Modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement and preparation method thereof
Technical field
The present invention relates to be applied to diffusive gradients in thin-films (Diffusive gradients in thin films in the A+E of surrounding mediums such as a kind of soil, sediment; DGT) fixedly film and preparation method thereof of determination techniques, especially a kind of diffusive gradients in thin-films measurement technology that is applicable to is analyzed modified phosphorus fixing film of sediment phosphorus and preparation method thereof.
Background technology
Phosphorus is the important nutrient of hydrobiont growth, also is the major limitation sex factor of lake primary productivity and body eutrophication.After external source phosphorus got into water body in lake, major part accumulated in sediment, and discharges into overlying water again under certain condition, keeps the eutrophic state of water body.The release potentiality of sediment phosphorus and its confidential relation that is distributed with at sediment-water micro-interface.Usually, because the sediment-greatest differences of water micro-interface on physics, chemistry and biological property causes phosphorus possibly exist strong concentration gradient to distribute at this near interface, drive phosphorus thus and between sediment and overlying water, exchange.Obtaining the distributed intelligence of phosphorus between sediment-water micro-interface, is the important evidence of estimating the sediment phosphorus activity and discharging to water body.Routine is obtained the resolution of technology below 1mm, can not satisfy the analysis requirement of micro-interface phosphorus on submillimeter level resolution.
(Diffusive gradients in thin films, DGT) determination techniques is that a kind of non-destructive, original position are obtained pollutant distribution and active new technology in the sediment to diffusive gradients in thin-films.This technique device is mainly formed (Fig. 1) by the stack of fixedly film and diffusion barrier, and both form by the gel configuration, and wherein fixedly film disposes through the fixing agent that adds ability absorb polluted matter ion to gel and forms.When the DGT device is put into sediment; Contaminant ion passes diffusion barrier with diffusion way; The film that is fixed is immediately caught; And the formation linear gradient distributes on diffusion barrier; Diffusion barrier contacts an end with fixing film ion concentration is maintained zero, and the concentration (
) that contacts an end with medium is:
In the following formula
MBe the accumulation (μ g) of object ion on the fixing film,
Be thickness of diffusion layer (cm),
Be the rate of diffusion (cm of ion in diffusion barrier
2/ s),
Be the fixing area (cm of film
2),
Be diffusion time (s),
Promptly be the content (10 of analyzing the sediment intermediate ion that obtains through DGT
3μ g/L).
High-resolution obtains that the pollutant space distribution information is one of emphasis of DGT technical development in recent years in the sediment.The high resolution analysis that satisfies DGT requires (spatial resolution < 0.5mm), and fixedly the fixing agent size distribution on film surface is one of its influence factor.Current fixing agent commonly used (like Chelex 100) particle diameter can not satisfy the high resolution analysis requirement of DGT all greater than 0.05mm.
" a kind of phosphorus fixing film that is applied to the diffusive gradients in thin-films measurement technology device " (ZL 200910183047.5) have disclosed a kind of phosphorus fixing film that is applied to the diffusive gradients in thin-films technology and preparation method thereof; This phosphorus fixed film has very high adsorption capacity to phosphonium ion; Having overcome in the existing DGT technology fixedly, film has enlarged the application of DGT in phosphorus such as soil, sediment are analyzed to the deficiency of phosphorus fixed capacity.But fixedly film surface fixing agent particle is bigger, and skewness can't satisfy the high resolution analysis requirement of DGT to sediment phosphorus.
Summary of the invention
The object of the invention provides a kind of modified phosphorus fixing film that is applied to diffusive gradients in thin-films (DGT) technology and preparation method thereof; Phosphorus fixing film of the present invention not only keeps the high-adsorption-capacity to phosphonium ion; Can significantly improve simultaneously the resolution of DGT in phosphorus is analyzed, satisfy the requirement of DGT the high resolution analysis of sediment phosphorus.
Above-mentioned purpose of the present invention realizes through following technical scheme:
Modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement is to comprise ZrO
2The polyacrylamide gel film, it is characterized in that: described phosphorus fixing film surface is the zirconium dioxide particle of distribution particle diameter≤5 μ m evenly.
Described modified phosphorus fixing film adopts following method preparation:
The preparation method of the modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement is that Zirconium dioxide powder and the acrylamide solution of 45-55% is by 1:3~1:6 (w/v, g/ml) mixing with water percentage; Grind the back ultrasonication, leave standstill remove sediment after, add the tetramethyl diethylamine (TEMED) of acrylamide solution volume 1/1600~1/1400 and 10% (wt) ammonium persulfate solution of 1/60 ~ 1/40; After mixing mixed liquor is injected glass mold, the following horizontal positioned of room temperature, treat zirconium powder free setting after; Be warming up to 40~60 ℃; Form gel mould until mixed liquor, in deionized water, soak more than 12 hours the phosphorus fixing film that is improved.
In theory, when the spatial resolution of analyzing as DGT was confirmed as 0.5mm, the fixing agent particle diameter at least should < 0.05mm can be controlled at the excessive analytical error that causes of fixing agent particle diameter in 10%; < during 0.01mm, analytical error then can be controlled in 2% when the fixing agent particle diameter.But, consider also there are other errors in the DGT analytic process that the actual fixedly peplomer footpath that requires should be much smaller than theoretical value.The inventive method makes the modified phosphorus fixing film (Fig. 2 b) of surperficial zirconium dioxide particle particle diameter≤5 μ m through measures such as grindings, ultrasonication, the high-adsorption-capacity of phosphonium ion not only, and be applied to the analysis of DGT phosphorus, resolution can reach below the 0.2mm.
Described Zirconium dioxide powder is by 1:15~1:30 (w/v by zirconium oxychloride and deionized water; G/ml) mixed dissolution; Use ammoniacal liquor regulator solution pH then between 6.9-7.1, after the precipitate with deionized water that is produced is washed, dry and to control its water percentage be between 45~55%.
The w/v of described Zirconium dioxide powder and acrylamide solution is preferably 1:4~1:6.
The WS of preferred 25~35 wt% acrylic amides of described acrylamide solution wherein comprises 0~5.0 wt % Methacrylamide.
Polyacrylamide gel is the improvement of film properties fixedly, except that fixing agent is carried out the fragmentation, need fixedly be optimized accent on the membrane preparation method simultaneously.The present invention optimizes the addition of Zirconium dioxide powder, acrylamide solution and proportioning thereof and crosslinking chemical TEMED and catalyzer ammonium persulfate; And to preparation method's improvement; Make not only after the film forming that fixedly film surface zirconium dioxide particle is evenly distributed; And zirconium dioxide and third rare acid amides mixed liquor can very successfully inject glass mold, and film formation time also shortened to 1.5 hours by former average 3 hours.ZL 200910183047.5 uses 80% ethanol to zirconium dioxide sediment rinsing 1 ~ 2 time, to impel zirconium dioxide sediment fast dewatering when the preparation phosphorus fixing film; It is thick very easily to become sticky after the zirconium dioxide that this method prepares and third rare acid amides mixed liquor are ultrasonic, makes mixed solution can not inject glass mold smoothly.Therefore when the preparation Zirconium dioxide powder, the present invention does not adopt the ethanol rinsing, only adopts the method for washing.Prepared fixedly film has very excellent physical strength, and retractility is extremely low, can be used for the DGT technical operation more easily.
Advantage of the present invention and beneficial effect comprise:
(1) compares with existing phosphorus fixing film (ZL 200910183047.5); The outstanding advantage of modified phosphorus fixing film of the present invention is through measures such as grinding and ultrasonications the zirconium dioxide particle diameter to be controlled; Reduced the particle diameter of film surface zirconium dioxide fixing agent significantly; Particle diameter is reduced in the 5 μ m from about 30 μ m, makes zirconium dioxide particle at fixing film surface distributed even compact (Fig. 2), has higher phosphorus adsorption capacity; Improved the resolution that DGT phosphorus is analyzed simultaneously, therefore fixedly film can satisfy the high resolution analysis requirement of DGT technology to sediment phosphorus fully.Prepared fixedly film also has very excellent physical strength, and retractility is extremely low, can be used for the DGT technical operation more easily.
(2) compare with the other types phosphorus fixing film of report, modified phosphorus fixing film of the present invention continues the DGT capacity (> that keeping very high; 100 μ g P cm
-2) (Fig. 3), be respectively traditional F eO film, modified FeO film and Metsorb film 50 times, more than 14 times and 8 times.Owing to this advantage, can the DGT device of modified phosphorus fixing film assembling be used to analyze the eutrophic lake of high phosphorus background.
(3) modified of the present invention fixedly film have very large development space at DGT high resolution analysis technical elements; Outstanding behaviours exists: combine to process composite membrane with other particulate footpath fixing agents, can realize synchronous, the high-resolution DGT of the different contaminant ions of sediment are analyzed.As add the AgI particle simultaneously, DGT technology capable of using to the phosphorus in the sediment, sulphur plasma carry out synchronously, high resolution analysis; Add SPR-IDA resin fixing agent, can realize synchronous, the high resolution analysis of phosphorus, heavy metal.
Describe the present invention below in conjunction with specific embodiment.Protection scope of the present invention is not exceeded with embodiment, but is limited claim.
Description of drawings
Fig. 1 is a DGT device synoptic diagram.
Fig. 2 Fig. 2 a and Fig. 2 b are the phosphorus fixing film (a) of disclosure among the ZL 200910183047.5 and the electron-microscope scanning image of modified phosphorus fixing film of the present invention (b).Can find out through both contrasts, the densification that is evenly distributed of modified phosphorus fixing film of the present invention surface zirconium dioxide particle, particle diameter≤5 μ m, and phosphorus fixing film rough surface before improving, particle diameter is about 30 μ m.
Fig. 3 is the standing time of DGT device in phosphorus solution and the graph of a relation of phosphorus accumulation of modified phosphorus fixing film assembling of the present invention.The figure cathetus is a theoretical value, can find out the DGT Rong Liang > of modified phosphorus fixing film through contrast; 100 μ g P cm
-2
Embodiment
Embodiment 1
Modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement, its preparation method is following:
The zirconium oxychloride that takes by weighing 25g is dissolved in the 600ml deionized water; Use the ammoniacal liquor of 25% (volume ratio) that pH value of solution is regulated and is stabilized between the 6.9-7.1 then; The precipitate with deionized water that is produced is washed 8-9 time, with hair-dryer its water percentage is dried up between 45~55% at last.By mass volume ratio 1:4 Zirconium dioxide powder and the 7.2ml acrylamide solution (WS of 28.5% acrylic amide and 1.5% Methacrylamide) that 1.8g prepares mixed, ground 10~30 minutes, used clasmatosis appearance 20% frequency more ultrasonic 5~15 minutes with agate mortar; Left standstill 10~30 minutes, remove sediment after, in solution, add the tetramethyl diethylamine (TEMED) of 4.5 μ L and the ammonium persulfate solution (mass ratio 10%) of 180 μ L successively; Then solution is slowly injected the two glass sheets spaces that accompany the U-shaped plastic tab, catch up with bubble to the greatest extent after, glass plate horizontal positioned half an hour under 10 ℃ of low temperature; After treating zirconium powder free setting; Be warming up to 45 ℃, placed 1 hour, make the solution gel film forming; Glass plate after the film forming is put into deionized water to be soaked 24 hours; Pry open glass plate then, take out gel film, be the modified phosphorus fixing film.
The electron-microscope scanning image of prepared modified phosphorus fixing film is seen Fig. 2 b, the densification that is evenly distributed of its surperficial zirconium dioxide particle, particle diameter≤5 μ m.
Embodiment 2
Modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement, its preparation method is following:
The zirconium oxychloride that takes by weighing 25g is dissolved in the 600ml deionized water; Use the ammoniacal liquor of 25% (volume ratio) that pH value of solution is regulated and is stabilized between the 6.9-7.1 then; The precipitate with deionized water that is produced is washed 8-9 time, with hair-dryer its water percentage is dried up between 45~55% at last.By mass volume ratio 1:5 Zirconium dioxide powder and the 7.2ml acrylamide solution (WS of 28.5% acrylic amide and 1.5% Methacrylamide) that 1.45g prepares mixed, ground 10~30 minutes, used clasmatosis appearance 20% frequency more ultrasonic 5~15 minutes with agate mortar; Left standstill 10~30 minutes, remove sediment after, in solution, add the tetramethyl diethylamine (TEMED) of 5.1 μ L and the ammonium persulfate solution (mass ratio 10%) of 120 μ L successively; Then solution is slowly injected the two glass sheets spaces that accompany the U-shaped plastic tab, catch up with bubble to the greatest extent after, glass plate is 20 ℃ of following horizontal positioned half an hour; After treating zirconium powder free setting; Be warming up to 60 ℃, placed 1 hour, make the solution gel film forming; Glass plate after the film forming is put into deionized water to be soaked 24 hours; Pry open glass plate then, take out gel film, be the modified phosphorus fixing film.
Embodiment 3, the modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement, and its preparation method and embodiment 1 are basic identical,
Be outside the difference that acrylamide solution is 35.0% acrylamide aqueous solution.
Embodiment 4, the modified phosphorus fixing film in a kind of diffusive gradients in thin-films measurement, and its preparation method and embodiment 1 are basic identical,
Be outside the difference that acrylamide solution is the WS of 27.5% acrylic amide and 2.5% Methacrylamide.
Embodiment 5
Modified phosphorus fixing film and existing phosphorus fixing film (ZL 200910183047.5) film that embodiment 1 is made are cut into the disk of diameter 2.5cm; Be assembled into the DGT device; Put into the phosphorus solution that concentration is 21mg/L, place behind the different time withdrawing device and fixing film.
At first fixedly film is cut into 10 * 10mm square; Be cut into 0.2 * 10mm rectangular (being spatial resolution 0.2mm) then, select 20 arbitrarily, put into 1 ml centrifuge tube every; Adding 0.2 ml 1M NaOH solution extracts; Vibrated 16 hours, and analyzed the phosphorus concentration in the extract, be converted into each rectangular unit area phosphorus fixed amount that goes up with the molybdenum blue colorimetric method.Measure the result and see table 1.
Can find out from table 1; With non-modified fixedly film compare, modified fixedly film assembling DGT measure the unit area phosphorus fixed amount that obtains and theoretical value coincide better, simultaneously after placement 4 hours; Error at measurment promptly can be controlled in 10%, but not modified fixedly the error of film surpass 20%.Comparing result can find out, the modified fixedly film DGT that can be used for resolution 0.2mm is measured, and non-modified fixedly film then can't be used for the mensuration under this resolution condition.
Phosphorus fixing film recorded at different time before and after table 1 improved unit area phosphorus fixed amount and analytical error (one dimension resolution is 0.2mm) thereof