Adsorption of dyes from aqueous solutions on activated charcoal

Adsorption of industrially important dyes namely bromophenol blue, alizarine red-S, methyl blue, methylene blue, eriochrome black-T, malachite green, phenol red and methyl violet from aqueous media on activated charcoal has been investigated. The effect of shaking time, pH and temperature on the adsorption behaviour of these dyes has been studied. It was noted that adsorption of all the dyes on activated charcoal decreases with an increase in the pH and the temperature. The adsorption isotherms at different temperatures were found to be of L-type. Adsorption data was fitted to Freundlich, BET and Langmuir isotherms and various adsorption parameters have been calculated. The thermodynamic parameters such as DeltaG, DeltaH and DeltaS were calculated from the slopes and intercepts of the linear variation of lnK against 1/T, where K is the adsorption coefficient obtained from Langmuir equation, was used. The calculated values for the heat of adsorption and the free energy indicate that adsorption of dyes is favored at low temperatures and the dyes are chemisorbed on activated charcoal.     

Inhibition of phosphine liberation from amorphous red phosphorus

An extensive study of the liberation of phosphine from commercial red phosphorus was undertaken. The influence of water, trace metals, magnesium, calcium and aluminium oxides and a selection of carbamates, phenols and quinones was investigated. Accelerated ageing tests at 50°C were used to assess the value of 1% (w/w) additions of p-benzoquinone and 1,4-naphthoquinone in particular, as inhibitors to the generation of phosphine from commercial phosphorus and a pyrotechnic composition including spindle oil and poly(vinylbutyral). The two quinones suppress the liberation of phosphine to < 5% the rate of generation from commercial unoiled phosphorus. The mechanism of phosphine generation is obscure, but involves dissociation of water in the phosphorus surface region and the formation of phosphorus acids which may disproportionate yielding phosphine. Alternatively, or simultaneously, hydrogenation of phosphorus may take place liberating phosphine. The quinones presumably arrest these processes by preferentially combining with hydrogen or free-radical intermediates. The use of silver-nitrate-impregnated charcoal cloth and granules to remove gaseous phosphine was also studied.     

Adsorption of gold-thiourea complex on activated carbon

The adsorption kinetics of the gold-thiourea complex on activated charcoal was studied. Experimental runs were made in a batch reactor at constant temperatures and stirred by a magnetic system. Samples were taken at different periods of time and were analyzed for gold in a Perkin-Elmer Model 360 atomic absorption spectrophotometer. The samples were prepared with synthetic solution of gold with thiourea, sulfuric acid, and iron sulfate with concentrations similar to the ones in the leaching process. The gold adsorbed on activated charcoal was 99% at 20°C. The adsorption behavior was characterized by the Freundlich model at different temperatures (20°C, 35°C and 50°C).     

Comparison of different procedures for the detoxification of eucalyptus hemicellulosic hydrolysate for use in fermentative processes

Eucalyptus (Eucalyptus grandis) shavings were submitted to an acid hydrolysis process with the aim of obtaining a hemicellulosic hydrolysate rich in fermentable sugars. However, the hydrolysate obtained contained, in addition to sugars, several compounds that are toxic to microorganisms, namely furfural, hydroxymethylfurfural, acetic acid and phenolics. In order to produce a hydrolysate suitable for use in fermentative processes, several procedures were evaluated for hydrolysate detoxification, including concentration by vacuum evaporation and adsorption on activated charcoal, diatomaceous earths, ion‐exchange resin or adsorbent resin. Hydrolysate concentration was especially effective for furfural removal, whereas the adsorbent resin was efficient in removing hydroxymethylfurfural, phenolics and acetic acid. Combination of this resin with activated charcoal was better than with diatomaceous earths for removal of acetic acid and phenolics. The best detoxification procedure evaluated was based on hydrolysate concentration followed by adsorption on activated charcoal and adsorbent resin. By this treatment, removal rates of 82.5, 100, 100 and 94% were attained for acetic acid, furfural, hydroxymethylfurfural and phenolics, respectively. Copyright © 2005 Society of Chemical Industry     

Pyrolysis of coconut shells in a concentric three tubes reactor

To improve energy efficiency, coconut shells were pyrolyzed in a concentric three tubes reactor using a combination of external and internal heating method. Coconut shells were oxidized partially at the bottom of the reactor, and the gas rised through the redhot charcoal packing to be cracked to smaller compounds and burnt by the air. The hot gas diverged outward and flowed down along the outside wall of the second tube before it left the reactor. The higher the temperature and the longer the time of pyrolysis, the less charcoal and light oil, but the more tar were produced. The charcoal obtained was in between that produced from external and internal heating procedures. Under the optimum time of 95 minutes and temperature of 579°C, the products were 19.53% charcoal, 5.22% tar, and 0.16 % light oil.     

可用于耐火材料的酚醛树脂

探索了用于耐火材料的酚醛树脂的合成方法，以及介绍此酚醛树脂具有加热固化或加入一定量的固化剂，在室温下固化等特点，可大量节约能源，节约劳动力。它完全固化后的粘结力强，机械强度高，在镁炭砖生产行业值得大力推广应用。     

接枝改性对HDPE基微波竹炭复合材料性能的影响

采用高密度聚乙烯(HDPE)作为基体树脂,微波改性竹炭作为填料,通过熔融接枝法制备了HDPE基微波竹炭复合材料,分析了顺丁烯二酸酐(MAH)、过氧化二异丙苯(DCP)的含量及比例,对复合材料静态、动态力学性能和热稳定性能的影响。静态力学性能结果表明,随着MAH、DCP含量的增加,HDPE基微波竹炭复合材料的力学性能呈先增大后降低的趋势;当MAH含量一定,MAH∶DCP比例为2∶0.1时,HDPE基微波竹炭复合材料的力学性能较优。动态热机械分析仪(DMA)与热重分析仪(TGA)分析表明,MAH熔融接枝改性提高了HDPE与微波竹炭两相之间的界面作用力,有利于改善HDPE与微波竹炭的界面性能,与SEM分析结果一致;并且,还能提高复合材料在高温下的热稳定性。     

Kinetics of zirconium ions adsorption on activated charcoal from aqueous solutions

The batch kinetics of adsorption of the zirconium ions from aqueous solutions on activated charcoal has been investigated over a wide range of concentration of zirconium ions (1.0–5.0 g/l) and temperatures (10–50°C). The adsorption process of zirconium ions proceeds via two stages; the first stage is rather fast, followed by a much slower one. The Bangham equation was used to study the kinetics of the zirconium ions' adsorption on activated charcoal. It is observed that the diffusion of zirconium ions into the pores of the activated charcoal controls the kinetics of the adsorption process. Moreover, zirconium ion adsorption obeys the Freundlich and Langmuir isotherms in the concentration range studied. The adsorption equilibrium constant (k_c) values for zirconium ions adsorption on activated charcoal have also been calculated at different temperatures. Various thermodynamic quantities, ΔG, ΔH, and ΔS were computed from k_c values. The results showed that the adsorption of zirconium ions on activated charcoal is an endothermic process.     

基于循环经济的毛竹产业链设计

为改变我国毛竹产业高消耗、低效率、粗放型经营的现状,以循环经济理念为指导,对毛竹产业进行了产业链设计.产业链以毛竹资源的深加工为主线,构建了从毛竹林培育、鲜笋加工到毛竹全株利用的产业体系,形成了多层次的产品结构;设计了一条生产竹叶黄酮的清洁工艺,对竹炭生产中产生的余热进行了合理的利用,并对各生产流程中的部分环节进行了工艺的选择;通过笋竹两用林、笋制品厂、竹叶黄酮厂、竹材人造板厂、竹炭厂、手工厂和饲料厂之间物质交换、能量和水的高效利用,基本实现了物质和能量的闭路循环.所设计的产业链低消耗、低排放、高效率,是一种毛竹产业可持续发展的模式.     

马钢1号高炉炉役末期炉缸维护实践

处于炉役末期的马钢1#高炉,通过加强原燃料的管理,加强炉体监控,量化钛元素的沉积量,严格控制铁口状态等多种手段,在炉缸炭砖遭到严重侵蚀的条件下,实现炉役末期的安全生产,充分挖掘高炉的边际价值。针对炉役末期炉缸的状况展开分析,钛元素的使用量要与高炉的产量相匹配,堵风口操作的同时要兼顾炉缸活跃性的变化。