基于羧酸型扩链剂超支化水性聚氨酯的合成和表征

以二乙醇胺(DEA)和丁二酸酐为原料,甲醇为溶剂,合成一种新型羧酸型亲水单体N,N-二羟乙基-2-氨基丙酸(DMCA),优化得到DMCA的最佳条件为:冰水浴0℃,n(DEA)∶n(丁二酸酐)为1∶1.2,时间为80 min,甲醇用量为300 m L/mol(DEA),在最佳条件下DMCA的转化率为86.18%。采用红外(FTIR)、核磁(1H NMR)、X射线衍射(XRD)、热重(TG)、元素分析等手段对DMCA进行结构和性能的表征。以DMCA作为亲水扩链剂制备超支化水性聚氨酯DMCA-HWPU,其性能检测结果表明,DMCA-HWPU为非结晶性体系,其乳液呈乳白色泛蓝光,无沉淀,乳液稳定性高,并且具有很好的热稳定性。     

Combined permeable pavement and photocatalytic titanium dioxide oxidation system for urban run‐off treatment and disinfection

Permeable pavement systems (PPS) are frequently associated with high removal efficiencies for water quality parameters. Their effluent can, therefore, be recycled, for example, for sprinkling onto gardens. Nevertheless, some stakeholders fear that potentially pathogenic organisms within the treated run‐off could be too high, and therefore they request disinfection before recycling. The aim of this paper is, therefore, to assess the efficiency of a batch flow combined titanium dioxide (TiO₂) and ultraviolet (UV) light photocatalytic reactor in removing water‐borne microbial contaminants from the effluent of PPS. Combined TiO₂ and UV photocatalytic reaction times between 80 and 100 min were required for the complete removal of Escherichia coli, total coliforms and faecal Streptococci, which had mean initial counts of 1.5 × 10⁷, 4.4 × 10⁶ and 6.9 × 10⁵ colony‐forming units (CFU) per 100 mL, respectively. In comparison, UV disinfection alone resulted in insignificant microbial removal. Suspended TiO₂ powder was more effective than small immobilised TiO₂ crystals.     

Reducing wood drying time by application of ultrasound pretreatment

Industrial wood is typically dried artificially after felling. The drying process is often very lengthy and consumes a large amount of energy, however, and inappropriate drying schedule can cause defects in the wood. Pretreatments such as ultrasound show the potential to reduce wood drying time without impacting quality. This study investigated the influence of ultrasound pretreatment on vacuum drying behavior, hydroxyl content, and microstructural properties of fast-growing wood samples. Pretreatments were performed at ultrasound intensity of 10 W cm^?2 and frequencies of 28 and 40 kHz, respectively, for 30, 60, and 90 min, respectively, then pretreated samples were dried at 40°C temperature under absolute pressure of 0.08 MPa. Results showed that ultrasound pretreatment did shorten the wood vacuum drying time, increase effective water diffusivity, open water channels, decompose wood extractives, and decrease hydroxyl content. In effect, ultrasound pretreatment can be applied to successful reduce wood drying time.     

电化学处理废水过程中羟基自由基的测定

采用三维电极-电Fenton耦合法降解模拟苯酚废水,验证模拟苯酚废水降解过程中羟基自由基的存在,考察不同电压、起始p H值、铁粉加入量、曝气等因素对羟基自由基生成量的影响,实验结果表明:当溶液的p H为6.86(原溶液),加入3.0 g/300 m L Fe粉,5 V电压下1.5 L·min-1的曝气下电解30 min后,苯酚降解过程中羟基自由基的生成量最大。     

玉米秸秆木质素的去甲基化/羟乙基化复合改性研究

利用亚硫酸钠和乙二醛对玉米秸秆木质素进行去甲基化/羟乙基化复合改性,以提高木质素的羟基含量和反应活性。通过FT-IR、TG、DSC以及乙酰化滴定等技术研究了木质素复合改性效果。结果表明:经过去甲基化/羟乙基化复合改性后的玉米秸秆木质素具有优异的活性,其总羟基质量分数较原料木质素提升了88.33%,酚羟基提升了14.70%,反应活性得到明显增强。FT-IR表征发现:复合改性从多方面提升了木质素的羟基含量,对羟基含量的增加有着较为显著的效果。热重和DSC表征发现:复合改性木质素(G-DL)相较于原料木质素降解得更加彻底,其放热峰出现在77℃,放热量达459.82 J/g,反应活性较去甲基化木质素(DL)和原料木质素更高。     

Acid Hydrogen Peroxide Treatment of Norway Spruce TMP: The Effect of an Extended pH Range when Catalyzed by Free Ferrous and Free or EDG/EDTA-Chelated Ferric Ions

The influence of different types of iron salts (i.e., ferrous or ferric cations with sulphate, nitrate or chloride anions) on the reaction between coarse thermomechanical pulp and acid hydrogen peroxide (Fenton chemistry) was studied when the initial pH was 3.2 and 5.3. Also, ferric ions chelated with EDTA or EDG at different molar ratios were compared with ferrous sulphate when the initial pH was extended from about 3 to 8. Different anions of ferric ion salt gave a similar catalytic effect. At an initial pH of 7–8, the ferric-EDTA catalyzed reaction resulted in similar or higher hydrogen peroxide consumption and more detectable hydroxyl radicals than the ferrous sulphate catalyzed reaction, but less reaction with the pulp was indicated. Between pH 5–8, using Fe-EDG as a catalyst gave higher hydrogen peroxide consumption and more detectable hydroxyl radicals than if using ferrous sulphate; however, the measured effect on the pulp was similar or less.     

高固体分、高羟值聚酯树脂的合成及性能研究

通过设计羟基聚酯树脂分子结构,选择六氢苯酐、1,6-己二醇、1,4-环己烷二甲醇、三羟甲基丙烷、三羟乙基异氰脲酸酯等原料,制备了高固体分、高羟值聚酯树脂,研究了不同原材料及合成工艺对树脂性能的影响。结果表明:采用脂环族二元酸制备的聚酯树脂综合性能优于芳香族及脂肪族二元酸制备的聚酯树脂;三羟乙基异氰脲酸酯分子中的环状结构对相邻的酯键起到了"屏蔽"作用,提高了树脂的耐水性;叔碳酸缩水甘油酯用量为固体树脂总量的15%时聚酯树脂的综合性能较好。     

超声作用对短切碳纤维在水溶液中分散性的影响

利用超声波振动对短切碳纤维进行分散。研究了超声振动功率、时间及分散剂质量分数对短切碳纤维在水溶液中分散性的影响。结果表明,超声振动和羟丙基甲基纤维素(HPMC)分散剂的添加能显著改善短切碳纤维的分散性;在一定范围内,短切碳纤维分散率随着超声波振动功率和作用时间先增加后趋于饱和;HPMC在水溶液中的质量分数为0.13%时分散性较好,超声振动功率为800 W,振动7 min时短切碳纤维在水溶液中可达到较好的分散效果。