阅读说明：本技术 Pizza结构的纳米片氮化碳复合pH敏水凝胶、其制备方法及应用 (Nanosheet carbon nitride composite pH-sensitive hydrogel with Pizza structure, and preparation method and application thereof ) 是由 葛家国 刘境廷 牛何晶英 陈捷 焦正 马梦迪 于 2019-09-23 设计创作，主要内容包括：本发明涉及一种Pizza结构的纳米片氮化碳复合水凝胶、其制备方法及应用。本发明通过紫外在一定条件下辐照丙烯酸溶液直接聚合成聚丙烯酸膜(PAA),以此为基底沉缚上一定质量的纳米片氮化碳(CNNS),其后通过氙灯在420nm滤光片的过滤下辐照CNNS/PAA与丙烯酰胺溶液,CNNS可以引发丙烯酰胺在CNNS/PAA上发生聚合生成具有互穿网络结构的Pizza CNNS复合水凝胶。发现制备的互穿网络结构的PAM/CNNS/PAA,相较于PAA抗拉强度大幅提高,而且PAM/CNNS/PAA复合水凝胶的膜形态结构区别于常见的有机聚合材料与光催化类材料的团块水凝胶结构,在印染废水处理中PAM、PAA的吸附作用与CNNS的光降解作用可以高效地协调作用,同时解决了多数光催化剂回收难的问题。(The invention relates to a nano-sheet carbon nitride composite hydrogel with a Pizza structure, and a preparation method and application thereof. The invention directly polymerizes into a polyacrylic acid film (PAA) by irradiating acrylic acid solution under certain conditions in ultraviolet, nano-sheet carbon nitride (CNNS) with certain mass is bound on a substrate by taking the PAA as the substrate, and then the CNNS/PAA and acrylamide solution are irradiated by a xenon lamp under the filtration of a 420nm optical filter, so that the CNNS can initiate acrylamide to polymerize on the CNNS/PAA to generate the Pizza CNNS composite hydrogel with an interpenetrating network structure. The PAM/CNNS/PAA with the interpenetrating network structure is found to be greatly improved in tensile strength compared with PAA, the membrane morphology structure of the PAM/CNNS/PAA composite hydrogel is different from the agglomerate hydrogel structure of common organic polymeric materials and photocatalysis materials, the adsorption effect of PAM and PAA and the photodegradation effect of CNNS can be efficiently coordinated in the printing and dyeing wastewater treatment, and the problem that most photocatalysts are difficult to recover is solved.)

1. A nano-sheet carbon nitride composite hydrogel with a Pizza structure is characterized in that the nano-sheet carbon nitride composite hydrogel is a film-shaped composite hydrogel with an interpenetrating network structure, which is formed by polyacrylamide PAM, nano-sheet carbon nitride CNNS and polyacrylic acid PAA, a PAA film is used as a substrate, the CNNS is deposited in the network structure, then PAM and PAA form an interpenetrating network structure, and the CNNS is firmly bound in the interpenetrating network structure, so that the nano-sheet carbon nitride composite hydrogel with the Pizza structure is formed; wherein the mass ratio of PAM, CNNS and PAA is as follows: (0.5-8): (1.5-3): 8.

2. a method for preparing the VOC catalyst according to claim 1, wherein the VOC catalyst is characterized by the ordered arrangement of composite metal oxide and ferroferric oxide:

a. preparing an acrylic acid solution with the mass percentage concentration of 5-20%, under the protection of inert atmosphere, using an ultraviolet lamp with the central wavelength of 365nm and the power of 300w to keep the distance of 5-18 cm, and irradiating for 60-140 min to obtain a polyacrylic acid film; cleaning and drying the polyacrylic acid film, immersing the polyacrylic acid film in distilled water, and standing for 30 min;

b. placing CNNS in distilled water, ultrasonically shaking for 30min, taking CNNS out, and drying;

c. and c, mixing the polyacrylic acid film obtained in the step a and the CNNS obtained in the step b according to the ratio of (8-16): 3, putting the mixture into acrylamide according to the mass ratio, wherein the total mass percentage concentration is 2-8 wt%, and swelling for 4-8 hours;

d. and c, placing the swelling solution obtained in the step c under an ultraviolet lamp with the central wavelength of 365nm and the power of 300w under the protection of inert atmosphere, keeping the distance of 18cm, irradiating for 30-60 min to obtain PAM/CNNS/PAA with different mass fractions, and drying to obtain the nano-sheet carbon nitride composite hydrogel with the Pizza structure.

3. The use of the Pizza-structured nanosheet carbon nitride composite hydrogel according to claim 1 in printing and dyeing wastewater treatment.

Technical Field

The invention relates to the fields of high polymer, photocatalysis and organic sewage treatment, belongs to the field of interdisciplinary application in the wastewater treatment direction, and particularly relates to a nano-sheet carbon nitride composite pH-sensitive hydrogel, and a preparation method and application thereof.

Background

In recent years, people pay more attention to the direction of solar energy utilization for energy conservation and environmental protection. Photocatalysis has been considered as one of the most promising technologies in terms of solar energy conversion and pollutant elimination. In the search for excellent and stable visible light induced photocatalyst, Carbon Nitride (CN) has attracted great attention. However, the CN catalyst needs to be uniformly distributed in the sewage by blowing air in the using process, and the problem is similar to that of a secondary sedimentation tank in industrial wastewater treatment, and the powder catalyst is usually precipitated in more than two days after the organic pollutants in the water are degraded, so that the CN catalyst is not suitable for recycling and reusing.

A method of solving the problem of difficulty in recycling organic high-molecular-weight photocatalyst and powder photocatalyst by using the same in combination is currently studied by a large number of researchers. However, many of the composite hydrogels prepared are agglomerated hydrogel water, and the catalyst contained therein hardly functions, and the contact area of the polymer in water is too small, so that the advantages of both cannot be efficiently combined.

As is known, polyacrylic acid and polyacrylamide are common organic pollutants and heavy metal ion adsorbents, PAA has pH sensitive hydrogel, PAM has temperature sensitive hydrogel, and polyacrylic acid prepared by an ultraviolet irradiation method under a certain condition has special form and performance.

At present, the photocatalyst in the composite block hydrogel bound with the photocatalyst is difficult to play, and meanwhile, the high polymer has the defect of over-small contact area in water.

Disclosure of Invention

The invention aims to provide a nanosheet carbon nitride composite hydrogel with a Pizza structure.

The second purpose of the invention is to provide a preparation method of the nano sheet carbon nitride composite hydrogel.

The invention also aims to provide the application of the nano-sheet carbon nitride composite hydrogel in printing and dyeing wastewater treatment, the tensile strength of the nano-sheet carbon nitride composite hydrogel is enhanced by an interpenetrating network structure, the adsorption effect of PAA and PAM and the photocatalysis effect of CNNS are more efficiently cooperated by a membrane structure, and the problem of difficult recovery of CNNS is solved, so that the aim of recycling is fulfilled.

In order to achieve the purpose, the invention adopts the technical scheme that:

a nano-sheet carbon nitride composite hydrogel with a Pizza structure is characterized in that the nano-sheet carbon nitride composite hydrogel is a film-shaped composite hydrogel with an interpenetrating network structure, which is formed by polyacrylamide PAM, nano-sheet carbon nitride CNNS and polyacrylic acid PAA, a PAA film is used as a substrate, the CNNS is deposited in the network structure, then PAM and PAA form an interpenetrating network structure, and the CNNS is firmly bound in the interpenetrating network structure, so that the nano-sheet carbon nitride composite hydrogel with the Pizza structure is formed; wherein the mass ratio of PAM, CNNS and PAA is as follows: (0.5-8): (1.5-3): 8.

the method for preparing the VOC catalyst with the characteristic ordered arrangement of the composite metal oxide and the ferroferric oxide is characterized by comprising the following steps of:

a. preparing an acrylic acid solution with the mass percentage concentration of 5-20%, under the protection of inert atmosphere, using an ultraviolet lamp with the central wavelength of 365nm and the power of 300w to keep the distance of 5-18 cm, and irradiating for 60-140 min to obtain a polyacrylic acid film; cleaning and drying the polyacrylic acid film, immersing the polyacrylic acid film in distilled water, and standing for 30 min;

b. placing CNNS in distilled water, ultrasonically shaking for 30min, taking CNNS out, and drying;

c. and c, mixing the polyacrylic acid film obtained in the step a and the CNNS obtained in the step b according to the ratio of (8-16): 3, putting the mixture into acrylamide according to the mass ratio, wherein the total mass percentage concentration is 2-8 wt%, and swelling for 4-8 hours;

d. and c, placing the swelling solution obtained in the step c under an ultraviolet lamp with the central wavelength of 365nm and the power of 300w under the protection of inert atmosphere, keeping the distance of 18cm, irradiating for 30-60 min to obtain PAM/CNNS/PAA with different mass fractions, and drying to obtain the nano-sheet carbon nitride composite hydrogel with the Pizza structure.

An application of the nano-sheet carbon nitride composite hydrogel with the Pizza structure in printing and dyeing wastewater treatment.

Compared with the composite block gel formed by most organic polymers and photocatalytic materials, the PAM/CNNS/PAM prepared by the invention is a membrane-shaped composite hydrogel with an interpenetrating network structure, can efficiently enable the PAA and the PAM to be adsorbed on the CNNS under the photocatalytic synergistic action in the printing and dyeing wastewater treatment, and 0.13g of PAM/CNNS/PAM can degrade more than 99% of RhB in 30ml (10mg/L) of rhodamine B (RhB) solution within 120 min. Meanwhile, the pH sensitivity of PAA and the temperature sensitivity of PAM can facilitate the recovery of materials, and simultaneously solve the recovery problem of CNNS.

Compared with the prior composite block hydrogel technology combining high polymer and photocatalyst, the invention has the beneficial effects that:

the invention provides a brand-new preparation method of a nano-sheet carbon nitride composite pH sensitive hydrogel with a Pizza structure, the problem of low efficiency of a photocatalyst in a lump gel is solved by a membranous form and a Pizza structural mode, so that the PAA and PAM hydrogels can adsorb organic pollutants more efficiently due to better swelling performance, and the pH sensitive property of the PAA and PAM hydrogels is beneficial to the recovery of the photocatalyst; the interpenetrating network structure improves the tensile strength of PAM/CNNS/PAA.

Drawings

FIG. 1 is a flow chart for preparing PAM/CNNS/PAA composite pH-sensitive hydrogel.

FIG. 2 is a graph showing the swelling ratios of PAA, CNNS/PAA, PAM/CNNS/PAA (mass ratio 2: 3: 8) in a phosphate buffer solution at pH1 to 9.

FIG. 3 is a graph of tensile strength-elongation for PAA, CNNS/PAA, PAM/CNNS/PAA (mass ratio 2: 3: 8; 6: 3: 8).

FIG. 4 shows an optical power density of 100 mWcm under the filtration of a 420nm filter at 0.13g PAM/CNNS/PAA (mass ratio 2: 3: 8)^-2The cycle test chart of degradation of 30ml (10mg/L) of RhB solution under the irradiation of a xenon lamp simulating sunlight.

FIG. 5 shows PAM/CNNS/PAA in a mass ratio of (0, 2, 4, 6, 8): 3: 8 hours, under the filtration of a 420nm optical filter, the optical power density is 100 mWcm^-2The time chart required for degrading Rhb in 30ml (10mg/L) of RhB solution by more than 99% under the irradiation of a xenon lamp simulating sunlight.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the present invention is more clearly defined by the scope of the present invention.