Study On The Trace And Control Of Low Molecular Weight Chlorinated Organic Compounds In PAE

Polyamide epichlorohydrin resin?PAE?,as a paper wet-strength agent,has been widely used in papermaking industry due to it can impart paper good wet-strength,improve fiber filtration and be used at low dosage without releasing formaldehyde.However,during the synthesis and storage of PAE,low molecular weight chlorinated organic compounds?LMWC?are formed which can enter the paper and white water as the PAE using in the papermaking process.LMWC are highly toxic and pose a threat to people's health and environmental safety.Therefore,establishing the methods to detect the LMWC content in PAE,paper and white water,studying the trace of LMWC in applications of PAE and finding a way to effectively remove LMWC in PAE provide guidance for the safe use of PAE.The research work of the thesis first established a solid phase microextraction-gas chromatography?SPME-GC?method for the determination of LMWC in PAE.The optimal conditions were headspace extraction and the headspace to sample volume ratio was 9:1,the NaCl addition amount was 0.42 g·mL^-1,the extracted fiber with 85?m thick polyacrylate?PA?coated extraction head extracted analytes at 45°C for 30 min,the desorption temperature was 240°C,and the desorption time was 6 min.The analytes limit of detection?LOD?obtained under these conditions was relative lower,linear?r²?0.9934?and precision?RSD?4.38%?were good,and the recoveries were between 91.59%and 109.69%.A solid phase microextraction-gas chromatography/mass spectrometry?SPME-GC/MS?method for detecting the content of LMWC in paper and white water was established based on the method of detecting the LMWC content in PAE.The LOD of 0.03?g·kg^-1,r² of 0.9972,RSD of 3.67%and recovery rate of 96.31%¹04.74%for 1,3-DCP in paper were obtained.The LOD of 0.05?g·kg^-1,the r² of 0.9978,the RSD of 4.27%,and the recovery rate of 97.21%¹03.17%for 1,3-DCP in white water were obtained.The effect of storage time of PAE on the change of LMWC content,the distribution of LMWC in paper and white water during PAE application and the influence of paper drying temperature and storage time on LMWC content in paper were investigated.The results showed that the total content of LMWC in PAE is above 5000 mg·L^-1 and increases with the prolongation of storage time.As the amount of PAE increased during the papermaking process,the amount of LMWC entering the paper increased first and then decreased,and a maximum amount of 30?g was reached at 20 kg·t paper^-1.However,LMWC mainly entered into the white water during the papermaking process and the proportion increased with the addition of PAE.When the PAE addition amount was 30 kg·t paper^-1,there was more than 80%of LMWC in white water;the LMWC content in the paper decreased with the increase of drying temperature,and decreased with the increase of storage time,eventually reduced by30%.The specific surface area and pore diameter of activated carbon pores were investigated by BET specific surface and porosity analyzer,the diameter of LMWC were calculation by Gaussian09,the particle size of PAE polymer,the adsorption kinetics,adsorption isotherms and adsorption thermodynamics of activated carbon on LMWC were studied by adsorption kinetics model and isothermal adsorption model.The results show that the diameter of LMWC is about 0.5 nm,which is within the range of adsorption of activated carbon micropores,while the particle size of PAE macromolecules is more distributed at 1?m and 10?m,making it difficult to enter the pores of activated carbon.;the adsorption of activated carbon on LMWC was a spontaneous and exothermic physical adsorption process.The effect of temperature and additive amount during activated carbon adsorption process on the removal of LMWC and the reproducibility of activated carbon were investigated.The results showed that the removal rate of LMWC was 99.6%when the addition amount of activated carbon was 200 g·L^-1.The adsorption reaction of LMWC by activated carbon in PAE was suitably carried out at a lower temperature.The degradable material mixed in the activated carbon was substantially decomposed at 450°C.Nevertheless,when the activated carbon was recovered at 650°C,the regeneration efficiency was low,mainly because the activated carbon was covered and blocked by the sheet-like substance and the specific surface area and pore volume are reduced.