CN107953569B

CN107953569B - Preparation method of biological carrier for thermoplastic resin immobilized biomass charcoal

Info

Publication number: CN107953569B
Application number: CN201711144681.9A
Authority: CN
Inventors: 全燮; 毛彦俊; 陈硕; 于洪涛; 张耀斌
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2017-11-17
Filing date: 2017-11-17
Publication date: 2021-04-27
Anticipated expiration: 2037-11-17
Also published as: CN107953569A

Abstract

The invention discloses a preparation method of a biological carrier for thermoplastic resin immobilized biomass charcoal, belonging to the technical field of biological treatment and functional materials of pollutants. The invention takes thermoplastic resin extrusion grade polyethylene particles or extrusion grade polypropylene particles as basic raw materials, takes one or a combination of grass wood carbon, straw carbon, rice hull carbon, fruit shell carbon, sludge biomass carbon and animal waste biomass carbon as functional materials, and prepares the thermoplastic resin fixed biomass carbon carrier by a screw extrusion process. The preparation method provided by the invention has the advantages of simple process, flexible and controllable method, strong adaptability, large-scale production and high efficiency in removing the organic pollutants difficult to degrade.

Description

Preparation method of biological carrier for thermoplastic resin immobilized biomass charcoal

Technical Field

The invention relates to a preparation method of a biological carrier of thermoplastic resin immobilized biomass charcoal, which is applied to biological treatment of environmental pollutants, is particularly suitable for biological treatment of sewage, and belongs to the technical field of biological treatment and functional materials of pollutants.

Background

Domestic sewage and industrial wastewater are main pollution sources of water in China. Compared with domestic sewage, the discharge amount of industrial wastewater and the types of pollutants in the wastewater are increasing, the components are more complex, and various refractory organic pollutants are contained in the wastewater. The organic pollutants which are difficult to degrade are organic compounds which can hardly be degraded by microorganisms or can be degraded for a long time, and are easy to accumulate in natural media such as water, soil and the like, thereby causing harm to the environment. The refractory organic wastewater relates to a wide range of industries, mainly including chemical industry, light industry, printing and dyeing, pharmacy, pesticides, coal chemical wastewater and the like. The waste water mainly contains refractory organic components such as phenols, halogenated compounds, monocyclic aromatic compounds, polycyclic aromatic hydrocarbons, polychlorinated biphenyl, pesticides, herbicides, dyes and the like, and the harm of the organic components to the environment is generally regarded by countries all over the world. The control of refractory organic pollutants is an important subject in the field of water pollution prevention and control. Recent related researches show that the addition of the artificial redox mediator can accelerate the extracellular electron transfer rate of microorganisms, thereby being beneficial to enhancing the biodegradation performance of refractory organic pollutants and shortening the degradation time. Therefore, the redox mediator has potential application value and is more and more concerned widely at home and abroad.

The redox mediator transfers electrons through the redox capacity of the redox mediator, mainly participates in the extracellular electron transfer process of microorganisms, so that the electron transfer rate is accelerated, and the degradation rate of pollutants is remarkably improved. At present, the redox mediators generally used are mainly some quinones, phenazines, phthalocyanines, etc. These substances all have a pi-pi conjugated system and have active sites capable of gaining and losing electrons, such as carbonyl (C ═ O). However, the substances are soluble, and need to be added periodically in the biological water treatment process, so that the problems of high treatment cost, secondary pollution to the environment and the like exist. Carbonaceous materials such as: graphene, carbon nanotubes, biochar, and the like are many redox mediators with high recycling rate studied in recent years. Among them, Biochar (biocar), also called Black carbon (Black carbon), is a type of insoluble, stable, highly aromatic, carbon-rich solid residue produced by pyrolysis (carbonization) of biomass at high temperatures (generally < 700 ℃) in the presence of low or no oxygen. The raw materials for preparing the biochar have low cost and wide sources, and mainly comprise wood, shells, straws, sludge, animal wastes and the like. The relevant research results show that the surface of the biochar is rich in oxygen-containing functional groups (such as carbonyl, hydroxyl and the like), the biochar can receive electrons generated by biodegradation in the bioremediation process of pollutants, the reduced biochar can transfer the electrons to an electron acceptor after receiving the electrons, and the biochar serving as a redox mediator improves the treatment efficiency in the whole degradation process. However, when the metal oxide is directly used as a redox mediator, the metal oxide is lost, so that the problems of increased adding cost, secondary pollution to the environment and the like also exist. Based on the above, the invention aims to fix the biochar material on the thermoplastic resin, and develops a novel biological carrier for fixing the biomass carbon on the thermoplastic resin.

Disclosure of Invention

The invention aims to solve the problem that the treatment rate of refractory organic matters in a water body is low due to the limitation of the electron transfer rate in a biological water treatment technology, and provides a preparation method of a biological carrier of thermoplastic resin immobilized biomass carbon.

The technical scheme of the invention is as follows:

a preparation method of a biological carrier for thermoplastic resin immobilized biomass charcoal comprises the following steps:

(1) grinding the biomass charcoal functional material into powder, and drying the powder to constant weight at the temperature of less than or equal to 80 ℃ for later use;

(2) mechanically blending the biomass charcoal functional material powder pretreated in the step (1) with thermoplastic resin particles and uniformly stirring for later use; the mass ratio of the biomass charcoal functional material powder to the thermoplastic resin particles is 20-50%;

(3) carrying out melt blending extrusion and strip forming on the solid mixture in the step (2) by using a screw extruder, and obtaining a granular blend through mechanical cutting; the processing temperature of the screw extruder is 115-190 ℃, and the thermoplastic resin is fully mixed with the biomass charcoal functional material powder in a molten state;

(4) mechanically stirring the granular blend prepared in the step (3) and thermoplastic resin granules uniformly, adding the mixture into a screw extruder for blending and extruding, and obtaining carrier pipes with different shapes according to the design of a die head; the mass ratio of the biomass charcoal in the granular blend to the total mass of the thermoplastic resin granules is not more than 20 percent;

(5) and (4) cutting the carrier pipe prepared in the step (4) in a mechanical cutting mode according to the required size to obtain the biological carrier.

The biomass charcoal functional material is one or the combination of more than two of grass charcoal, straw charcoal, rice hull charcoal, fruit shell charcoal, sludge biomass charcoal and animal waste biomass charcoal.

The thermoplastic resin particles are extrusion-grade polyethylene particles or extrusion-grade polypropylene particles.

The screw extruder is heated in four sections, and the temperature range and the effect of heating in each section are as follows: (1) the temperature is 120-140 ℃, so that the thermoplastic resin can reach a semi-molten state, and the continuity of solid conveying is facilitated; (2) the temperature is 130-160 ℃, the function of accelerating the transformation of the thermoplastic resin from a semi-molten state to a molten state is realized, and the blend is favorably and uniformly mixed in the heating section; (3) the temperature is 140-; (4) the temperature is 115 ℃ and 145 ℃ so as to ensure the quantitative and constant-pressure outflow of the blend and ensure the stability and continuity of extrusion and subsequent smooth setting.

The invention has the beneficial effects that: the preparation method of the biological carrier for fixing the biomass carbon by the thermoplastic resin, provided by the invention, has the advantages of simple process, flexible and controllable method, strong adaptability and large-scale production, and the biological carrier has high efficiency in removing the organic pollutants difficult to degrade.

Detailed Description

The following describes the embodiments of the present invention in detail with reference to the technical solutions.

Example 1

Preparing a thermoplastic resin immobilized biomass charcoal biological carrier: (1) grinding the straw carbon functional material into powder, and drying the powder at the temperature of 60 ℃ to constant weight for later use; (2) mechanically blending the straw carbon functional material powder pretreated in the step (1) with high-density polyethylene particles and uniformly stirring for later use; (3) and (3) carrying out melt blending extrusion on the solid mixture in the step (2) by using a screw extruder, forming into strips, and mechanically cutting to obtain granular blends. The processing temperature of the screw extruder was 175 ℃. The mass percentage of the straw carbon functional material to the high-density polyethylene particles is 30 percent; (4) and (4) mechanically stirring the granular blend prepared in the step (3) and thermoplastic resin uniformly, adding the mixture into a screw extruder, and blending and extruding the mixture. The percentage of the mass of the straw carbon in the granular blend to the total mass of the high-density polyethylene is 4 percent; (5) the materials extruded by melt mixing are subjected to strip forming, cooling, traction and grain cutting, and carriers with different shapes are obtained according to the design of a die head.

The biological carrier is applied to aerobic biodegradation experiments of phenol wastewater (dissolved oxygen is controlled to be 2.0-3.0mg/L), and the influence of the biological carrier on the biodegradability of microorganisms in a water body is examined. In the experiment, the adding amount of the carrier is 30 percent of the effective volume of the reactor, and the hydraulic retention time is 8 hours. The experimental results show that: (1) the adsorption experiment of the carrier to phenol in the water body is carried out in the absence of microorganisms, and the result shows that: the removal rate of phenol by adsorption on the carrier was less than 3%. (2) Compared with a high-density polyethylene carrier without fixed biochar, the reactor using the high-density polyethylene to fix the straw carbon bio-carrier improves the removal rate of phenol by nearly 10% through biodegradation in the presence of microorganisms.

Example 2

Preparing a thermoplastic resin immobilized biomass charcoal biological carrier: (1) grinding the rice husk carbon functional material into powder, and drying the powder at the temperature of 60 ℃ to constant weight for later use; (2) mechanically blending the rice hull carbon functional material powder pretreated in the step (1) with high-density polyethylene particles and uniformly stirring for later use; (3) and (3) carrying out melt blending extrusion on the solid mixture in the step (2) by using a screw extruder, forming into strips, and mechanically cutting to obtain granular blends. The processing temperature of the screw extruder was 185 ℃. The mass percentage of the rice husk carbon functional material to the high-density polyethylene particles is 50 percent; (4) and (4) mechanically stirring the granular blend prepared in the step (3) and the high-density polyethylene granules uniformly, adding the mixture into a screw extruder, and blending and extruding. The percentage of the mass of the rice husk charcoal to the total mass of the high density polyethylene in the granular blend is 8%; (5) the materials extruded by melt mixing are subjected to strip forming, cooling, traction and grain cutting, and carriers with different shapes are obtained according to the design of a die head.

The preparation method of the biological carrier taking the carbonylation modified graphene oxide as the functional material comprises the following steps: (1) preparing a carbonylation modified graphene oxide functional material: adjusting the pH of the graphene oxide dispersion liquid to 10 by using ammonia water, and carrying out hydrothermal treatment at 90 ℃ for 6 hours; cooling; drying at 60 ℃, and marking the obtained solid as N-GO; adding 0.2g of N-GO into 20mL of water, fully dispersing by ultrasonic treatment, adding 5mL of H2SO4 and 1.2g of potassium dichromate under the condition of ice-water bath, fully stirring, reacting for 3 hours, and drying at 60 ℃. The resulting carbonylated modified graphene oxide (Q-GO). (2) Preparation of biological carrier: performing ultrasonic treatment on the carbonylation modified graphene oxide functional material in water to fully disperse the carbonylation modified graphene oxide functional material, adding a polyethylene particle base raw material into a dispersion liquid, wherein the mass ratio of the insoluble redox mediator functional material to the base raw material is 1: 100; soaking for 2h, and stirring once every half hour to ensure that the functional materials in the water can be fully contacted with the high-density polyethylene particles; drying at 80 ℃ for later use. And (3) carrying out melt extrusion on the materials by using a screw extruder, and cooling, drawing and granulating to obtain the columnar carrier.

The biological carrier with the thermoplastic resin fixed with the biochar, the biological carrier with the carbonylation modified graphene oxide as the functional material and the unmodified carrier are applied to aerobic and anaerobic biodegradation experiments of phenol wastewater, and the influence of reactors added with different carriers on the biodegradability of microorganisms in a water body is comparatively discussed under different water inlet load conditions. In the experiment, the adding amount of the carrier is 30% of the effective volume of the reactor. The results of the experiment are shown in table 1. It can be seen from the table that the biodegradation performance of the reactor loaded with the modified carrier on phenol is better than that of the reactor without the modified carrier under the conditions of aerobic and anaerobic conditions and different concentrations of the phenol fed into water. Between the reactors of the modified carrier, the biodegradation performance of the reactor of the biochar modified carrier is slightly better than that of the reactor carrying the carbonyl graphene oxide modified carrier. In addition, compared with the preparation method of the biological carrier taking the carbonylation modified graphene oxide as the functional material, the preparation method of the biological carrier of the thermoplastic resin immobilized biochar is simpler, is convenient to operate, saves time and is more beneficial to ensuring the continuity of the production process. Compared with the method that the carbonylation modified graphene oxide is used as the functional material, the biomass charcoal functional material has wider sources, is low in cost and is more beneficial to realizing large-scale production and application.

TABLE 1 Effect of modified Supports on the biodegradability of phenol

Tab.1Effect of modified carriers on biodegradability of phenol

Note: PE represents the reactor to which the unmodified bio-carrier is added;

Q-GO represents a reactor to which a carbonylated graphene oxide-modified support is added;

biochar refers to a reactor to which a biomass charcoal-modified carrier is added.

Claims

1. A preparation method of a biological carrier for thermoplastic resin immobilized biomass charcoal is characterized by comprising the following steps:

(1) grinding the biomass charcoal functional material into powder, and drying the powder to constant weight at the temperature of less than or equal to 80 ℃ for later use; the surface of the biomass charcoal functional material is rich in oxygen-containing functional groups and has the function of a redox mediator;

(3) carrying out melt blending extrusion and strip forming on the solid mixture in the step (2) by using a screw extruder, and obtaining a granular blend through mechanical cutting; the processing temperature of the screw extruder is 130-190 ℃, and the thermoplastic resin is fully mixed with the biomass charcoal functional material powder in a molten state;

(5) and (4) cutting the carrier pipe prepared in the step (4) in a mechanical cutting mode according to the required size to obtain the biological carrier, and applying the biological carrier to biological treatment of sewage.

2. The method for preparing bio-carrier according to claim 1, wherein the biomass charcoal functional material is one or a combination of more than two of grass charcoal, straw charcoal, rice hull charcoal, fruit shell charcoal, sludge biomass charcoal and animal waste biomass charcoal.

3. The method of claim 1 or 2, wherein the thermoplastic resin particles are extruded polyethylene particles or extruded polypropylene particles.

4. The bio-carrier preparation method according to claim 1 or 2, wherein the screw extruder is heated in four sections, and the temperature range of each section is as follows:

(1) the temperature is increased to 140 ℃, so that the thermoplastic resin reaches a semi-molten state, and the continuity of solid conveying is facilitated;

(2) the temperature is 130-160 ℃, the function of accelerating the transformation of the thermoplastic resin from a semi-molten state to a molten state is realized, and the blend is favorably and uniformly mixed in the heating section;

(3) the temperature is 140-;

(4) the temperature is 115 ℃ and 145 ℃ so as to ensure the quantitative and constant-pressure outflow of the blend and ensure the stability and continuity of extrusion and subsequent smooth setting.

5. The bio-carrier preparation method according to claim 3, wherein the screw extruder is heated in four sections, and the temperature range of each section is as follows:

(3) the temperature is 140-;