Summary of the invention
In view of the existing problem of background technology, the object of the present invention is to provide a kind of simple, preparation method of rice hull active carbon/earth silicon/titanic oxide composite cheaply, with rice hull active carbon loaded with nano silica and nanometer titanium dioxide composite material, with the photocatalytic activity of raising nano titanium oxide, and effectively solve easily the come off problem of nano titanium oxide at carrier surface.
The technical solution used in the present invention comprises the steps: 1, the preliminary treatment of rice husk: rice husk is cleaned with clear water, dry, pulverize, cross 100 ~ 250 mesh sieves, the adding mass percentage concentration is 3% ~ 10% hydrochloric acid, and the mass ratio of rice husk and hydrochloric acid solution is 0.1 ~ 1:1, stirs 1 ~ 7 hour under 40 ~ 85 ℃ of temperature, be washed to neutrality, obtain the pickling powdered rice hulls; 2, soda boiling: the NaOH solution that in described pickling powdered rice hulls, adds 0.5-3mol/L, wherein the mass ratio of pickling powdered rice hulls and NaOH is 0.5 ~ 2:1, the soda boiling temperature maintenance is at 50 ~ 95 ℃ under constantly stirring, and insulation soda boiling 2 ~ 8 hours, obtains the mixed serum of rice husk and sodium metasilicate composition; 3, the preparation of rice husk/earth silicon/titanic oxide precursor: the TiCl that under constantly stirring, in described mixed serum, adds 0.5-3.5mol/L earlier
4Solution, reaction temperature remain on 45 ~ 90 ℃; PH value to 5.5 ~ 7.5 of conditioned reaction system then, TiCl
4The solution adding finishes, and continues to stir insulation slaking 0.5 ~ 3 hour; At last with the dope filtration of gained, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing, the filter cake of gained 70 ~ 140 ℃ of vacuum drying 5 ~ 12 hours, is pulverized to filtrate, make rice husk/earth silicon/titanic oxide composite; 4, charing: described rice husk/earth silicon/titanic oxide composite under nitrogen atmosphere, in 300 ~ 550 ℃ of roastings 2 ~ 6 hours, is naturally cooled to room temperature, make rice hull carbon/earth silicon/titanic oxide composite; 5, activation: it is 30 ~ 60% ZnCl that described rice hull carbon/earth silicon/titanic oxide composite is immersed in mass percentage concentration
2Stir in the aqueous solution, wherein composite and ZnCl
2Mass ratio be 0.2 ~ 0.8:1, dip time is 12 ~ 24 hours, dry back in 400 ~ 650 ℃ of activation 1 ~ 4 hour, naturally cools to room temperature and obtains activation products under nitrogen atmosphere; 6, post processing: with described activation products is earlier 4 ~ 20% chlorohydric acid pickling with mass percentage concentration, uses the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying, and pulverizing makes rice hull active carbon/earth silicon/titanic oxide composite.
The present invention at first carries out pickling to rice husk, then by soda boiling with the amorphous silica in the rice husk with the stripping of sodium metasilicate form, with the precipitation method technology nano silicon and nano titanium oxide are deposited on the rice husk surface equably again, utilize silica that rice husk and the nano titanium oxide form with chemical bond is combined, prepare rice hull active carbon/earth silicon/titanic oxide composite by charing, activation at last, its advantage is:
1, utilizes the absorption property and the good photocatalysis performance of nano titanium oxide of excellence of the rice hull active carbon/earth silicon/titanic oxide composite material concurrent rice hull active carbon of precipitation method technology preparation.
2, between rice hull active carbon and nano titanium oxide, introduce nano silicon, silica combines rice hull active carbon and nano titanium oxide securely by chemical bond, avoided easily the come off problem of nano titanium oxide effectively, significantly improved the stability of composite at carrier surface.
3, rice hull active carbon in the composite and nano silicon all come from the agricultural wastes rice husk, and the present invention has made full use of rice husk raw material self characteristics and this renewable resource of rice husk, have solved rice husk and have piled up the environmental problem of bringing.
4, preparation process technology is simple, the raw material cheapness, and cost is low, not with an organic solvent, pollutes few.
The specific embodiment
Earlier rice husk is carried out preliminary treatment, pretreated method is that rice husk is cleaned with clear water, dry, pulverize, cross 100 ~ 250 mesh sieves, add mass percentage concentration and be 3% ~ 10% hydrochloric acid and carry out pickling, wherein the mass ratio of rice husk and hydrochloric acid solution is 0.1 ~ 1:1, under 40 ~ 85 ℃ of temperature, stirred 1 ~ 7 hour, be washed to neutrality, obtain the pickling powdered rice hulls.In the pickling powdered rice hulls of gained, add in the NaOH solution of 0.5-3mol/L, wherein the mass ratio of pickling powdered rice hulls and NaOH is 0.5 ~ 2:1, and under constantly stirring, the soda boiling temperature maintenance is at 50 ~ 95 ℃, and be incubated soda boiling 2 ~ 8 hours, obtain the mixed serum that rice husk and sodium metasilicate are formed.Prepare rice husk/earth silicon/titanic oxide precursor again, promptly under constantly stirring, in the mixed serum of rice husk that obtains and sodium metasilicate composition, add the TiCl of 0.5-3.5mol/L
4Solution, reaction temperature remain on 45 ~ 90 ℃, pH value to 5.5 ~ 7.5 of conditioned reaction system, TiCl when reaction system pH is adjusted to 5.5 ~ 7.5
4The solution adding finishes, continue to stir, insulation slaking 0.5 ~ 3 hour, dope filtration with gained, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate, the filter cake of gained 70 ~ 140 ℃ of vacuum drying 5 ~ 12 hours, is pulverized, made rice husk/earth silicon/titanic oxide composite.Carry out charing then and handle, the rice husk/earth silicon/titanic oxide composite that is about to gained in 300 ~ 550 ℃ of roastings 2 ~ 6 hours, naturally cools to room temperature under nitrogen atmosphere, make rice hull carbon/earth silicon/titanic oxide composite.Carry out activation processing again: it is 30 ~ 60% ZnCl that the rice hull carbon/earth silicon/titanic oxide composite that is about to gained is immersed in mass percentage concentration
2Stir in the aqueous solution, wherein composite and ZnCl
2Mass ratio be 0.2 ~ 0.8:1, dip time is 12 ~ 24 hours, dry back in 400 ~ 650 ℃ of activation 1 ~ 4 hour, naturally cools to room temperature and obtains activation products under nitrogen atmosphere.Be post processing at last, the activation products that are about to gained are earlier 4 ~ 20% chlorohydric acid pickling with mass percentage concentration, use the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying, pulverize, make rice hull active carbon/earth silicon/titanic oxide composite.
Below provide 4 embodiment and 3 comparative examples to further specify the present invention:
Embodiment 1
1 kilogram of rice husk clear water cleaning, drying, pulverize earlier, cross 250 mesh sieves, the mass percentage concentration that adds 10 kilograms is in 3% the hydrochloric acid solution, and 85 ℃ of stirrings 7 hours are washed to neutrality, obtain the pickling powdered rice hulls.16.7 liters of NaOH solution that add 3mol/L in the pickling powdered rice hulls, under constantly stirring, the soda boiling temperature maintenance is at 95 ℃, and the insulation soda boiling obtained the mixed serum of rice husk and sodium metasilicate composition in 8 hours.Under constantly stirring, in the mixed serum that the rice husk and the sodium metasilicate of gained are formed, add the TiCl of 3.5mol/L again
4Solution, reaction temperature remain on 90 ℃, the pH value of conditioned reaction system then, and when the pH of reaction system is adjusted to 5.5, TiCl
4The solution adding finishes, and continues to stir insulation slaking 3 hours, filter, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate, with the filter cake of gained 140 ℃ of vacuum drying 12 hours, pulverize, make rice husk/earth silicon/titanic oxide composite.Again with the rice husk/earth silicon/titanic oxide composite of gained under nitrogen atmosphere, in 550 ℃ of roastings 6 hours, naturally cool to room temperature, make rice hull carbon/earth silicon/titanic oxide composite.In the rice hull carbon/earth silicon/titanic oxide composite of gained, add mass percentage concentration again and be 60% ZnCl
2The aqueous solution stirs, and wherein the mass ratio of composite and zinc chloride is 0.8:1, floods 24 hours, and dry back in 650 ℃ of activation 4 hours, naturally cools to room temperature and obtains activation products under nitrogen atmosphere.Be 4% hydrochloric acid solution pickling at last with the activation products mass percentage concentration of gained, use the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying is pulverized, and makes rice hull active carbon/earth silicon/titanic oxide composite.
Embodiment 2
1 kilogram of rice husk clear water cleaning, drying, pulverize earlier, cross 100 mesh sieves, the mass percentage concentration that adds 1 kilogram is in 10% the hydrochloric acid solution, and 40 ℃ of stirrings 1 hour are washed to neutrality, obtain the pickling powdered rice hulls.25 liters of NaOH solution that add 0.5mol/L in the pickling powdered rice hulls, under constantly stirring, the soda boiling temperature maintenance is at 50 ℃, and the insulation soda boiling obtained the mixed serum of rice husk and sodium metasilicate composition in 2 hours.Under constantly stirring, in the mixed serum that the rice husk and the sodium metasilicate of gained are formed, add the TiCl of 0.5mol/L again
4Solution, reaction temperature remain on 45 ℃, the pH value of conditioned reaction system then, and when reaction system pH is adjusted to 7.5, TiCl
4The solution adding finishes, and continues to stir insulation slaking 0.5 hour, filter, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate, with the filter cake of gained 70 ℃ of vacuum drying 5 hours, pulverize, make rice husk/earth silicon/titanic oxide composite.Again with the rice husk/earth silicon/titanic oxide composite of gained under nitrogen atmosphere, in 300 ℃ of roastings 2 hours, naturally cool to room temperature, make rice hull carbon/earth silicon/titanic oxide composite.In the rice hull carbon/earth silicon/titanic oxide composite of gained, add mass percentage concentration again and be 30% ZnCl
2The aqueous solution stirs, and wherein the mass ratio of composite and zinc chloride is 0.2:1, floods 12 hours, and dry back in 400 ℃ of activation 1 hour, naturally cools to room temperature and obtains activation products under nitrogen atmosphere.Be 20% hydrochloric acid solution pickling at last with the activation products mass percentage concentration of gained, use the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying is pulverized, and makes rice hull active carbon/earth silicon/titanic oxide composite.
Embodiment 3
1 kilogram of rice husk clear water cleaning, drying, pulverize earlier, cross 200 mesh sieves, the mass percentage concentration that adds 5 kilograms is in 5% the hydrochloric acid solution, and 70 ℃ of stirrings 5 hours are washed to neutrality, obtain the pickling powdered rice hulls.12.5 liters of NaOH solution that add 2mol/L in the pickling powdered rice hulls, under constantly stirring, the soda boiling temperature maintenance is at 80 ℃, and the insulation soda boiling obtained the mixed serum of rice husk and sodium metasilicate composition in 6 hours.Under constantly stirring, in the mixed serum that the rice husk and the sodium metasilicate of gained are formed, add the TiCl of 2.5mol/L again
4Solution, reaction temperature remain on 75 ℃, the pH value of conditioned reaction system then, and when reaction system pH is adjusted to 7, TiCl
4The solution adding finishes, and continues to stir insulation slaking 2 hours, filter, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate, with the filter cake of gained 120 ℃ of vacuum drying 10 hours, pulverize, make rice husk/earth silicon/titanic oxide composite.Again with the rice husk/earth silicon/titanic oxide composite of gained under nitrogen atmosphere, in 450 ℃ of roastings 5 hours, naturally cool to room temperature, make rice hull carbon/earth silicon/titanic oxide composite.In the rice hull carbon/earth silicon/titanic oxide composite of gained, add mass percentage concentration again and be 50% ZnCl
2The aqueous solution stirs, and wherein the mass ratio of composite and zinc chloride is 0.5:1, floods 18 hours, and dry back in 600 ℃ of activation 3 hours, naturally cools to room temperature and obtains activation products under nitrogen atmosphere.Be 10% hydrochloric acid solution pickling at last with the activation products mass percentage concentration of gained, use the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying is pulverized, and makes rice hull active carbon/earth silicon/titanic oxide composite.
Embodiment 4
1 kilogram of rice husk clear water cleaning, drying, pulverize earlier, cross 150 mesh sieves, the mass percentage concentration that adds 4 kilograms is in 7% the hydrochloric acid solution, and 60 ℃ of stirrings 3 hours are washed to neutrality, obtain the pickling powdered rice hulls.11.1 liters of NaOH solution that add 1.5mol/L in the pickling powdered rice hulls, under constantly stirring, the soda boiling temperature maintenance is at 70 ℃, and the insulation soda boiling obtained the mixed serum of rice husk and sodium metasilicate composition in 5 hours.Under constantly stirring, in the mixed serum that the rice husk and the sodium metasilicate of gained are formed, add the TiCl of 2mol/L again
4Solution, reaction temperature remain on 55 ℃, the pH value of conditioned reaction system then, and when reaction system pH is adjusted to 6, TiCl
4The solution adding finishes, and continues to stir insulation slaking 1.5 hours, filter, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate, with the filter cake of gained 110 ℃ of vacuum drying 8 hours, pulverize, make rice husk/earth silicon/titanic oxide composite.Again with the rice husk/earth silicon/titanic oxide composite of gained under nitrogen atmosphere, in 400 ℃ of roastings 2 hours, naturally cool to room temperature, make rice hull carbon/earth silicon/titanic oxide composite.In the rice hull carbon/earth silicon/titanic oxide composite of gained, add mass percentage concentration again and be 35% ZnCl
2The aqueous solution stirs, and wherein the mass ratio of composite and zinc chloride is 0.3:1, floods 18 hours, and dry back in 550 ℃ of activation 2 hours, naturally cools to room temperature under nitrogen atmosphere.Be 15% hydrochloric acid solution pickling at last with the activation products mass percentage concentration of gained, use the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying is pulverized, and makes rice hull active carbon/earth silicon/titanic oxide composite.
Comparative example 1
In comparative example 1, with the rice husk pickling process among the embodiment 3 deletion, be about to " earlier 1 kilogram of rice husk clear water cleaning, drying; pulverize; cross 200 mesh sieves, the mass percentage concentration that adds 5 kilograms is that 70 ℃ were stirred 5 hours; be washed to neutrality; obtain the pickling powdered rice hulls in 5% the hydrochloric acid solution " this step deletion, other operations are all identical with embodiment 3, and the concrete operations step is as follows: elder generation is clean with clear water 1 kilogram of rice husk, dry, pulverize, cross 200 mesh sieves, obtain powdered rice hulls, 12.5 liters of NaOH solution that in powdered rice hulls, add 2mol/L, under constantly stirring, the soda boiling temperature maintenance is at 80 ℃, and the insulation soda boiling obtained the mixed serum of rice husk and sodium metasilicate composition in 6 hours.Under constantly stirring, in the mixed serum that the rice husk and the sodium metasilicate of gained are formed, add the TiCl of 2.5mol/L again
4Solution, reaction temperature remain on 75 ℃, when reaction system pH is adjusted to 6.5, and TiCl
4The solution adding finishes, and continues to stir insulation slaking 2 hours, filter, with the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate, with the filter cake of gained 120 ℃ of vacuum drying 10 hours, pulverize, make rice husk/earth silicon/titanic oxide composite.Again with the rice husk/earth silicon/titanic oxide composite of gained under nitrogen atmosphere, in 450 ℃ of roastings 5 hours, naturally cool to room temperature, make rice hull carbon/earth silicon/titanic oxide composite.In the rice hull carbon/earth silicon/titanic oxide composite of gained, add mass percentage concentration again and be 50% ZnCl
2The aqueous solution stirs, and wherein the mass ratio of composite and zinc chloride is 0.5:1, floods 18 hours, and dry back in 600 ℃ of activation 3 hours, naturally cools to room temperature and obtains activation products under nitrogen atmosphere.Be 10% hydrochloric acid solution pickling at last with the activation products mass percentage concentration of gained, use the electrical conductivity≤260 μ S/cms of deionized water cyclic washing to filtrate then, drying is pulverized, and makes rice hull active carbon/earth silicon/titanic oxide composite.
Comparative example 2
In comparative example 2, with the rice husk among the embodiment 4/earth silicon/titanic oxide composite under nitrogen atmosphere in 400 ℃ of roastings 2 hours, naturally cool to room temperature, make this operation deletion of rice hull carbon/earth silicon/titanic oxide composite, other operations are all identical with embodiment 3.
Comparative example 3
In comparative example 3, with " 1 kilogram of rice husk is cleaned with clear water; drying; pulverize; cross 200 mesh sieves; the mass percentage concentration that adds 5 kilograms is in 5% the hydrochloric acid solution; 80 ℃ of stirrings 5 hours among the embodiment 3, be washed to neutrality, obtain the pickling powdered rice hulls " the rice husk pickling process and " rice husk/earth silicon/titanic oxide composite of gained under nitrogen atmosphere, in 450 ℃ of roastings 5 hours, is naturally cooled to room temperature, make rice hull carbon/earth silicon/titanic oxide composite " the step deletion, other operations are all identical with embodiment 3.
Below rice hull active carbon/earth silicon/titanic oxide composite is carried out the photocatalytic activity evaluation, result of the test is as shown in table 1.
Rice hull active carbon/earth silicon/titanic oxide the composite that in the photochemical reaction instrument, adds 0.2 gram, the reactive red M-2B solution that adds 500 milliliters of 20mg/L again, open the air that stirs and feed flow 0.02L/min from the bottom, open uviol lamp (power 15W, wavelength 254nm), reacting took a sample after 4 hours places the centrifuge tube centrifugation, get supernatant liquor and test, measure solution absorbency by spectrophotometer under its maximum absorption wavelength, degradation rate is calculated as follows:
ηFor the dyestuff degradation rate (
%);
A 0,
A tBe respectively the degraded before,
tDye solution absorbance after time;
C 0,
C tBe respectively the degraded before,
tDyes concentration after time (mg/L).
As can be seen from Table 1, the photocatalytic activity of the prepared rice hull active carbon/earth silicon/titanic oxide composite of the present invention significantly improves.
The photocatalysis test of table 1 rice hull active carbon/earth silicon/titanic oxide composite
Title |
Dyestuff degradation rate (%) |
The pure titinium dioxide P25 of company (German Degussa) |
70.69 |
Embodiment 1 |
91.23 |
Embodiment 2 |
92.88 |
Embodiment 3 |
97.67 |
Embodiment 4 |
93.36 |
Comparative example 1 |
78.44 |
Comparative example 2 |
75.22 |
Comparative example 3 |
73.75 |