Amino acid is a common nitrogenous compound in water. Iodine disinfection by-products could be produced in the process of tryptophan chlorination disinfection in present of I^-. To investigate the generation and mechanism of iodoacetic acid from amino acid during the use of UV and chlorine for disinfection, this paper selected a typical iodoacetic acid, namely, tryptophan, and developed a generation kinetic model. In the investigation, first, the influences of different factors including UV irradiation time, chlorine dosage, pH value, Br^- content, and I^- content on the generation of iodoacetic acid were explored, and the generation pathway of iodoacetic acid was further analyzed. The results show that the generation process of iodoacetic acid fits the pseudo first-order reaction kinetic model, with a generation rate constant k of 0.17 h^-1. UV irradiation time, chlorine dosage, pH value, Br^- content, and I^- content all exert big influence on the generation process of iodoacetic acid. UV irradiation time promotes the generation of iodoacetic acid, and the yield of iodoacetic acid increases with the increase of UV irradiation time. When the pH value is in the range of 6 ~ 8, the yield of iodoacetic acid increases with the pH value. The generation of iodoacetic acid exhibits a firstly increase and then decrease trend with the increase in chlorine. When the ration of the concentrations of tryptophan and chlorine dosage is 1∶2, the production of IAA reaches the highest (15.30 μg/L). The paper also established an equation describing the relationship among Br^- content, I^- content and iodoacetic acid yield. It is found that Br^- has a negative correlation to the generation of iodoacetic acid, while I^- content has a greater positive one. In addition, four products including butanoic acid anhydride and isovaleric anhydride were detected using LC-MS-MS and GC-MS. It is speculated that the generation path of iodoacetic acid is that C₁₂H₁₇NO₃ is firstly produced from tryptophan through the action of UV photohydrolysis and hydroxyl radicals, and then isovaleric acid and butyrate acid are generated sequentially under the oxidation of HOCl and HOI, and finally iodoacetic acid is generated.

The existing static molding methods of ultra-high molecular weight polyethylene (UHMWPE) generally have the problems of long forming cycle, high energy consumption, easy thermal decomposition and so on, and the primary phase characteristic structure of their products has been completely eliminated, leading to failure in keeping good mechanical properties and excellent wear resistance at the same time. Therefore, UHMWPE products (PVM-UHMWPE) were prepared efficiently at low temperature by pulse vibration molding (PVM) technology in this paper, and the influence of pulse vibration frequency during molten hot pressing stage on structure and properties of UHMWPE products were studied. The results show that PVM can promote the interfacial fusion of particles at low molding temperature by friction between UHMWPE particles, and effectively preserve the structure characteristics of high regularity and crystallinity of nascent phase to increase the crystallinity and lamellae thickness. With the increase of pulse vibration frequency during molten hot pressing stage, the effect of pulse vibration increases, and this can improve the quality of particles interface consolidation. The yield strength, tensile modulus, break strength and work to failure of PVM-UHMWPE are all improved. However, when the frequency exceeds 3.0 Hz, the damage degree of such structure characteristics as high regularity and crystallinity of UHMWPE is aggravated by the effect of pulse vibration, and the overall crystallinity and melting temperature are reduced, resulting in the decrease of tensile modulus without further improving fracture toughness. As compared with sample CM-210 ℃-60 min with double molding cycle and 40 ℃ higher molding temperature, yield strength and tensile modulus of PVM-UHMWPE with a molding temperature of 170 ℃ and a pulsation frequency of 3.0 Hz (PVM-170 ℃-3.0 Hz) is improved by about 9% and 23%, respectively, and wear rate and wear index decrease by about 24% and 22%, respectively. That is, as compared with sample CM-210 ℃-60 min, sample PVM-170 ℃-3.0 Hz has higher mechanical strength and be-tter wear resistance.

The pollution problem of plasticizers in water has attracted more and more attention, and the research on their testing methods is also increasing, but the research on testing different types of plasticizers at the same time is relatively rare. And most of these studies use headspace solid phase microextraction, which is difficult to ensure good extraction efficiency and low detection limit. Therefore, this paper developed a SPME-GC-MS method to test 11 plasticizers included in two types in groundwater by using immersion solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). This method used 65 μm DVB/PDMS fiber, and the extraction was carried out at 80 ℃ for 50 min with a constant stirring speed of 1 000 r/min. The fiber was introduced into GC injector port, the extract was desorbed at 270 ℃ for 2.5 min and then detected by GC-MS. Qualitative analysis was performed by using retention time and characteristic ion, and quantitative by internal standard method. The results show that the linearity of 11 plasticizers is good in the range of 0.1 ~ 2.0 μg/L and the correlation coefficients are greater than 0.996; the detection limit is 0.03 ~ 0.06 μg/L; the recovery is 60.9% ~ 128.0%; and the relative standard deviation (RSD) is 6.68% ~ 19.00%. The proposed method is simple, reliable and sensitive, and it’s suitable for the determination of phthalate esters and adipate esters in groundwater. Moreover, aiming at the blank interference in plasticizer analysis, this paper conducted an in-depth study on this difficulty for the first time, carried out a detailed analysis from various aspects such as reagents, consumables and instrument maintenance, and proposed practical and operable solutions, which can effectively reduce the blank interference of plasticizers in the analysis process and further ensure the reliability of the analysis results.

With the development of China’s economy and the acceleration of the urbanization process, the amount of municipal sludge has increased sharply. Sludge treatment and disposal has become an urgent problem to be solved. By taking the sludge from a sewage treatment plant as the research object, this paper studied its thermal drying characteristics and pollutant discharge law. In the study, the thermal weight loss experiment was carried out at seven sets of temperatures at 100 ~ 250 ℃ equidistantly with homemade equipment, and the drying properties were characterized by the drying rate and the dehydration rate. It is found that the best temperature for drying is 200 ℃. Moreover, the gaseous pollutants were measured online with a flue gas analyzer. It is found that, besides NH₃ and H₂S, the gaseous pollutants also contain acid gases such as NO, SO₂ and HCl, as well as hydrocarbon components such as CO, CO₂, H₂, C₂H₆ and C₂H₄. The experiment also finds that the temperature being controlled below 200 ℃ is beneficial to inhibit the release of gaseous pollutants. Under the experimental conditions, the drying condensate is high-concentration organic wastewater, the pH values are concentrated in the range of 8.88 ~ 9.17 at 125 ~ 250 ℃, forming a buffer system; the COD increases as the temperature increases, and is up to 16 000.0 mg/L under the experimental conditions. Through the basic fuel characteristics test results of the dried sludge, it can be found that the carbon content and calorific value at 125 ~ 275 ℃ decrease with the increase of temperature, but at 300 ℃, due to the conditions of low-temperature carbonization, both the carbon content and calorific value increase. This provides ideas for the energy conversion of sludge. Combining SEM, BET and other methods to characterize the sludge, it finds that temperature increase can increase the microporous structure of the dried sludge, the structure of sludge becomes loose, so that the sludge can be used as a low-grade adsorbent or building material. The results in this paper provide a new idea for sludge resource utilization.