A kind of preparation method for Adsorption of Chromium acid group material
Technical field
The present invention relates to a kind of preparation method for Adsorption of Chromium acid group material.
Background technology
Heavy metal ion has the toxicity of height, but be difficult to biological degradation, and easily again to be accumulated in organism by food chain, along with the propelling of global industry process, heavy metal ion causes great threat to the existence of the mankind and the water surrounding eubiosis to the pollution of water quality, relevant isolation technique and material anxious to be developed.Therefore, from water medium, heavy-metal ion removal is the key subjects of environmental protection and treatment.
The pollution of heavy metal chromium to soil and water body causes people and pays close attention to greatly, and it is mainly from waste water and the waste of the industries such as plating, process hides, metallurgy, chemical industry and mining.Chromium exists with sexavalence and trivalent two kinds of forms usually, and wherein, sexavalent chrome (anionic metal) is very large to the toxicity of human body, and its toxicity is 500 times of trivalent chromium toxicity, has been confirmed as the heavy metal species with serious carcinogenesis.At present, Cr(VI in water medium) existence, the health of human body in serious threat.In Environmental Protection Agency (EPA) given application tap water and industrial discharge water, the exempt quantities of chromate is respectively 50 and 200 μ g/L, and this standard is also recommended by the World Health Organization (WHO).Investigators have adopted multiple method to be devoted to the removal of chromate in water medium, such as chemical precipitation method, chemical reduction method, ion exchange method, membrane separation process, electrocoagulation, reverse osmosis method, absorption method etc.All kinds of method is compared, absorption method due to operation run easy, cost is low, removal efficiency is high, sorbent material also renewable with recycle, therefore, be a kind of effective method, be widely adopted.The sorbent material used at present has the materials such as clay, zeolite, gac, fluoropolymer resin, biomass.These sorbent materials existing are very responsive to the pH value of medium, dependency strong, especially in basic solution, extremely low to the loading capacity of chromate ion.
Therefore in order to promote that absorption method develops, be necessary to study the high-performance solid sorbent material that a kind of loading capacity of preparation is high, selectivity good, cost is low, green environmental protection is strong.
Summary of the invention
The present invention is that the pH value dependency to medium in order to solve the existence of existing chromate sorbent material is strong, the problem that loading capacity is extremely low in basic solution, and provides a kind of preparation method for Adsorption of Chromium acid group material.
Invention thinking of the present invention is, first adopt surperficial Inducing Graft Polymerization method, macromole polymethyl acrylic acid dimethylamino ethyl ester (PDMAEMA) containing tertiary amine chain link is grafted on micron order silica particle surface efficiently, then passes through macromolecular reaction method to grafting particulate PDMAEMA/SiO
2carry out quaternized (Quaternization) modification, made it change into be grafted with the grafting particulate QPDMAEMA/SiO of cationic polyelectrolyte
2, by means of strong electrostatic interaction, particulate QPDMAEMA/SiO
2very strong adsorption can be produced to chromate ion.
The present invention is realized by above technical scheme:
For a preparation method for Adsorption of Chromium acid group material, comprise the following steps:
(1) aerosil particles of surface modification:
10-15g activated silica gel is joined in 100-150ml water solvent, and add the γ-aminopropyltrimethoxysilane (AMPS) of 10-15ml, at 50 DEG C, react 20-24h, the ethanol repetitive scrubbing of the product after suction filtration, vacuum-drying, the aerosil particles AMPS-SiO of obtained surface modification
2;
(2) silica particle surface chemical graft polymethyl acrylic acid dimethylamino ethyl ester DMAEMA:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the aerosil particles AMPS-SiO of the surface modification of 1.5-1.6 g
2, add 80-85mL water and 15-16 mL monomer DMAEMA again, logical nitrogen 30 min, get rid of the air in reaction system, then system temperature is risen to 35 DEG C, the aqueous solution that 20 mL are dissolved with 0.150-0.155 g ammonium persulphate is added in system, the surperficial Inducing Graft Polymerization of DMAEMA is carried out under the constant temperature of 35 DEG C and agitation condition, reaction is terminated after 6 h, suction filtration, collect product particles, with methyl alcohol extracting 24 h in Soxhlet extractor, to remove the homopolymer that physics is adsorbed on grafting microparticle surfaces, vacuum-drying is to constant weight, namely at silica particle surface chemical graft polymethyl acrylic acid dimethylamino ethyl ester DMAEMA, obtain grafting particulate PDMAEMA/SiO
2,
(3) grafting particulate PDMAEMA/SiO
2quaternized transformation:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the grafting particulate PDMAEMA/SiO of 1-1.2 g
2add 50-55 mL epoxy chloropropane again, constant temperature is in 60 DEG C, make the quaterisation between the tertiary amine group of grafting macromole PDMAEMA and epoxy chloropropane carry out 3 h, after reaction terminates, filter, collect product particles, repeatedly wash with acetone, vacuum-drying, to constant weight, obtains the functional particles QPDMAEMA/SiO2 that quaternized transformation occurs.
Further, described dimethylaminoethyl methacrylate DMAEMA is replaced by amino acrylates.
Described quaternizing agent is that epoxy chloropropane is replaced by monochlorethane.
By functional particles QPDMAEMA/SiO obtained according to the method described above
2fully swelling in aqueous, then adopt silver nitrate titration method to measure its quaternization degree, QPDMAEMA/SiO
2quaternized degree (Quaternization degree, QD%) be 63-65%.
In order to verify the adsorption to chromate, temperature 25 DEG C, under the condition of pH=7, use aerosil particles, grafting particulate PDMAEMA/SiO respectively
2carry out adsorption isotherm experiment with quaternized grafting particulate to chromate, Fig. 2 gives the adsorption isothermal line in neutral solution.
As can be seen from Figure 2, aerosil particles is to CrO
4 2-ionic adsorption amount is very low, and aerosil particles adsorbs CrO hardly in other words
4 2-ion; But after silica particle surface grafting macromole PDMAEMA, grafting particulate PDMAEMA/SiO
2by means of protonated amido and CrO
4 2-electrostatic interaction between ion, to CrO
4 2-ion presents stronger adsorption (loading capacity is 34mg/g); And quaternized grafting particulate QPDMAEMA/SiO
2then rely on quaternary ammonium cation and CrO
4 2-electrostatic interaction between ion, to CrO
4 2-ion shows very strong adsorptive power (loading capacity is 64 mg/g), fully shows the high-adsorption-capacity feature of quaternized grafting particulate to chromate; And why two kinds of particulate absorption properties have large difference, its reason is: in neutral solution, only have the amido atom N of 60% to be in protonation state, grafting particulate PDMAEMA/SiO
2the positive charge density on surface has become less, causes it in neutral solution to CrO
4 2-the loading capacity of negatively charged ion reduces; And quaternized grafting particulate QPDMAEMA/SiO
2in neutral solution, the positive charge density on its surface is still very high, with CrO
4 2-electrostatic interaction between ion is still very strong, result in high loading capacity.
At various ph values, grafting particulate PDMAEMA/SiO is measured
2with functional particles QPDMAEMA/SiO
2to CrO
4 2-the adsorption isothermal curve of negatively charged ion, the sorption isotherm under the different pH value of two systems obtains saturated extent of adsorption, draws saturated extent of adsorption (Q
m) and pH value between relation curve, as shown in Figure 3.
As can be seen from Figure 3, functional particles QPDMAEMA/SiO
2to CrO
4 2-the loading capacity of ion, although decline to some extent with the increase of pH value, by impact very little (pH=3, the Qm=70mg/g of PH values; PH=9, Qm=62mg/g), namely show the non-sensibility of its absorption property to PH values; Functional particles QPDMAEMA/SiO
2surface macromolecular chain exists the not quaternised amido atom N (35%) of part, they 70% are protonated in an acidic solution, but along with the increase of pH value, the protonation of these amido atom N constantly reduces, the loading capacity of functional particles is caused slightly to decline with the increase of pH value; But due to QPDMAEMA/SiO
2to CrO
4 2-adsorption mainly from quaternary ammonium cation, and the contribution of protonated amido atom N is secondary, therefore loading capacity is very little by the impact of PH values.Grafting particulate PDMAEMA/SiO
2to CrO
4 2-loading capacity very large by the impact of solution ph, loading capacity to decline rapidly (pH=3, Qm=63mg/g with the increase of pH value; PH=9, Qm=23mg/g; ), namely show the susceptibility of its absorption property to PH values.Grafting particulate PDMAEMA/SiO
2to CrO
4 2-adsorption depend on the protonated of amido atom N in PDMAEMA macromolecular chain, in an acidic solution, amido atom N 70% is in protonation state, therefore to CrO
4 2-there is higher loading capacity; Along with the increase of pH value, amido atom N protonation constantly reduces, therefore loading capacity continuous decrease; But as pH=9, protonation is down to 32%, cause grafting particulate PDMAEMA/SiO
2to CrO in basic solution
4 2-loading capacity be down to very low.
Three kinds of particulate SiO
2, modified granular AMPS-SiO
2with grafting particulate PDMAEMA/SiO
2infrared spectrogram as shown in Figure 4, as can be seen from Figure 4, SiO
2infrared spectra in, be positioned at 3440 cm
-1neighbouring peak is the absorption peak relevant to silicone hydroxyl, at modified granular AMPS-SiO
2spectrogram in, this peak greatly weakens, meanwhile at 2920 cm
-1there is the asymmetrical stretching vibration absorption peak of c h bond in place, 700 cm
-1there is the flexural vibration absorption peak of primary amine groups N-H key in place; The change of above-mentioned spectrum peak data shows that coupling agent AMPS and silicone hydroxyl there occurs reaction, is bonded in silica particle surface, at grafting particulate PDMAEMA/SiO
2infrared spectra in, in 1732 cm
-1there is the stretching vibration absorption peak of ester carbonyl group C=O in place, at 1395 cm
-1near there is the absorption peak of tertiary amine groups C-N key, meanwhile, at 2950 cm
-1with 2850 cm
-1place, has shown methyl-CH
3with methylene radical-CH
2the stretching vibration absorption peak of (methyl in grafting macromolecular chain PDMAEMA main chain and methylene radical); The change at above-mentioned spectrum peak fully shows that monomer DMAEMA there occurs graft polymerization at Silica Surface, defines grafting particulate PDMAEMA/SiO
2.
Fig. 5 is grafting particulate PDMAEMA/SiO
2, functional particles QPDMAEMA/SiO
2infrared spectrogram, as can be seen from Figure 5, with grafting particulate PDMAEMA/SiO
2spectrum peak compare, functional particles QPDMAEMA/SiO
2at 908 cm
-1there is the characteristic absorbance of epoxide group in place, the tertiary amine nitrogen indicating grafting macromole PDMAEMA with epoxy chloropropane generation quaterisation, be transformed into the cationic polyelectrolyte QPDMAEMA of grafting, grafting particulate PDMAEMA/SiO
2change functional particles QPDMAEMA/SiO into
2.
Fig. 6 is SiO
2the stereoscan photograph of particulate, Fig. 7 is grafting particulate PDMAEMA/SiO
2stereoscan photograph, as can see from Figure 6, SiO before grafting
2particle surface is more coarse, uneven, and corner angle are high-visible; And see from Fig. 4, SiO after grafting
2particle surface obviously becomes comparatively level and smooth, fuzzy thick and heavy; Grafting particulate PDMAEMA/SiO
2have the high graft(ing) degree of 24 g/100g, grafting macromole PDMAEMA serves good filling up and coating function to aerosil particles, makes the pattern of particulate there occurs obvious change.
Fig. 8 is AMPS-SiO
2with grafting particulate PDMAEMA/SiO
2thermal weight loss spectrogram, as seen from Figure 8, modified granular AMPS-SiO
2with grafting particulate PDMAEMA/SiO
2all near 130 DEG C, slight weightlessness occurs, this is the volatile weight loss of planar water, and modified granular is complete in 730 DEG C of decomposition, weightless 8.20%, corresponding to the bonded amount of coupling agent AMPS; Grafting particulate is complete in 750 DEG C of decomposition, and weightless 32.80%.Therefore, the grafting particulate PDMAEMA/SiO analyzed
2sample, the graft(ing) degree of its PDMAEMA should be 24.60g/100g.
Zeta potential analyser is used to determine aerosil particles, grafting particulate PDMAEMA/SiO respectively
2with quaternized grafting particulate and functional particles QPDMAEMA/SiO
2zeta potential under condition of different pH, measurement result is shown in Fig. 9, shows in figure: (1) after silica particle surface grafting PDMAEMA, within the scope of larger pH, grafting particulate PDMAEMA/SiO
2zeta potential by the negative value of former silica gel change on the occasion of, fully demonstrate the macromolecular cationic characteristic of PDMAEMA, this be due to tertiary amine group protonated extremely; (2) quaternized grafting particulate QPDMAEMA/SiO
2zeta potential higher than grafting particulate PDMAEMA/SiO
2, and all high Zeta potential value can be kept in the scope of pH=3-9, show that quaterisation makes QPDMAEMA/SiO
2higher, more stable positive charge density is held on surface, and this is that quaternary ammonium cation caused; (3) grafting particulate PDMAEMA/SiO
2zeta potential to pH value be highly rely on, when after pH > 5, its Zeta potential sharply declines with the increase of pH, this be due to the protonated pH to medium of tertiary amine group extremely sensitive caused by, in an acidic solution, amido is highly protonated; And in neutrality and weakly alkaline solution, protonation greatly weakens; To not occur in compared with strong alkali solution protonated.In a word, current potential is higher than grafting particulate PDMAEMA/SiO
2with quaternized grafting particulate QPDMAEMA/SiO
2positive charge is all carried in surface, can expect, by means of electrostatic interaction, and the CrO in two kinds of all adsorbable water mediums of particulate
4 2-ion.
Compared with prior art, the present invention has the following advantages:
(1) overcome the dependency of amine sorbent material to PH values, within the scope of larger pH, even in basic solution, all high-adsorption-capacity is presented to chromate ion;
(2) this sorbing material belongs to polymer/inorganic functional composite material, is organically combined by physical and chemical performance excellent to the functional of functional polymer and silica gel material with low cost, has potential application prospect.
Accompanying drawing explanation
Fig. 1 is preparation embodiment 1 functional particles QPDMAEMA/SiO
2chemical reaction process;
Fig. 2 is aerosil particles, grafting particulate PDMAEMA/SiO
2with quaternized grafting particulate to the adsorption isothermal line of chromate;
Fig. 3 is saturated extent of adsorption (Q
m) and pH value between relation curve;
Fig. 4 is three kinds of particulate SiO
2, modified granular AMPS-SiO
2with grafting particulate PDMAEMA/SiO
2infrared spectrogram;
Fig. 5 is grafting particulate PDMAEMA/SiO
2, functional particles QPDMAEMA/SiO
2infrared spectrogram;
Fig. 6 is SiO
2the stereoscan photograph of particulate;
Fig. 7 is grafting particulate PDMAEMA/SiO
2stereoscan photograph;
Fig. 8 is AMPS-SiO
2with grafting particulate PDMAEMA/SiO
2thermal weight loss spectrogram;
Fig. 9 is Zeta potential figure.
Embodiment
Below in conjunction with specific embodiment, the invention will be further described.
Embodiment 1
For a preparation method for Adsorption of Chromium acid group material, comprise the following steps:
(1) aerosil particles of surface modification:
10g activated silica gel is joined in 100ml water solvent, and adds the γ-aminopropyltrimethoxysilane (AMPS) of 10ml, at 50 DEG C, react 20h, the ethanol repetitive scrubbing of the product after suction filtration, vacuum-drying, the obtained aerosil particles AMPS-SiO through surface modification
2;
(2) silica particle surface chemical graft polymethyl acrylic acid dimethylamino ethyl ester DMAEMA, implements the graft polymerization of monomer DMAEMA in aqueous solution polymerization system:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the modified granular AMPS-SiO of 1.5 g
2add 80 mL water and 15 mL monomer DMAEMA again, logical nitrogen 30 min, get rid of the air in reaction system, then system temperature is risen to 35 DEG C, the aqueous solution that 20 mL are dissolved with 0.150 g ammonium persulphate is added in system, the surperficial Inducing Graft Polymerization of DMAEMA is carried out under the constant temperature of 35 DEG C and agitation condition, terminate reaction after 6 h, suction filtration, collect product particles, with methyl alcohol extracting 24 h in Soxhlet extractor, to remove the homopolymer that physics is adsorbed on grafting microparticle surfaces, vacuum-drying, to constant weight, obtains grafting particulate PDMAEMA/SiO
2;
(3) grafting particulate PDMAEMA/SiO
2quaternized transformation:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the grafting particulate PDMAEMA/SiO of 1 g
2add 50 mL epoxy chloropropane (not only as reaction reagent but also double as solvent) again, constant temperature is in 60 DEG C, make the quaterisation between the tertiary amine group of grafting macromole PDMAEMA and epoxy chloropropane carry out 3 h, after reaction terminates, filter, collect product particles, repeatedly wash with acetone, vacuum-drying, to constant weight, obtains the functional particles QPDMAEMA/SiO quaternized (Quaternization) occurring and changes
2, make functional particles QPDMAEMA/SiO
2fully swelling in aqueous, then adopt silver nitrate titration method to measure its quaternization degree, QPDMAEMA/SiO
2quaternized degree (Quaternization degree, QD%) be 65%.
Embodiment 2
For a preparation method for Adsorption of Chromium acid group material, comprise the following steps:
(1) aerosil particles of surface modification:
15g activated silica gel is joined in 150ml water solvent, and adds the γ-aminopropyltrimethoxysilane (AMPS) of 15ml, at 50 DEG C, react 24h, the ethanol repetitive scrubbing of the product after suction filtration, vacuum-drying, the obtained aerosil particles AMPS-SiO through surface modification
2;
(2) silica particle surface chemical graft amino acrylates:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the modified granular AMPS-SiO of 1.6 g
2add 85 mL water and 16 mL monomer amino acrylates again, logical nitrogen 30 min, get rid of the air in reaction system, then system temperature is risen to 35 DEG C, the aqueous solution that 20 mL are dissolved with 0.154 g ammonium persulphate is added in system, the surperficial Inducing Graft Polymerization of amino acrylates is carried out under the constant temperature of 35 DEG C and agitation condition, terminate reaction after 6 h, suction filtration, collect product particles, with methyl alcohol extracting 24 h in Soxhlet extractor, to remove the homopolymer that physics is adsorbed on grafting microparticle surfaces, vacuum-drying, to constant weight, obtains grafting particulate;
(3) the quaternized transformation of grafting particulate:
Electric mixer is being housed, in the four-hole boiling flask of reflux condensing tube and thermometer, add the grafting particulate of 1.2g, add 52 mL epoxy chloropropane (not only as reaction reagent but also double as solvent) again, constant temperature is in 60 DEG C, the quaterisation between the macromolecular tertiary amine group of grafting and epoxy chloropropane is made to carry out 3 h, after reaction terminates, filter, collect product particles, repeatedly wash with acetone, vacuum-drying is to constant weight, obtain the functional particles that quaternized transformation occurs, make functional particles fully swelling in aqueous, then silver nitrate titration method is adopted to measure its quaternization degree, quaternized degree be 63%.
Embodiment 3
For a preparation method for Adsorption of Chromium acid group material, comprise the following steps:
(1) aerosil particles of surface modification:
12g activated silica gel is joined in 120ml water solvent, and adds the γ-aminopropyltrimethoxysilane (AMPS) of 13ml, at 50 DEG C, react 22h, the ethanol repetitive scrubbing of the product after suction filtration, vacuum-drying, the obtained aerosil particles AMPS-SiO through surface modification
2;
(2) silica particle surface chemical graft polymethyl acrylic acid dimethylamino ethyl ester DMAEMA, implements the graft polymerization of monomer DMAEMA in aqueous solution polymerization system:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the modified granular AMPS-SiO of 1.5 g
2add 82 mL water and 15 mL monomer DMAEMA again, logical nitrogen 30 min, get rid of the air in reaction system, then system temperature is risen to 35 DEG C, the aqueous solution that 20 mL are dissolved with 0.155 g ammonium persulphate is added in system, the surperficial Inducing Graft Polymerization of DMAEMA is carried out under the constant temperature of 35 DEG C and agitation condition, terminate reaction after 6 h, suction filtration, collect product particles, with methyl alcohol extracting 24 h in Soxhlet extractor, to remove the homopolymer that physics is adsorbed on grafting microparticle surfaces, vacuum-drying, to constant weight, obtains grafting particulate PDMAEMA/SiO
2;
(3) grafting particulate PDMAEMA/SiO
2quaternized transformation:
In the four-hole boiling flask that electric mixer, reflux condensing tube and thermometer are housed, add the grafting particulate PDMAEMA/SiO of 1.1g
2add 55mL monochlorethane again, constant temperature is in 60 DEG C, make the quaterisation between the tertiary amine group of grafting macromole PDMAEMA and monochlorethane carry out 3 h, after reaction terminates, filter, collect product particles, repeatedly wash with acetone, vacuum-drying, to constant weight, obtains the functional particles QPDMAEMA/SiO quaternized (Quaternization) occurring and changes
2, make functional particles QPDMAEMA/SiO
2fully swelling in aqueous, then adopt silver nitrate titration method to measure its quaternization degree, QPDMAEMA/SiO
2quaternized degree (Quaternization degree, QD%) be 64%.