Preparation Of Functional Polymer Microspheres By Self-Stable Precipitation Polymerization And Their Applications In Remediation Of Dye Containing Wastewater

Owing to complicated composition,high toxicity,and low degradability,the uncontrolled and massive discharge of dye wastewater has caused great harm to human health and ecological environment.In addition,there are high content of organic compounds in dye containing wastewater,which have poor biodegradability and are difficult to decolorize.To address these problems,a wide variety of techniques have been developed in recent years,and the adsorption process is one of the most effective technologies of dye wastewater treatment owing to its simplicity,wide applicability and cost effectiveness.The key to the treatment of dye wastewater by adsorption is the adsorbent.However,the traditional adsorbents have the disadvantages of tedious fabrication process,low adsorption capacity,high cost,difficult regeneration and difficult separation,which cannot meet the requirements of practical application.Therefore,it is of great significance to develop adsorbents with high adsorption capacity,low cost,easy separation and excellent reusability.In this paper,functional hollow polymer microspheres were synthesized by self-stable precipitation polymerization based on a widely available biomass monocyclic terpene limonene,which could act as efficient adsorption material to remove dyes.Then,in order to reduce the cost,anhydride functionalized crosslinked polymer microspheres（PMC9）were directly prepared by self-stable precipitation polymerization based on cracking C9resources,which are further modified and act as adsorption material.On this basis,Ti O₂ were further immobilized on these PMC9 microspheres to prepare Ti O₂ modified PMC9（PMC9@Ti O₂）composite microspheres for both adsorption and photocatalytic degradation of dyes.In order to solve the difficult separation problem of hollow polymer microspheres（HPPs）adsorbents,polyurethane foam（PUF）modified by functional HPPs was synthesized by one-step process,and the adsorption properties of the composite PUF were studied.Follows are the main results:1.Based on biomass limonene monomer,a novel kind of sustainable limonene-derived HPPs（LHPP-COOH）with unique mesoporous shell structure was synthesized by self-stable precipitation polymerization.The hollow void was verified by TEM and the mesoporous structure was characterized by BET analysis.Taking methylene blue（MB）and Ni²⁺as model pollutants,the sorption kinetics,isotherms,p H-responsiveness,and recyclability were discussed comprehensively for evaluation of the adsorption property of LHPP-COOH.Owing to the unique hollow porous structure,developed microporous/mesoporous multi-level pore structure and the existence of large number of carboxylic groups in the cross-linked shell layer,the LHPP-COOH exhibited outstanding sorption performance for the removal of MB and Ni²⁺.The q_max of LHPP-COOH for MB was 871.7 mg/g at p H=10,while the q_max for Ni²⁺was 74.9 mg/g at p H=6,and the saturated sorption could be attained within 5 min.Additionally,the sorption behavior fitted better with Langmuir model and pseudo-second-order equation,indicating that the adsorption of MB and Ni²⁺on LHPP-COOH is monolayer adsorption and electrostatic attraction plays a significant role in the adsorption process.Furthermore,because of the remarkable p H-responsiveness,LHPP-COOH can be facilely regenerated in acidic solution and reused for next adsorption process.The MB removal efficiency of the recycled LHPP-COOH was still higher than 99%after 5 successive sorption/desorption cycles.2.C9-maleic anhydride copolymer microspheres（PMC9）were directly prepared by self-stable polymerization of C9 resource and maleic anhydride.The effects of solvent,monomer concentration,temperature and the dosage of crosslinking agent on the size and morphology of PMC9 were systematically studied.The experimental data demonstrated that PMC9 were regular spherical with a particle size of 850 nm when using isoamyl acetate as solvent,monomer concentration of 25%,temperature of 75°C and the dosage of crosslinking agent of 10%.After hydrolyzation and reaction with diethylenetriamine（DETA）,carboxyl functionalized PMC9（PMC9-COOH）and ammonium functionalized PMC9（PMC9-NH₃⁺）were successfully obtained,respectively,which can serve as efficient adsorbents for cationic MB and anionic dye methyl blue.The saturated adsorption capacity of PMC9-COOH for MB was 877 mg/g,and the sorption equilibrium was reached within 30 min.The saturated adsorption capacity of PMC9-NH₃⁺for methyl blue is 562 mg/g,and the saturated sorption could be attained within 120 min.PMC9-COOH and PMC9-NH₃⁺have great application potential as adsorbents for dye wastewater treatment.3.The as-prepared PMC9 was used as a support for the deposition of Ti O₂,and PMC9@Ti O₂ composite microspheres with both adsorption and photocatalytic degradation properties were prepared.The PMC9@Ti O₂ were characterized by IR,SEM,XRD and XPS.The results showed that Ti O₂ were uniformly loaded on the surface of PMC9 through covalent bonds,which effectively inhibited the agglomeration of Ti O₂.Meanwhile,accompanied with the synergetic effect of PMC9-COOH with high adsorption performance,the photocatalytic efficiency of Ti O₂ can be further improved.Taking MB as a model pollutant,the effects of Ti O₂ loading,initial dye concentration and PMC9@Ti O₂ dosage on the photocatalytic degradation properties of the PMC9@Ti O₂ were systematically studied.The photocatalytic degradation ability of PMC9@Ti O₂ is better than that of Ti O₂.When the dosage of PMC9@Ti O₂ is 0.25 g/L,the initial concentration of MB is 100 mg/L and the removal rate of methylene blue is 90%.It suggests that the PMC9@Ti O₂composite microsphere have great potential for use as an excellent photocatalyst for wastewater remediation.4.A novel kind of polyurethane foam（PUF）modified with carboxylate-functionalized hollow polymer particles（HPPs-COO^-）were specially designed and synthesized through one-step process without any post-modification,and the HPPs were uniformly and chemically immobilized in the as-formed HPPs-COO^-/PUF.Combining the advantages of high adsorption capacity of HPPs-COO^-and easy separation of PUF,HPPs-COO^-/PUF exhibit unique selectivity and high adsorption capacity for cationic dye.Batch adsorption experiments were performed to evaluate and optimize various parameters affecting the adsorption performance of HPPs-COO^-/PUF,including the content（mass ratio）of HPPs-COO^-,initial MB concentration,and solution p H.With increasing mass ratio of HPPs-COO^-,the q_e of HPPs-COO^-/PUF varied significantly in the range of 46.17-115.60 mg/g.Besides,the sorption results were fitted well with Langmuir isotherm model with a q_max of 120.96 mg/g at p H=10 and 25°C.Moreover,the adsorption behavior followed the PSO kinetic model,indicating electrostatic attraction acts an important part during the course of sorption.Furthermore,HPPs-COO^-/PUFs exhibit a remarkable p H-responsive q_e,which decreased sharply with the reduction of solution p H.Accordingly,the regeneration of HPPs-COO^-/PUF was simply realized in acidic ethanol,and the regenerated HPPs-COO^-/PUFs show excellent reusability even after five consecutive cycles.