Hydroxypropylation of Guar Splits: Kinetics and Rheology | Industrial

Jun 12, 2019 - Hydroxypropyl guar (HPG) is one of the most important derivatives of natural guar gum. In this paper, we describe the hydroxypropylatio...
0 downloads 0 Views 1MB Size
Download PDF
Article pubs.acs.org/IECR

Cite This: Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Hydroxypropylation of Guar Splits: Kinetics and Rheology Jie Gao and Brian P. Grady* School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, United States

Downloaded via NOTTINGHAM TRENT UNIV on August 9, 2019 at 19:45:57 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

S Supporting Information *

ABSTRACT: Hydroxypropyl guar (HPG) is one of the most important derivatives of natural guar gum. In this paper, we describe the hydroxypropylation kinetics when these functional groups are added to guar splits, which are the form of guar gum typically modified in an industrial process. NMR spectroscopy was applied to quantify the amount of reacted propylene as a function of reaction time. A kinetic model was then established, enabling the derivation of a reaction rate law for the hydroxypropylation of guar. Finally, we investigated the rheological properties of aqueous-phase HPG and its cross-linked derivatives as a function of propylene content and cross-linker amount.

1. INTRODUCTION Guar gum (GG) is derived from the seeds of guar beans. GG is a nonionic, water-soluble, and biocompatible heteropolysaccharide composed of a β-(1−4) D-mannopyranose backbone linked with α-(1−6) D-galactopyranose residues as side chains (Figure 1).1−3 With the property of producing highly viscous

Previously, we reported the reaction kinetics of the carboxymethylation of guar splits and the rheological properties of the corresponding products.18 Guar splits are the product after guar seeds are dehusked.19 Most laboratory studies use guar powder, which results after splits are milled and screened.20−24 Guar gum powder can be easily dissolved in water; however, for a variety of cost reasons, most industrial processes use guar splits, which do not dissolve but only swell in water under industrial conditions. Preparation of HPG has been reported using guar powders.20,25,26 A procedure for producing HPG from guar splits has not been published in the open literature to our knowledge. We were the first group to report a laboratory procedure for the chemical modification of guar splits, and we use part of that procedure for propoxylation as well. In the present work, we determine the rate equation to quantify the kinetics of the reaction of guar splits with propylene oxide. Further, we establish the relationships between substitution levels and the corresponding rheological properties of both the un-cross-linked and cross-linked products with borate and zirconium cross-linkers. Quantifying propoxylation kinetics as well as rheological properties improves structure−property knowledge of HPG substantially and provides valuable insights for industrial manufacturing and applications.

Figure 1. Structure of guar gum.

aqueous solutions, guar gum has been extensively employed as a thickener, binder, and stabilizer in many industrial applications.4−10 Although the use of guar gum without any chemical modification is common, many advantages of chemically modified GG exist, such as improved clarity, solubility, and stability in aqueous dispersion.11 The subject of this paper, hydroxypropyl guar (HPG), which is guar reacted with propylene oxide, is more hydrophobic than guar; the propylene oxide shifts the hydrophilic−lipophilic balance (HLB), which enables more pronounced partitioning of the molecules into the oil phase in the water−oil environment.11 Compared with pristine guar gum, HPG is expected to display faster dissolution and greater temperature resistance, which enable applications as natural additives in detergent and coal and in the medical industry.12−14 Guar and its derivatives are used as gellants in cross-linked fracking fluids used for the enhanced recovery of crude oil.15−17 © 2019 American Chemical Society

2. EXPERIMENTAL SECTION 2.1. Materials. Guar gum splits were provided by United Guar LLC. Sodium hydroxide (NaOH) was purchased from Sigma-Aldrich. Propylene oxide (PO) was purchased from Acros Organics. Boric acid and sodium zirconium lactate were purchased from City Chemical LLC. All chemicals were used as received without further purification. Received: Revised: Accepted: Published: 11673

March 27, 2019 June 10, 2019 June 12, 2019 June 12, 2019 DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Article

Industrial & Engineering Chemistry Research

2.3. 1H NMR Spectroscopy. 1H NMR spectroscopy was performed at 400 MHz with a Varian VNMRS-400 spectrometer. Prior to the NMR measurements, HPG products were partially hydrolyzed by being dispersed in 3.0 mol/L HCl (75% acetone solution), washed, and dried in a vacuum. All samples were dissolved in D2O. 1H NMR spectra were recorded at a probe temperature of 298 K. 2.4. Determination of the Degree of Molar Substitution. The degree of molar substitution (MS) was used to evaluate the extent of the reaction. The MS measures the average number of moles of propylene oxide substituted per mole of monosaccharide unit. The MS values of HPG could be measured by 1H NMR spectroscopy, because the chemical environment of the methyl group hydrogens is different from that of the hydrogens on the guar gum backbone. Specifically, the chemical shift of the methyl group protons on the hydroxypropyl group is located at high field (δ < 2.0 ppm), whereas the chemical shifts of other protons are at low field (δ > 3.0 ppm). Hence, the hydroxypropyl group can be quantified, and MS of HPG can be obtained by using this characteristic peak. Figure 2 shows a comparison of the 1H NMR spectra for guar gum and hydroxypropyl guar gum. The new peaks at δ ∼ 1.1 ppm, which belong to three protons from methyl groups, prove the success of the reaction. Low field peaks at δ above 4.8 ppm are attributed to the anomeric protons from each monosaccharide unit. The other sugar protons were located in the range of δ = 3.3−4.2 ppm. The MS value of HPG could be calculated according to the following equation.20

2.2. Synthesis of Hydroxypropyl Guar Gum. A two-step procedure starting with guar splits was applied to prepare HPG, as shown below. In the first step, which is identical to that of the method for carboxymethylation,18 guar splits are hydrated; this is followed by the addition of sodium hydroxide as an alkaline catalyst to deprotonate the hydroxyl groups and thereby increase their nucleophilicity (Reaction 1). This step also swells the splits,

which is critical for high conversions.18 In the second step, the etherification agent propylene oxide (PO) is used to allow nucleophilic substitution, forming the modified guar HPG (Reaction 2). The reaction proceeds easily because of the large

ring strain of the propylene oxide. Once propylene oxide substitutes on the hydroxyl group, another propylene oxide may react, leading to an oligomeric propylene oxide unit (Reaction 3).

The reactions were performed in a 2CV helicone mixer from Design Integrated Technologies, Inc., at room temperature because of the low boiling point (34 °C) of propylene oxide. Guar splits (32.4 g) were hydrated for 30 min by a weight equivalent amount of water. Then, 20 g of 40% sodium hydroxide was added under a nitrogen atmosphere for another 30 min to deprotonate the hydroxyl groups. Different amounts of propylene oxide were finally added to generate different levels of substituted products. After the reaction, the product was dispersed into 80% (v/v) ethanol, neutralized with diluted hydrochloric acid, washed with 80% acetone, and dried overnight in a vacuum.

MS =

(1/3) × Imethyl Ianomeric

where Imethyl is the integral of the methyl group hydrogen atoms in the hydroxypropyl moieties. The 1/3 term in the equation results from the fact that the methyl groups of the hydroxypropyl moieties each have three hydrogen atoms. Ianomeric is the integral of all the hydrogen atoms of anomeric

Figure 2. 1H NMR spectra of guar gum (top) and hydroxypropyl guar gum (bottom). 11674

DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Article

Industrial & Engineering Chemistry Research kexptl = k[PO]0 n

carbons in a guar gum molecule; there is one anomeric hydrogen atom per monosaccharide unit. The integration ratio of the peak area is used to determine the MS for the produced HPG. Two-dimensional NMR spectra were also studied to investigate the reaction of propylene oxide attached to guar gum. Unfortunately, we could not determine either the average length of the propylene oxide oligomer or the fraction of hydroxyl groups reacted. 2.5. Rheological Studies. Rheological properties of HPG with different MS values were evaluated in both steady-shear and oscillating experiments. Measurements were carried out on a TA Instruments Discovery Series hybrid rheometer (DHR-2) with 40 mm parallel-plate geometry. The temperature was maintained at 25 °C throughout the experiments. For oscillatory experiments, shear strains at different compositions were varied as determined by the strain sweep because of the desire to maximize the response while still maintaining the linear viscoelastic region for each sample. Aqueous HPG solutions were prepared in a series of concentrations from 0.018 to 1% by weight. In order to prevent biodegradation, a 0.1% (v/v) concentration of glutaraldehyde bactericide was added to the sample solutions. Steady-state viscosities of solutions prepared at different HPG concentrations were recorded at different shear rates. The oscillatory measurements were performed for a 1% solution of each HPG sample. Cross-linked samples were prepared with one HPG product (MS = 0.53) at a concentration of 0.5 wt %, which is within the range recommended and used in the oil field industry.27 Sodium thiosulfate (0.12%) was added as a gel stabilizer.28 Sodium carbonate was used to adjust the pH above 9.5. Rheological properties were evaluated first with no cross-linker, and then boric acid and sodium zirconium lactate cross-linkers were added at concentrations of 20, 50, 100, and 200 ppm.

Then, the rate law equation is expressed as r = k[GG−ONa]m [PO]n = (k[PO]0 n )[GG−ONa]m = kexptl[GG−ONa]m

In the equation, the reaction rate is only related to the concentration of GG. 1 H NMR was used to monitor the reaction progress by determining the MS value as a function of the reaction time. As shown in Figure 3, it was observed that the reaction nearly

Figure 3. MS values at different reaction times.

reached an equilibrium state with a maximum MS (MSmax) of 1.2. This MS value indicates that chain propagation (Reaction 3) plays a minor role in the reaction kinetics; otherwise, an ever-increasing curve for MS with reaction time should be expected to be observed. The slow increase in MS at 8 h and above in Figure 3 is possibly due to the considerably slower reaction rate of the hydroxypropyl chain. On the basis of the assumption of one rate constant for all hydroxides on each AGU, the order and rate constant of the reaction can be determined. Because the GG concentration is proportional to (MSmax − MS), the following is used:

3. RESULTS AND DISCUSSION 3.1. Kinetics of the Hydroxypropylation Reaction with Guar Splits. In this two-step reaction, the deprotonation step is fast, so the reaction of propylene oxide with alkoxides is the rate-determining step. The method of pseudo-first-order conditions was applied to design a reaction model for the hydroxypropylation step and to derive the rate law.29 In this procedure, the concentration of one reactant is monitored independently while the concentrations of the other species are kept constant. The rate law for the hydroxypropylation reaction is expressed as

[GG−ONa] = [GG−ONa]0 (MSmax − MS)

The data points of (MSmax − MS) at the initial stages of the reaction were used to determine the rate of reaction according to Figure 4. Because the linear fit was best (R2=0.9895) for the mathematical expression characteristic of first order dependency, the data indicate that the rate order of GG−ONa is 1. To determine the rate order for PO, we performed another reaction to monitor the concentrations of reactants with an initial AGU/PO ratio of 1:1.4. We calculated the concentrations of reactants at three time points, and then the values were input into the equation below:

r = k[GG−ONa]m [PO]n

where m is the order of the reaction with respect to guar, and n is the reaction order with respect to propylene oxide. We determined the rate constant, k, at room temperature (∼25 °C) with a large excess amount of propylene oxide in a mole ratio of AGU/NaOH/PO = 1:1:10. The concentration of PO, under the conditions of this experiment, could be assumed constant because no PO + PO reaction should occur under these conditions,30 and the maximum change in PO concentration was ∼10%. We combined the actual rate constant for the reaction (k) with the constant initial concentration of PO ([PO]0) to form a new constant that we called kexptl, which would be the rate constant determined by the experimental data.

Δ[GG−ONa] = r = k[GG−ONa]m [PO]n Δt We got two equations: −

−

[GG−ONa]t2 − [GG−ONa]t1 t 2 − t1

= rt1

= k[GG−ONa]t1m [PO]t1n 11675

DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Article

Industrial & Engineering Chemistry Research

3.2. Rheology of HPG. HPG samples dissolve significantly faster in water than pristine guar gum.31 Figure 5A shows the viscosity curves for HPG for the same with MS value of 0.53. As expected, the viscosity curves of the HPG solution shows non-Newtonian behavior at low shear rates and a shearthinning region at higher shear rates, which is a typical characteristic for guar and guar derivatives. The shearthickening at high shear rates for low-viscosity samples is an artifact caused by instrument inertia. The solution viscosity increases with increasing sample concentration. HPG had a much lower shear viscosity than pristine GG at the same concentration (1%).18 The added hydroxypropyl groups sterically block the hydrogen bonding sites on the guar backbone and reduce the hydrogen bonding between guar molecules. Stirring in the reaction process may lead to a reduction in the molecular weight to a certain extent.32 Zero shear viscosity was plotted versus HPG concentration, which is shown as Figure 5B. In this plot, the crossover concentration, c*, represents the concentration at which the polymer chains begin to entangle with one another. HPGs with higher degrees of molar substitution (MS = 0.74 and 0.94) were studied, and their steady-shear rheological properties were determined (see the Supporting Information, Figures S1 and S2). The overlap concentration was previously found to decrease from 0.21 to 0.17 wt % when the level of substitution for CMG increased from DS of 0.31 to 0.49.18 With HPG, the crossover concentration was independent of MS level; in all cases, c* = 0.18 wt %. The similarities between samples with different MS values is likely caused by increased solubility, resulting in reductions in entanglements and intermolecular interactions. Oscillatory measurements were performed to evaluate the viscoelastic behavior of the HPG samples. The storage (G) and loss modulus (G″) represent the elastic and viscous part or the amount of energy dissipated in the HPG sample. Figure 6 shows a comparison of the G′ and G″ curves of HPG samples at three MS levels. Normally, including for CMG and GG, the curves are increasing but convex down or linear; that is, the curves at higher frequency change less or the same as the frequency increases. Frequency independent values of G′ and G″ at low frequency are indicative of a sample that is crosslinked on the time scale of the experiment. This behavior indicates that the breaking and reforming of hydrogen bonds is faster than the time scale of the experiment. We are unaware of such clear frequency-independent behavior for un-cross-linked HPG being previously reported. As this horizontal feature moves to higher frequency with MS = 0.74 versus 0.53,

Figure 4. Linear fitting using the first order of the reaction.

−

[GG−ONa]t3 − [GG−ONa]t2 t3 − t 2

= rt2

= k[GG−ONa]t2 m [PO]t2 n

With the previous fitting results for m (m = 1), these two equations with two unknown variables (the rate constant, k, and reaction order, n, for PO) were solved to be n = 0.035 ≈ 0 and k = 0.11 h−1. The integrated rate law is as follows (with concentration in moles per liter): r=

d(HPG) = 0.11 × [GG−ONa] dt

Hence, the reaction is first order in guar and zero order in PO. This modeling result is different from the reaction rate law of carboxymethylation in our previous study, for which the reaction order of the guar was 2 and that for the other reactant 1.18 For hydrophilic carboxymethyl substitution, reactants were added in the form of 40% aqueous solution to the system, whereas for the hydroxypropyl modification of guar splits with relative hydrophobic groups, propylene oxide was introduced to the reaction in its pure liquid form. However, the PO concentration is far above the solubility limit in water, and the zero order dependency suggests that the concentration of PO in the reacting media (i.e., water) is constant. If true, the reaction rate law should be accurate in an industrial setting (assuming the PO is a liquid), because the diffusion of PO to the surface and the probability of reaction will determine the rate law, and neither of these characteristics should be affected by scale.

Figure 5. (A) Viscosity vs shear rate curves for different HPG (MS = 0.53) concentrations. (B) Zero shear viscosities at different concentrations. 11676

DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Article

Industrial & Engineering Chemistry Research

Figure 6. G′, G″, and tan delta curves of 1.0 wt % HPG solutions with different MS values: (A) 0.53, (B) 0.74, and (C) 0.94.

Figure 7. Storage and loss moduli (at 25 °C) of a 0.5% HPG solution with varied concentrations of zirconium cross-linker: (A) 20, (B) 50, (C) 100, and (D) 200 ppm.

borate cross-linker and a zirconium cross-linker were applied to study gel formation. Borate cross-linkers have been used commonly in fracturing applications in the oil industry, where they have been found to be effective at increasing viscosity and improving the fluid-loss control and proppant transportability of guar and its derivative fluids.33−35 Boric acid is known as such a pH-sensitive cross-linker that can reversibly cross-link polymers through hydroxyl groups.36 At higher pH values, the boron is more inclined to attach itself as a borate ion to a polymer molecule in the basic solution and acts as a crosslinker. HPG solutions with 200 ppm boric acid showed rheological properties with no obvious variation compared

perhaps hydrogen bonds are more quickly formed with attached PO chains. However, the fact that G′ and G″ are not frequency independent for the highest MS is surprising, and we have no obvious explanation for this behavior. For MS = 0.53 and 0.74 HPG samples, G″ is mostly higher than G′ (tan delta >1) within the measured frequencies (0.1−100 rad/ s), indicating the sample is more viscous than elastic in this frequency range; such samples are not considered gels because G″ is higher than G′. A high MS (0.94) HPG solution was measured as tan delta < 1 at frequencies above 6 rad/s. 3.3. Cross-Linked Derivatives. Cross-linking changes weaker viscoelastic fluids into stronger viscoelastic gels. A 11677

DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Industrial & Engineering Chemistry Research

■

ACKNOWLEDGMENTS This work was financially supported by United Guar LLC and the Oklahoma Center for the Advancement of Science and Technology, Grant AR15-057. We gratefully thank Dr. Lewis Norman and Dr. Lynn Norman for providing the samples and technical discussion. We also acknowledge Dr. Susan Nimmo for helpful suggestions about NMR.

with those of the non-cross-linked HPG solution (Figure S3); this absence of variation indicates the cross-linked gel was not well formed. Similar low cross-linking effectiveness on HPG by boric acid was observed in a previous study.18 Zirconium(IV) compounds are common metallic crosslinkers that can be used to cross-link guar molecules by bridging hydroxyl groups. Cross-links by zirconium compounds, unlike those with borate cross-linkers that require alkaline pH, are considered to be effective and stable at a relatively wide range of pH values.37 Figure 7 presents the viscoelastic characteristics of the HPG solution with increased Zr(VI) concentrations. The zirconium cross-linker provided much higher effectiveness in cross-linking HPG than the borate cross-linker. With Zr(VI) concentrations above 50 ppm, G′ was always higher than G″ in the full range of our frequency sweep. The higher the zirconium concentration was, the larger the measured G′ was. When the concentration reached 200 ppm, G′ exhibited characteristic curves nearly independent of the frequency over a wide range, indicating the formation of a gel.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.9b01674. Steady-shear rheological properties of HPG with MS = 0.74 and 0.94 and storage and loss moduli of an uncross-linked HPG solution and an HPG solution with 200 ppm borate cross-linker (PDF)

■

REFERENCES

(1) Chudzikowski, R. J. Guar Gum and Its Applications. J. Soc. Cosmet. Chem. 1971, 22, 43. (2) Reuben, J. Description of Heteropolysaccharide EthersHydroxypropyl Guar and Carboxymethyl Guar. Macromolecules 1985, 18, 2035. (3) Mccleary, B. V.; Clark, A. H.; Dea, I. C. M.; Rees, D. A. The Fine-Structures of Carob and Guar Galactomannans. Carbohydr. Res. 1985, 139, 237. (4) Mudgil, D.; Barak, S.; Khatkar, B. S. Guar Gum: Processing, Properties and Food Applications-A Review. J. Food Sci. Technol. 2014, 51, 409. (5) Sharma, G.; Sharma, S.; Kumar, A.; Al-Muhtaseb, A. H.; Naushad, M.; Ghfar, A. A.; Mola, G. T.; Stadler, F. J. Guar Gum and Its Composites as Potential Materials for Diverse Applications: A review. Carbohydr. Polym. 2018, 199, 534. (6) Sostar, S.; Schneider, R. Guar Gum as an Environment-Friendly Alternative Thickener in Printing with Reactive Dyes. Dyes Pigm. 1998, 39, 211. (7) Thombare, N.; Jha, U.; Mishra, S.; Siddiqui, M. Z. Guar Gum as a Promising Starting Material for Diverse Applications: A review. Int. J. Biol. Macromol. 2016, 88, 361. (8) Fijan, R.; Basile, M.; Sostar-Turk, S.; Zagar, E.; Zigon, M.; Lapasin, R. A Study of Rheological and Molecular Weight Properties of Recycled Polysaccharides Used as Thickeners in Textile Printing. Carbohydr. Polym. 2009, 76, 8. (9) Prajapati, V. D.; Jani, G. K.; Moradiya, N. G.; Randeria, N. P. Pharmaceutical Applications of Various Natural Gums, Mucilages and Their Modified Forms. Carbohydr. Polym. 2013, 92, 1685. (10) Rana, V.; Rai, P.; Tiwary, A. K.; Singh, R. S.; Kennedy, J. F.; Knill, C. J. Modified Gums: Approaches and Applications in Drug Delivery. Carbohydr. Polym. 2011, 83, 1031. (11) Hasan, A. M.; Abdel-Raouf, M. E. Applications of Guar Gum and Its Derivatives in Petroleum Industry: A Review. Egypt. J. Pet. 2018, 27, 1043. (12) Oikonomou, E. K.; Christov, N.; Cristobal, G.; Bourgaux, C.; Heux, L.; Boucenna, I.; Berret, J. F. Design of Eco-Friendly Fabric Softeners: Structure, Rheology and Interaction with Cellulose Nanocrystals. J. Colloid Interface Sci. 2018, 525, 206. (13) Shi, Q. L.; Qin, B. T.; Bi, Q.; Qu, B. Fly Ash Suspensions Stabilized by Hydroxypropyl Guar Gum and Xanthan Gum for Retarding Spontaneous Combustion of Coal. Combust. Sci. Technol. 2018, 190, 2097. (14) Uchiyama, E.; Di Pascuale, M. A.; Butovich, I. A.; McCulley, J. P. Impact on Ocular Surface Evaporation of an Artificial Tear Solution Containing Hydroxypropyl Guar. Eye Contact Lens 2008, 34, 331. (15) Wang, S. B.; Zhang, Y. Y.; Guo, J. C.; Lai, J.; Wang, D.; He, L.; Qin, Y. Y. A Study of Relation Between Suspension Behavior and Microstructure and Viscoelastic Property of Guar Gum Fracturing Fluid. J. Pet. Sci. Eng. 2014, 124, 432. (16) Budd, P. M.; Chakrabarti, S. Ultracentrifugal Studies of the Degradation of a Fracturing Fluid Polymer-Hydroxypropyl Guar. J. Appl. Polym. Sci. 1991, 42, 2191. (17) Hurnaus, T.; Plank, J. Behavior of Titania Nanoparticles in Cross-linking Hydroxypropyl Guar Used in Hydraulic Fracturing Fluids For Oil Recovery. Energy Fuels 2015, 29, 3601. (18) Gao, J.; Grady, B. P. Reaction Kinetics and Subsequent Rheology of Carboxymethyl Guar Gum Produced from Guar Splits. Ind. Eng. Chem. Res. 2018, 57, 7345.

4. CONCLUSIONS An eco-friendly two-step protocol was able to produce hydroxypropyl guar successfully at room temperature from guar splits. The degree of molar substitution was verified by NMR spectroscopy. A pseudo-first-order method was used to model the propylene oxide reaction with deprotonated guar splits, through which we found a kinetic rate law that is first order in guar and zero order in propylene oxide and which should be relevant for an industrial-scale reaction. The rheological properties of hydroxypropyl guar products with different substituted extents were evaluated and compared. All three samples gave similar crossover concentrations, c*, in steady shear testing, whereas high MS samples showed crosslinked behaviors at higher frequencies in oscillatory measurements, consistent with terminal hydroxyl groups being the most effective hydrogen bond moieties. In addition, we investigated cross-link effects on HPG with boric acid and zirconium cross-linkers. The former produces little changes in viscoelastic properties at concentrations up to 200 ppm, whereas the latter offers stronger cross-links at concentrations between 50 and 200 ppm.

■

Article

AUTHOR INFORMATION

Corresponding Author

*Tel.: (+1)-405-325-4369. E-mail: [email protected]. ORCID

Brian P. Grady: 0000-0002-4975-8029 Notes

The authors declare no competing financial interest. 11678

DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679

Article

Industrial & Engineering Chemistry Research (19) Nemade, S.; Sawarkar, S. Recovery and Synthesis of Guar Gum and Its Derivatives. Int. J. Adv. Res. Chem. Sci. 2015, 2, 33. (20) Zhan, Z. S.; Du, B.; Peng, S. H.; He, J. P.; Deng, M. Y.; Zhou, J.; Wang, K. Homogeneous Synthesis of Hydroxypropyl Guar Gum in an Ionic Liquid 1-Butyl-3-Methylimidazolium Chloride. Carbohydr. Polym. 2013, 93, 686. (21) Xiong, R. C.; Chang, M. Z.; Chen, J. M.; Zhou, N.; Wei, G. Synthesis of Hydroxypropyl Guar Gum by Phase Transfer Catalysis. Chin. Chem. Lett. 2005, 16, 545. (22) Pal, S. Carboxymethyl Guar: Its Synthesis and Macromolecular Characterization. J. Appl. Polym. Sci. 2009, 111, 2630. (23) Dodi, G.; Hritcu, D.; Popa, M. I. Carboxymethylation of Guar Gum: Synthesis and Characterization. Cellul. Chem. Technol. 2011, 45, 171. (24) Prabhanjan, H.; Gharia, M. M.; Srivastava, H. C. Guar Gum Derivatives. Part I: Preparation and Properties. Carbohydr. Polym. 1989, 11, 279. (25) Venkataiah, S.; Mahadevan, E. Rheological Properties of Hydroxypropyl- and Sodium Carboxymethyl-Substituted Guar Gums in Aqueous Solution. J. Appl. Polym. Sci. 1982, 27, 1533. (26) Lapasin, R.; DeLorenzi, L.; Pricl, S.; Torriano, G. Flow Properties of Hydroxypropyl Guar Gum and Its Long-Chain Hydrophobic Derivatives. Carbohydr. Polym. 1995, 28, 195. (27) Ely, J. W. Stimulation engineering handbook; Pennwell Corp.: Tulsa, OK, 1994. (28) Aliu, A. O.; Guo, J. C.; Wang, S. B.; Zhao, X. Hydraulic Fracture Fluid for Gas Reservoirs in Petroleum Engineering Applications Using Sodium Carboxy Methyl Cellulose as Gelling Agent. J. Nat. Gas Sci. Eng. 2016, 32, 491. (29) Corbett, J. F. Pseudo First-Order Kinetics. J. Chem. Educ. 1972, 49, 663. (30) St. Pierre, L. E.; Price, C. C. The Room Temperature Polymerization of Propylene Oxide. J. Am. Chem. Soc. 1956, 78, 3432. (31) Risica, D.; Barbetta, A.; Vischetti, L.; Cametti, C.; Dentini, M. Rheological Properties of Guar and Its Methyl, Hydroxypropyl and Hydroxypropyl-Methyl Derivatives in Semidilute and Concentrated Aqueous Solutions. Polymer 2010, 51, 1972. (32) Chambers, W. P. The Evaluation of Tragacanth by Means of the Apparent Viscosity Determined in a Standard U-Tube Viscometer: Part II.-Whole Gum. J. Pharm. Pharmacol. 1949, 1, 103. (33) Holtsclaw, J.; Rocı ́o Montenegro Galindo, G.; Chopade, P. Next-Generation Boron-Crosslinked Fracturing Fluids: Breaking the Lower Limits on Polymer Loadings. SPE Prod. Oper. 2017, 32, 440. (34) Goel, N.; Shah, S. N.; Yuan, W. L.; O’Rear, E. A. Suspension Characteristics of Borate-Crosslinked Gels: Rheology and Atomic Force Microscopy Measurements. J. Appl. Polym. Sci. 2001, 82, 2978. (35) Goel, N.; Shah, S. N.; Asadi, M. New Empirical Correlation to Predict Apparent Viscosity of Borate-Crosslinked Guar Gel in Fractures. SPE Prod. Facil. 2000, 15, 90. (36) Wang, S. B.; Tang, H. B.; Guo, J. C.; Wang, K. J. Effect of pH on the Rheological Properties of Borate Crosslinked Hydroxypropyl Guar Gum Hydrogel and Hydroxypropyl Guar Gum. Carbohydr. Polym. 2016, 147, 455. (37) Li, L.; Al-Muntasheri, G. A.; Liang, F. A Review of Crosslinked Fracturing Fluids Prepared with Produced Water. Petroleum 2016, 2, 313.

11679

DOI: 10.1021/acs.iecr.9b01674 Ind. Eng. Chem. Res. 2019, 58, 11673−11679