| Phenolic compounds have broad spectrum antibacterial, fungicidal and insecticidal efficacy. And as multi-purpose industrial and agricultural raw materials in the production process, they are widely used in dyes, plastics, herbicides, petrochemicals, paper and other industries. However, phenolic compounds is a kind of accumulated and unbiodegradable endocrine disruptors, which can enter into the organism through skin contact or respiratory and other means, causing a variety of diseases by destructing the cell viability, such as cardiovascular, neurological system and reproductive system disease, and even result in carcinogenic, teratogenic, mutagenic effect, which is a serious threat to human health and natural environment. With the large-scale industrial production, a large number of rich phenolic waste water pollutants are released into the environment. Therefore, the development of economical and effective pollution-control and technologies to remediate contaminated water environment has a very important practical significance.Currently, the treatment method of phenolic pollutants mainly refers to advanced oxidation, microbial degradation, membrane separation, adsorption separation and so on. The adsorptive separation based on porous adsorbent material has the feature of low cost, high efficiency, no pollution, simple operation, and easily removed to achieve the separation of target pollutants, which is a high-effective green separation technology. However, the conventional porous absorbing materials still have some shortcomings, such as poor targeting adsorption process, tedious separation and recovery process and difficult control on the adsorption process. Molecular Imprinting Technology (MIT) is a process for preparing molecular recognitive adsorption material (Molecularly Imprinted Polymers, MIPs) which can achieve selective identification and removal of the target. In recent years, in order to further expand the application of MIPs, the intelligent material were introduced to the preparation of MIPs, and the most typical materials are magnetic molecularly imprinted polymers (MMIPs) and thermal responsive molecularly imprinted polymer (TRMIPs). The fast separation of magnetic response was achieved owing to the feature of superparamagnetism of MMIPs. Under the effect of temperature, the mutation of hydrophilic to hydrophobic surface of TRMIPs can be achieved, thus controllably adjust adsorption-desorption process.Based on the above work, in this paper, the preparation of porous adsorbent materials using suspension polymerization and miniemulsion polymerization was the main line, while the ability of separation and removal of phenolic pollutants (phenol,2,4-dichlorophenol,2,4-dichlorophenol and 2,4,6-trichlorophenol) were critical control points. The magnetic porous absorbents, MMIPs and TRMIPs were prepared by combining the advantages of the adsorption and separation technology and the advantages of porous adsorbent materials, MIPs, magnetic materials, and temperature-sensitive materials, respectively. For three kinds of adsorbent materials, their morphology, magnetic properties, elemental composition, thermal stability, surface wettability and other physical and chemical properties were analyzed by using various characterizations, while the behavior of separation and removal of aquatic environment phenolic was also studied via combination of static and dynamic adsorption experiment, the possibility of adsorption mechanism was further discussed, and the equilibrium, thermodynamics and kinetics were explained thoroughly. The results of this thesis are as follows:1. Preparation of magnetic porous microspheres via suspension polymerization and research of applications in effectively adsorption and separation chlorophenol pollutants(1) Styrene-divinylbenzene (St-DVB) porous microspheres were first prepared via suspension polymerization, then Fe3O4 magnetic nanoparticles (Te3O4) were grafted on the surface of porous St-DVB microspheres by the sulfonated ion exchange and the oxidation process, St-DVB magnetic porous microspheres were finally obtained and were used to absorb and separate 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) from aqueous solution. The structure, morphology, magnetic properties, surface wettability and other physical and chemical characteristics were characterized by various characterization methods. Of the results showed that:the diameter of St-DVB magnetic porous microspheres was about 7.0 μm; and exhibited superparamagnetism (Ms=39.78emu/g) and thermal stability; the specific surface area and the average pore diameter were 75.25 m2/g and 11.02 nm, respectively; and the static water contact angle was 81° showing that microspheres are hydrophilic adsorbent. Batch mode of static adsorption experiments were carried out to investigate the adsorption equilibrium, kinetics and thermodynamics. At pH 2.0 (2,4-DCP) and pH 3.0 (2,4,6-TCP) for optimum conditions, the saturated mono layer adsorption capacity of St-DVB magnetic porous microspheres towards 2,4-DCP and 2,4,6-TCP were 45.87 mg/g and 64.94 mg/g at 25℃, respectively, and the adsorption equilibrium were reached at 300 min and 250 min, respectively. While the adsorption equilibrium and kinetic data can be fitted well by the Langmuir isotherm model and pseudo-second-order kinetic equation, respectively. Regeneration experiments were repeated three times, the adsorption capacity of St-DVB magnetic porous microspheres for 2,4-DCP and 2,4,6-TCP were decreased only 18.47% and 16.10%, respectively, indicating the superior regeneration performance.(2) St-DVB magnetic porous microspheres for absorb and separate 2,4-dichlorophenol (2,4-DCP) and 2,6-dichlorophenol (2,6-DCP) were prepared via suspension polymerization. The morphology, magnetic and thermal stability and other physical and chemical characteristics of the St-DVB magnetic porous microspheres were studied using a variety of characterization methods, the results showed:the diameter of St-DVB magnetic porous microspheres was about 20μm, a large number of cavities were distributed on the surface; and exhibited superparamagnetism (Ms=6.97 emu/g) and thermal stability; the specific surface area and average pore diameter were 418.38 m2/g and 5.49 nm, respectively; the static water contact angle was 136° indicating that microspheres were hydrophobic adsorption material. Batch mode of static adsorption experiments were carried out to investigate the adsorption equilibrium, kinetics and thermodynamics. pH 2.0 was optimum condition for both 2,4-DCP and 2,4,6-TCP, the saturated monolayer adsorption capacity of St-DVB magnetic porous microspheres towards 2,4-DCP and 2,6-DCP were 132.83 mg/g and 128.52 mg/g at 25℃, respectively, and the adsorption equilibrium were both reached at 400 min. While the adsorption equilibrium and kinetic data can be fitted well by the Langmuir isotherm model and pseudo-second-order kinetic equation, respectively. Regeneration experiments were repeated four times, the adsorption capacity of St-DVB magnetic porous microspheres for 2,4-DCP and 2,6-DCP were decreased only 14.70% and 19.27%, respectively, indicating the superior regeneration performance.2. Preparation of intelligent molecularly imprinted polymers via suspension polymerization and research of applications in controllably absorbion and separation chlorophenols/phenolic pollutants(1) Thermal responsive molecularly imprinted polymers (TRMIPs) for selectively recognize phenol was prepared via suspension polymerization by using acrylamide (AM) as the functional monomer, N-isopropyl acrylamide (NIPAm) as the temperature responsive monomer. By morphological characterization, TRMIPs was spherical and pores were distributed on the surface; the lowest critical solution temperature of TRMIPs and thermal responsive non-imprinted polymers (TRNIPs) were 35.97℃ and 35.76℃, respectively. The static adsorption experiment showed: the optimum temperature of TRMIPs and TRNIPs for adsorption and release of phenol were 35℃ and 45 ℃, respectively. The saturated monolayer adsorption capacity of TRMIPs and TRNIPs towards phenol were 77.09 mg/g and 32.89 mg/g at 35℃, respectively, and the adsorption equilibrium were both reached at 480 min. While the adsorption equilibrium and kinetic data can be fitted well by the Langmuir isotherm model and pseudo-second-order kinetic equation, respectively. Regeneration experiments were repeated five times, the adsorption capacity of TRMIPs for phenol was decreased only 6.78%, indicating that TRMIPs has excellent regeneration performance. Selective recognition experiments demonstrated the superior selective recognition ability of TRMIPs towards phenol over competitive phenolic compounds.(2) Fe3O4 magnetic nanoparticles were firstly prepared via hydrothermal method and then magnetic molecularly imprinted polymers (MMIPs) for selectively recognize 2,4,6-trichlorophenol (2,4,6-TCP) was prepared via suspension polymerization by using methacrylic acid (MAA) as the functional monomer. According to a variety of characterization methods, MMIPs were spherical, the diameter was about 10μm, and large amount of pores were distributed on the surface. MMIPs had superparamagnetic characteristics (Ms=10.14 emu/g), which can realize rapid separation in the presence of an externally placed magnet. Static adsorption experiments showed that pH 6.0 is the optimum adsorbent environment. The saturated monolayer adsorption capacity of MMIPs and magnetic non-imprinted polymers (MNIPs) for 2,4,6-TCP were 181.82 mg/g and 103.11 mg/g at 25℃, respectively. The equilibrium was reached at 230 min for both MMIPs and MNIPs. The adsorption equilibrium and kinetic data can be fitted well by Langmuir isotherm model and pseudo-second-order kinetic model. The influence of different experimental conditions (such as bed depth, pH, initial concentration, velocity and temperature) on the penetration curve was studied by dynamic adsorption experiments, and the mechanism of adsorption was further explored. The Thomas model was fitted well to the dynamic adsorption data of the MMIPs. Selective recognition experiments demonstrated the superior selective recognition ability of MMIPs towards 2,4,6-TCP over competitive phenolic compounds. Regeneration experiments were repeated five times, the adsorption capacity of MMIPs for 2,4,6-TCP was decreased only 17.53%, indicating that MMIPs has good regeneration performance. The MMIPs were successfully applied to the selective solid phase extraction of 2,4,6-TCP from cucumber samples (50μg/L), the recovery was 84.37%.3. Preparation of surface molecularly imprinted polymers upon biological materials as substrate via miniemulsion polymerization and research of applications in selective adsorption and separation chlorophenols pollutants(1)Molecularly imprinted polymers (SMIPs) for selectively recognize 2,4-dichlorophenol (2,4-DCP) was prepared via miniemulsion polymerization by using yeast as substrate material, methylacrylic acid (MAA) and styrene (St) as functional monomer. Morphology characterization showed that the imprinting layer coated on the elliptical spherical surface of the yeast cells were about 0.33μm and 0.35μm for the SMIPs and non-imprinted polymers (SNIPs), respectively. Static adsorption results showed that under the optimized adsorption condition of pH 6.0 and 25℃, the saturated monolayer adsorption capacity of SMIPs and SNIPs for 2,4-DCP were 45.05 mg/g and 15.92 mg/g, respectively. The adsorption equilibrium was reached at 245 min for both SMIPs and SNIPs. The adsorption equilibrium and kinetic data can be fitted well by Langmuir isotherm model and pseudo-second-order kinetic model. Selective recognition experiments proved that the superior selective recognition of the SMIPs for 2,4-DCP. After five regeneration cycles, the adsorption capacity of SMIPs for 2,4-DCP was decreased only 11.75%, indicating that SMIPs has excellent regeneration performance. The SMIPs prepared were successfully applied to the selective solid phase extraction of 2,4-DCP from tomato samples (50 μg/L), the recovery was 80.70%.(2) Fe3O4 magnetic nanoparticles were firstly prepared via coprecipitation method and then magnetic molecularly imprinted polymers (MMIPs) for selectively recognize 2,4,6-trichlorophenol (2,4,6-TCP) was prepared via miniemulsion polymerization by using bacillus as substrate material, methylacrylic acid (MAA) and styrene (St) as functional monomer. The structure, morphology and magnetic characteristics of MMIPs were studied with a variety of characterization methods. The results showed that nanoscale molecularly imprinted polymers were coated on the surface of bacillus cells and the MMIPs exhibited superparamagnetism (Ms=1.46 emu/g), which can realize rapid magnetic response performance during separation processes. Static adsorption experiment showed that under the optimum absorption condition of pH 5.0, the saturated monolayer adsorption capacity of MMIPs and magnetic non-imprinted polymer (MNIPs) for 2,4,6-TCP were 58.14 mg/g and 25.00 mg/g, respectively, and adsorption equilibrium were reached at 150 min and 100 min. Adsorption equilibrium and kinetic data could be fitted well by the Langmuir isotherm adsorption data model and the pseudo-second-order kinetice model. Selective recognition experiment showed that MMIPs had superior selective recognition for 2,4,6-TCP. After five regeneration experiments, the adsorption capacity of MMIPs for 2,4,6-TCP was decreased only 11.09%, indicating ideal regeneration performance. Finally, MMIPs were used to selective solid phase extraction of 2,4,6-TCP in spiked milk samples (50μg/L), the recovery was 81.70%. |
