Carbon Skeleton Reinforced Porous Starch and Preparation Method thereof

Abstract

A carbon skeleton reinforced porous starch and a preparation method thereof. The method of preparing the porous starch includes bonding starch to transition metal ions, then treating the starch attached with the transition metal ions and amylase via an extruding device, and finally forming a starch-based porous material having a high strength recombination structure, that is, the carbon skeleton reinforced porous starch.

Claims

1. A carbon skeleton reinforced porous starch, wherein the carbon skeleton reinforced porous starch is prepared by the following method: bonding starch to transition metal ions, then treating the starch attached with the transition metal ions and amylase via an extruding device, and finally forming the carbon skeleton reinforced porous starch.

2. The carbon skeleton reinforced porous starch according to claim 1, wherein the method of preparing the carbon skeleton reinforced porous starch comprises the following steps: (1) mixing the starch with a transition metal aqueous solution, stirring and soaking for 1-12 h under a condition of 20-40 C., pouring and sieving the starch, and rinsing for 1-3 times, and drying at 30-50 C. in an oven to obtain a transition metal ion reinforced starch; (2) mixing the amylase with a non-transition metal ion aqueous solution, stirring at 20-40 C., and mixing for 1-4 h to obtain a non-transition metal ion-amylase composite liquid; and (3) mixing and pre-moisturizing the transition metal ion reinforced starch obtained in the step (1) with the non-transition metal ion-amylase composite liquid obtained in the step (2) to obtain a premix, then feeding the premix into the extruding device and discharging to form the carbon skeleton reinforced porous starch.

3. The carbon skeleton reinforced porous starch according to claim 2, wherein the starch in the step (1) is one or more selected from the group consisting of a corn starch, a rice starch, a potato starch and a cassava starch; the transition metal is one or more selected from the group consisting of manganese, iron, cobalt, nickel, copper, zinc, zirconium and palladium added in a form of a soluble metal salt.

4. The carbon skeleton reinforced porous starch according to claim 2, wherein the transition metal aqueous solution in the step (1) has an ion concentration of 0.1 to 5 mol/L; a mass to volume ratio of the starch to the transition metal aqueous solution is 50 to 250:1 g/L.

5. The carbon skeleton reinforced porous starch according to claim 2, wherein the amylase in the step (2) is one or more selected from the group consisting of mesophilic -amylase, thermostable -amylase, -amylase and saccharifying enzyme; the non-transition metal ion is one or more selected from the group consisting of sodium, potassium, magnesium and calcium.

6. The carbon skeleton reinforced porous starch according to claim 2, wherein the non-transition metal ion aqueous solution in the step (2) has an ion concentration of 0.001 to 0.01 mol/L; the amylase and the non-transition metal ion aqueous solution has a mass to volume ratio of 0.2 to 2:1 g/L.

7. The carbon skeleton reinforced porous starch according to claim 2, wherein the transition metal ion reinforced starch and the non-transition metal ion-amylase composite liquid in the step (3) has a mass to volume ratio of 800-2500:1 g/L.

8. The carbon skeleton reinforced porous starch according to claim 2, wherein the premix in the step (3) has a water content of 28.5 to 55.5 wt %; the premix has an enzyme activity of more than 12 U/g, and after an enzyme activity is defined as the enzyme added per gram of starch, the enzyme activity of the system is more than 12 U.

9. The carbon skeleton reinforced porous starch according to claim 2, wherein system parameters of the extruding device in the step (3) include a material temperature is 35-105 C., a pressure is less than 5 MPa, and a mechanical energy is less than 300 kJ/kg; number of kneading or reversing element zones are less than or equal to two groups, a temperature from a feed port to a discharge port is set within a range of 30 C. to 100 C., a rotating speed of a screw is set at 50-250 rpm, and a die head is assembled or not assembled at an outlet.

Description

DETAILED DESCRIPTION

[0026] The present disclosure will be specifically described with reference to examples.

EXAMPLE 1

[0027] A carbon skeleton reinforced porous starch, wherein the preparation method includes the following specific steps:

[0028] (1) mixing 500 g of corn starch with 2 L, 5 mol/L of zirconium sulphate (Zr(SO.sub.4).sub.2) aqueous solution, stirring and soaking for 12 h at 40 C., pouring and sieving the starch, and rinsing for 3 times, and drying at 50 C. in an oven to obtain zirconium ion reinforced starch;

[0029] (2) mixing 2 g of mesophilic -amylase with 1 L, 0.01 mol/L of calcium chloride (CaCl.sub.2) aqueous solution, stirring at 40 C., and mixing for 4 h to obtain a calcium-amylase composite liquid; and

[0030] (3) taking 450 g of zirconium ion enhanced starch (preparation loss rate is less than 3%, starch wet basis content 93.7%) to mix with 0.56 L of calcium-amylase composite liquid, pre-moisturizing to a water content of 55%, preparing an enzyme-containing premix, and then adding the moisturized enzyme-containing premix into a twin-screw extruder at a feeding rate of 2 kg/h. After being cooled and dried, the extrudate can be kept in an overall shape, and starch-based porous materials of different particle sizes also can be prepared by cutting (or crushing) and sieving. A kneading element and an adjacent reversing element are arranged in the extrusion slot of the extruder, a rotating speed of a screw is set at 250 rpm, the temperature at a feed port is set at 30 C., the intermediate temperature is 45 C., the temperature at a discharge port is set at 60 C., a die head with an aperture of 2 mm is assembled at the outlet, during the extrusion process, the pressure is 2.7 MPa and the mechanical energy is 145 kJ/kg.

[0031] The porous starch prepared in this embodiment has a pore size distribution range of 1-10 m, a good water absorbability, structural strength and biodegradability, wherein, the water absorption rate can reach 446%, and the strength is 27.6 MPa.

EXAMPLE 2

[0032] A carbon skeleton reinforced porous starch, wherein the preparation method includes the following specific steps:

[0033] (1) mixing 500 g of cassava starch with 10 L, 0.1 mol/L of manganese sulfate (MnSO.sub.4) aqueous solution, stirring and soaking for 1 h at room temperature, pouring and sieving the starch, and rinsing once, and drying at 30 C. in an oven to obtain manganese ion reinforced starch;

[0034] (2) mixing 0.04 g of thermostable -amylase with 0.2 L, 0.001 mol/L of potassium chloride (KCl) aqueous solution, stirring at 30 C., and mixing for 4 h to obtain a potassium-amylase composite liquid;

[0035] (3) taking 450 g of manganese ion enhanced starch (preparation loss rate is less than 3%, starch wet basis content 95.2%) to mix with 0.18 L of potassium-amylase composite liquid, pre-moisturizing to a water content of 29%, preparing an enzyme-containing premix, and then adding the moisturized enzyme-containing premix into a twin-screw extruder at a feeding rate of 2 kg/h. After being cooled and dried, the extrudate can be kept in an overall shape, and starch-based porous materials of different particle sizes also can be prepared by cutting (or crushing) and sieving.

[0036] A kneading element and no reversing element is arranged in the extrusion slot of the extruder, a rotating speed of a screw is set at 50 rpm, the temperature at a feed port is set at 50 C., the intermediate temperature is 60-80 C., the temperature at a discharge port is set at 95 C., a die head with an aperture of 2 mm is assembled at the outlet, during the extrusion process, material temperature is 56-103 C., the pressure is 4.8 MPa and the mechanical energy is 275 kJ/kg.

[0037] The porous starch prepared in this embodiment has a pore size distribution range of 5-20 m, a good water absorbability, structural strength and biodegradability, wherein, the water absorption rate can reach 238%, and the strength is 19.2 MPa.

EXAMPLE 3

[0038] A carbon skeleton reinforced porous starch, wherein the preparation method includes the following specific steps:

[0039] (1) mixing 500 g of rice starch with 5 L, 2.5 mol/L of ferric chloride (FeCl.sub.3) aqueous solution, stirring and soaking for 6 h at 30 C., pouring and sieving the rice starch, and rinsing twice, and drying at 40 C. in an oven to obtain ferric ion reinforced starch;

[0040] (2) mixing 0.5 g of -amylase with 0.5 L, 0.005 mol/L of sodium chloride (NaCl), stirring at 30 C., and mixing for 4 h to obtain a sodium-amylase composite liquid;

[0041] (3) taking 450 g of ferric ion enhanced starch (preparation loss rate is less than 3%, starch wet basis content 93.9%) to mix with 0.30 L of sodium-amylase composite liquid, pre-moisturizing to a water content of 43%, preparing an enzyme-containing premix, and then adding the moisturized enzyme-containing premix into a twin-screw extruder at a feeding rate of 2 kg/h. After being cooled and dried, the extrudate can be kept in an overall shape, and starch-based porous materials of different particle sizes also can be prepared by cutting (or crushing) and sieving.

[0042] Two kneading elements and no reversing element are arranged in the extrusion slot of the extruder, a rotating speed of a screw is set at 150 rpm, the temperature at a feed port is set at 40 C., the intermediate temperature is 40-50 C., the temperature at a discharge port is set at 60 C., a die head with an aperture of 2 mm is assembled at the outlet, during the extrusion process, material temperature is 42-63 C., the pressure is 3.4 MPa and the mechanical energy is 183 kJ/kg.

[0043] The porous starch prepared in this embodiment has a pore size distribution range of 10-30 m, a good water absorbability, structural strength and biodegradability, wherein, the water absorption rate can reach 286%, and the strength is 26.5 MPa.