Lignocellulose nanofibril material, stable foam system based thereon, preparation method and application thereof

Abstract

A lignocellulose nanofibril material, a stable foam system based thereon, a preparation method and an application thereof are provided. The lignocellulosic nanofibril material includes the following components: 0.5-20 wt % of wood flour, 0.1-10 wt % of (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, 2-25 mmol/g of an oxidant, 6-15 wt % of NaBr, and the remaining is water. The stable foam system based on the lignocellulosic nanofibril material includes: 0.1-1.0 wt % of the lignocellulosic nanofibril material, 0.2-1.0 wt % of a surfactant, 0.1-10 wt % of sodium chloride, 0.1-1.0 wt % of calcium chloride, 0.1-1.0 wt % of magnesium chloride, 0.1-1.0 wt % of sodium sulfate, and a balance of water.

Claims

1. A stable foam system based on a lignocellulosic nanofibril material, comprising: 0.1-1.0 wt % of the lignocellulosic nanofibril material, 0.2-1.0 wt % of a surfactant, 0.1-10 wt % of sodium chloride, 0.1-1.0 wt % of calcium chloride, 0.1-1.0 wt % of magnesium chloride, 0-0.04 wt % of sodium sulfate, and a balance of water; wherein the lignocellulosic nanofibril material comprises: 0.5-20 wt % of wood flour, 0.1-10 wt % of (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl TEMPO), 2-25 mmol/g of an oxidant, 6-15 wt % of NaBr, and a balance of water.

2. The stable foam system based on the lignocellulosic nanofibril material according to claim 1, comprising: 0.1 wt % of the lignocellulosic nanofibril material, 0.4 wt % of the surfactant, 3.44 wt % of the sodium chloride, 0.64 wt % of the calcium chloride, 0.18 wt % of the magnesium chloride, 0.018 wt % of the sodium sulfate, and a balance of water.

3. The stable foam system based on the lignocellulosic nanofibril material according to claim 1, wherein the surfactant is a mixture of sodium secondary alkyl sulfonate and α-alkenyl sulfonate in a molar ratio of 1:1.

4. The stable foam system based on the lignocellulosic nanofibril material according to claim 1, wherein the stable foam system is applied in an oil field exploitation.

5. The stable foam system according to claim 1, wherein the lignocellulosic nanofibril material comprises 15 wt % of the wood flour, 5 wt % of the TEMPO, 10 mmol/g of the oxidant, 12 wt % of the NaBr, and a balance of water.

6. The stable foam system according to claim 1, wherein the wood flour has a particle size of 20-120 mesh, and the oxidant is NaClO or NaClO.sub.2.

7. The stable foam system based on the lignocellulosic nanofibril material according to claim 2, wherein the surfactant is a mixture of sodium secondary alkyl sulfonate and α-alkenyl sulfonate in a molar ratio of 1:1.

8. The stable foam system based on the lignocellulosic nanofibril material according to claim 2, wherein the stable foam system is applied in an oil field exploitation.

9. The stable foam system based on the lignocellulosic nanofibril material according to claim 3, wherein the stable foam system is applied in an oil field exploitation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A and 1B show energy dispersive X-ray (EDX) spectra of LCNF and CNF in embodiment 1.

(2) FIGS. 2A and 2B show scanning electron microscopy (SEM) images of LCNF and CNF in embodiment 1.

(3) FIG. 3 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a foaming volume and a drainage half-life (without oil).

(4) FIG. 4 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a foaming volume and a drainage half-life (containing 1 vol % of oil).

(5) FIG. 5 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in defoaming speed (without oil).

(6) FIG. 6 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in defoaming speed (containing 1 vol % of oil).

(7) FIG. 7 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in liquid film thickness (without oil).

(8) FIG. 8 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in liquid film thickness (containing 1 vol % of oil).

(9) FIG. 9 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in liquid film liquid fraction.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiment 1

(10) A lignocellulosic nanofibril material includes the following components: 15 wt % of needlebush wood flour, 5 wt % of (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO), 10 mmol/g of NaClO, 12 wt % of NaBr, and a balance of water; wherein, the particle size of the needlebush wood flour is 50-100 mesh.

(11) A method for preparing the above-mentioned lignocellulosic nanofiber material includes the following steps.

(12) (1) The needlebush wood flour is evenly dispersed into water and the concentration of the needlebush wood flour is controlled to be 15 wt %. Then, TEMPO and NaBr are added and the pH of the reaction system is adjusted to be 10-10.5, followed by adding NaClO. During the reaction, the pH value of the reaction system is kept constant, the reaction is performed for 4 hours. Finally, an oxidized fiber is obtained after washing.

(13) (2) The oxidized fiber is added to water and the concentration of the oxidized fiber is controlled to be 5 wt %. Then, a homogenization treatment is performed by a high-pressure homogenizer with a homogenization pressure of 50 MPa and a homogenization number of 10 times to obtain the lignocellulosic nanofibril material (LCNF-1).

(14) By a TAPPI T 222 om-11 (2011) method, the lignin content in the LCNF-1 was determined to be 15.5 wt %.

(15) The dosage of NaClO in the above components is changed to be 13 mmol/g, and the remaining components and their contents are not changed. A lignocellulosic nanofibril material is obtained according to the above preparation process and is denoted as LCNF-2 with a lignin content of 11.7%.

(16) The dosage of NaClO in the above components is changed to be 18 mmol/g, and the remaining components and their contents are not changed. A lignocellulosic nanofibril material is obtained according to the above preparation process and is denoted as LCNF-3 with a lignin content of 8.66%.

(17) The dosage of NaClO in the above components is changed to be 25 mmol/g, and the remaining components and their contents are not changed. A lignocellulosic nanofibril material is obtained according to the above preparation process and is denoted as LCNF-4 with a lignin content of 4.49%.

Embodiment 2

(18) The lignocellulosic nanofibril material in embodiment 1 is used to prepare a stable foam system. The foam system includes the following components in mass percentage: 0.1 wt % of the LCNF-1, 0.4 wt % of a surfactant, 3.44 wt % of sodium chloride, 0.64 wt % of calcium chloride, 0.18 wt % of magnesium chloride, 0.018 wt % of sodium sulfate, and a balance of water; wherein, the surfactant is a mixture of sodium secondary alkyl sulfonate and α-alkenyl sulfonate mixed at a molar ratio of 1:1.

(19) A method for preparing the above-mentioned stable foam system includes the following steps.

(20) (1) At room temperature, sodium chloride, calcium chloride, magnesium chloride and sodium sulfate are dissolved in deionized water and stirred evenly.

(21) (2) At room temperature, the surfactant is dissolved in the solution obtained in step (1) and stirred evenly.

(22) (3) At room temperature, the lignocellulosic nanofibril material is dissolved in the solution obtained in step (2) and stirred evenly until no obvious flocculent precipitate is present.

(23) (4) The solution obtained in step (3) is transferred to a foam meter, and air is blown in from the bottom until the foam volume no longer increases, so as to obtain the stable foam system.

Embodiment 3

(24) A stable foam system based on a lignocellulosic nanofibril material includes the following components in mass percentage: 0.1 wt % of the LCNF-2, 0.4 wt % of a surfactant, 3.44 wt % of sodium chloride, 0.64 wt % of calcium chloride, 0.18 wt % of magnesium chloride, 0.018 wt % of sodium sulfate, and a balance of water; wherein, the surfactant is a mixture of sodium secondary alkyl sulfonate and α-alkenyl sulfonate mixed at a molar ratio of 1:1.

(25) A method for preparing the above-mentioned stable foam system includes the following steps.

(26) (1) At room temperature, sodium chloride, calcium chloride, magnesium chloride and sodium sulfate are dissolved in deionized water and stirred evenly.

(27) (2) At room temperature, the surfactant is dissolved in the solution obtained in step (1) and stirred evenly.

(28) (3) At room temperature, the lignocellulosic nanofibril material is dissolved in the solution obtained in step (2) and stirred evenly until no obvious flocculent precipitate is present.

(29) (4) The solution obtained in step (3) is transferred to a foam meter, and air is blown in from the bottom until the foam volume no longer increases, so as to obtain the stable foam system.

Embodiment 4

(30) A stable foam system based on a lignocellulosic nanofibril material includes the following components in mass percentage: 0.1 wt % of the LCNF-3, 0.4 wt % of a surfactant, 3.44 wt % of sodium chloride, 0.64 wt % of calcium chloride, 0.18 wt % of magnesium chloride, 0.018 wt % of sodium sulfate, and a balance of water; wherein, the surfactant is a mixture of sodium secondary alkyl sulfonate and α-alkenyl sulfonate mixed at a molar ratio of 1:1.

(31) A method for preparing the above-mentioned stable foam system includes the following steps.

(32) (1) At room temperature, sodium chloride, calcium chloride, magnesium chloride and sodium sulfate are dissolved in deionized water and stirred evenly.

(33) (2) At room temperature, the surfactant is dissolved in the solution obtained in step (1) and stirred evenly.

(34) (3) At room temperature, the lignocellulosic nanofibril material is dissolved in the solution obtained in step (2) and stirred evenly until no obvious flocculent precipitate is present.

(35) (4) The solution obtained in step (3) is transferred to a foam meter, and air is blown in from the bottom until the foam volume no longer increases, so as to obtain the stable foam system.

Embodiment 5

(36) A stable foam system based on a lignocellulosic nanofibril material includes the following components in mass percentage: 0.1 wt % of the LCNF-4, 0.4 wt % of a surfactant, 3.44 wt % of sodium chloride, 0.64 wt % of calcium chloride, 0.18 wt % of magnesium chloride, 0.018 wt % of sodium sulfate, and a balance of water; wherein, the surfactant is a mixture of sodium secondary alkyl sulfonate and α-alkenyl sulfonate mixed at a molar ratio of 1:1.

(37) A method for preparing the above-mentioned stable foam system includes the following steps.

(38) (1) At room temperature, sodium chloride, calcium chloride, magnesium chloride and sodium sulfate are dissolved in deionized water and stirred evenly.

(39) (2) At room temperature, the surfactant is dissolved in the solution obtained in step (1) and stirred evenly.

(40) (3) At room temperature, the lignocellulosic nanofibril material is dissolved in the solution obtained in step (2) and stirred evenly until no obvious flocculent precipitate is present.

(41) (4) The solution obtained in step (3) is transferred to a foam meter, and air is blown in from the bottom until the foam volume no longer increases, so as to obtain the stable foam system.

(42) The LCNF-1 prepared in embodiment 1 and the existing CNF (purchased from Tianjin Woodelfbio Cellulose Co., Ltd., with the product name of Microfibrillated Cellulose) were tested, and the EDX spectra thereof are shown in FIGS. 1A and 1B. It can be seen from FIG. 1B that the mass percentages of carbon (C) and oxygen (O) in the LCNF are 75.4% and 21.49%, respectively, which is extremely analogous to the lignin in an elemental composition. However, the contents of C, O, and hydrogen (H) in the CNF show a typical fiber composition. Thus, it is indicated that the LCNF prepared by the present invention contains a certain amount of lignin.

(43) FIGS. 2A and 2B are SEM images of the LCNF-1 obtained in embodiment 1 and the existing CNF. It can be seen from FIGS. 2A and 2B that the surface structure of the LCNF is rougher than that of the CNF, and is suspended with a sheet-like substance. Combining with the results of EDX analysis, it can be proved that the sheet-like substance is lignin.

(44) FIG. 3 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a foaming volume and a drainage half-life (without oil). It can be seen from FIG. 3 that due to gravity, the foam volume of the LCNF-stabilized foam is lower than that of the blank sample-stabilized foam, but the drainage half-life of the LCNF-stabilized foam is significantly longer than that of the blank sample-stabilized foam, indicating that the LCNF-stabilized foams have a high stability.

(45) FIG. 4 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a foaming volume and a drainage half-life (containing 1 vol % of oil). The addition of crude oil causes foam instability and accelerates the foam drainage rate. It can be seen from FIG. 4 that compared to the blank sample, the LCNF-stabilized foam has a longer drainage half-life, indicating that the LCNF-stabilized foam has an excellent oil resistance.

(46) FIG. 5 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a defoaming speed (without oil). It can be seen from FIG. 5 that in the blank sample-stabilized foam has a higher defoaming speed and the foam volume decreases rapidly after 6 hours, while the LCNF-stabilized foam has a lower defoaming speed and no significant change occurs within 12 hours, indicating that the LCNF-stabilized foam has an excellent stability.

(47) FIG. 6 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a defoaming speed (containing 1 vol % of oil). It can be seen from FIG. 6 that the blank sample-stabilized foam has a higher defoaming speed and the foam volume decreases rapidly after 30 minutes, while the LCNF-stabilized foam has a lower defoaming speed and the significant change occurs after 120 minutes, indicating that the LCNF-stabilized foam has an excellent stability.

(48) FIG. 7 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample containing only a surfactant) in a liquid film thickness (without oil). It can be seen from FIG. 7 that the liquid film thickness of the blank sample-stabilized foam decreases linearly with time, while the liquid film thickness of the LCNF-stabilized foam decreases more slowly, especially for the LCNF-1 and LCNF-3, which decrease the most slowly, indicating that that the LCNF-stabilized foam provided in the present invention has a good stability.

(49) FIG. 8 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing only a surfactant) in a liquid film thickness (containing 1 vol % of oil). It can be seen from FIG. 8 that although the liquid film thickness of the foam decreases rapidly with time, at the same time point, the liquid film thickness of the LCNF-stabilized foam is higher than that of the blank sample-stabilized foam, indicating that the stability of the LCNF-stabilized foam is better than that of the blank sample-stabilized foam.

(50) FIG. 9 shows comparison results of the stable foams in embodiments 2-5 and an ordinary foam (as a blank sample only containing a surfactant) in a liquid film liquid fraction. It can be seen from FIG. 9 that when the initial liquid fractions are equal, the liquid film liquid fraction of the LCNF-stabilized foam decreases significantly slower, which indicates that the LCNF-stabilized foam has a smaller drainage rate and is more stable.

(51) A porous media with a rock core almost analogous to that of sandstone in pore permeability is used. The flow of foam in the porous media is simulated to measure the pressure difference between the rock core inlet and outlet. It can be seen from the test results that under the same experimental conditions, the pressure difference generated by the LCNF-stabilized foam is significantly higher than that of the blank sample-stabilized foam (Contains only a surfactant), especially for the LCNF-3. This phenomenon indicates that the stability of the LCNF-stabilized foam in the porous media is better.

(52) The interfacial elasticity of a foam can suppress the foam coarsening and the collapse of the foam skeleton, thereby improving the stability of the foam. In the present invention, the dilational elasticity and viscosity at the gas-liquid interface of the foams are measured, and the measurement results are shown in Table 1.

(53) TABLE-US-00001 TABLE 1 Results of interface elasticity of foams Dilational Dilational Dilational modulus elasticity viscosity Samples (mN/m) (mN/m) (mN/m) Blank sample 6.71 6.56 1.41 LCNF-1 9.44 9.42 0.51 LCNF-2 12.35 12.34 0.36 LCNF-3 14.94 14.91 1.04 LCNF-3 10.91 10.84 1.24

(54) As can be seen from Table 1, the interfacial elasticity of the LCNF-stabilized foams is 1.4-2.3 times higher than that of the ordinary foam, indicating that the stability of the LCNF-stabilized foams is good.

(55) In the present invention, a foam scan instrument is used to measure the stability parameters of the foams, and the measurement results are shown in Table 2.

(56) TABLE-US-00002 TABLE 2 Stability parameters of foams Foam expansion Foam capacity FVS Samples (FE) (FC) (stability index) Blank sample 6.8 1.35 2.23 LNCF-1 6.7 1.35 9.07 LNCF-2 6.7 1.36 9.39 LNCF-3 6.9 1.39 11.58 LNCF-4 10.1 1.28 9.68

(57) It can be known from Table 2 that the stability index of the LCNF-stabilized foams is significantly higher than that of the blank sample-stabilized foam, which is increased by 4.1-5.2 times relative to the blank sample-stabilized foam, indicating that the LCNF-stabilized foams have a good stability.