Study On Treatment Of Nitrophenol Toxic Substances Using PNIPAm/PHEMA Supported NZVI

Nitrophenol compounds are one of the most important raw materials for chemical production.They are widely used in many fields,such as pesticides,pharmaceuticals,dyes,rubber and organic chemicals.Nitrophenol compounds are teratogenic,carcinogenic and mutagenic.They are difficult to biodegradeand easy to accumulate in organisms.In the process of production,use,storage,transportation and abandonment,the environment is polluted due to leakage,safety accidents and improper treatment of industrial waste water.It poses a great threat to ecological security,water safety and human health.In this thesis,the new porous interpenetrating thermosensitive hydrogels,poly?N-isopropylacrylamide?/polymethacrylic acid?PNIPAm/PHEMA?loaded nano-zero-valent iron?NZVI?was designed and synthesized,and used forde gradation of nitrophenols.The main contents are as follows:?1?The thermosensitive hydrogel?PNIPAm/PHEMA?carriers were prepared by free radical polymerization with N-isopropyl acrylamide?NIPAm?as monomer,poly?methacrylic acid-beta hydroxyethyl ester??PHEMA?as the second monomer and polyethylene-glycol?PEG1500?as porogen.FTIR infrared spectroscopy showed that C=O and C-O in PHEMA appeared in 1600cm^-1and 1049cm^-1,indicating PHEMA was successfully introduced into PNIPAm.SEM showed that the gels have better porous penetrating structure,with hole diameter of 2um²0?m.The temperature sensitive material PNIPAm/PHEMA shows better swelling properties.When temperature was 17^oC and 35^oC,the equilibrium swelling ratio was20 and 1,respectively.The swelling kinetics of the gels showed that the composite gel had a faster swelling rate about 0.75 after 120 min and tended to swelling equilibrium after 150min.The pH value of the solution has effect on the swelling property of the gels,and the gels showed better swelling property in alkaline conditions.?2?PNIPAm/PHEMA was used as a carrier to adsorb Fe³⁺,which was then reduced by NaBH₄,and finally PNIPAm/PHEMA-nZVI was prepared.XRD showed that there was a very obvious peak of Fe⁰ at 44.67?.SEM showed that the loaded NZVI was uniformly dispersed in gel pores.The particle diameter is 70¹00 nm.Weighing method and EDS test results showed thatthe content of NZVI in PNIPAm/PHEMA-nZVI is 0.1545g/g.?3?P-nitrophenol?4-NP?was used as the treatment object to study the degradation effect of PNIPAm/PHEMA-n ZVI on 4-NP at different concentrations?150mg/L?250mg/L?400mg/L?500mg/L?,pH?pH=3?pH=5?pH=7?pH=9?and temperature?10??18??25??35??.Meanwhile,the reaction mechanism was analyzed.The results show that the degradation efficiency of 4-NP was the best with temperature of 18^oC,pH of 5 and shock rate of 100r/min.Under the optimal conditions,0.3548g PNIPAm/PHEMA-nZVI was used to treat 4-NP waste water?100m L,400mg/L?.After 30min,the degradation rate reached 96.08%,4-NP of 94.95%was converted to p-aminophenol?4-AP?,and 4-AP had lower toxicity and better biodegradability.The reaction was first order reaction,K_obs was 0.0885.Mass balance analysis showed that the average adsorption rates were 13.29%and 6.24%of gel carriers on 4-NP and4-AP.The PNIPAm/PHEMA can be reused after cleaning and regeneration.After 5 times of reuse,4-NP degradation rate can still reach more than 80%.Because of the temperature sensitivity of the carrier,PNIPAm/PHEMA-n ZVI composites have good storage stability.After105 days of storage,the storage stability of the gel is still over 75%.?4?The degradation ability of PNIPAm/PHEMA-nZVI for other nitrophenolmaterials such as 2-NP,3-NP,2C4NP and 2C5NP was investigated.The order of degradation effect of PNIPAm/PHEMA-n ZVI on 2-NP,3-NP and 4-NP was 4-NP>2-NP>3-NP.PNIPAm/PHEMA-nZVI also showed excellent degradation ability for 2C4NP and 2C5NP.After 30min,the degradation rate was 96.16%and 97.12%respectively,and the final product was aminophenol.