CN103611543A - Method for preparing ZnFeCr hydrotalcite photocatalyst - Google Patents

Abstract

The invention discloses a method for preparing a ZnFeCr hydrotalcite photocatalyst and relates to preparation methods of catalysts. The method comprises the following preparation steps of (1) preparing a salt solution of ferric nitrate, zinc nitrate and chromic nitrate, wherein the ratio of n(Zn) to n(Fe) to n(Cr) is 1: 1: 1, and the total concentration of metal ions is 1M; (2) preparing a 0.5M solution of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3), wherein the ratio of NaOH to Na2CO3 is 2: 1; (3) simultaneously dropwise adding a metal salt solution and an alkali solution into the salt solution, and controlling the pH value to be 9-10; (4) carrying out hydrothermal crystallization on slurry, obtained after the dropwise adding is ended, for 24 hours at the temperature of 100 DEG C, then, filtrating, washing and drying, thereby obtaining the product. According to the method, the product has good performance in photocatalytic degradation of organic substances; the ZnFeCr hydrotalcite photocatalyst prepared by the method is low in cost, simple and convenient in operation and easy in large-scale production.

Description

The preparation method of ZnFeCr houghite photocatalyst

Technical field

The present invention relates to a kind of preparation method of catalyst, particularly relate to a kind of preparation method of ZnFeCr houghite photocatalyst.

Background technology

Along with improving constantly of industrial expansion and living standards of the people, oneself is on the rise problem of environmental pollution, and cleaning harmful gas, sewage disposal etc. is subject to people's attention day by day.In sewage disposal, current transformation processing method is for the pollutant that discharge capacity is large, concentration is higher mostly, and the purification of lower for concentration in water body, to be difficult to conversion pollutant is also helpless.And the Photocatalyst growing up gradually is in recent years for addressing this problem the approach that provides good.Research in recent years shows, light-catalyzed reaction can be that harmless water discharges by the wastewater treatment that contains dyestuff, agricultural chemicals, halogenated organic compounds, surfactant, greasy dirt, inorganic pollution, and cost is not high, non-secondary pollution, can be used as the pretreatment of other processing method, also can be used as the advanced treating of other processing method, can also use separately.

Nano-TiO ₂make the focus that catalyst oxidation water pollutant is current research work, now demonstrated good application prospect.But TiO ₂the Main Bottleneck of photocatalytic applications is the restriction of excitation wavelength, due to TiO ₂excitation wavelength at 387 n m, belong to ultraviolet region, can only do light source with mercury lamp or uviol lamp, cost is very high.Therefore, the improvement of traditional catalysis material and the catalysis material of seeking novel high-efficiency environment friendly are become the study hotspot of photocatalysis field.In recent years, reported visible light catalyst has the (AgTaO of silver system ₃, AgNbO ₃, Ag ₃vO ₄deng), (Bi of bismuth system ₂o ₃, Bi ₃nbO ₇, BiVO ₄deng) and doping TiO ₂or other composite oxide catalysts.

Hydrotalcite, claim again layered di-hydroxyl composite metal oxidate (LDHs), houghite compound (HTLCs) or anionic clay, this structure is comprised of the metallic element (being generally divalence and trivalent or higher valence state) that is surrounded the oxidation valence state that is regular octahedron by oxo bridge and hydroxyl, this structure is layered arrangement, because the existence of trivalent metallic element makes laminate positively charged, the anion that interlayer existence can exchange and the positive charge balance on laminate, make the overall structure of LDHs be electroneutral.When light-catalyzed reaction, light induced electron is led away layer by layer in layer structure, avoids the compound of electronics.

The people such as Garc í a in 2009 report Zn/Cr-, Zn/Ti-, the Zn/Ce-LDHs that has synthesized different layers sheetmetal ratio, study the performance of its photodissociation aquatic products oxygen under visible ray condition.The bright grades of Ni Zhe in 2013 have been reported the performance of CuMgAl hydrotalcite degradation of dye RhB, when n(Cu): n(Mg): n(Al) LDH of=2:1:1, rhodamine B (RhB) solution that is 10 mol/L to 50 mL initial concentrations carries out photocatalysis experiment, discovery is at 13 ℃ (logical recirculated waters), under the condition of pH=7.84,150 mg LDHs reach 85.2% to the degradation rate of rhodamine B, and photocatalytic degradation amount proportion is more than 50%.

Summary of the invention

The object of the present invention is to provide a kind of preparation method of ZnFeCr houghite photocatalyst, it is raw material that the method be take the nitrate of zinc, iron, chromium and NaOH and sodium carbonate, adopt coprecipitation to prepare calcareous type zinc-iron chromium houghite photocatalyst, the organic matter under visible ray in energy degradation water.

The object of the invention is to be achieved through the following technical solutions:

The preparation method of ZnFeCr houghite photocatalyst, described method comprises following preparation process:

(1) salting liquid of preparation ferric nitrate, zinc nitrate, chromic nitrate, wherein n(Zn): n(Fe): n(Cr)=1:1:1, and total concentration of metal ions is 1M;

(2) sodium hydroxide solution and the sodium carbonate liquor of preparation 0.5M, wherein NaOH:Na ₂cO3=2:1;

(3) metal salt solution and aqueous slkali are added drop-wise in salting liquid simultaneously, control pH=9 ~ 10;

(4) drip the slurries that obtain after finishing hydrothermal crystallizing 24 hours at 100 ℃, filter afterwards, wash, dry, obtain product.

Advantage of the present invention and effect are:

It is raw material that the nitrate of zinc, iron, chromium and NaOH and sodium carbonate are take in the present invention, the calcareous type zinc-iron chromium hydrotalcite that adopts coprecipitation to prepare.The zinc-iron chromium hydrotalcite of preparation can make full use of the visible light part in sunshine, has the performance of good photocatalysis to degrade organic matter.

Accompanying drawing explanation

Fig. 1 is the XRD spectra of the ZnFeCr houghite photocatalyst based on visible light-responded of preparation;

Fig. 2 is the ultraviolet-visible absorption spectroscopy figure of the ZnFeCr houghite photocatalyst based on visible light-responded of preparation;

The different methyl orange initial concentration of Fig. 3 Methyl Orange degradation rate is relation over time;

Fig. 4 different catalysts concentration Methyl Orange degradation rate is relation over time.

The specific embodiment

Below in conjunction with accompanying drawing illustrated embodiment, the invention will be further described.

The feature that the present invention is based on the layer structure of hydrotalcite and be easy to large-scale production, adopts coprecipitation to prepare ZnFeCr hydrotalcite, utilizes CrO on laminate ₆d-d transition in octahedral structure, produce visible light-responded, for the organic matter of degradation water.

Embodiment 1:

The XRD spectra of the ZnFeCr hydrotalcite of preparation is shown in accompanying drawing 1.The photochemical catalyst that can find out preparation has typical hydrotalcite characteristic diffraction peak.

The ultraviolet-visible light spectrogram of the ZnFeCr hydrotalcite of preparation is shown in accompanying drawing 2.The photochemical catalyst that can find out preparation has visible light-responded.

The xenon long-arc lamp (wavelength > 400 nanometers) of 500 W of take is simulation visible light source, and the effective length of visible light source fluorescent tube is 6 cm, and light intensity is 1.5 kW/m ².Xenon lamp is put in quartz socket tube, at the interlayer of sleeve pipe, passes into cooling water, make reaction solution keep constant temperature.At 25 ℃, the methyl orange solution of 150ml variable concentrations and 1.25 g/L catalyst are joined in beaker.Before photocatalysis, in dark, stir 2 h, make catalyst adsorb-dissociate and reach balance.Open xenon source and carry out Visible Light Induced Photocatalytic, every 30 min get sample volume 5 ml one time, and centrifugation is got supernatant liquor 4ml and is put in quartz colorimetric utensil, use Zi Wai – visible spectrophotometer to measure its absorbance in 464 nanometers, by absorbance, calculate the degradation rate of methyl orange.Accompanying drawing 2 is degradation rate relations over time of methyl orange.Can find out, the photochemical catalyst of preparation has the performance of good photo-catalytic degradation of methyl-orange.

Embodiment 2:

At methyl orange initial concentration, be 30 mg/L, adopt different catalyst concns to carry out photo-catalytic degradation of methyl-orange, other photocatalysis performance testing procedure is with embodiment 1, and test result is shown in accompanying drawing 3.

The result of accompanying drawing 3 shows, the ZnFeCr houghite photocatalyst of preparation has good methyl orange degradation effect.

Claims (1)

1. the preparation method of ZnFeCr houghite photocatalyst, is characterized in that, described method comprises following preparation process:

(1) salting liquid of preparation ferric nitrate, zinc nitrate, chromic nitrate, wherein n(Zn): n(Fe): n(Cr)=1:1:1, and total concentration of metal ions is 1M;

(2) sodium hydroxide solution and the sodium carbonate liquor of preparation 0.5M, wherein NaOH:Na ₂cO3=2:1;

(3) metal salt solution and aqueous slkali are added drop-wise in salting liquid simultaneously, control pH=9 ~ 10;

(4) drip the slurries that obtain after finishing hydrothermal crystallizing 24 hours at 100 ℃, filter afterwards, wash, dry, obtain product.

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