CN101804328B - Titanate porous monolithic adsorbent using straws as template and preparation method thereof - Google Patents

Abstract

The invention provides a titanate porous block adsorbent with straw as a template and a preparation method thereof. It uses the cell structure of the residual cell wall of agricultural waste-straw as a template, and through a suitable method, titanate The salt sol-gel is impregnated on the cell wall, calcined at high temperature, oxidatively decomposes the organic matter in the straw and titanate gel, and generates a porous bulk material composed of nano-sized titanate crystals. The porous titanate adsorbent prepared by the preparation method of the invention has the advantages of low cost, simple process, large adsorption capacity, wide application range, stable performance, and convenient regeneration and recovery. The porous titanate bulk material of the invention can be used for the enrichment and separation of trace heavy metals in the field of analysis and the adsorption removal and recovery of heavy metals in the field of water treatment.

Description

It with the stalk titanate porous monolithic adsorbent of template and preparation method thereof

Technical field

The present invention relates to analytical test and water treatment field, relate to a kind of concentration and separation biology, food, environmental sample and/or purify waste water in heavy metal based on titanate porous adsorbent of stalk template and preparation method thereof.

Background technology

Heavy metal is one type of polluter that toxicity is very strong, and along with the development and use of the mankind to heavy metal, heavy metal gets into environment, various biological generations are had a strong impact on, and enrichment in food chain, accumulate, and then the mankind are produced great harm.In recent years, along with expanding economy, People more and more was paid attention to heavy metal pollution problem.Aspect Monitoring of Heavy Metal Pollution and improvement, obtaining certain progress.

Aspect the analysis monitoring, mainly adopt atomic absorption method and ICP method for measuring Determination of Heavy Metal.Though the sensitivity of these two kinds of methods is very high,, for low content or the sample of serious interference still needs preenrichment and separates.Enrichment and separation method commonly used at present has chelate extraction method, ionic liquid preenrichment method, chemical coprecipitation, ion-exchange and cloud point extraction method etc.In these methods, what have uses poisonous and hazardous reagent, and the cost that has is high, the poor stability that has, and the complex operation that has, the enrichment factor that has is lower.Solid phase extraction is the new method that grows up recent years, because of its have simple to operate, pollution-free, enrichment factor is high, speed is fast and be convenient to and advantages such as other technological coupling, and receives extensive concern.Particularly in recent years, along with the development of nano science with technology, nano adsorber was as solid extracting agent.The inventor successfully is used for nano barium-strontium titanate and nano barium titanate calcium powder body the adsorption and enrichment of water heavy metal ion first.Compare with other solid extracting agent, the Nano titanate powder has stronger adsorption capacity, bigger adsorption capacity and stronger chemical stability.

In water polluted, heavy metal pollution had accounted for sizable ratio.At present, the heavy metal method of handling in the water mainly contains chemical precipitation method, oxidation-reduction method, solvent extraction, ion-exchange, membrane separation process and biological concentration method etc.In these methods, the solid waste that the generation that has is a large amount of causes secondary pollution; The poor processing effect that has does not reach requirement; What have uses a large amount of toxic reagents, is detrimental to health; The poor stability that has is prone to lose efficacy; The cost that has is high, is difficult for popularization and application; The long processing period that has, weak effect.In recent years, adsorption separation technology had had very big development, adapted to widely because of it has, and treatment effect is good, and non-secondary pollution can reclaim utility when handling waste water, the existing application in heavy metal containing wastewater treatment.Adsorbent commonly used has active carbon, bentonite, flyash, zeolite and artificial synthetic high polymer etc., but these adsorbents existing regeneration and reclaiming problems such as difficulty, poor processing effect, adsorption capacity are lower, repeated use poor stability in practical application.By comparison, the adsorption capacity of Nano titanate adsorbent is high, and renovation process is simple, and good stability is a kind of good heavy metal absorbent.The absorption of heavy metal is removed and reclaimed in water has very wide application prospect.

But, no matter be the gathering and measuring of heavy metal, still use in water treatment field; The same with other nano-powder adsorbent, it is trickle that Nano titanate powder sorbing material also exists particle, is difficult for sedimentation in water; Be prone to the reunion inactivation; Be prone to run off, recycling limits its application in reality than shortcomings such as difficulties.And compare with nano-powder, the porous blocks material of surface area is more conducive to reclaim.Stalk as agricultural residue; Normally incinerated in China, this is contaminated environment not only, but also is the waste of resource; The stalk main component is cellulose, protein, starch, carbohydrate and lipoid substance etc., the loose structure that its structure is made up of the cell membrane of plant.The present invention is a template with the stalk, utilizes Prepared by Sol Gel Method to possess the cyto-architectural porous nano titanate of stalk block adsorbent, is used for concentration and separation biology, food, environmental sample and/or adsorption cleaning and recycle-water heavy metal.

Summary of the invention

In order to overcome the defective that above-mentioned sodium rice titanate powder adsorbent exists, it is the titanate porous monolithic adsorbent and preparation method thereof of template with the agricultural stalk that the present invention provides a kind of.

The technical scheme that adopts:

With the stalk is the titanate porous monolithic adsorbent of template, it is characterized in that with stalk cell wall be morphogenetic honeycomb structure structure, and described stalk is broomcorn straw or maize straw.

With the stalk is the titanate porous preparation method of template, may further comprise the steps:

(1), chooses required stalk;

(2), the preliminary treatment of stalk: after the stalk peeling, be cut into the long cylindrical segment of 0.4-0.6cm, 0.5moL/L nitric acid dousing activation 1 hour, washing be to neutral, 70-90 ℃ dry 20-30 hour;

(3), the preparation of titanate colloidal sol: under vigorous stirring, butyl titanate is introduced in the hydrogen peroxide solution of citric acid, to 6-7, stirred under 50 ℃ of-70 ℃ of temperature and formed Ti (IV) precursor solution in 0.8-1.2 hour with the pH value of ammoniacal liquor regulator solution.Nitrate with strontium/barium (or calcium or magnesium or aluminium or zinc) is dissolved in the citric acid solution respectively, forms the precursor solution of stable metal ion.The precursor solution that mixes Ti (IV) and metal ion makes that citric acid and total metal ion mol ratio are 2: 1, continues to stir promptly to get titanate colloidal sol in 0.8-1.2 hour, and is for use in beaker.

(4), the dipping of titanate colloidal sol on the stalk: the broomcorn straw that (2) step is handled well is immersed in the titanate colloidal sol of (3) step preparation, vacuumizes 25-35min, leaves standstill 3-5 hour, takes out 80 ℃ of oven dry.

(5), the calcining of template removes: the stalk of titanate sol-gel on the dipping that will dry in (4) step, in 600 ℃-900 ℃ temperature lower calcination 0.8-1.2 hour, be cooled to room temperature in the drier, obtain the titanate porous monolithic material, it is subsequent use to bottle.

The invention has the advantages that:

Nano titanate porous adsorbent based on the stalk template of the present invention belongs to twice laid, and synthetic originally low, technology is simple.

It is big to have adsorption capacity based on the Nano titanate porous adsorbent of stalk template, and adsorption rate is fast, stable performance, and it is convenient to reclaim, wide accommodation.

The specific embodiment

In the face of being the preparation process further explain of the titanate porous monolithic adsorbent of template with the stalk, still embodiment of the present invention is not limited to this down:

1, embodiment 1:

The barium strontium titanate porous monolithic adsorbent preparation process that with the stalk is template is following:

(1), chooses required stalk;

(2), the preliminary treatment of stalk: after the stalk peeling, be cut into the long cylinder of 0.5cm, 0.5moL/L nitric acid dousing activation 1 hour, washing be to neutral, 80 ℃ of dryings 24 hours;

(3), the preparation of barium strontium titanate colloidal sol: deliver document (Zhang Dong etc., " analytical chemistry ", 2009 years in earlier stage according to the inventor; 37 volumes, the 1188-1192 page or leaf), under vigorous stirring; The 34mL butyl titanate is introduced in the hydrogen peroxide solution of citric acid (wherein citric acid 68g, hydrogen peroxide solution 3.5mL, water 112mL); With the pH value to 6 of ammoniacal liquor regulator solution, 60 ℃ are stirred 1h and form Ti (IV) precursor solution.Respectively barium nitrate and strontium nitrate are dissolved in citric acid (regulating with the ammoniacal liquor) solution of pH=6, form stable Ba (II)-Sr (II) precursor solution.Mix Ti (IV) and Ba (II)-Sr (II) precursor solution, make that citric acid and total metal ion mol ratio are 2: 1, wherein the mol ratio of barium, strontium and titanium is 0.5: 0.5: 1, continues to stir 1h and promptly gets Ba _0.5Sr _0.5TiO ₃Colloidal sol.For use in beaker.

(4), the dipping of barium strontium titanate colloidal sol on the stalk: the stalk that (2) step is handled well is immersed in the barium strontium titanate colloidal sol of (3) step preparation, places closed container in the lump, vacuumizes 30min; After slowly opening vent valve; Left standstill 4 hours, and took out stalk, 80 ℃ of oven dry.Repeated impregnations drying operation 3 times.Obtained flooding the stalk of barium strontium titanate gel.

(5), the calcining of template is removed: with the stalk of barium strontium titanate sol-gel on the dipping of (4) step oven dry, in 750 ℃ of air atmosphere calcining 6h, be cooled to room temperature in the drier, obtain barium strontium titanate porous blocks sorbing material.

2, embodiment 2:

The calcium titanate porous monolithic adsorbent preparation process that with the stalk is template is following:

(1), chooses required stalk;

(2), the preliminary treatment of stalk: after the stalk peeling, be cut into the long cylinder of 0.5cm, 0.5moL/L nitric acid dousing activation 1 hour, washing are extremely neutral, 80 ℃ of dry 24h;

(3), the preparation of calcium titanate colloidal sol: document (Zhang Dong etc., " chemical journal ", 2009 67 volumes of delivering in earlier stage according to the inventor; 12 phases, the 1336-1342 page or leaf), take by weighing calcium nitrate 56.68g and 6.00g citric acid and dissolve in the 120mL absolute ethyl alcohol; Magnetic agitation 30min forms homogeneous A solution.Take by weighing butyl titanate 83.34g, under vigorous stirring, be dissolved in the absolute ethyl alcohol of 90mL, stir 30min, the glacial acetic acid continuing to drip under the stirring condition 330mL forms stable B solution.Continue to stir, the A drop is gone into B liquid, after dripping off, add the water that is dissolved with the 6g polyethylene glycol of 195mL, the pH value to 3 of adjustment solution stirred 1 hour, obtained flaxen colloidal sol, and is for use in beaker.

(4), the dipping of calcium titanate colloidal sol on the stalk: the stalk that (2) step is handled well is immersed in the calcium titanate colloidal sol of (3) step preparation, places closed container, vacuumizes 30min, and slowly venting was left standstill 4 hours, took out stalk, 80 ℃ of oven dry.Repeated impregnations drying operation 3 times.Obtained flooding the stalk of calcium titanate gel.

(5), the calcining of template is removed: with the stalk of calcium titanate sol-gel on the dipping of (4) step oven dry, in 750 ℃ of air atmosphere calcinings 6 hours, be cooled to room temperature in the drier, obtain calcium titanate porous blocks sorbing material.

For the porous adsorbent of other titanate, can be with reference to the method preparation of instance 1 and 2.

Claims (1)

1. The titanate porous block adsorbent with stalks as a template is characterized in that it is a honeycomb pore structure formed in the form of sorghum stalk cell walls, and its preparation method comprises the following steps: (1), select required sorghum stalks; (2) Pretreatment of sorghum stalks: After peeling the sorghum stalks, cut them into 0.4-0.6cm long cylindrical sections, soak and activate them in 0.5moL/L nitric acid for 1 hour, wash with water until neutral, dry at 70-90°C for 20- 30 hours; (3) Preparation of titanate sol: under vigorous stirring, introduce butyl titanate into the hydrogen peroxide solution of citric acid, adjust the pH value of the solution to 6-7 with ammonia water, and stir at 50°C-70°C for 0.8 Form Ti(IV) precursor solution in -1.2 hours; Dissolve the nitrate of strontium/barium in citric acid solution respectively, form the precursor solution of stable metal ion; Mix the precursor solution of Ti(IV) and metal ion, Make the molar ratio of citric acid to total metal ions 2:1, continue to stir for 0.8-1.2 hours to obtain titanate sol, and put it in a beaker for use; (4) Impregnation of titanate sol on sorghum stalks: immerse the sorghum stalks treated in step (2) in the titanate sol prepared in step (3), vacuumize for 25-35min, and let stand for 3-5 hour, take it out, and dry it at 80°C; (5) Calcination removal of the template agent: calcining the sorghum straw impregnated with titanate sol dried in step (4) at a temperature of 600°C-900°C for 0.8-1.2 hours, and cooling to room temperature in a desiccator to obtain Titanate porous bulk material, bottled for later use.