高氟地下水混凝沉淀降氟试验研究

本文开展了山西运城地区高氟地下水的降氟试验，对聚铁、硫酸铝和明矾等不同混凝剂降氟效果进行对比，探讨了地下水硬度对混凝沉淀除氟效果的影响。实验结果表明：明矾混凝沉降效果优于其它混凝剂，0．3g／L的明矾溶液可使含氟浓度4．0mg／L的地下水降低到浓度1．0mg／L以下；地下水的硬度对明矾混凝降氟效果没有明显影响。     

人类饮水氟中毒与饮水中氟存在形式的关系

作者在黑龙江省某地区采集大量地下水样品,针对与氟（Ｆ＾－）可形成络合物的中心离子进行化验,采用化学热力学的基本理论建立物理化学模型,定量地给出了氟病与饮用水中氟的存在形式的关系,初步探讨了引起氟病异常的原因。     

高氟土壤的氟动力学吸附试验研究

通过室内水土试验,研究山东高密高氟地区的土壤对氟的动力学吸附特性,并用典型的低氟土试验进行对比。从化学动力学的角度讨论高氟土壤对氟的吸附行为。高氟土壤对氟的吸附有其特殊性;高氟土壤对氟的吸附分为快、慢两个阶段;羟基是影响氟吸附的重要因素。     

晋中平川高氟地下水与地方性氟斑牙病之关系浅析

通过对晋中地区平川区祁县、平遥、介休三县汾河沿线浅层高氟地下水中Ｆ、Ｃａ、Ｍｇ组分存在形式与地方性氟斑牙病患病率之相关分析表明，Ｆ、Ｃａ、Ｍｇ元素对地方性氟斑牙病之影响，不仅取决于Ｆ、Ｃａ、Ｍｇ的总浓度，而且与各种元素在地下水中的组分存在密切相关，元素的组分存在形式不同，对地方性氟斑牙病的影响出不同。根据患病率与Ｆ总，Ｆ＾－，ＭｇＦ＾＋、ＣａＦ＾＋成正相关，以及浅层高氟地下水中ＭｇＦ＾＋和ＣａＦ＾     

应用氟离子选择电极测定岩石和矿物中的氟

许多元素,尤其是稀有元素的演化,迁移和富集,与氟有着密切的关系。为搞清楚这些元素的成矿规律,从而进一步指导寻找有用的矿产资源,就必须对氟的行为有所了解。这样对氟的分析质量和数量都有更高的要求。氟离子选择电极测定氟的方法与蒸馏法比较,前者具有设备和操作简单、快速、灵敏度高、准确度较好的特点。因此,近几年来发展     

Uptake of fluoride by serpentine

Fluoride uptake by serpentine depends on a number of parameters, viz. the chemical composition of serpentine, its particle size, pH of the medium, etc. Exchangeable (OH)^? in serpentine minerals is essential for fluoride uptake. Data are also presented indicating the existence of an equilibrium between the fluoride concentrations in the solution and that taken up by serpentine over a wide range of experimental conditions. The available evidence strongly suggests the proxy of F^? for (OH)^? group as contributing to the principal mechanism of the process.     

Uptake of fluoride by aragonite

The uptake of F by aragonite is attributed to the ion-exchange process, in which one CO₃^2? ion in the structure is replaced by two F^? ions. Under the equilibrium condition at 15° C and 1 atm., the partition of F between aragonite and aqueous solution is described by:

$\text{log}\text{(}\text{[}\text{F}\text{]}\text{a}{}_{\mathrm{<mtext>F</mtext>}}\text{)=1.95 + 0.54}\text{log}\text{a}{}_{\mathrm{<mtext>Ca</mtext>}}$

were [F] denotes the F content of aragonite in mol/g, and a_F and a_Ca are the aqueous activities of F^? and Ca²⁺, respectively. The equation was successfully applied to estimating the F content of marine aragonite.     

萤石中氟化钙的测定

应用电感耦合等离子体发射光谱法(ICP-OES)测定萤石中钙的含量,经标准物质验证,方法准确度和精密度较高,萤石矿物标准物质中氟化钙的测定值与认定值相符,相对标准偏差小于1%。与传统EDTA滴定的分析方法相比,本法操作简单、快速,适合萤石矿中氟化钙含量的测定。     

Tveitite,a new calcium yttrium fluoride

Tveitite is a new mineral with formula of the type $\text{Ca}{}_{\mathrm{1?x}}\text{(}\text{Y, RE}\text{)}{}_{\mathrm{x}}\text{F}{}_{\mathrm{2+x}}\text{where}\text{x}$ is approximately 0.3. It is found in a cleavelandite pegmatite at Høydalen in Tørdal, Telemark, S. Norway. The sub-cell is thought to be monoclinic, $\text{a}\text{′=3.924,}\text{b}\text{′=3.893,}\text{c}\text{′=5.525, ß=90°26′,}\text{Z}\text{=2}$. The structure is very similar to that of fluorite and can be described in terms of a pseudo-cubic cell $\text{[1}\text{1}\text{0]}{}_0\text{= 5.527, [110]}{}_0\text{= 5.527,}\text{c}\text{= 5.525, α = 90°18′, γ = 89°37′}$ which contains approximately 1[YCa₃F₉]. The mineral shows twinning in at lest three different directions giving a grating structure probably due to high-low inversion. DTA studies show an inversion point at about 670°C. Material heated above this temperature gives X-ray diffraction patterns corresponding to yttrofluorite (a₀ 5.528). The effect of trivalent ions on the stability of fluorite is discussed.     

Problems of high fluoride waters in Turkey

The geochemistry theory can provide information about the distribution, contents and migration in nature of the chemical elements in minerals, rocks, soils, waters, atmospheres, etc. Therefore, it has been applied extensively. Nowadays the petroleum supply throughout the world is in tension. The coal resources are unfriendly to the environment, because coals contain many harmful chemical elements. How to exploit the efficient clean liquid energy from coals is a hot subject of study. This paper deals with the present domestic and international applications of geochemistry in coal liquefaction research, on the basis of coal geology, points out the shortages and problems that need to be dissolved, clarifies the necessity of coal liquefaction technique research under the coal geochemistry background. To enhance the oil production and reduce environmental effects, the direct coal liquefaction technique research should take it into consideration the three-aspects coupling pattern, which includes the influence of coal direct liquefaction activity combined with different geochemical parameters, the different migration behaviors of harmful elements in the coal liquefaction process, and the geological control factors of coal-forming environments. It is indicated that the coal geochemistry is extensively applied in coal direct liquefaction technique research.     

含氟废水的粉煤灰处理实验研究

进行了影响粉煤灰处理含氟废水的各种条件实验，（pH、水灰比、氟浓度、振荡平衡时间），结果表明最佳处理条件是pH值为2．5、水灰比为小于20、氟浓度小于500mg/l、振荡平衡时间大于2．5h，并研究了粉煤灰处理含氟废水的机理，给出了其吸附等温式。     

Adsorption of fluoride on goethite surfaces-implications on dental epidemiology

Fluoride ion interaction with synthetically prepared goethite has been investigated over a range of pH values (4–9) and F^– concentrations (10^–3–10^–5 M). The amount of F^– retained by goethite suspensions was found to be a function of pH, media ionic strength, F^– concentration, and goethite concentration. The lowest ionic strength (0.001 M KNO₃) gave the highest adsorption medium. Uptake was minimal at pH >7 and increased with decreasing pH. Thermodynamic properties for fluoride adsorption at 298 K and 323 K were investigated. The isosteric heat of adsorption (H _r) was calculated and the heterogeneity and homogeneity of the surface examined for goethite. In view of the importance of fluoride in dental health, the interaction of fluoride on goethite in the physical environment has important implications on dental epidemiology.     

Analysis of fluoride in rocks and an application to exploration

The fluoride^* content of rocks can be measured using a selective ion electrode. Analyses were made using a sodium hydroxide fusion and ammonium citrate buffer and measurements can be compared to standard or can be made by standard addition using the Gran's Plot method. The Gran's Plot method yields fluoride values in agreement with known values for standard rocks. Values obtained by these two methods vary sympathetically. Furthermore, whole rock fluoride values vary sympathetically with water-leachable fluoride values, which permits use of simpler, less expensive methods for field exploration purposes. Application of these procedures to an area of tin mineralization indicates that easily distinguishable anomalous fluoride values for water leach and total fluoride in rocks are associated with areas of tin mineralization.     

Solubility and dissolution rate of silica in acid fluoride solutions

We performed 57 batch reactor experiments in acidic fluoride solutions to measure the dissolution rate of quartz. These rate data along with rate data from published studies were fit using multiple linear regression to produce the following non-unique rate law for quartz

where 10^−5.13 < a_HF < 10^1.60, −0.28 < pH < 7.18, and 298 < T < 373 K. Similarly, 97 amorphous silica dissolution rate data from published studies were fit by multiple linear regression to produce the following non-unique rate law for amorphous silica

where 10^−2.37 < a_HF < 10^1.61, −0.32 < pH < 4.76 and 296 < T < 343 K. Regression of the rates versus other combinations of solution species, e.g.  + H⁺, F⁻ + H⁺, HF + , HF + F⁻, or  + F⁻, produced equally good fits. Any of these rate laws can be interpreted to mean that the rate-determining step for silica dissolution in fluoride solutions involves a coordinated attack of a Lewis acid, on the bridging O atom and a Lewis base on the Si atom. This allows a redistribution of electrons from the Si–O bond to form a O–H group and a Si–FH group.