Removal of nitrate-nitrogen from drinking water using bamboo powder charcoal

The adsorption effectiveness of bamboo powder charcoal (BPC); made from the residual of Moso bamboo manufacturing; in removing nitrate-nitrogen from water has been investigated. Commercial activated carbon (CAC) was also used to compare the effectiveness of adsorption in removal of nitrate-nitrogen. The adsorption effectiveness of BPC was higher than that of CAC; regardless of the concentration of nitrate-nitrogen; in the range of 0-10 mg/l. The effect of temperature on adsorption by BPC and CAC in the range of 10-20 degrees C was also investigated. From the results, it was found that the temperature dependency of the adsorption effectiveness of BPC was weaker than that of CAC. This fact indicates that BPC can be an attractive option for the in situ treatment by adsorption of nitrate-nitrogen-contaminated underground and surface water.     

Physicochemical factors affecting ethanol adsorption by activated carbon

Powder and granular activated charcoal were evaluated for ethanol adsorptivity from aqueous mixtures using an adsorption isotherm. Ethanol adsorption capacity was more pronounced at 25 degrees C as compared to 5, 15, and 40 degrees C. When pH of the ethanol-buffer mixture (0.09 ionic strength) was changed from acidic (2.3) to neutral and then to alkaline (11.2), ethanol adsorption was decreased. Increasing ionic strength of the ethanol-buffer mixtures from 0.05 to 0.09 enhanced ethanol adsorption but a further increase to 0.14 showed no significant effect. Ethanol adsorption was more efficient from an aqueous ethanol mixture as compared to semidefined and nondefined fermentation worts, respectively. Heating granular charcoal to 400 degrees C for 1 h and 600 degrees C for 3 h in N(2) increased ethanol adsorptivity and heating to 1000 degrees C (1 h) in CO(2) decreased it when ethanol was removed from dilute solutions by simple pass adsorption in a carbon packed column. Granular charcoal was superior to powdered charcoal and an inverse relationship was noted between the weight of the granular carbon bed in the column and ethanol adsorbed/g carbon. Decreasing the column feed flow rate from 7.5 to 2.0 L aqueous ethanol/min increased the adsorption rate.     

Activated carbon from olive kernels in a two-stage process: industrial improvement

Activated carbons have been prepared from olive kernels and their adsorptive characteristics were investigated. A two stage process of pyrolysis-activation has been tested in two scales: (a) laboratory scale pyrolysis and chemical activation with KOH and (b) pilot/bench scale pyrolysis and physical activation with H(2)O-CO(2). In the second case, olive kernels were first pyrolysed at 800 degrees C, during 45 min under an inert atmosphere in an industrial pyrolyser with a throughput of 1t/h (Compact Power Ltd., Bristol, UK). The resulting chars were subsequently activated with steam and carbon dioxide mixtures at 970 degrees C in a batch pilot monohearth reactor at NESA facility (Louvain-la Neuve, Belgium). The active carbons obtained from both scales were characterized by N(2) adsorption at 77 K, methyl-blue adsorption (MB adsorption) at room temperature and SEM analysis. Surface area and MB adsorption were found to increase with the degree of burn-off. The maximum BET surface area was found to be around 1000-1200 m(2)/g for active carbons produced at industrial scale with physical activation, and 3049 m(2)/g for active carbons produced at laboratory with KOH activation. The pores of the produced carbons were composed of micropores at the early stages of activation and both micropores and mesopores at the late stages. Methylene blue removal capacity appeared to be comparable to that of commercial carbons and even higher at high degrees of activation.     

Preparation and characterization of activated carbon from palm shell by chemical activation with K2CO3

Palm shell was used to prepare activated carbon using potassium carbonate (K2CO3) as activating agent. The influence of carbonization temperatures (600-1000 degrees C) and impregnation ratios (0.5-2.0) of the prepared activated carbon on the pore development and yield were investigated. Results showed that in all cases, increasing the carbonization temperature and impregnation ratio, the yield decreased, while the adsorption of CO2 increased, progressively. Specific surface area of activated carbon was maximum about 1170 m2/g at 800 degrees C with activation duration of 2 h and at an impregnation ratio of 1.0.     

Development of monolithic eco-composites from carbonized blocks of solid iron bamboo (Dendrocalamus strictus) by impregnation with furfuryl alcohol

The purpose of this work was to manufacture the porous biomorphous composite using carbonized shapes cut from solid stem of solid iron bamboo, Dendrocalamus strictus, as a monolithic support. Bamboo carbonized at 800 degrees C was next infiltrated with liquid filler--furfuryl alcohol. After the polymerization and cross-linking of the filler, the shapes were carbonized again to obtain carbon/carbon composite. TGA method was used to investigate the thermal decomposition of the resulting composite as well as of the raw and carbonized bamboo. The ultrasonic measurements, optical microscopy observations, the adsorption of N(2) at -196 degrees C and mercury porosimetry were applied to characterize the structure of the investigated materials. The obtained composite was found to be highly porous (over 80%), thermo-resistant in inert atmosphere (up to 940 degrees C). It possessed stiff hierarchically ordered pore structure with elastic moduli >4 GPa along the stem, and >1 GPa perpendicularly to the stem. Furthermore, the layer of carbon from the polymer coated the support accurately and did not affect the shape of the monolithic pieces of carbonized bamboo. The resulting composite possessed also more uniform, mesoporous structure than the support.     

Development of mesoporosity during phosphoric acid activation of wood in steam atmosphere

Oak and birch were used as precursors to produce the activated carbons (ACs) with well-developed mesoporosity by phosphoric acid-promoted activation in a steam atmosphere. The effect of experimental variables such as the amount of activating agent, the soaking time and the type of wood on the development of porous structure upon heating at 480 degrees C was investigated. The materials were characterized by N2 adsorption at 77K, mercury porosimetry and elemental analysis. It was demonstrated that increasing impregnation ratio favors the development of micropores and small mesopores of 2-5nm, whereas the soaking time promotes the creation of large mesopores, between 10 and 50nm. Compared to birch, the oak activation using phosphoric acid in the same conditions gives ACs with lower mesopore volume and higher contribution of small mesopores that reflects the differences between both precursors in their biopolymer composition. The presence of steam in the H3PO4 activation process compared to nitrogen facilitates the development of mesoporosity to much higher extent for the birch than that of oak. The ACs prepared in this work show the BET surface area ranging from 800 to 2250m2g(-1), the total pore volume of 0.35-2.04cm3g(-1) with mesopore fraction between 0.06 and 0.68.     

Activated carbon from Eucalyptus camaldulensis Dehn bark using phosphoric acid activation

The powdered activated carbon prepared by phosphoric acid activation was significantly affected by the carbonization temperature and the weight ratio between raw material and phosphoric acid. With an activation time of 1h and an impregnation ratio of 1:1, the activated carbons with better adsorption capacity were obtained at 500 degrees C. A reduction in the adsorption capacity of the carbon product at higher acid content than this was observed, possibly due to the collapse of the micropore structure. The properties of the resulting activated carbon were: bulk density 0.251gcm(-3), ash content 4.88%, yield 26.2%, iodine adsorption 1043mgg(-1), methylene blue adsorption number 427mgg(-1), and BET surface area 1239m(2)g(-1).     

竹炭固定化施氏假单胞菌Pseudomonas stutzeri ZH-1降解苯酚的研究

通过竹炭固定化以加强施氏假单胞菌Pseudomonas stutzeri ZH-1对苯酚的降解能力。采用正交试验优化竹炭对菌株ZH-1固定化条件,冷场发射扫描电镜（SEM）观察固定化后的菌株在竹炭上的附着情况,对比固定化菌和游离菌的降解性能并对固定化菌做重复利用性能测试。结果显示,竹炭固定化P. stutzeri ZH-1的最适条件为竹炭1 g,接种量5%(体积分数),吸附时间24 h;SEM显示菌附着在竹炭表面和内部空隙中;竹炭固定化后菌株ZH-1对苯酚的降解率显著增加（P<0.05）,处理48 h时降解率增加15%;竹炭固定化菌ZH-1经10轮重复利用后仍有很高的苯酚降解性能,48 h时降解率增加173%（P<0.05）。竹炭固定化菌ZH-1在去除含苯酚类有机废水中具有较好的应用前景。     

Granular activated carbons from broiler manure: physical, chemical and adsorptive properties

Broiler manure produced at large concentrated facilities poses risks to the quality of water and public health. This study utilizes broiler litter and cake as source materials for granular activated carbon production and optimizes conditions for their production. Pelletized manure samples were pyrolyzed at 700 degrees C for 1 h followed by activation in an inert atmosphere under steam at different water flow rates, for a period ranging from 15 to 75 min. Carbon physical and adsorptive properties were dependent on activation time and quantity of steam used as activant, yields varied from 18% to 28%, surface area varied from 253 to 548 m2/g and copper ion adsorption varied from 0.13 to 1.92 mmol Cu2+/g carbon. Best overall performing carbons were steam activated for 45 min at 3 ml/min. Comparative studies with commercial carbons revealed the broiler cake-based carbon as having the highest copper ion efficiency.     

Ammonia adsorption in a fixed bed of activated carbon

The rise in atmospheric pollution caused by gases such as ammonia has led many researchers to conduct studies aimed at decreasing or treating the emissions of such polluting gases. The present work attempted to study the adsorption of ammonia in the fixed bed of activated carbon as a means to treat its emissions. The effects of the initial concentration of ammonia (C0) and of the bed temperature (TL) on the adsorption of ammonia by the activated carbon were also considered. Adsorption capacity of activated carbon was determined using data from the breakthrough curves and from a balance of mass in the bed. Adsorption capacities were obtained employing the Langmuir and Freudlich isotherms. The results showed that within the NH3 concentration range of 600-2400 ppm, adsorption capacity varied from 0.6 to 1.8 mg NH3/g carbon at 40 degrees C, from 0.2 to 0.7 mg NH3/g carbon at 80 degrees C and from 0.15 to 0.35 mg NH3/g carbon at 120 degrees C. These numbers highlight the tendency toward a lower adsorption capacity with the decrease in temperature. As to mass of the bed, this latter variable had no significant influence over adsorption capacity.     

Thermal reactivity of rapeseed (Brassica napus L.) under different gas atmospheres

Non-isothermal thermogravimetric method was applied to rapeseed to investigate its thermal reactivity under both individual dynamic atmospheres of nitrogen, steam, carbon dioxide and dry air, and under several mixtures of these gases (nitrogen+steam), (steam+dry air), and (nitrogen+carbon dioxide+steam). In this method, the sample was heated from ambient to 1273 K with a constant heating rate of 20 K/min. The trend of the TGA curves and the derived DTG profiles were interpreted regarding the conversion yields and the reactivity of the samples. Conversion yields of biomass to gaseous products changed in the range of 75-94% on original basis, with respect to the atmosphere under which the experiment was carried out. The maximum rates of the mass losses from the sample were found between 2.6 and 4.3 mg/min. The activation energies were calculated using the method of Coats-Redfern, and varied between 21.3 and 96.0 kJ/mol.     

微波改性竹炭颗粒对实验性腹泻大鼠免疫性能和消化吸收功能的影响

旨以研究活性竹炭颗粒(MABCP)对实验性腹泻大鼠免疫性能和消化吸收功能的影响,在大鼠饲粮中分别添加0.05,0.10,0.15%的经KOH微波活化处理的竹炭颗粒,对模型大鼠进行为期一周的饲养试验。研究发现:经KOH微波活化的竹炭颗粒,比表面积与吸附性能大幅增强,其能显著降低腹泻大鼠稀便率(P<0.05),有效增加胸腺和脾脏指数(P<0.05);显著提高腹泻大鼠血清D-木糖含量(P<0.05),但对消化酶如淀粉酶活性无显著影响(P>0.05);肠道线粒体琥珀酸脱氢酶、NADH脱氢酶、H+-ATP酶活性显著增强(P<0.05),MDA生成量显著降低(P<0.05)。试验表明MABCP可提高体积免疫性能,改善小肠吸收功能,减少肠道自由基生成,有效维持或改善细胞氧化磷酸化水平,其中以低剂量添加效果更为明显。     

Physicochemical properties of carbons prepared from pecan shell by phosphoric acid activation

Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part.     

Utilization of an exopolysaccharide produced by Chryseomonas luteola TEM05 in alginate beads for adsorption of cadmium and cobalt ions

Cadmium and cobalt adsorption from aqueous solution onto calcium alginate, sodium alginate with an extracellular polysaccharide (EPS) produced by the activated sludge bacterium Chryseomonas luteola TEM05 and immobilized C. luteola TEM05 was studied. In addition, solutions containing both of these ions were prepared and partial competitive adsorption of these mixtures was investigated. Metal adsorption onto gel beads was carried out at pH 6.0 and 25 degrees C. The maximum adsorption capacities determined by fitting Langmuir isotherms to the data for calcium alginate, calcium alginate+EPS, calcium alginate + C. luteola TEM05 and calcium alginate + EPS + C. luteola TEM05 were 45.87, 55.25, 49.26, 51.81 mg g(-1) for Co(II) and 52.91, 64.10, 62.5, 61.73 mg g(-1) for Cd(II), respectively. The biosorption capacity of the carrier for both metal ions together in competition was lower than those obtained when each was present alone.     

Evaluation of the potential of biodegradation for the disposal of cutting fluid from the machining of uranium

The disposal of used cutting fluid from the machining of uranium is problematical. Biodegradation offers the potential to convert this material into forms amenable to disposal as low level radioactive waste. The real bonus of biodegradation for radioactive applications crucially depends on the degree of mineralisation achieved. In non-radioactive trials using a consortium of bacteria selected from used cutting fluid, only 33% of the organic carbon was converted to carbon dioxide, even though 90% of the principal component (hydrocarbons) was biodegraded. Intermediate degradation products (identified as naphthenic acids) accumulated. Downstream processing of the biotreated fluid by ultrafiltration and adsorption onto activated charcoal produced a waste stream that would qualify as aqueous radioactive waste. Separated biomass was immobilised in a cement matrix that would qualify as solid radioactive waste, albeit in a volume which would make the overall process inefficient. Future work to optimise the process is proposed.     

Selective removal of molybdenum traces from growth media of N2-fixing bacteria

A new method for the selective removal of traces of molybdenum from growth media of N2-fixing bacteria (Rhodobacter capsulatus and Klebsiella pneumoniae) was developed. This method is based on the filtration of nutrient solutions through a layer of activated carbon (pulverized charcoal). The adsorption of Mo (molybdate) to activated carbon was optimal if a charcoal suspension (50 g/liter) was degassed by boiling before use and if the pH of the solutions, which had to be purified, was adjusted to values between 1.5 and 4. In this pH region no or only negligible amounts of other metal ions were adsorbed. The activated carbon method was compared with other Mo-eliminating procedures, including 8-hydroxyquinoline/dichloromethane extraction, Chelex 100 chromatography, and treatment with Mo-starved Azotobacter vinelandii cells. The activated carbon filtration appeared to be the most effective, specific, and rapid method. Whereas the untreated Rhodobacter growth medium was contaminated with 1.2 ppb Mo, as analyzed by inductively coupled plasma mass spectrometry (ICP-MS), the activated carbon-treated medium was below the ICP-MS detection limit (less than 0.05 ppb). A similarly effective removal of Mo impurities was obtained by the Azotobacter treatment. Even at low optical densities (2-5 at 436 nm) Mo traces were removed very rapidly within 10-15 min. However, because the Mo uptake/Mo adsorption capacity of A. vinelandii depended on freshly cultivated cells and on the growth phase at which the cells were harvested, this microbiological method was generally more time-consuming and less reproducible than the activated carbon method.(ABSTRACT TRUNCATED AT 250 WORDS)     

壳聚糖改性竹炭对铜吸附性能研究

为了提高竹炭去除废水中重金属离子能力,采用交联法设计合成新型的磁性壳聚糖改性竹炭复合吸附剂,并采用傅里叶红外光谱对改性竹炭复合吸附剂进行表征,同时开展不同Cu2+初始浓度、吸附剂投加量、吸附时间、pH和温度等因素对Cu2+吸附去除率的影响。结果表明,吸附效率与Cu2+初始浓度和吸附剂投加量成正效应;吸附平衡时间约8 h;在作用温度范围内,吸附效率随温度升高而上升;pH为7时吸附效果最好。振荡条件吸附效果优于静置处理。该结果为废水重金属深度处理及水环境保护提供依据。     

Supercritical carbon dioxide extraction of chamomile flowers: extraction efficiency, stability, and in-line inclusion of chamomile-carbon dioxide extract in beta-cyclodextrin

The extraction of chamomile flowers using supercritical carbon dioxide was investigated with respect to extraction efficiency and compared with solvent extraction. The stability of matricine, a sensitive constituent of the essential oil of chamomile, in these extracts was studied during storage at different temperatures over 6 months. Matricine was stable at -30 degrees C. A slight decrease (80-90% recovery) occurred at +5 degrees C, whereas complete decomposition of matricine took place within 3-4 months at room temperature and at +30 degrees C, respectively. An in-line inclusion of chamomile constituents in beta-cyclodextrin (beta-CD) during the extraction process was assessed and inclusion rates between 40 and 95% were obtained depending on the amount of beta-CD and the type of chamomile constituent. No further stabilization of matricine in the carbon dioxide extract/beta-CD complexes was achieved. High residual water contents in the complexes even after freeze-drying were identified as accelerating the decomposition. In addition, the extractability of flavonoids, such as apigenin and apigenin-7-glucoside, was determined. Apigenin-7-glucoside, the more hydrophilic substance, was not extractable with pure carbon dioxide and showed a recovery of 11% using methanol modified carbon dioxide (18%, w/w) at 60 degrees C and 380 bar. Extraction conditions in the two-phase region of the binary mixture carbon dioxide-methanol (70 degrees C, 100 bar) led to a drastic change in fluid polarity and hence extractability increased to 92-95%.     

Adsorption of volatile organic compounds by pecan shell- and almond shell-based granular activated carbons

The objective of this research was to determine the effectiveness of using pecan and almond shell-based granular activated carbons (GACs) in the adsorption of volatile organic compounds (VOCs) of health concern and known toxic compounds (such as bromo-dichloromethane, benzene, carbon tetrachloride, 1,1,1-trichloromethane, chloroform, and 1,1-dichloromethane) compared to the adsorption efficiency of commercially used carbons (such as Filtrasorb 200, Calgon GRC-20, and Waterlinks 206C AW) in simulated test medium. The pecan shell-based GACs were activated using steam, carbon dioxide or phosphoric acid. An almond shell-based GAC was activated with phosphoric acid. Our results indicated that steam- or carbon dioxide-activated pecan shell carbons were superior in total VOC adsorption to phosphoric acid-activated pecan shell or almond shell carbons, inferring that the method of activation selected for the preparation of activated carbons affected the adsorption of VOCs and hence are factors to be considered in any adsorption process. The steam-activated, pecan shell carbon adsorbed more total VOCs than the other experimental carbons and had an adsorption profile similar to the two coconut shell-based commercial carbons, but had greater adsorption than the coal-based commercial carbon. All the carbons studied adsorbed benzene more effectively than the other organics. Pecan shell, steam-activated and acid-activated GACs showed higher adsorption of 1,1,1-trichloroethane than the other carbons studied. Multivariate analysis was conducted to group experimental carbons and commercial carbons based on their physical, chemical, and adsorptive properties. The results of the analysis conclude that steam-activated and acid-activated pecan shell carbons clustered together with coal-based and coconut shell-based commercial carbons, thus inferring that these experimental carbons could potentially be used as alternative sources for VOC adsorption in an aqueous environment.     

Biofixation of carbon dioxide by Spirulina sp. and Scenedesmus obliquus cultivated in a three-stage serial tubular photobioreactor

The increase in the concentration of atmospheric carbon dioxide is considered to be one of the main causes of global warming. As estimated by the Intergovernmental Panel on Climate Change (IPCC) criteria, about 10-15% of the gases emitted from the combustion coal being in the form of carbon dioxide. Microalgae and cyanobacteria can contribute to the reduction of atmospheric carbon dioxide by using this gas as carbon source. We cultivated the Scenedesmus obliquus and Spirulina sp. at 30 degrees C in a temperature-controlled three-stage serial tubular photobioreactor and determined the resistance of these organisms to limitation and excess of carbon dioxide and the capacity of the system to fix this greenhouse gas. After 5 days of cultivation under conditions of carbon limitation both organisms showed cell death. Spirulina sp. presenting better results for all parameters than S. obliquus. For Spirulina sp. the maximum specific growth rate and maximum productivity was 0.44 d(-1), 0.22 g L(-1)d(-1), both with 6% (v/v) carbon dioxide and maximum cellular concentration was 3.50 g L(-1) with 12% (v/v) carbon dioxide. Maximum daily carbon dioxide biofixation was 53.29% for 6% (v/v) carbon dioxide and 45.61% for 12% carbon dioxide to Spirulina sp. corresponding values for S. obliquus being 28.08% for 6% (v/v) carbon dioxide and 13.56% for 12% (v/v) carbon dioxide. The highest mean carbon dioxide fixation rates value was 37.9% to Spirulina sp. in the 6% carbon dioxide runs.