活化膨润土吸附Pb~(2+)离子的研究

研究了热活化及酸活化的膨润土对重金属 Pb2 +离子的吸附。结果表明 ,活化膨润土对Pb2 +离子具有较强的吸附性能 ,p H值是影响吸附的主要因素 ,较高温度热活化的膨润土具有最大的吸附容量 ,基本符合 Langmuir吸附等温线 ,离子交换和表面络合反应是主要吸附形式     

膨润土对Zn(Ⅱ)和Cd(Ⅱ)离子的吸附作用研究

在静态条件下 ,研究了膨润土对重金属离子 (如 Zn2 +、Cd2 + )的吸附与交换。结果表明 ,膨润土对重金属离子具有较强的吸附性能 ,p H值是影响吸附的主要因素 ,离子交换和表面络合反应是主要吸附形式。     

Hydraulic Conductivity and Compressibility of Soil-Bentonite Backfill Amended with Activated Carbon

Flexible-wall permeability tests and rigid-wall consolidation/permeability tests were performed to evaluate the hydraulic conductivity and compressibility of a model soil-bentonite (SB) backfill amended with granular activated carbon (GAC) or powdered activated carbon (PAC). The tests were performed as part of an assessment of enhanced SB backfill with improved attenuation capacity for greater longevity of barrier containment performance. Backfill specimens containing fine sand, 5.8% sodium bentonite, and GAC or PAC (0, 2, 5, and 10% by dry weight) were prepared to target slumps of 125±12.5?mm. Hydraulic conductivity (k) and compressibility of backfill test specimens were measured in consolidometers as a function of effective stress, σ′ (24 ? σ′ ? 1,532?kPa), whereas flexible-wall k was measured for backfill specimens consolidated to σ′ = 34.5?kPa. The results indicate that addition of GAC has little impact on the hydraulic and consolidation properties of the backfill, whereas addition of PAC causes a decrease in k and consolidation coefficient (cv) and a slight increase in compression index (Cc). Differences in behavior between GAC-amended backfills and PAC-amended backfills are attributed primarily to differences in GAC and PAC particle size.     

膨润土及改性膨润土在造纸行业中的应用

膨润土特殊的构造使其具有离子交换性、吸水性、膨胀性、触变性、粘结性、吸附性等多重性质,其常用改性方法有活化法和添加改性剂法两种。概括了近期的文献资料,对膨润土和改性膨润土在造纸行业中的应用情况进行了综述,对今后的发展提出了建议。     

Utilisation of waste clay from boron production as a landfill liner material

The objective of this study was to investigate the potential utilisation of waste clay from boron production in sanitary landfills. The waste clay (CW) was mixed with bentonite (B) and waste tyre (TW) at different ratios. Results show that, any of the CW-TW mixtures were not acceptable to use in landfills because of insufficient bearing capacity values. On the other hand, CW and 2B/98CW mixtures have sufficient values from the point of experimental tests. As a conclusion, it has been concluded that CW can be used as a liner material for landfills without an addition.     

Arsenic (V) removal from aqueous solutions using natural clay ceramic monoliths

Abstract

An adsorbent material arranged in a ceramic monolith (CM) obtained by extrusion technique using natural bentonite and alumina (as raw materials) is presented. Ceramic and raw materials were characterized by X-ray fluorescence, thermal analysis, X-ray diffraction, and textural analysis (with N₂ adsorption–desorption at 77?K and Hg intrusion–extrusion porosimetry) to determine their chemical and physical properties. Then, As (V) adsorption capacity of the CM at different pH (3–9) using arsenic aqueous solution (with 2000?µg As (V) L^?1) was evaluated. Additionally, studies of kinetics and equilibrium of As (V) adsorption on CM were performed. It was found that: (i) the As (V) removal capacity is favored at acidic pH, reaching an average value of 15?µg As (V) per gram of CM; (ii) from kinetic studies, As (V) adsorption on CM occur in two stages, the first of them reaching a lower As uptake in a short time period, followed by an slow second stage with a subsequent higher As uptake, which continued for a longer time period, reaching equilibrium conditions in approximately 24?h; and (iii) the As (V) adsorption isotherm is a type-Langmuir, indicating that the CM present an homo quantity of fixed sites to adsorb the As (V).     

Investigating the mechanism of downslope bentonite erosion in GCL liners using X-Ray CT

Exposed composite GMB-GCL liners are at risk of downslope bentonite erosion caused by the release of low ionic strength condensed water onto the top surface of the GCL following daily solar heating. This paper investigates the use of X-ray computed tomography (X-ray CT) to quantify the thinning of the bentonite layer and the application of X-ray diffraction techniques (XRD) to investigate the changes in clay chemistry (if any) of the bentonite from the virgin GCL to the eroded bentonite. The effect of specimen size and scanning orientation was investigated resulting in a revised testing procedure in which the CT scanning orientation was changed from horizontal to vertical to permit a longer test specimen which was also sealed at the bottom edge to minimise the edge boundary condition. The X-ray CT results provide highly visual evidence that a) bentonite thinning immediately under the upper cover geotextile is the initial location of erosion, and b) the bentonite core erodes at a significantly higher rate when not covered by a geotextile than when covered by a geotextile. These observations indicate that the upper geotextile of the GCL plays a significant role in controlling the rate of bentonite erosion. Finally, a comparison of the virgin and runoff bentonite properties was conducted to investigate potential changes in swell index, X-ray diffraction results, and concentration of Na and Ca cations. The runoff bentonite was observed to had a significantly higher swell index (40?ml/2?g) than the virgin bentonite (28?ml/2?g) and lower Na and Ca concentrations. This finding is consistent with the observation from XRD analyses of the runoff bentonite which illustrate that the clay fraction of the bentonite is preferentially eroded by the application of DI water.     

Bentonite deposits of Northern Patagonia

Some Argentine North Patagonia bentonite deposits have been characterised by chemical and differential thermal analysis (DTA), X-ray diffraction and Isoelectric Point (IEP), Cation Exchange capacity (CEC) and specific surface area (S) determinations.Samples with high degree of tetrahedral isomorphic substitution, and consequently high interlayer cation charge compensation, would be used as organic pollutant adsorbent when the adsorption was a cation exchange mechanism.     

Elemental sulfur fertilizers and their use on crops and pastures

This paper reviews the use of elemental sulfur (S°) as a fertiliser and its efficacy in different pastoral and cropping situations. The effect of S° particle size on rate of oxidation is critical to the effectiveness of S° fertilisers. Emphasis is therefore centred on the issue of how particle size of S° affects the rate of oxidation in different environments and cropping systems, and the size of S° in different S° fertiliser products. Rate constants of S° oxidation offer the opportunity to generalise particle size relationships needed in S° fertilisers for different crops in different environments, or alternatively, to calculate the agronomic effectiveness of different S° fertilisers available on the market. Conversely they offer a technique to set specifications as to S° particle size requirements, which together with dispersion rate specifications provide the basis for the design of S° fertilisers for specified crops and environments.     

新型活化工艺制备超轻硅钙保温材料的研究

针对目前国内硅钙材料生产中原材料单一、产品性能差等问题，以膨润土为硅质原料，采用新型活化工艺，成功研制出超轻量(表现密度＜170kg/m^3)、低成本的硅钙产品，同时也改善了硅钙产品的保温性能。