Gaseous products of the thermolysis of brown coal impregnated with potassium hydroxide

The yields of gaseous products (H₂, CO, CO₂, and C _n H_2n + 2 at n = 1−4) from brown coal and brown coal-KOH compounds were determined under conditions of nonisothermal heating (4°C/min) to 800°C followed by an isothermal exposure (1 h, 800°C). It was found that, in the presence of the alkali, the yields of H₂, CO, C₂H₆, and C₃H₈ increased; the yields of CO₂ and CH₄ decreased; and the formation of isobutane was completely suppressed. Changes in the gas compositions were explained by the alkali degradation of C-C bonds in the organic matter of coal and by the thermally initiated dehydrogenation and dealkylation reactions of arene and alkane structural fragments, in which KOH molecules served as H-atom donors in the formation of H₂ and alkanes.     

Formation of the pore structure of brown coal upon thermolysis with potassium hydroxide

The pore-structure characteristics of active carbons prepared by the thermolysis (800°C) of brown coal impregnated with potassium hydroxide were studied. The dependence of the specific surface area, total pore volume, micropore volume, micropore fraction, and micropore size distribution on the KOH/coal weight ratio R _KOH ≤ 1.0 g/g was found. Condensation processes with the formation of a low-porosity material were predominant at low ratios of R _KOH ≤ 0.1 g/g. The development of a micropore structure was observed at R _KOH ≥ 0.1 g/g, and it increased as R _KOH was increased to 1.0 g/g. It was hypothesized that pore formation was due to the thermally initiated reactions of the structural fragments of coal with KOH molecules, which occurred within the framework of coal.     

High hydrogen uptake capacity of mesoporous nitrogen-doped carbons activated using potassium hydroxide

Mesoporous nitrogen-doped carbons activated using potassium hydroxide have large surface areas and high pore volumes, are studied for their hydrogen storage properties. The activated material can store 6.84 wt.% of hydrogen at 77 K under a pressure of 20 bar, which is estimated to correspond to a maximum capacity of 8.24 wt.% based on the Langmuir simulation. The hydrogen adsorption values show linear relationships with the volumes of micropores and small mesopores under those conditions, which indicates that the small mesopores between the sizes 2 and 3 nm also make contributions to the hydrogen adsorption at high pressure.     

氢氧化钾活化烟杆制造活性炭及表征

以烟杆为原料,氢氧化钾为活化剂,采用一步炭化法制备了活性炭。采用正交实验研究了对活性炭得率和吸附性能的影响的主要因素,得到了最佳工艺条件,所制活性炭碘吸附值为1198.27 mg/g,亚甲基蓝吸附值为国家一级品标准的3倍。还测定了该活性炭的氮吸附等温线,通过H-K方程和密度函数理论表征了活性炭的孔结构,其结果与电子探针和透射电镜分析的活性炭微观结构相一致。     

Carbonization of trichloroethanes with anhydrous potassium hydroxide

Chemical dehydrochlorination of 1,1,1‐ and 1,1,2‐trichloroethanes with anhydrous potassium hydroxide (KOH) in the presence of a poly(ethylene glycol) oligomer as phase transfer catalyst leads to polymeric carbons with partly carbynoid structures. The FTIR spectra show a strong band at 2130 cm⁻¹ and FT‐Raman exhibits a strong line at around 1900 cm⁻¹, either of which is interpreted as the CC C stretching mode of the linear carbon chain with alternating carbon–carbon triple and single bonds (polyyne). Carbons prepared by this technique are amorphous nanoparticles with diameters in the 30–50 range nm. After iodine doping they have dc conductivities of 10⁻³ S cm⁻¹. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 185–189, 2000     

氢氧化镁吸附性能研究

采用氢氧化镁乳液对富含重金属离子废水、印染废水以及海水中的微量硼实施吸附处理。研究结果表明:氢氧化镁对废水中各类重金属离子均有很好的吸附效果,去除率最高达到98%;对印染废水的脱色率与COD去除率分别达到97.5%和80%;对海水中硼的吸附率达到74%。     

乙醇的氢氧化钾溶液浸泡石油焦制备活性炭的研究

以石油焦为原料,添加碱碳比2:1的KOH为活化剂,探究了以乙醇水溶液作为溶剂浸泡石油焦制备活性炭的最佳条件.结果表明,含8％水的乙醇溶液、浸泡时间6 h、浸泡温度45℃可制得最优活性炭.最优活性炭的比表面积为1885.3 m2/g,碘吸附值为1628.5 mg/g.对活性炭进行SEM分析、比表面积分析,表明利用乙醇溶液...     

低阶煤制备活性焦及其吸附性能研究

为解决煤化工废水处理难题,提高活性焦吸附性能,以5种典型低阶煤为原料,通过回转炉炭化和活化工序制备活性焦,研究活化温度、活化蒸气量和活化时间对活性焦吸附性能的影响,分析了不同活性焦对废水的吸附能力。结果表明:以褐煤为原料制备活性焦时,最佳活化温度为800℃,活化时间为3 h,活化蒸气量为1050 g;长焰煤最佳活化温度为850℃,活化时间为4 h,活化蒸气量为1200 g。在最佳条件下,褐煤活性焦的吸附值为36.32 mg/g,比长焰煤活性焦吸附值高10%。5种原煤制备的活性焦的比表面积与吸附值没有明显相关性。活性焦的孔容积越大,吸附值越高,造成不同活性焦吸附值差别的主要孔径为2~5 nm和5~20 nm。     

赤峰某地褐煤制取腐植酸钾实验研究

以内蒙古赤峰某地褐煤为原料,分别采用氢氧化钾溶液、氢氧化钾与碳酸钾混合溶液两种提取液,进行了制备腐植酸钾的条件实验和正交实验,探究提取剂用量、固液比、热处理时间对腐植酸提取率的影响。结果表明,制备腐植酸钾的优化工艺条件为:在90℃下水浴1 h,固液质量比1∶10,氢氧化钾与碳酸钾混合液浓度1.0%+0.5%。在此优化条件下,腐植酸钾提取率87.2%。水溶性腐植酸含量52.5%,氧化钾含量22.6%,水不溶物含量9.5%,p H值11.0,水分含量约1.5%。     

赤峰某地褐煤制取腐植酸钾实验研究

以内蒙古赤峰某地褐煤为原料,分别采用氢氧化钾溶液、氢氧化钾与碳酸钾混合溶液两种提取液,进行了制备腐植酸钾的条件实验和正交实验,探究提取剂用量、固液比、热处理时间对腐植酸提取率的影响。结果表明,制备腐植酸钾的优化工艺条件为:在90℃下水浴1 h,固液质量比1∶10,氢氧化钾与碳酸钾混合液浓度1.0%+0.5%。在此优化条件下,腐植酸钾提取率87.2%。水溶性腐植酸含量52.5%,氧化钾含量22.6%,水不溶物含量9.5%,p H值11.0,水分含量约1.5%。     

Adsorption of sulfur dioxide onto activated carbons prepared from oil‐palm shells impregnated with potassium hydroxide

Adsorption of sulfur dioxide (SO₂), a gaseous pollutant, onto activated carbons prepared from oil‐palm shells pre‐treated with potassium hydroxide (KOH) impregnation was studied. Experimental results showed that SO₂ concentration and adsorption temperature affected significantly the amount of SO₂ adsorbed and the equilibrium time. However, sample particle sizes influenced the equilibrium time (due to effect of diffusion rate) only. Desorption at the same temperature of adsorption and a higher temperature of 200 °C confirmed the presence of chemisorption due to pre‐impregnation. Impregnation with different activation agents was found to have limited effect on the inorganic components of the sample. Compared with the activated carbon pre‐treated with 30% phosphoric acid (H₃PO₄) that had larger BET and micropore surface areas, the sample impregnated with 10% KOH had a higher adsorptive capacity for SO₂, which was closely related to the surface organic functional groups of the sample. In general, the activated carbon prepared from oil‐palm shell impregnated with KOH was more effective for SO₂ adsorption and its adsorptive capacity was comparable to some commercial activated carbons. © 2000 Society of Chemical Industry     

Porosification behaviour of LTCC substrates with potassium hydroxide

The demand to meet advanced substrate requirements in terms of electrical, mechanical, thermal, and dielectric properties has led to an increasing interest in low temperature co-fired ceramics (LTCC). However, LTCC materials suffer from high permittivity. We recently showed that the wet-chemical porosification under acidic conditions allows the reduction of the permittivity of LTCCs in the as-fired state. In the present study, potassium hydroxide solution was employed as an alternative etchant which features a suitable bearing plane for further metallization lines. Various characterization techniques, including scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and electron energy loss spectroscopy were used for investigation of the morphology and chemical composition of the substrates. Three-dimensional information of the surface topography was acquired by means of MeX^® Alicona software and the obtained roughness parameters confirmed the advantage of the proposed approach over acid treatment when targeting an enhanced surface quality.     

A thermal analysis study of the thermooxidative degradation of mechanically activated brown coal

Changes in the reactivity of mechanically activated brown coal in the course of thermooxidative degradation were studied using thermal analysis. The thermogravimetric curves obtained at various heating rates were processed using the Model free software. It was found that the intense mechanical treatment of brown coal during crushing resulted in a decrease in the activation energy over the entire temperature range of thermooxidative degradation. A considerable decrease in this parameter for coal fractions enriched in coal matter was detected.     

Preparation of high surface area activated carbon from corn by chemical activation using potassium hydroxide

Activated carbons were prepared through chemical activation of corn cob precursor, using potassium hydroxide as the chemical agent. The effect of different parameters, such as particle size, method of mixing, chemical/corn ratio, activation time and activation temperature, on weight loss and BET surface area of the produced activated carbons were discussed. The porosity of the activated carbons was evaluated through nitrogen adsorption. The storage capacity of the activated carbon was evaluated using natural gas. Under the experimental conditions investigated, the optimal conditions for production of high surface area carbons by chemical activation were identified. The results were compared with commercial activated carbons from coal.     

Effects of brown coal quality and process parameters on the hydroliquefaction of brown coal

During the development of the HVB process the influence of different parameters on the process have been investigated. In this Paper the influence of the properties of the brown coal on the process is reported. It is shown that: (1) the petrographical composition of Rhenish brown coal has virtually no effect on the HVB process; (2) the problems of sedimentation caused by the ash composition of the brown coal can be overcome by a particular thermal pretreatment of the coal; and (3) the moisture content of the brown coal is of minor importance for the technical realization of the HVB process.     

钾长石-氧化钙-氢氧化钾体系提钾工艺研究

采用球磨反应和静态水热反应对钾长石-氧化钙-氢氧化钾体系提钾工艺进行了研究,结果显示：温度对钾长石提钾有较大的影响,静态水热反应提钾效果优于球磨反应.较适宜的静态水热反应工艺条件为：m（氧化钙）/m（钾长石）为1.5,m（钾长石）/m（氢氧化钾）为15,恒温220℃下反应10h,每克钾长石加水量为20 mL,此时钾溶出率达到90％以上.     

Study of competitive adsorption of malachite green and sunset yellow dyes on cadmium hydroxide nanowires loaded on activated carbon

Cadmium hydroxide nanowires loaded on activated carbon (Cd(OH)₂-NW-AC) was applied for removal of malachite green (MG) and sunset yellow (SY) in single and binary component systems. This novel material was characterized and identified by different techniques such as Brunauer, Emmett and Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis. Unique properties such as high surface area (>1271 m² g⁻¹) and low pore size (<35 Å) and average particle size lower than 50 Å in addition to high reactive atom and presence of various functional groups make it possible for efficient removal of these two dyes. In the single component system in this study, maximum adsorption capacity of 80.6 for SY and 19.0 mg g⁻¹ for MG at 25 °C was reported. The Langmuir model had very well fit with the experimental data (R² > 0.996). A better agreement between the adsorption equilibrium data and mono-component Langmuir isotherm model was found. The kinetics of adsorption for single and binary mixture solutions at different initial dye concentrations were evaluated by the nonlinear first-order and second-order models. The second-order kinetic model had very well fit with the dynamical adsorption behavior of a single dye for lower and higher initial dye concentrations. SY and MG without spectra overlapping were chosen and analyzed with high accuracy in binary solutions. The effect of multi-solute systems on the adsorption capacity was investigated. The isotherm constants for SY and MG were also calculated in binary component systems at concentrations within moderate ranges, the Langmuir isotherm model satisfactorily predicted multi-component adsorption equilibrium data. The competitive adsorption favored the SY in the A mixture solution (both SY and MG concentration at 10 mg L⁻¹) and B mixture solution (25 mg L⁻¹ of SY and 10 mg L⁻¹ of MG). Also, in both cases, kinetic data was fairly described by two-step diffusion model. An endothermic and spontaneous nature for the adsorption of the dyes studied were shown from thermodynamic parameters in single and binary component systems.     

Low-temperature oxidation of brown coal. 2. Elovich adsorption kinetics and porous materials

Computer-generated diffusion data are shown to be fitted closely for long periods by the Elovich equation. The graphs obtained also show the discontinuities that frequently occur in Elovich plots of experimental adsorption data. Use of the Elovich equation to interpret sorption on porous materials is therefore a dubious procedure.     

Optimized and functionalized paper sludge activated with potassium fluoride for single and binary adsorption of reactive dyes

The yield and adsorption uptake of optimized paper sludge activated carbon (PSAC) prepared using potassium fluoride as alternative chemical activation agent was investigated. The PSAC was functionalized with ethylenediamine (FPSAC) and both adsorbents were used for single and binary adsorption of Reactive orange 16 (RO16) and Reactive blue 19 (RB19). Effect of pH on the adsorption process, equilibrium, kinetics, isotherm and thermodynamic studies were carried out. Optimum PSAC preparation parameters were: activation temperature, X₁ = 810 °C; activation time, X₂ = 105 min; and impregnation ratio, X₃ = 0.95 which gave adsorption uptake of 178 and 158 mg/g for RO16 and RB19, respectively.     

碳酸钾改性油茶壳活性炭吸附水中氨氮的研究

利用所制备的油茶壳活性炭对水体中的氨氮进行了吸附,探讨了各因素对吸附效果的影响,并进行了吸附热力学和动力学分析。结果表明:活化温度及活化剂浓度的提高有利于油茶壳活性炭对氨氮的吸附。吸附过程在420 min左右达到平衡,符合准二级动力学模型。吸附过程符合Langmuir等温吸附模型,对氨氮的最大吸附量可达到10.83 mg/g。在最适的实验条件下,0.1 g的碳酸钾改性油茶壳活性炭对初始质量浓度为20 mg/L的氨氮废水中氨氮的去除率可以达到50.3%,吸附效果良好。