CN109999809A - A kind of preparation method and applications of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton - Google Patents

Abstract

The invention belongs to the technical field of material preparation and environmental pollution control, and provides a preparation method of iron oxide@biomass carbon fiber@pDA-PVDF optical Fenton composite beads. The preparation method is as follows: Step 1, preparing iron oxide@ Biomass carbon fiber composite photo-Fenton catalyst; step 2, preparing pDA-PVDF powder; step 3, preparing photo-Fenton composite beads based on phase inversion technology and dopamine self-polymerization technology. The invention uses pDA-PVDF beads as the carrier of the photo-Fenton catalyst, which can not only fix the powder catalyst, which is beneficial to practical application, but also effectively suppress the loss of iron ions and improve the stability of the catalytic system. This method has the advantages of simple synthesis and high degradation efficiency.

Description

Preparation of an iron oxide@biomass carbon fiber@pDA-PVDF photo-Fenton composite beads preparation method and its application

technical field

The invention belongs to the technical field of material preparation and environmental pollution control, and relates to a preparation method and use of iron oxide@biomass carbon fiber@pDA-PVDF optical Fenton composite beads for efficiently degrading methyl orange.

Background technique

Azo dyes refer to dyes that contain one or more azo groups (-N=N-) and are linked with at least one aromatic structure. Azo dyes have the characteristics of various colors, simple process, low production cost and strong dyeing ability, so they are widely used in the dyeing of textiles, the coloring of paper, leather, plastics and other products, and also in food and cosmetics. Although azo dyes are widely used, some azo dyes will produce 24 kinds of carcinogenic aromatic amine compounds after reductive cracking. If absorbed by the human body, it will seriously threaten human health. Especially in textiles, clothing and leather products, these dyes are in contact with the human body for a long time and can enter the human body through the respiratory tract, esophagus and skin mucous membranes. Therefore, it is of great significance to efficiently degrade residual azo dyes in water.

Advanced oxidation processes (AOPs) are characterized by the generation of hydroxyl radicals ( OH) with strong oxidizing effects, which can degrade these organic pollutants into low- or non-toxic small molecules. The heterogeneous photo-Fenton process is a promising water treatment strategy as an alternative to homogeneous Fenton reagents. However, there are two great challenges in the process of heterogeneous photo-Fenton reaction: (i) powdered photo-Fenton catalysts are difficult to recover in practical applications and difficult to operate; (ii) due to the seriousness of active metals in operation loss, the stability of the catalyst is poor.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the polymer beads constructed by the simple phase inversion technology of the present invention can easily and effectively fix the photo-Fenton catalyst, and at the same time, the hierarchical porous structure inside the beads will not hinder the diffusion of organic pollutants . Furthermore, polydopamine (pDA) is a versatile surface engineering coating that can be applied to the surface of almost any material without affecting the inherent structure of the polymer beads. Due to the abundant catechol groups and strong coordination ability of metal ions, the pDA layer can suppress the loss of iron ions. Moreover, polydopamine can act as a mediator to facilitate electron transfer, thereby enhancing the photocatalytic performance of the photo-Fenton reaction.

In the present invention, the film casting liquid is dropped dropwise into the solidification bath to prepare the optical Fenton composite beads. The diameter of the obtained beads is about 3 mm, which is easier for recycling and continuous treatment of actual water samples than the split photo-Fenton catalyst. In the photo-Fenton system, polydopamine, biochar, and elemental iron in iron oxides can promote the Fe ³⁺ /Fe ²⁺ cycle, thereby improving the catalytic performance. In addition, the polydopamine-modified PVDF acts as a "barrier", which can effectively inhibit the loss of iron samples and improve the stability of the photo-Fenton composite beads. The invention provides a universally applicable new method for the enlarged application of the photo-Fenton powder catalyst, and can achieve effective degradation of actual environmental wastewater to a certain extent.

A preparation method of iron oxide@biomass carbon fiber@pDA-PVDF optical Fenton composite beads, the steps are as follows:

Step 1. Preparation of iron oxide@biomass carbon fiber:

Take wild velvet, wash and dry, weigh a certain amount of velvet in a crucible, then transfer to a tube furnace, calcine for a certain period of time at a certain temperature and a nitrogen atmosphere, and take out after natural cooling to obtain biomass carbon fibers (Carbon fiber, CF);

Take a certain amount of CF and disperse it in water, then add a certain amount of FeSO ₄ ·7H ₂ O to the above dispersion liquid and shake it for a certain period of time, after drying, transfer the obtained solid to a tube furnace, and at a certain temperature and under a nitrogen atmosphere for the first time. After secondary calcination for a certain period of time, it was taken out after natural cooling to obtain Fe-based oxide@Carbon fiber (FCF), which was ground into powder with a mortar for use.

Step 2, prepare pDA-PVDF powder;

Dopamine (DA) and polyvinylidene fluoride (PVDF) were dispersed in Tris-HCl buffer solution in proportion, and then a certain amount of ethanol was added, and then adjusted to pH=8.5, followed by vigorous stirring at room temperature, and finally filtered to obtain pDA- PVDF powder and drying;

Step 3. Preparation of iron oxide@biomass carbon fiber@pDA-PVDF photo-Fenton composite beads:

The FCF powder prepared in step 1, the pDA-PVDF powder prepared in step 2, and N-methylpyrrolidone (NMP) were mixed in proportion, and then mechanically stirred at a certain temperature to obtain a bead casting solution A. Finally, the bead casting solution A was mixed Drop by drop into deionized water, and replace the deionized water several times to ensure that the NMP solvent is completely replaced into the water to form FCF@pDA-PVDF photo-Fenton composite beads, which are ready for use.

In step 1, the calcination temperature of the velvet is 800-850°C, the calcination time is 3-5h, and the heating rate of the tube furnace is 5°C/min; the ratio of the CF to FeSO ₄ ·7H ₂ O is 0.3g : 1～3mmol; the shaking time is 12h; the second calcination temperature is 550～850℃, the calcination time is 3～5h, and the heating rate is 5℃/min;

In step 2, the mass ratio of DA and PVDF is 1:10, the concentration of dopamine in the Tris-HCl buffer solution is 2 mg/mL; the volume ratio of Tris-HCl buffer solution and ethanol is 30:1; the The vigorous stirring time is 6h; the rotating speed is 500～800r/min;

In step 3, the mass ratio of FCF powder, pDA-PVDF powder and NMP in the bead casting solution A is 0.05-0.15g: 2g: 17.85-17.95g; the mechanical stirring temperature is 50°C, and the stirring time is 4 to 6 hours.

The NMP described in the above technical scheme acts as a solvent to dissolve PVDF to prepare a bead casting solution A.

The PVDF described in the above technical solutions acts as a matrix.

The deionized water described in the above-mentioned technical scheme acts as a non-solvent.

The iron oxide@biomass carbon fiber@pDA-PVDF photo-Fenton composite beads prepared by the present invention are used as photocatalytic degradation of methyl orange.

The beneficial effects of the present invention are:

(1) The existence of elemental iron and biochar can promote the cycle of Fe ³⁺ /Fe ²⁺ , thereby generating more hydroxyl radicals, improving the photocatalytic efficiency, and effectively degrading organic pollutants.

(2) Using pDA-modified PVDF beads to immobilize the photo-Fenton catalyst, the obtained composite beads can well solve the problem that the split photo-Fenton catalyst is difficult to apply in practice. In addition, polydopamine can effectively inhibit the loss of iron ions, thereby effectively improving the stability of the catalytic system. The whole preparation method is simple and convenient, and provides new insights for the expanded application of Fenton's catalytic system.

Description of drawings

Figure 1a is the XRD pattern of the prepared composites (where CF represents biomass carbon fibers, FCF represents iron oxide@biomass carbon fibers, PB represents PVDF beads, DPB represents pDA-PVDF beads, and FPB represents iron oxide@biomass Carbon fiber@PVDF beads, FDPB represents iron oxide@biomass carbon fiber@pDA-PVDF beads), Figure 1b is the real photo of the composite bead, and Figure 1c is the cross-sectional SEM photo of the bead;

Figure 2a shows the degradation efficiency curves of different materials at pH 3, and b shows the photocatalytic degradation efficiency curves of FDPB at different pH conditions.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific implementation examples.

In the present invention, the total mass of the bead casting solution is 20 g as an example.

Example 1:

(1) Preparation of FCF Composite Photo-Fenton Catalyst

Weigh the dried velvet in a crucible, transfer it to a tube furnace, calcine it at 800 °C for 3 h, the heating rate is 5 °C/min, and take out after natural cooling to obtain CF, which is ready for use; take 0.3 g CF and 1 mmol FeSO ₄ ·7H ₂ O was dispersed in 35 mL of deionized water, shaken at room temperature for 12 hours; after drying, the obtained solid was transferred to a tube furnace and calcined at 850°C for 3 hours to obtain FCF composite photo-Fenton catalyst.

(2) Preparation of FCF@pDA-PVDF Photo-Fenton Composite Beads

First, 0.6g of dopamine powder and 6g of PVDF powder were dispersed in 300mL of Tris-HCl buffer solution, then 10mL of ethanol was added, and the pH of the solution was adjusted to 8.5, and the mixture was vigorously stirred for 6h to complete the self-polymerization of polydopamine on the surface of PVDF powder. Finally, filter, wash and dry to obtain pDA-PVDF powder. 0.05 g of FCF, 2 g of pDA-PVDF powder and 17.95 g of NMP solvent were weighed and mixed together, and stirred at 50° C. for 4 h to obtain a bead casting solution. Then, the casting solution was drawn into a 10 mL syringe and dropped into deionized water drop by drop to obtain composite beads through phase inversion.

Example 2:

Under the condition of keeping other conditions unchanged, the comparison test was established as follows: when preparing FCF composite photo-Fenton catalyst, 0.3g CF and 1mmol FeSO ₄ ·7H ₂ O were dispersed in 35mL deionized water, and shaken at room temperature for 12h; after drying , the obtained solid was transferred to a tube furnace, and the FCF composite photo-Fenton catalyst was obtained by changing the calcination temperature to 550 °C and then calcining for 3 h.

Example 3:

Under the condition of keeping other conditions unchanged, the comparative experiment was established as follows: when preparing FCF composite photo-Fenton catalyst, the loading of iron oxide was investigated by changing the ratio of CF and FeSO ₄ ·7H ₂ O, taking 0.3 g CF and 3 mmol FeSO ₄ ·7H ₂ O was dispersed in 35 mL of deionized water, shaken at room temperature for 12 hours; after drying, calcined at 850° C. for 3 hours, the FCF composite photo-Fenton catalyst was obtained.

Example 4:

When preparing photo-Fenton composite beads (other conditions remain unchanged), by changing the addition amount of FCF (0.1g, 0.15g), the optimal addition amount of Fenton catalyst and the effect of addition amount on photocatalytic performance were investigated.

As can be seen in Figure 1, the composites have characteristic peaks of various iron oxides and bio-made carbon fibers, proving the successful synthesis of the composites.

As can be seen in Figure 2a, the constructed FDPB almost completely decolorized methyl orange within 60 min, with a good degradation efficiency, second only to that of powdered FCF; while the degradation performance of other composites was lower. It can be seen from Figure 2b that the constructed FDPB exhibited different degradation efficiencies under different pH conditions, and the degradation rate reached the highest at pH=1.7.

The constructed composite photo-Fenton beads had a degradation effect of more than 99% on methyl orange, and maintained good catalytic performance after 6 cycles.

Claims (7)

1. a kind of preparation method of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton, which is characterized in that Include the following steps:

The preparation of step 1, ferriferous oxide@biomass carbon fiber:

Take wild cattail wool clean drying, weigh a certain amount of cattail wool in crucible, be then transferred to tube furnace, in certain temperature, Certain time is calcined under nitrogen atmosphere, is taken out after natural cooling, biomass carbon fiber CF is obtained；

It takes a certain amount of CF to be dispersed in water, a certain amount of FeSO is then added in above-mentioned dispersion liquid₄·7H₂O simultaneously vibrates a timing Between, after drying, obtained solid is transferred to tube furnace, second of calcining certain time under certain temperature, nitrogen atmosphere, to certainly It is so taken out after cooling, obtains ferriferous oxide@biomass carbon fiber, FCF is ground to powder with mortar, spare；

Step 2, preparation pDA-PVDF powder；

Dopamine D A and polyvinylidene fluoride PVDF are dispersed in Tris-HCl buffer solution in proportion, added a certain amount of Ethyl alcohol, then adjusts pH, is then vigorously mixed at room temperature for, and pDA-PVDF powder is finally obtained by filtration and dries；

Step 3 prepares the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton；

PDA-PVDF powder and N-Methyl pyrrolidone NMP prepared by FCF powder prepared by step 1, step 2 are mixed in proportion It closes, then mechanical stirring obtains bead casting liquid A under certain temperature, and bead casting liquid A is finally instilled deionized water dropwise In, and deionized water is repeatedly replaced, guarantee that nmp solvent is replaced into water completely, forms FCF@pDA-PVDF light Fenton composite bead Grain, it is spare.

2. the preparation side of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton according to claim 1 Method, which is characterized in that in step 1, the cattail wool calcination temperature is 800~850 DEG C, and calcination time is 3~5h, the liter of tube furnace Warm rate is 5 DEG C/min.

3. the preparation side of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton according to claim 1 Method, which is characterized in that in step 1, the CF and FeSO₄·7H₂The ratio of O is 0.3g:1~3mmol；The duration of oscillation is 12h；Second of calcination temperature is 550~850 DEG C, and calcination time is 3~5h, and heating rate is 5 DEG C/min.

4. the preparation side of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton according to claim 1 Method, which is characterized in that in step 2, the mass ratio of the DA and PVDF are 1:10, dopamine in the Tris-HCl buffer solution Concentration be 2mg/mL；The volume ratio of Tris-HCl buffer solution and ethyl alcohol is 30:1；PH value is 8.5.

5. the preparation side of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton according to claim 1 Method, which is characterized in that described to be vigorously stirred the time as 6h in step 2；Revolving speed is 500~800r/min.

6. the preparation side of the compound bead of ferriferous oxide biomass carbon fiber pDA-PVDF light Fenton according to claim 1 Method, which is characterized in that in step 3, the mass ratio of FCF powder, pDA-PVDF powder and NMP in the bead casting liquid A is 0.05~0.15g:2g:17.85~17.95g；The mechanical stirring temperature is 50 DEG C, and mixing time is 4~6h.

7. by ferriferous oxide@biomass carbon fiber@pDA-PVDF made from the described in any item preparation methods of claim 1~7 The compound bead of light Fenton is used for the purposes of photo-catalytic degradation of methyl-orange.