
materials by refluxing overnight in 1 M HCl in ethanol; the solid
was collected by vacuum filtration. This process was repeated 2
more times. The collected solid was washed thoroughly with ethanol
and water, then dried at 110.degree. C. Grafting, sulfonation, and
sodium exchange for D13-Ph were completed using the protocols
described above . D13a, D13b, and D13c were not grafted with phenyl
groups prior to sulfonation and sodium exchange; the designations
a, b, and c refer to similarly but separately synthesized
materials. D13b in particular was sulfonated using 50%
H.sub.2SO.sub.4 rather than undiluted acid. D13-pH2 is the same
type of material as D13-Ph but was sulfonated with 50%
H.sub.2SO.sub.4 in the way that D13b was treated.
[0032] PDVB-2 and PDVB-3: Divinylbenzene (DVB) resins were
synthesized in a Teflon-lined autoclave reactor (23 mL capacity)
using a procedure adapted from Libu{hacek over (s)}e Hankova et al.
"Role of Water as a Coporogen in the Synthesis of Mesoporous
Poly(divinylbenzene)," Journal of Applied Polymer Science, 2014,
DOI:10.100.sup.2/app.41198, incorporated herein by reference for
this teaching. For PDVB-2, DVB (1.5 g; Aldrich technical grade,
80%) was added to tetrahydrofuran (15 mL) with water (0.75 mL) and
2,-2'-azobis(2-methylpropionitrile) (0.0375 g; Aldrich, 98%). The
reactor was heated at 100.degree. C. for 48 h. Following cooling to
room temperature, the reactor was opened and the resin was allowed
to dry overnight at room temperature followed by complete drying at
100.degree. C. PDVB-3 was synthesized identically with the
exception of the water coporogen used in the PDVB-2 synthesis which
was omitted. Ground resin was added to hexane (20 mL) to produce a
wet slurry, and sulfuric acid was added (25 mL) for the suflonation
step. The mixture was heated at 75.degree. C. for 1 d before
addition of water (300 mL). Sulfonated material was collected by
vacuum filtration and washed thoroughly with water before drying at
100.degree. C. Sodium exchange was completed by stirring the
material in 1 M NaCl (50 mL) at room temperature for 1 d. The resin
was then washed with water, collected by vacuum filtration, and
dried at 100.degree. C.
[0033] Sorbent Characteristics
[0034] Sulfonation of poly-(styrene-co-divinylbenzene) resin has
been described for increasing hydrogen bonding with and, therefore,
removal of glycerol by resin material..sup.29 The previous work in
this area did not consider the impact of the scaffold or the
morphology of the resin on target adsorption. Because the chemical
structures in close proximity to the sulfonate groups are likely to
impact the interaction of those groups with glycerol, a series of
porous organosilicate materials in which the pore wall composition
has been varied was synthesized. Many cases were considered;
S65/S85 and E25/E50 offer no sites for sulfonation on the base
sorbent. ED11 and D13 offer phenyl rings that comprise at least a
portion of the bridging groups. Sulfonation of the materials
directly (ED11 and D13) or sulfonation following grafting of
additional phenyl groups were completed for this range of
materials. The schematic provided in FIG. 1 illustrates the
variations in the resulting materials.
[0035] Table 1 provides a summary of morphological characteristics
for these materials.
TABLE-US-00001 TABLE 1 Morphological characteristics for the
sulfonated sorbents. Surface Pore Pore Area Volume Diameter
Material Type (m.sup.2/g) (cm.sup.3/g) (.ANG.) S65-Ph 1 515 0.548
56 S85-Ph 1 578 0.626 64 E25-Ph 2 803 0.740 64 E50-Ph 2 883 0.664
51* ED11-Ph1 3 147 0.151 48 ED11-Ph2 3 27 0.047 50 ED11 4 87 0.111
55 D13-Ph 5 4.0 0.010 --* D13-Ph2 5 310 0.510 67 D13a 6 3.1 0.007
--* D13b 6 337 0.536 75 D13c 6 3.2 0.013 --* ED13 -- 478 0.527 56
PDVB-2 -- 405 0.564 126 PDVB-3 -- 336 0.375 65 *Broad; no
well-defined peak in the pore size distribution
[0036] FIG. 1 illustrates chemical structures of various types of
sorbents described here, by type number 1 through 6. The Type 1
materials (FIG. 1) provide a sodium-exchanged, sulfonated phenyl
group pendant on a silicate scaffold. Nitrogen sorption analysis
indicates type IV isotherms characteristic of mesoporous materials
(FIG. 2A). The silicate scaffolds are ordered mesostructures with
2D hexagonally packed cylindrical mesopores. The pore sizes in the
two materials are influenced by the amounts of mesitylene swelling
agent included in the syntheses..sup.27,28 The Type 2 materials
provide the same pendant functional group on an ethane-bridged
organosilicate sorbent. The base E50 scaffold offers a combination
of disordered micropores and mesopores (FIG. 2B). The type IV
nitrogen sorption isotherm of the E25 sorbent is similar to those
of S65-Ph and S85-Ph.
[0037] Type 3 materials, based on ED11, have 50% of the ethane
bridging groups of the E50 and E25 scaffolds replaced with
diethylbenzene groups. This provided the potential for direct
sulfonation of phenylene groups within the pore walls in addition
to the grafted phenyl groups. Type 4 sorbents are sodium-exchanged
sulfonated ED11 with no grafted phenyl moieties. Most products
sulfonated with undiluted H.sub.2SO.sub.4 display type II nitrogen
sorption isotherms indicative of relatively non-porous materials
(e.g. ED11-Ph2 in FIG. 3).
[0038] Type 5 and 6 sorbents, based on D13, have the highest
concentration of diethylbenzene bridging groups in their scaffold
walls; Type 5 sorbents also include grafted pendant phenyl
moieties. Functionalization using undiluted H.sub.2SO.sub.4 leads
to collapse of the mesostructure (FIG. 4). D13b was treated with
50% H.sub.2SO.sub.4, preserving the mesostructure (FIG. 4). The
nitrogen isotherm shows considerable hysteresis between its
adsorption and desorption branches, indicative of "bottle-necks" in
the mesopore structure. Nitrogen adsorption isotherms for porous
sulfonated polydivinylbenzene resins PDVB-2 and PDVB-3 are provided
for comparison (FIG. 5).
[0039] Glycerol Binding from Aqueous Solutions. Batch type
experiments were used to generate isotherms for the binding of
glycerol from water by the sorbent variants. Analysis was completed
by determination of the glycerol remaining in solution following
overnight incubation of varying sorbent masses with glycerol
solutions of varied concentration. Analysis of glycerol was based
on the method described by ASTM D6584-13..sup.30 Samples and
control solutions were all water-based; water was removed from a 5
mL aliquot using a KD Scientific Centrifan PE-T (Model 78-0070). A
stock solution of N-methyl-n-(trimethylsilyl)trifluoroacetamide
(MSTFA; 1.2 mL) in pyridine (2 mL) was prepared. This solution (160
.mu.L) was added to the dried sample followed by incubation for 20
min. Heptane (1.6 mL) was then added, and the sample was
transferred to an autosampler vial for GC analysis. GC-MS analysis
was performed using a Shimadzu GCMS-QP2010 with AOC-20 autoinjector
equipped with a Restex Rtx-5 (30 m.times.0.25 mm ID.times.0.25
.mu.m df) cross bond 5% diphenyl 95% dimethyl polysiloxane column.
A GC injection temperature of 200.degree. C. was used with a 1:1
split ratio at a flow rate of 3.6 mL/min at 69.4 kPa. The oven
gradient ramped from 50.degree. C. (1 min hold time) to 180.degree.
C. at 15 C/min and then to 300.degree. C. at 20.degree. C./min
where it was held for 5 min.
[0040] FIG. 7 provides some examples of binding isotherms. Target
binding by these types of sorbents has previously been described by
phenomenological models such as those represented by the Langmuir
and Langmuir-Freundlich formulations..sup.20,26,31 For the glycerol
binding data, the Langmuir-Freundlich equation was used:
q = q s Ak [ L ] n 1 + k [ L ] n ##EQU00001##
[0041] Here, q is the amount of target bound per unit sorbent
surface area, L is the free ligand, k is the affinity coefficient,
n is the homogeneity factor, and A is the total surface area. The
typically used saturation capacity is q.sub.s. FIGS. 7A and 7B show
exemplary glycerol binding isotherms, and Table 2 provides a
summary of the calculated parameters for the various materials.
TABLE-US-00002 TABLE 2 Parameters generated from application of the
Langmuir- Freundlich equation to glycerol binding data. Material
q.sub.s (.mu.g/m.sup.2) k (1/mg) n S65-Ph 72.4 2.78 1 S85-Ph 42.4
1.92 1 E25-Ph 14.9 4.78 1 E50-Ph 5.87 10.8 1 ED11-Ph1 145 13.5 1
ED11-Ph2 450 24.0 1 ED11 207 0.920 1 D13-Ph 2689 3.95 1 D13-Ph2
1780 4.15 1 D13a 5290 4.56 1 D13b 811 1.96 1 D13c 5190 4.45 1 ED13
81.2 0.461 1 PDVB-2 1059 0.019 1 PDVB-3 1620 0.029 1
[0042] Glycerol Capture from Biodiesel. Several of the materials
used for capture of glycerol from aqueous solution were also
evaluated in a solution based on in-house prepared biodiesel. The
solution was prepared through adaptation of a widely available
small batch production protocol. Food grade canola oil (1 L) was
warmed to 50.degree. C. on a hotplate. In a separate container,
methanol (355 mL) and sodium hydroxide (3.5 g) were mixed. This
mixture was slowly added to the warmed oil and the result was
stirred for 2 h (50.degree. C.). The reacted solution was moved to
a reparatory funnel and allowed to settle so that bottom glycerol
could be drained. Rotary evaporation was used to remove residual
methanol from the final solution and the pH was verified to be
neutral. A known concentration of glycerol was added to this
preparation for sorbent evaluation and controls were analyzed using
a modification of the protocol described above for glycerol binding
from aqueous solutions. For sample preparation, the sorbent
containing solution was filtered to remove the sorbent (as
necessary). A 100 .mu.L aliquot was added to 100 .mu.L MSTFA. This
solution was mixed well and incubated at room temperature for 20
min before addition of heptane (8 mL). The result was transferred
to an auto sample vial for analysis by the GC-MS protocol described
above for glycerol binding from aqueous solutions.
[0043] FIG. 8 presents data for capture of glycerol from the
biodiesel preparation by several of the developed sorbents as well
as by the commercial products BD ZorbX Dry Wash Media and DudaLite
Dry Wash Resin DW-R10. The figure also shows data for sodium
exchanged versions of the commercial media. A Type 6 sorbent
dramatically out performs the commercial sorbents as does the Type
3 sorbent.
[0044] Capture of Other Targets. In addition to providing removal
of glycerol, the sorbents described here offer capture of other
targets of potential interest to biodiesel production and analysis.
Triton X-100 was used as a model for detergents. Table 3 provides
parameters from Langmuir-Freundlich fits of data sets resulting
from batch experiments in aqueous solution. Binding of Triton X-100
from spiked biodiesel samples was also evaluated. As shown in FIG.
9, capture of the target from biodiesel was similar to that from
aqueous solution.
TABLE-US-00003 TABLE 3 Parameters generated from application of the
Langmuir- Freundlich equation to Triton X-100 binding data.
Material q.sub.s (.mu.g/m.sup.2) k (1/mg) n S65-Ph 5960 0.17 1
S85-Ph 860 8.99 1 E50-Ph 310 0.02 1 ED11-Ph1 2200 0.15 1 ED11-Ph2
12200 0.03 1 ED11 2180 0.08 1 D13-Ph 48200 0.44 1 D13-Ph2 Binds
100% from all experiments D13a 5500 11.6 1 D13b Binds 100% from all
experiments D13c 31800 0.10 1 ED13 Binds 100% from all experiments
PDVB-2 220 0.60 1 PDVB-3 200 0.60 1
[0045] Prophetic Applications. The sorbents could be contacted with
biodiesel or other liquids for various lengths of time ranging from
minutes to hours to days or even longer, for example by introducing
a biodiesel to a vessel containing the sorbent and removing a
cleaned biodiesel from the vessel. The contacting could occur in
various formats allowing continuous, column, or batch type
applications. The contacting in these formats could occur as a
gravity driven process, with added pressure, or be driven through
application of a vacuum. The contacting could be with or without
agitation including mechanical agitation such as stirring and/or
sonication. The contacting can be at ambient or other temperature,
for example at an elevated temperature between ambient and a flash
point of the liquid. One or more different types of sorbent can be
used. Following contacting, the sorbent(s) can be separated by
filtration, centrifugation, or other techniques known in the art.
In other embodiments, separation can be aided by passing a liquid
(such as biodiesel) over immobilized sorbent, for example in a
column. The used be washed (e.g., with alcohol and/or a aqueous
solution) and reused, with glycerol optionally recovered.
[0046] Concluding Remarks
[0047] Reagents of the type described here provide the potential
for improved dry wash media in biodiesel purification processes.
The approach, controlling the distribution and concentration of
sulfonate groups within the sorbent structure, provides a
significant advantage over previous approaches utilized for
development of these types of sorbents. The materials offer
additional potential in analysis of biodiesel. Similar sorbents
have been applied for solid phase extraction, resulting in
concentration and purification of targets.
[0048] Current efforts in reducing the water necessary for
purification of biodiesel are focused on inexpensive and, often,
disposable media. The advantages described here offer the potential
for media with improved performance characteristics as well as a
method for reuse of the material. These characteristics also lead
to the potential for enhancing analytical methods applied to
biodiesel analysis through their use as a solid-phase extraction
sorbent.
[0049] All documents mentioned herein are hereby incorporated by
reference for the purpose of disclosing and describing the
particular materials and methodologies for which the document was
cited.
[0050] Although the present invention has been described in
connection with preferred embodiments thereof, it will be
appreciated by those skilled in the art that additions, deletions,
modifications, and substitutions not specifically described may be
made without departing from the spirit and scope of the invention.
Terminology used herein should not be construed as being
"means-plus-function" language unless the term "means" is expressly
used in association therewith.
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