羟基镧改性树脂的制备及其对氟离子的吸附

采用共沉淀法制备了羟基镧改性D101树脂复合吸附剂,利用扫描电子显微镜及能谱分析仪、红外光谱和比表面积分析仪对复合吸附剂的结构和形貌进行了分析,并对水溶液中氟离子(F~-)进行吸附研究,探讨了该复合吸附剂对F~-的吸附特性,并将其应用于实际含氟废水的处理。结果表明:在25℃、F~-初始质量浓度为10 mg/L、吸附剂量为0.4 g/L、溶液pH=5时,F~-吸附量最大,为24.45 mg/g;复合吸附剂对F~-的吸附动力学数据遵循拟二级动力学反应模型,整个吸附反应为多级控制过程;复合吸附剂对F~-的吸附符合Langmuir吸附等温模型,在10℃、25℃和35℃下,吉布斯自由能(ΔGo)均小于0,焓变(ΔHo)大于0,熵变(ΔSo)大于0,表明该吸附反应为自发吸热熵增过程。采用羟基镧改性D101树脂复合吸附剂可以有效去除实际含氟废水中的氟化物,实现废水的达标排放。     

Dental Fluorosis in Wild Deer: Its Use as a Biomarker of Increased Fluoride Exposure

The relationships between age (range: 3 to 14 yr), mandibular bone fluoride level (marker of accumulated internal dose, range: 597 to 4680 mg F^- kg^-1> dry wt) and intensity of dental fluorosis (reflecting fluoride exposure during enamel formation) were studied in a sample of 53 fluorosed red deer from a fluoride-polluted area in the Czech-German border region (Ore mountains and their southern foreland). Assessment of the severity of dental fluorosis was performed for the 3 permanent premolars and 3 molars of one hemimandible per animal by using an ordinal measurement scale. For statistical analysis, the maximum tooth score of fluorosis (MTS) and the dental lesion index of fluorosis (DLI, sum of the six tooth scores per individual) were used. In the sample, both MTS (r_s = 0.850) and DLI (r_s = 0.813) were highly significantly (p <0.00001) correlated with bone fluoride content. A weaker correlation existed between age and bone fluoride content (r_s = 0.322, p <0.05). The results demonstrate that in case of regional, long-term fluoride pollution, dental fluorosis (measured as MTS or DLI) can be used as a sensitive biomarker of fluoride exposure in deer and thus as an indicator of the level of environmental contamination by fluorides. In many countries, skulls and mandibles of wild deer are regularly and continuously collected by hunters. Assessment of the prevalence and severity of dental fluorosis in this material offers the opportunity for an efficient large-scale biomonitoring of environmental pollution by fluorides at very low cost.     

制冷剂二氟甲烷热解生成氟化氢的实验研究

空调制冷剂二氟甲烷(R32)是R22的替代制冷剂之一,其分子中含有氟元素,受热可产生剧毒物质氟化氢(HF),一旦泄漏分解,将会对人员造成极大危害.首次通过实验研究了R32泄漏后的受热分解情况,利用激光气体分析仪,测量了不同工况下HF的实时浓度,分析了R32受热分解的影响因素.结果表明R32泄漏后,在受热状态下很容易产生HF,HF浓度随着泄漏量和受热状态的变化而异,浓度可达1000ppm以上；研究结果可为含氟制冷剂的应用提供技术支持.     

Groundwater NO3 and F Contamination Processes in Pushkar Valley, Rajasthan as Reflected from 18O Isotopic Signature and 3H Recharge Studies

Agricultural activity in the Pushkar Valley, Rajasthan is constrained due to limited availability of good quality water. In this context, occurrence of nitrate and fluoride in the groundwater was investigated and reported. Integration of stable isotope (18O) data with recharge characteristics (based on 3H-tracer studies) helps in clearly characterizing the processes controlling contamination by point and non-point sources. High nitrate and fluoride groundwaters are associated with high 18O waters. This indicates that significant quantities of evaporated (isotopically enriched) surface run-off water and rain water infiltrate along with nitrate and fluoride salts in the soil. The applicability of this approach under different hydrometeorological conditions is also confirmed.     

氟与硒对大型溞的联合毒性研究

研究氟离子与四价硒、氟离子与六价硒对大型溞的急性联合毒性,并采用相加指数法和毒性单位分析法评价其联合效应。结果表明,氟离子与两种价态硒的联合毒性都为拮抗作用;氟与四价硒的拮抗作用程度大于氟与六价硒的作用;氟离子与四价硒在不同浓度比例下混合作用,其拮抗作用程度不同,并呈一定规律性变化     

三元缔合物抑制分光光度法测定痕量氟

利用氟离子对锆－水杨基荧光酮－溴化十六烷基三甲基铵三元缔合物形成的竞争抑制作用,建立了测定痕量氟的抑制分光光度法,确定了测定的最佳条件为：「ＳＡＦ」＝６．０×１０＾－５ｍｏｌ．Ｌ＾－１「ＣＴＭＡＢ」＝８．０×１０＾－４ｍｏｌ．Ｌ＾－１,「Ｚｒ（ＩＶ）」＝１．０μｇ．ｍｌ＾－１,「ＨＣｌ」＝０．０８ｍｏＬ．Ｌ＾－１,２５℃。     

复合分子筛去除水中氟化物的研究

通过使用复合分子筛对模拟含氟水进行静态吸附实验,研究了复合分子筛对水中氟化物的吸附性能,并分析了吸附过程中温度、pH值和停留时间等因素对分子筛除氟效率的影响。结果表明,用80 g粒径0.9 mm的分子筛处理150 mL浓度为5 mg/L的模拟含氟水,分子筛的除氟效率达到90%以上,而同样条件下天然沸石和改性涂铁沸石的去除率分别为23.35%和80.69%。分子筛的除氟效率随着温度呈现先上升后下降的趋势,50℃时去除效率达到最高,为92.7%;在弱酸性条件下的去除率比碱性条件要高,在pH=4时去除率最大,为91.8%;停留时间初始阶段与去除率保持正相关,在45 min后反应达到平衡。分子筛的吸附速率符合二级动力学方程dqe/dt=k(qe-qt)2,吸附等温线符合Langmuir方程。     

离子选择电极法测定水中氟离子影响因素的探讨

离子选择电极法测定水中氟离子的监测方法,因其操作简单、干扰少、不必进行预处理等优点,广泛应用于环境监测领域。但国家标准检测方法对检测过程条件控制及影响因素等没有明确写明。本文结合实验和文献资料,对检测过程中出现的结果偏差进行了探讨。     

高温灰化—电极法测定乌伦古湖鱼中氟的方法初探

以乌伦古湖鱼体(鱼肉,不含鱼内脏)为研究对象,在碱性条件下,用硝酸镁固定样品中氟,高温灰化去除有机物,盐酸浸提,用离子缓冲溶液消除干扰离子,离子选择电极法测定乌伦古湖鱼中的氟。实际样品中加入1.00 mg/kg氟标准品,测定回收率分别为89.5%和88.0%,RSD为3.02%和4.29%。     

混合添加剂对PVDF平板疏水膜结构及性能的影响

以不同添加剂采用浸没沉淀相转换法制备基于无纺布支撑的聚偏氟乙烯(PVDF)平板疏水膜,考察了不同添加剂的加入对膜性能与结构的影响;并利用扫描电子显微镜(SEM)、原子力学显微镜(AFM)、红外光谱(FTIR)、接触角测量及膜蒸馏实验等对疏水膜的结构及性能进行表征。结果表明,引入混合型添加剂制备的膜具有较高通量和盐截留率,其疏水性最强,而添加剂对聚合物的晶型影响较小。以35 g/L的NaCl盐溶液为进料液对制备的平板膜进行直接接触式膜蒸馏实验,在热侧进水温度为50℃、冷侧温度为20℃的条件下,所制备的疏水膜通量最高可达12.45 kg/(m2.h),截留率为99.99%。