废旧电视机外壳热解过程阻燃剂的传质现象

采用红外光谱和气质联用分析了电视机外壳塑料成分,通过热解及热重分析实验研究了电视机外壳塑料中多溴二苯醚(PBDEs)阻燃剂脱除过程的质量传递,根据传质理论建立了一个理想的PBDEs脱除传质模型,并用本模型对实验数据进行分析。结果表明,电视机外壳塑料主要成分是渗杂了PBDEs阻燃剂的高抗冲聚苯乙烯(HIPS),PBDEs脱除传质模型反映了电子塑料阻燃剂脱除基本特征,阻燃剂脱除过程传质系数κ为11.5 g/(s.m2),电视机外壳塑料中阻燃剂质量分数为12.53%。     

废旧电视机外壳塑料中十溴联苯醚的溶剂法分离

以d-柠檬烯为溶剂、正丙醇为沉淀剂建立了溶剂法再生废旧电视机外壳塑料(主要成分为高抗冲聚苯乙烯,HIPS)的新工艺,考察了外壳塑料溶液中十溴联苯醚在固-液两相的分布特征及影响因素,探讨了反溶剂沉淀过程中十溴联苯醚的转移机制,提出了减少十溴联苯醚进入再生HIPS产品的措施,通过实验确立了从废旧电视机外壳塑料中分离十溴联苯醚的工艺条件. 当电视机外壳塑料浓度为20%,使用管式离心分离机,在温度30℃、转速12000 r/min下能去除溶液中87.7%的十溴联苯醚;每100 mL离心液补加40 mL柠檬烯溶解十溴联苯醚颗粒后,再用等体积正丙醇在50℃下沉淀HIPS,所得再生塑料的多溴联苯醚总含量低于0.1%,十溴联苯醚的脱除率超过99%.     

塑料制品中溴代阻燃剂多溴联苯醚的检测

多溴联苯醚(PBDEs)是一类性能优异的阻燃剂。研究表明,PBDEs是持久性有机污染物(POPs)。本文建立了气相色谱-质谱联用法测定塑料制品中多溴联苯醚的方法。以二氯甲烷为提取溶剂,超声提取塑料中多溴联苯醚(PBDEs),提取2次,合并提取液后用氮吹浓缩,再进样气相色谱-质谱法(GC-MS)检测。SCAN和SIM同时扫描,采用特征离子定量分析。结果表明:10种多溴联苯醚(PBDEs)的线性关系(r~2=0.9985~0.9997)、检出限(8.2×10~(-3)~8.9×10~(-3))回收率和精密度符合要求,RSD为2.25%~5.31%,回收率在82.97%~109.9%之间。本方法前处理简便,灵敏度高,定性、定量分析准确可靠,且分析时间短,适用于塑料制品中PBDEs的测定。     

加拿大全面禁用溴化阻燃剂

加拿大政府最近公布了多溴联苯醚（PBDE）法规,以减少溴化阻燃剂（PBDEs）进入环境,涉及3种化合物。即五溴联苯醚（pentaBDE）、八溴联苯醚（octaBDE）及十溴联苯醚（decaBDE）。溴化阻燃剂因有延缓火焰燃烧的特性,常用作阻燃剂及绝热材料,广泛应用在塑料、纺织品、电子设备、密封胶等产品中。     

多溴联苯醚的污染状况及其生态毒理研究进展

多溴联苯醚(PBDEs)作为一种常用溴代阻燃剂被大量地应用于建筑材料、纺织产品、化工原料、电子电器设备等领域。PBDEs为添加型阻燃剂,容易脱落进入到环境中造成环境污染。PBDEs毒性效应主要包括神经毒性、内分泌毒性、生殖毒性、细胞毒性等。对多溴联苯醚的理化性质、环境污染水平及生态毒理效应等进行了总结,并对今后的研究工作进行展望。     

废旧电视机塑料外壳中的阻燃剂脱除

采用热重分析仪和管式炉反应器对废旧电视机塑料外壳进行低真空和氮气奈件下的热分解实验,高效液相色谱法、气相色谱-质谱法检测废旧电视机外壳中阻燃剂脱除的情况.讨论真空和氮气条件下电视机塑料外壳热解的差异.实验结果表明:真空降低了电视机外壳的表观活化能,提高了热解产物的挥发性,减少了二次裂解反应,因而真空有利于提高低温条件下分离舍卤阻燃剂的效率.通过实验得出高溴代阻燃剂最佳脱除温度在280℃.     

加拿大禁用溴化阻燃剂

加拿大政府最近公布了多溴联苯醚(PBDE)法规,以减少溴化阻燃剂(PBDEs)进入环境,涉及化合物有三种,即PentaBDE、OctaBDE及DecaBDE。溴化阻燃剂因有延缓火焰燃烧的特性,常用作阻燃剂及绝热材料,广泛应用在塑料、纺织品、电子设备、黏胶、密封胶等产品中。但因溴化阻燃剂的毒害性和一定的致畸致癌性,自瑞典最早禁用某些溴化阻燃剂后,     

气相色谱-质谱联用法测定塑料产品中的溴系阻燃剂

溴系阻燃剂是目前全世界范围内使用的主要阻燃剂,常用的有十溴联苯醚、四溴双酚A、四溴双酚A-双(2,3-二溴)丙醚、六溴环十二烷、三溴苯酚、十溴联苯乙烷等。溴系阻燃剂的分解温度大多在200~300℃左右,与各种高聚物的分解温度匹配,因此能在最佳时刻以气相及凝聚相同时起到阻燃作用,阻燃效果好,且添加量小。但是越来越多的研究表明这类阻燃剂对环境造成了严重的污染,从而给人的健康带来巨大的危害。欧共体在2002年公布了《关于在电子电气设备中禁止使用某些有害物质指令》(RoHS:Restriction of Hazardous Substances 2002/95/EC),限制所有在欧盟市场出售的电子电气设备限量使用多溴联苯醚(PBDEs)和多溴联苯(PBBs)等溴系阻燃剂。采用气相色谱-质谱联用技术测定塑料产品中的溴系阻燃剂,方法满足欧盟指令的要求。     

超临界二氧化碳萃取分离塑料溶液中多溴联苯醚的研究

建立了利用超临界CO2从阻燃高抗冲聚苯乙烯塑料溶液中萃取分离多溴联苯醚的新工艺,研究了超临界CO2的温度、压力、体积及十溴联苯醚浓度等因素对超临界萃取分离过程的影响规律,提出了从阻燃塑料中分离十溴联苯醚的措施.实验结果表明,采用离心分离除去塑料溶液中大部分十溴联苯醚颗粒后,再在65℃、20 MPa超临界条件下,使用2倍于塑料溶液体积的超临界CO2进行萃取,所得的再生塑料的多溴联苯醚总含量低于0.1％(干基),多溴联苯醚的脱除率超过97％.     

加拿大全面禁用溴化阻燃剂

加拿大政府最近公布了多溴联苯醚（PBDE）法规,以减少溴化阻燃剂（PBDEs）进入环境,涉及的化合物有3种,即PentaBDE、OctaBDE及DecaBDE。溴化阻燃剂因有延缓火焰燃烧的特性,常用作阻燃剂及绝热材料,广泛应用在塑料、纺织品、电子设备、胶黏剂、密封胶等产品中。     

Extraction separation of toluene/cyclohexane with hollow fiber supported ionic liquid membrane

A supported liquid membrane with ionic liquid was used for the separation of toluene/cyclohexane. The interactions of ionic liquid with toluene and cyclohexane were calculated and experimentally studied by quantum chemical calculation and liquid-liquid extraction process. The results showed [BPy][BF₄] have stronger interaction with toluene than that with cyclohexane. The selectivity of SILM processes was larger than 10 at the temperature of 323 K and the flow rate of 13.5 mL·min^?1 on both shell side and lumen side. Due to the higher viscosity of IL, SILM process had good long-term stability. As the effects of mass transfer driving force of SILM process, the flux and removal efficiency increased with increase of initial toluene concentration, while the selectivity decreased because of the competitive transport. Base on the resistance in-series model and experimental results, the mass transfer resistance was mainly lay liquid membrane phase. The influence of flow rates on both sides was slight. The higher temperature could enhance the mass transfer performance significantly. The removal efficiency increased from 28.2% to 45.1% with the increasing of operation temperature from 298 K to 323 K.     

Enhancement of Ozone Mass Transfer by Stainless Steel Wire Mesh and Its Effect on Hydroxyl Radical Generation

ABSTRACT

In order to improve the mass transfer efficiency of ozone in water, stainless steel wire mesh (SSWM) corrugated structure was packed into a microbubble ozone reactor to enhance the mass transfer efficiency. The results showed that the SSWM/O₃ system could effectively improve the mass transfer efficiency. When the concentration of ozone in the liquid phase reached a stable state, it was about 21 mg/L, which was about 14% higher than that of ozone alone; the apparent mass transfer coefficient (K_La) was 0.7255 min^?1, which was about 51% higher than that by ozone alone systems. The hydroxyl radicals in the SSWM/O₃ system were more generated than that of ozone alone. After 6 min of operation, the concentration of hydroxyl radicals increased by 60 µmol/L compared with that in ozone alone system. The Chemical Oxygen Demand (COD) removal efficiency of biologically treated leachate by SSWM/O₃ system was about 10% higher than that of ozone alone system after 120 min of reaction. The effects of pressure, temperature, ozone inlet concentration, and flow rates on the ozone concentration in the liquid phase and the generation of hydroxyl radicals were also investigated. The results indicated that reactor pressure has little effect on ozone concentration in liquid phase, but increasing pressure helps to generate ·OH; ozone concentration and ·OH generation in liquid phase increase with the increase of inlet ozone concentration and flow rate; ozone concentration in the liquid phase decreases with the increase of temperature, but ·OH generation increases with the increase of temperature. Our results indicate that the system consisting of SSWM and microbubble column reactor is an efficient process for the intensification of ozone-based advanced oxidation processes.     

Toughness enhancement of high‐impact polystyrene based on γ‐radiation vulcanized natural rubber latex by using block copolymer

Polyisoprene‐block‐polystyrene‐block‐polyisoprene (ISI) was synthesized by the iniferter route and its use, as compared to a commercial polystyrene‐block‐polyisoprene‐block‐polystyrene (SIS), in the enhancement of the toughness of high‐impact polystyrene (HIPS), prepared by the γ‐radiation vulcanized natural rubber (RVNR) latex/phase transfer/bulk polymerization technique, was investigated. Addition of 5% SIS was adequate as an interfacial agent, which effectively increased the unnotched Izod impact energy of HIPS, whereas use of 10% of ISI was required. A long polyisoprene block with two polystyrene segments of SIS was favorable for compatibilization of HIPS. Transmission electron micrographs revealed the uniform distribution of the block copolymer at the shell region of the rubber particle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1307–1316, 2002     

ABS/HIPS共混材料的改性研究

研究了(丙烯腈/丁二烯/苯乙烯)共聚物(ABS)与高抗冲聚苯乙烯(HIPS)质量比对ABS/HIPS共混材料力学性能和加工流动性的影响,并着重对质量比分别为80/20和70/30的两种ABS/HIPS共混材料进行了改性研究。结果表明,氯化聚乙烯(PE-C)、(苯乙烯/丁二烯/苯乙烯)嵌段共聚物(SBS)和K树脂对ABS/HIPS共混材料有不同程度的增容增韧改性作用。如采用9份PE-C与3份SBS并用改性的ABS/HIPS(70/30)共混材料的拉伸强度为27.04MPa,冲击强度为32.60kJ/m2,比改性前约提高2.7倍。转矩流变仪分析表明,PE-C、SBS和K树脂改性的ABS/HIPS共混材料加工流动性和稳定性良好。维卡软化温度测试表明,改性后ABS/HIPS共混材料的耐热性能略有降低,但影响不大。扫描电子显微镜照片清晰反映出改性后ABS与HIPS两相的相容性得到了改善。     

Gas cyclone-liquid jet absorption separator used for treatment of tail gas containing HCl in titanium dioxide industry

In the titanium dioxide industry, there is a lack of a low-cost and high-efficiency treatment method for chloride containing tail gas. In this paper, the removal of HCl from the titanium dioxide industry by gas cyclone-liquid jet separator was studied, while Ca(OH)₂, Na₂CO₃, NaOH solution, and water were used as absorbents. This paper investigated the influence of gas cyclone-liquid jet separator’s various process parameters on the removal rate of hydrogen chloride gas. The mechanism of mass transfer in the process of removing hydrogen chloride was discussed, and the effect and feasibility of HCl gas removal in the gas cyclone-liquid jet absorption separator were studied. The results showd that the removal efficiency of hydrogen chloride maintained above 95%, up to 99.9%, and the total mass transfer coefficient reached 0.28 mol·m^-3·s^-1·kPa^-1. Under the same conditions, the absorption effect and total mass transfer coefficient of weak basic absorption liquid can be greatly improved by increasing the flow rate of absorption liquid, but the absorption effect and total mass transfer coefficient of strong alkaline absorption liquid can’t be improved obviously. The larger the inlet gas volume, the higher the gas concentration, the lower the absorption efficiency and the lower the total volumetric mass transfer coefficient.     

不同无卤阻燃剂对PPO/HIPS合金性能影响研究

制备了不同质量比的聚苯醚/高抗冲聚苯乙烯(PPO/HIPS)合金材料,PPO/HIPS质量比为60∶40时合金的综合性能最佳。研究了不同无卤阻燃剂三苯基氧化膦(PX220)、PX220/三聚氰胺聚磷酸盐(MPP)及红磷阻燃剂(RPM650)对PPO/HIPS合金材料阻燃性能、力学性能及热性能的影响。结果表明:在添加相同质量阻燃剂的情况下,PX220/MPP复配阻燃剂可使PPO/HIPS合金材料具有较高的负荷变形温度和熔体质量流动速率,以及优异的阻燃性能和力学性能;无卤阻燃剂的加入使PPO/HIPS合金的初始分解温度降低,最大热失重速率峰值向低温区移动。     

磷酸活化法制备花生壳活性炭工艺

采用正交试验方法探讨了以花生壳为原料,通过磷酸活化法制备的高效活性炭吸附剂。以活性炭的收率和Pb2+吸附容量为考察指标,选择了磷酸质量浓度、浸渍质量比和活化温度3个因素,3个水平的正交试验方法。结果表明,对活性炭收率影响最大的因素是活化温度,对活性炭吸附Pb2+容量影响最大的是磷酸活化剂的质量浓度。综合考察各影响因素,得出在磷酸活化剂质量浓度为1 220 kg/m3,浸渍质量比为150%和活化温度为400℃时可以在保持活性炭收率较高的情况下制备高Pb2+吸附容量的花生壳活性炭吸附剂,该活性炭的比表面为1 018.5 m2/g,总孔容积为0.754 m3/g,平均孔径为2.961 nm,对低质量浓度含铅废水中铅离子的去除率接近100%,是合适的液相吸附用活性炭材料。     

高冲击强度聚苯乙烯加氢反应的研究

在氢气压力为4MPa的条件下,以环己烷为溶剂,采用环烷酸镍和三异丁基铝制备的齐格勒-纳塔型催化剂,对高冲击强度聚苯乙烯(HIPS)进行均相选择性氢化反应。研究了溶剂用量、催化剂用量、反应温度及反应时间等对HIPS加氢度的影响。结果表明:在温度60℃,Al/Ni=5且Ni用量为0.3g/100gHIPS,反应进行3h时,HIPS的加氢度为100%;加氢后HIPS的拉伸性能和弯曲性能得到大幅度提高,但冲击性能明显下降,热稳定性能基本不变。