Process for the preparation of a cationic arabic gum coagulant modified with a titanium salt

Abstract

The application discloses a preparation method of a cationic arabic gum coagulant modified by titanium salt, and comprises the following steps: (1) dissolving arabic gum in a NaOH solution, slowly stirring for 2-3 hours at room temperature until uniform; (2) adding an isopropyl alcohol solution containing 3-chloro-2-hydroxypropyl trimethyl ammonium chloride into the above solution, slowly stirring for 2-3 hours until swelling; (3) placing the mixed solution of step (2) into a microwave, taking out the modified cationic arabic gum after reaction, and repeatedly immersing and cleaning the cationic arabic gum in an ethanol aqueous solution and distilled water until the conductivity is less than 10; (4) placing the cationic arabic gum of step (3) into an oven, and obtaining the cationic arabic gum in powder form after drying; and (5) adding the cationic arabic gum into a titanium sulfate solution according to the mass ratio of titanium sulfate to the cationic arabic gum being 20-30:1, stirring for 3-4 hours, and obtaining the cationic arabic gum coagulant modified by titanium salt with high molecular weight.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a cationic gum arabic coagulant modified by titanium salt. BACKGROUND

[0002] Chemical coagulation process is a common process in wastewater treatment, that is, inorganic or organic coagulants are added to water, under the action of the coagulant, colloids and fine suspended solids in wastewater are coagulated into flocculation bodies, and then the water treatment method is separated and removed. Currently commonly used flocculants include inorganic flocculants (such as PAC, PFS), organic flocculants (PAM, etc.), biological flocculants and compound flocculants. Although the inorganic flocculant has low cost, but the addition amount is large, the sludge production is large, the efficiency is low, the flocculation body settling speed is slow, and the leakage of aluminum salt and iron salt will cause membrane pollution; the efficiency of the organic flocculant is several times to several tens of times higher than that of the inorganic salt flocculant, but there are problems such as great toxicity of residual monomer, large molecular weight and difficult degradation. SUMMARY

[0003] The purpose of the present application is to provide a preparation method of a cationic gum arabic coagulant modified by titanium salt. In the wastewater treatment process, the cationic coagulant prepared by the present application can replace inorganic flocculants, and has good flocculation and sedimentation effect, can reduce sludge production and TDS of effluent, and can also effectively reduce the addition amount of organic flocculants.

[0004] Technical scheme: The preparation method of the cationic gum arabic coagulant modified by titanium salt provided by the present application comprises the following steps:

[0005] (1) preparing cationic gum arabic: dissolving gum arabic in NaOH solution, slowly stirring at room temperature for 2-3 h until uniform mixing;

[0006] (2) adding 3-chloro-2-hydroxypropyl trimethylammonium chloride isopropyl alcohol solution to the above solution, slowly stirring for 2-3 h until swelling; this step is an etherification reaction; after the gum arabic is swelled in isopropyl alcohol, active centers are formed by alkalization, and then react with the etherifying agent 3-chloro-2-hydroxypropyl trimethylammonium chloride with a quaternary ammonium salt group to prepare quaternary ammonium type gum arabic; on the one hand, this step can generate polymers with dendritic structure, and the dendritic structure of cationic organic matter has higher ductility, so that the distribution of flocculation groups on the structure is more extensive and dispersed, which is beneficial to enhance the ability to capture suspended particles and adsorb pollutants, thereby making it have stronger capture and sedimentation promotion effect on particles in the suspended system; on the other hand, it can increase the number of active groups on the molecular chain, which is beneficial to the subsequent loading of titanium salt;

[0007] (3) the mixed solution of step (2) is placed in a microwave, and after reaction, the modified cationic gum arabic is taken out, and repeatedly soaked and washed with an ethanol aqueous solution and distilled water until the conductivity is less than 10; the cationic modification increases the active groups on the gum arabic, and the increase of the active groups can load more titanium ions;

[0008] (4) the cationic gum arabic of step (3) is placed in an oven, and after drying, the cationic gum arabic in powder form is obtained;

[0009] (5) the cationic gum arabic is added into a titanium sulfate solution according to the mass ratio of titanium sulfate to cationic gum arabic of 20-30:1, and stirred for 3-4 h, to obtain the cationic gum arabic coagulant modified by the titanium salt of high molecular weight; in order to improve the settling performance of the cationic gum arabic as a flocculant, therefore, the titanium ions are loaded on the cationic gum arabic.

[0010] In step (1), the mass concentration of the NaOH solution is 5-6%.

[0011] In step (2), the molar ratio of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMA) to isopropyl alcohol in the isopropyl alcohol solution containing 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is 1:1-1:1.5.

[0012] In step (3), the microwave power is 500 W, and the reaction time is 15-20 min.

[0013] In step (3), the mass concentration of the ethanol aqueous solution is not less than 80%.

[0014] In step (4), the drying temperature is 45-50 DEG C, and the drying time is 22-24 h.

[0015] In step (5), the mass fraction of the titanium sulfate solution is 2%-5%.

[0016] The present application uses gum arabic as a modified polysaccharide, and uses a microwave irradiation method to perform cationic modification, the purpose of the cationic modification is to make the generated polymer have a dendritic structure, and disperse flocculation groups, so that the flocculation groups have stronger capturing and promoting settling effects on the particulate matters in a suspension system; and the cationic modification can greatly increase the number of active groups on the molecular chain, thereby facilitating the subsequent loading of titanium ions. The microwave irradiation method can improve the uniformity of the product substitution degree, and improve the reaction efficiency; the titanium ions are loaded on the modified cationic gum arabic, which can improve the settling performance of the cationic gum arabic as a flocculant, and the sludge after flocculation and precipitation can be calcined at high temperature to obtain TiO2 with high photocatalytic activity, so that waste is turned into treasure, and the treatment cost of solid waste is reduced.

[0017] Beneficial effects: compared with the prior art, the present application has the following remarkable effects:

[0018] (1) The present application uses gum arabic as modified polysaccharide, gum arabic contains rich hydroxyl groups, and the chemical structure of gum arabic can be changed by etherification of the free hydroxyl groups, and is converted into a quaternary ammonium type high molecular polysaccharide, so that the number of active groups on the molecular chain is increased, thereby facilitating the subsequent loading of titanium ions, and the generated polymer has a dendritic structure, which can disperse and flocculate groups, and has a stronger adsorption effect on pollutants (the cationic organic matter with a dendritic structure has higher ductility, and the distribution of flocculation groups is more extensive and dispersed, thereby facilitating the enhancement of the ability to capture suspended particles and adsorb pollutants);

[0019] (2) The present application uses a microwave irradiation method to modify gum arabic, and the microwave irradiation method can improve the uniformity of the product substitution degree and improve the reaction efficiency during the modification process;

[0020] (3) The titanium salt is loaded on the modified cationic gum arabic, which can greatly improve the settling performance of the cationic gum arabic as a flocculant; the titanium salt hydrolyzes rapidly, and a coagulation effect comparable to that of aluminum salt and iron salt coagulants can be achieved, especially in the treatment of low-temperature and low-turbidity water;

[0021] (4) When the present application is used as a coagulant aid, the dosage of the organic flocculant can be reduced by 40% to 60%. DETAILED DESCRIPTION

[0022] Example 1

[0023] The preparation method of the titanium salt modified cationic gum arabic coagulant aid of the present application comprises the following steps:

[0024] (1) 45g of gum arabic is dissolved in 22mL of a 5% NaOH solution, and slowly stirred at 25°C for 2-3h until the mixture is uniform;

[0025] (2) 33g of an isopropyl alcohol solution containing 25g of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMA) is added to the above solution, and slowly stirred for 2-3h until the gum arabic swells in the isopropyl alcohol solution;

[0026] (3) The microwave power is set to 500W, and the mixed solution in step (2) is placed in the microwave, and reacted for 15-20min;

[0027] (4) The modified cationic gum arabic in step (3) is taken out, and repeatedly soaked and washed with an 80% ethanol aqueous solution and distilled water until the conductivity of the cationic gum arabic is less than 10;

[0028] (5) The cationic gum arabic is put into a 45℃ oven and dried for 24h to obtain powder cationic gum arabic;

[0029] (6) Titanium sulfate with a mass fraction of 2%-5% is placed in a stirred tank for stirring;

[0030] (7) The cationic gum arabic is added into the titanium sulfate solution according to a mass ratio of 20:1, and stirred for 3-4h to obtain the titanium salt modified cationic gum arabic coagulant.

[0031] Example 2

[0032] The method for treating papermaking wastewater by using the titanium salt modified cationic gum arabic coagulant prepared in Example 1 as a coagulant is as follows:

[0033] (1) The titanium salt modified cationic gum arabic coagulant prepared in Example 1 is diluted 10 times by water to obtain a coagulant diluent; the mass concentration of the coagulant in the coagulant diluent is 10%;

[0034] (2) The coagulant diluent is added into the papermaking wastewater, and the stirring speed is set to 300rpm for 15min; the mass concentration of the coagulant in the papermaking wastewater is 200mg / L;

[0035] (3) The pH of the wastewater is adjusted to neutral, 3-5mg / L of PAM with a mass fraction of 1‰ is added into the wastewater, the stirring speed is set to 150rpm for 2-3min, and the wastewater is left to stand and precipitate.

[0036] The water quality indexes of the papermaking wastewater before and after the treatment are shown in the following table:

[0037] Table 1 Effect of the titanium salt modified cationic gum arabic on the treatment of papermaking wastewater

[0038] Index COD (mg / L) Turbidity (NTU) Color (degree) Raw water 7150 392 1253 After treatment 3115 5.99 207 Removal rate (%) 56.43 98.47 86.95

[0039] Comparative Example 1

[0040] The papermaking wastewater treated in Comparative Example 1 and Example 2 is treated by using PAC, and the specific steps are as follows:

[0041] (1) PAC is added into the papermaking wastewater, and the stirring speed is set to 300rpm for 15min; the mass concentration of the PAC in the papermaking wastewater is 2000mg / L;

[0042] (2) The pH of the wastewater is adjusted to neutral, 3-5mg / L of PAM with a mass fraction of 1‰ is added into the wastewater, the stirring speed is set to 150rpm for 2-3min, and the wastewater is left to stand and precipitate.

[0043] The water quality indexes of the papermaking wastewater before and after treatment are shown in the following table:

[0044] Table 2 Effect of PAC on treatment of papermaking wastewater

[0045] Index COD (mg / L) Turbidity (NTU) Color (degree) Raw water 7150 392 1253 After treatment 6860 231 856 Removal rate (%) 4.06 41.07 31.68

[0046] As can be seen from the table, the dosage of the cationic arabic gum modified by titanium salt is 1% of the mass of PAC, but the removal effects of COD, turbidity and colority in the papermaking wastewater are better than those of PAC.

[0047] Comparative Example 2

[0048] A preparation method of a cationic arabic gum coagulant aid, comprising the following steps:

[0049] (1) 45 g of arabic gum is dissolved in 22 mL of a 5% mass fraction NaOH solution, and slowly stirred at 25°C for 2-3 h until mixed uniformly;

[0050] (2) 33 g of an isopropyl alcohol solution containing 25 g of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMA) is added to the above solution, and slowly stirred for 2-3 h until the arabic gum is swelled in the isopropyl alcohol solution;

[0051] (3) The mixed solution in step (2) is placed in a microwave with a microwave power of 500 W, and reacted for 15-20 min;

[0052] (4) The modified cationic arabic gum in step (3) is taken out, and repeatedly soaked and washed with an 80% mass fraction ethanol aqueous solution and distilled water until the conductivity of the cationic arabic gum is less than 10;

[0053] (5) The cationic arabic gum is placed in a 45°C oven, and dried for 24 h to obtain a powder-like cationic arabic gum.

[0054] Example 3

[0055] Example 3 is basically the same as Example 2, except that the cationic arabic gum coagulant aid prepared in Comparative Example 2 is used to treat the papermaking wastewater in Example 2, and the specific steps are as follows:

[0056] (1) The cationic arabic gum is added to the papermaking wastewater, and the stirring speed is set to 300 rpm, and reacted for 15 min; the dosage of the cationic arabic gum is that the mass concentration of the cationic arabic gum in the papermaking wastewater is 200 mg / L;

[0057] (2) The pH of the wastewater is adjusted to neutral, 3-5 mg / L of PAM with a mass fraction of 1‰ is added to the wastewater, the stirring speed is set to 150 rpm, and reacted for 2-3 min, and then settled.

[0058] The water quality indexes of the papermaking wastewater before and after treatment are shown in the following table:

[0059] Table 3 Effect of cationic gum arabic on treatment of papermaking wastewater

[0060]

[0061]

[0062] As can be seen from the table, when the dosage of the titanium salt modified cationic gum arabic and the cationic gum arabic is the same, the titanium salt modified cationic gum arabic has better removal effect on COD, turbidity and colority in the papermaking wastewater than the cationic gum arabic.

[0063] Example 4

[0064] The operation method of Example 4 is completely same as that of Example 2, and the only difference is that the wastewater treated in Example 4 is CMP wastewater in electronic industry, and the specific steps are as follows:

[0065] (1) The titanium salt modified cationic gum arabic coagulant aid prepared in Example 1 is diluted by 10 times to obtain a coagulant aid diluent; in the coagulant aid diluent, the mass concentration of the coagulant aid is 10%;

[0066] (2) The coagulant aid diluent is added into the CMP wastewater, the stirring speed is set to 300 rpm, and the reaction is carried out for 15 min; the dosage of the coagulant aid is that the mass concentration of the coagulant aid in the CMP wastewater is 200 mg / L;

[0067] (3) The pH of the wastewater is adjusted to neutral, 3-5 mg / L of PAM with a mass fraction of 1‰ is added into the wastewater, the stirring speed is set to 150 rpm, and the reaction is carried out for 2-3 min, and then the wastewater is left to stand and precipitate.

[0068] The water quality indexes of the CMP wastewater before and after treatment are shown as follows:

[0069] Table 4 Effect of titanium salt modified cationic gum arabic on treatment of CMP wastewater

[0070] Index Color (degree) Turbidity (NTU) SS (mg / L) Ti (mg / L) Raw water 105 43.3 14 ND After treatment ND 0.18 2 ND Removal rate (%) 100 99.58 85.71 /

[0071] As can be seen from the table, the titanium salt modified cationic gum arabic coagulant aid has good removal effect on turbidity and SS in the CMP wastewater, and almost no metal is dissolved out, so that the influence of the filter membrane in the subsequent water treatment process (further treatment of the water after solid-liquid separation) can be avoided.

[0072] Example 5

[0073] The operation method of Example 5 is exactly the same as that of Example 2, the only difference is that the wastewater treated in Example 5 is low-temperature and low-turbidity wastewater, and the specific steps are as follows:

[0074] (1) Select wastewater with turbidity of 10-20 NTU, store in refrigerator until water temperature is about 4℃, and use thermal insulation cotton to ensure that the water temperature rises no more than 2℃ during the experiment;

[0075] (2) Dilute the titanium salt modified cationic gum coagulant prepared in Example 1 by 10 times to obtain a coagulant diluent; the mass concentration of coagulant in the coagulant diluent is 10%;

[0076] (3) Add coagulant diluent to low-temperature and low-turbidity wastewater, set stirring speed to 300 rpm, and react for 15 min; the dosage of coagulant is: the mass concentration of coagulant in low-temperature and low-turbidity wastewater is 50, 150, and 250 mg / L, respectively;

[0077] (4) Adjust the pH of the wastewater to neutral, add 3-5 mg / L of PAM with a mass fraction of 1‰ to the wastewater, set the stirring speed to 150 rpm, react for 2-3 min, and stand for sedimentation.

[0078] Table 5 Treatment effect of titanium salt modified cationic gum on low-temperature and low-turbidity wastewater

[0079]

[0080] As can be seen from the above table, the titanium salt modified gum has good treatment effect on low-temperature and low-turbidity wastewater, and under appropriate dosage, the wastewater turbidity can even be reduced to below 1 NTU, meeting the sanitary standards for drinking water.

Claims

1. A process for the preparation of a cationic gum arabic coagulant modified with a titanium salt, characterized in that, The method comprises the following steps: (1) dissolving gum arabic in NaOH solution, slowly stirring at room temperature until mixed evenly; (2) adding 3-chloro-2-hydroxypropyltrimethylammonium chloride-containing isopropanol solution to the above solution, slowly stirring until swelling; (3) placing the mixed solution of step (2) in a microwave, after reaction, taking out the modified cationic gum arabic, repeatedly soaking and cleaning with ethanol aqueous solution and distilled water until the conductivity is less than 10; the microwave power is 500 W, and the reaction time is 15-20 min; (4) placing the cationic gum arabic of step (3) in an oven, after drying, obtaining powder-like cationic gum arabic; (5) according to the mass ratio of titanium sulfate to cationic gum arabic being 20-30:1, adding cationic gum arabic to titanium sulfate solution, stirring for 3-4 h, obtaining high-molecular-weight titanium salt modified cationic gum arabic coagulant.

2. The method of preparing a titanium salt-modified cationic gum arabic coagulant according to claim 1, characterized by: In step (1), the mass concentration of NaOH solution is 5-6%.

3. The method of preparing a titanium salt-modified cationic gum arabic coagulant according to claim 1, characterized by: In step (2), in the 3-chloro-2-hydroxypropyltrimethylammonium chloride-containing isopropanol solution, the molar ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride to isopropanol is 1:1-1:1.

5.

4. The method of preparing a titanium salt-modified cationic gum arabic coagulant according to claim 1, characterized by: The molar ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride to NaOH is 1:0.05-1:0.

1.

5. The method of preparing a titanium salt-modified cationic gum arabic coagulant according to claim 1, characterized by: In step (3), the mass concentration of the ethanol aqueous solution is not less than 80%.

6. The method of preparing a titanium salt modified cationic gum conditioner as claimed in claim 1, wherein: In step (4), the drying temperature is 45-50°C, and the drying time is 22-24 h.

7. The method of preparing a titanium salt-modified cationic gum arabic coagulant according to claim 1, characterized by: In step (5), the mass fraction of the titanium sulfate solution is 2%-5%.

Images