In situ grown nanoscale platinum on carbon powder as catalyst layer in proton exchange membrane fuel cells(PEMFCs)

An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.

Adsorption of Cholesterol on Carbon Powders

Carbon powders have the ability to remove cholesterol from solution by adsorption. Various combinations from among 12 different types of carbon powders （including two medical carbons）, having a wide range of surface area and porosity, were used to perform cholesterol adsorption experiments. The cholesterol concentration in a cyclohexane solvent （37 ~C, shaking 200 rpm） was detected at 215 nm using ultraviolet spectroscopy. Most adsorption occurred in the first 30 to 60 minutes. A Langmuir model was used to fit the amount of cholesterol adsorbed per gram of carbon. The medical carbon, Natural Elements Activated Charcoal, adsorbed 234 mg of cholesterol adsorption per gram of carbon. The experimental percentages of cholesterol removed from solution （maximum 98%） were correlated with nitrogen Branauer-Emmett-Teller （BET） surface areas and micro, meso, and macropore volume distributions. Surface area alone was not a suitable predictor of cholesterol adsorption. However, carbon powders exhibiting a large surface area along with significant meso and macropores were shown to be effective in adsorbing cholesterol from a nonpolar environment. Ingestion of a medically approved carbon powder with a large surface area and sufficient meso and macroporosity may be able to adsorb cholesterol in the intestinal tract and thereby lower cholesterol levels in the body.

Carbon and oxygen behavior in the RH degasser with carbon powder addition

For ultra-low-carbon(ULC)steel production,the higher oxygen content before Ruhrstahl-Heraeus(RH)decarburization(de-C)treatment could shorten the de-C time in the RH degasser.However,this would lead to oxidation rates being exceeded by molten steel production,affecting ULC steel surface quality.In this work,a carbon powder addition(CPA)process was proposed to reduce the dissolved oxygen content at the end of RH de-C through addition of carbon powder to molten steel in the vacuum vessel.Carbon and oxygen behavior during the CPA and conventional process was then studied.The results demonstrated that the de-C rate with CPA was lower compared to the conventional process,but the carbon content at the end of de-C presented no difference.The de-C reaction for CPA process took place in the four reaction sites:(1)within the bulk steel where the spontaneous CO bubbles form;(2)splashing area on the liquid steel surface;(3)Ar bubble surface;(4)molten steel surface.The CPA process could significantly reduce the dissolved oxygen content at the end of de-C,the sum content of FeO and MnO in the slag,the aluminum consumption,and the defect rate of rolled products.This was beneficial in improving ULC steel cleanliness.

Effect of powdered activated carbon on Chinese traditional medicine wastewater treatment in submerged membrane bioreactor with electronic control backwashing

Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors （SMBRs） operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR （CSMBR） while the other was dosed with powdered activated carbon （PAC） （PAC-amended SMBR, PSMBR）. The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d （576 h） was 5.87 L/h with average hydraulic residence time （HRT） of 5.97 h and that of PSMBR during a steady periodic state of 30 d （720 h） was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand （COD） removal efficiency of CSMBR was 89.29% with average organic loading rate （OLR） at 4.16 kg COD/（m^3.d） while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/（m^3.d）. COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry （300 mg/L）. Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.

Removal of aqueous Ni(Ⅱ) with carbonized leaf powder: Kinetics and equilibrium

Nickel is a heavy metal which has the potential threaten to human＇s health and attracts public concern recently. The carbonized leaf powder is expected as suitable adsorbent for Ni（II） removal became of the composition of some beneficial groups. In this work, carbonized leaf powder was evaluated for its adsorption performance towards Ni（II）. According to the results, adsorbent component, dosage, initial solute concentration, solution pH, temperature and contact time can significantly affect the efficiency of Ni（II） removal. Sips model fits the test results best, and the adsorption capacity towards Ni（II） is determined around 37.62 mg/g. The thermodynamic behaviors reveal the endothermic and spontaneous nature of the adsorption. The free adsorption energy （fluctuate around 8 kJ/mol） predicted by D-R model indicates that the adsorption capacity originated from both physical and chemical adsorption. Room temperature （15-25 ℃） is suitable for Ni（II） removal as well as low energy consumption for temperature enhancement. Further conclusions about the mechanism of chemical adsorption are obtained through analysis of the FT-IR test and XRD spectra, which indicates that the adsorption process occurs predominantly between amine, carbonate, phosphate and nickel ions.

Synthesis of Cordierite by Decomposition of Metal Nitrates on the Surface of Carbon Black Powder

Cordierite precursor was obtained through a process, which involved the decomposition of metal nitrates on the surface of ultrafine carbon black powder between 100-300℃ and the gasification of the carbon black at higher temperature in air. The average size of the particles, which were heat-treated at 700℃ for 10h, is about 1020nm, and the specific surface area is about 129m 2/g. The experimental results show that the ultrafine particles of cordierite precursor can be produced by this process. The precursor powder was calcined at different temperatures. X-ray diffraction examination indicates that β-quartz is crystallized from the amorphous matrix around 850℃ firstly and then MgO-Al 2O 3 spinel and α-cordierite appears. Above 1000℃, MgO-Al 2O 3 spinel and cristobalite disappear gradually and form an intermediate phase (sapphirine). At around 1300℃, the main phase is α-cordierite, and no other phase is detected.

Studies on the Behaviors of PbSO_4/Pb and PbO_2/PbSO_4 Electrodes Prepared from Lead Carbonate by Powder Microelectrode Technique

The behaviors ot PbSO4/Pb and PbO4/PbSO4 electrode prepared from PbCO3 have been examined using powder microelectrode(PME) technique and cyclic voltammetry(CV). Firstly, PMEs parked with Pb- CO3 transformed into PtSO4 PME in 1. 0 mol/L H2SO4 solution at 30 C, and then the PbSO4 in the PMEs were formed to Pb or PbO2 using an unsymmetrical signal(Qa/Qe for PbSO4/Pb electrode and Qe/Qa for PsO2/ PbSO4 electrode being 0. 1-0. 3) in 2. S mol/L H2SO4 solution. The results show that the CV characteristic of either PbSO4/Pb or PsO2/PbSO4 PME prepared from PhCO3 are as good as that of both electrodes made from lead oxide powder produced by ball mill.

Evaluation of Powdered Activated Carbon Treatment Process in Petrochemical Wastewater Purification

The powdered activated carbon treatment(PACT) process has been widely used in many industrial fields, however,very few PACT processes are built for petrochemical wastewater treatment in China. An industrial PACT unit launched in a petrochemical plant was introduced and evaluated from both the practice and mechanism study. Practically, the PACT process showed excellent capability in pollutants removal, shock resistance, toxicity tolerance, and the COD and ammoniumN in effluent of PACT unit assisted by PAC was equal to 15.5 mg/L and 0.7 mg/L lower than that without PAC addition,respectively. The wet oxidation regeneration unit was quite efficient in supplying regenerated PAC, and, however, the hard calcium sulphate scale and the high pollutant concentration solution needed to be carefully controlled. Moreover, although the carbon balance showed that the adsorption capability of regenerated PAC was negligible, the biological tests proved that the regenerated PAC increased microbe activity up to 17% more than pure activated sludge system, which was almost compatible with the fresh activated carbon.

Preparation and characterization of carbon nano-sheet powders

Carbon nanosheet films were deposited on A1 substrates by using plasma assisted chemical vapor deposition （PACVD） technique. And after being peeled off from A1 substrates, carbon nanosheet powders （CNSPs） were obtained. In Raman spectrum of carbon film, there was a strong and broadened peak at about 1,580 cm^-1, indicating a carbon diamond-like film. Atomic force microscope image showed that the carbon diamond-like film had a grain size less than 100 nm, and its surface roughness Ra was 17.95 nm in an area of 5×5 μm^2. The CNSPs were irregular sheets with curly edges and a length of several micrometers to several hundreds of micrometers. The BET surface area of CNSPs was 6.66 m^2/g with no micro-pore present, which was confirmed by N2 adsorption-desorption characterization. In the adsorption testing, when the relative pressure p/po was higher than 0.3, the adsorption behavior did not follow the Langmuir equation. The addition of CNSPs to carbon black （catalyst support） could improve hydrodesulfurization performance of carbon supported Ni-W catalysts for diesel oil.

Study on Regeneration of Powdered Activated Carbon by Electron Beam

The powdered activated carbon which had adsorbed phenylglycine solution from pharmaceutics factory can be regenerated by mean of irradiation of high-energy electron beams in oxygen, nitrogen and water vapor respectively. The effects of radiation dose and beam current on regeneration of activated carbon in different atmosphere were studied. Differential scanning calorimetry (DSC) and the iodine number of activated carbon were used to monitor the change of carbon adsorption. The results show that the powder activated carbon polluted with phenlglycine could be regenerated effectively by irradiation of high energy electron beams in nitrogen stream. The generation did not need high temperature, and the weight loss of carbon and energy consumption were minimum.

Pilot Study on Powder Active Carbon / Flotation/Microflocculation / Ultrafiltration Combined Process for Treatment of Reservoir Water

[Objective] The study aimed to discover the effects of powder active carbon（ PAC） /flotation /micro-flocculation /ultrafiltration combined process on the treatment of reservoir water. [Method]Taken the water from a mountainous reservoir for the initial samples,the parameters such as turbidity,COD Mn,chlorophyll-a and methylisobormeol（ MIB） of water samples were monitored before and after treated with combined processes of micro-flocculation /ultrafiltration, flotation /micro-flocculation /ultrafiltration, PAC /flotation /micro-flocculation /ultrafiltration. [Result] The results showed that the removal rates of turbidity of water samples by the above three processes were 97. 5%,98. 0% and 98. 6%,respectively. The removal rates of COD Mn were 30. 9%,35. 0% and 52. 0%. The removal rates of chlorophyll-a were 80. 6%,91. 0% and 99. 0%. The removal rates of MIB were 17. 0%,34. 2% and 97. 0%. [Conclusion]The PAC /flotation /micro-flocculation ultrafiltration combined process can be flexibly combined based on the characteristics of algae and odor in water,and is suitable for water plant construction or reconstruction.

THERMAL DECOMPOSITION OF ZINC CARBONATE HYDROXIDE HYDRATE POWDERS OF DIFFERENT PARTICLE SIZE AND SAMPLE MASS

ＴＨＥＲＭＡＬＤＥＣＯＭＰＯＳＩＴＩＯＮＯＦＺＩＮＣＣＡＲＢＯＮＡＴＥＨＹＤＲＯＸＩＤＥＨＹＤＲＡＴＥＰＯＷＤＥＲＳＯＦＤＩＦＦＥＲＥＮＴＰＡＲＴＩＣＬＥＳＩＺＥＡＮＤＳＡＭＰＬＥＭＡＳＳ①ＣｈｅｎＪｉａｎｘｕｎ，ＺｈａｏＲｕｉｒｏｎｇａｎｄＪｉａｎ...

Adsorption Characteristics of the Powdered Activated Carbon on Pesticide in the Water

The adsorption characteristics of the powdered activated carbon on four kinds of pesticides （ dichlorvos, chlorothalonil, lindane and chlorphyrifos） were studied, and the influential factors of adsorption effect were discussed. Results showed that the powdered activated carbon could effectively remove the above four kinds of pesticides. It was rapid adsorption period before 30 min, and removal rate has reached 90%. Adsorption kinetics of the powdered activated carbon on pesticides corresponded with quasi-two-level kinetic equation, and both Freundlich and Langmuir adsorption isotherms could simulate the adsorption process of the activated carbon on pesticide well. Competitive adsorption between small-molecule organics in the water diverting from Yellow River and Desticides on microDore of the activated carbon would occur.

Dispersion of multiwalled carbon nanotubes in aluminum powders

Multiwalled carbon nanotubes (MWNTs) were treated with the reflux within the concentrated nitric acid for 0-25 h to purify and disperse the tangled MWNTs. The effect of reflux time on the morphology and the weight loss of MWNTs were investigated. Meanwhile,the dispersion of MWNTs with 0-2.0 wt.% in 2024Al powders using mechanical stirring with an assisting ultrasonic shaker in ethanol was also studied. The results show that the reflux time markedly affects the morphology of MWNTs. The weight loss of MWNTs i...

Fast adsorption of microcystin-LR by Fe(Ⅲ)-modified powdered activated carbon

Microcystins(MCs) are cyclic hepatotoxic peptides produced by the bloom-forming cyanobacterium Microcystis and present a public health hazard to humans and livestock. The removal of MCs from contaminated water with powdered activated carbon(PAC) has been employed as a simple and economic treatment strategy. In this study, PAC-Fe(Ⅲ) was prepared and utilized for the fast and efficient removal of MCs from water. PAC-Fe(Ⅲ) exhibited superior microcystin-LR(MC-LR) removal capacity and efficiency compared to the unmodified PAC. The MC-LR removal efficiency of PAC-Fe(Ⅲ) increased with decreasing p H within the pH range of 4.3 to 9.6. PAC-Fe(Ⅲ) could be reused for 3 times by methanol elution while the MC-LR removal efficiency was still over 70 percent. The removal efficiency was positively correlated to the ionic strength of water and negatively correlated to alkalinity. Natural organic matter(NOM) such as humic acid(HA) and salicylic acid(SA) generated low interference with MC-LR adsorption by PAC-Fe(Ⅲ). The complexation reaction between Fe^(3+) in PAC-Fe(Ⅲ) and the functional groups of MCLR was suggested as the key mechanism of MC-LR removal by PAC-Fe(Ⅲ). The results suggest that Femodified PAC is a promising material for the treatment of MC-contaminated waters.

Early Carbonation Behavior of High-volume Dolomite Powder-cement Based Materials

Combined with DTG analysis, X-Ray diffraction analysis （XRD） and field emission scanning electron microscopy analysis （FSEM） affiliated with energy dispersive spectrometer analysis （EDS）, the early hydration and carbonation behavior of cement paste compacts incorporated with 30% of dolomite powder at low water to cement ratio （0.15） was investigated. The results showed that early carbonation curing was capable of developing rapid early strength. It is noted that the carbonation duration should be strictly controlled otherwise subsequent hydration might be hindered. Dolomite powder acted as nuclei of crystallization, resulting in acceleration of products formation and refinement of products crystal size. Therefore, as for cement-based material, it was found that early carbonation could reduce cement dosages to a large extent and promote rapid strength gain resulting from rapid formation of products, supplemental enhancement due to water release in the reaction of carbonation, and formation ofnanometer CaCO3 skeleton network at early age.

Modification of Carbon Nanotube Powder Microelectrode and Nitrite Reduction

The properties of the carbon nanotube powder microelectrodes (denoted CNTPME) are remarkably altered by anodic pretreatment and preadsorption of mediators. It seems that anodic pretreatment leads the long and tangled carbon nanotubes to be partially cut shorter, resulting in more openings as shown by TEM. Besides, the anodic pretreatment may adjust the hydrophobicity of nanotubes to match with that of Os(bpy)32+. As a result, the real surface area and the ability of adsorbing mediator Os(bpy)32+ of the nanotubes are markedly increased so as to effectively catalyze NO2- reduction in acidic solution.

Effect of Spherical Ni Powder on Microstructure of Secondary Carbon in MgO-C Refractories Matrix

In order to tackle the shortcomings of high brittleness,hard graphitization,and poor oxidation resistance resulted from carbonization of phenolic resin of Mg O- C refractories, effects of 2 mass% spherical Ni, and2 mass% spherical Ni plus 7. 5 mass% Al composite powder on microstructure of the secondary carbon in Mg O- C refractories matrix were investigated. The results show that a large number of carbon whiskers form after the carbonization of phenolic resin with Ni powder;in the Mg O- C refractories matrix with only Ni powder,the carbon microspheres form at all treatment temperatures and change slightly with the temperature rising;the carbon whiskers begin to generate in the specimens with composite powder at 1 000 ℃,the diameter of the carbon whiskers is about 0. 4- 0. 5 μm,and the length is about 3- 4 μm,and the formed carbon whiskers increase gradually with the temperature rising.

Development and application of fluorine-free mold powder for low carbon steel

Fluorine in mold powder is known as harmful to human health and the environment. Being the advocate of green production, Baosteel developed an environmentally friendly mold powder without fluorine. The main problem of fluorine-free flux film is small heat resistance and thus the heat transfer intensity of the mold is too large, which to some extent hinders the increase of the casting speed. With the heat flow simulation equipment, controlling precipitation of crystal in flux and solidification temperature properly, fluorine-free mold powder for low carbon steel,which substitutes F with B203 ,was successfully developed and applied in industrial production. The production results show that, by using boronic fluorine-free mold powder,the boron increment in molten steel is less than 1.3ppm for conventional aluminium killed low carbon steel.

Distribution of Colloidal and Powdered Activated Carbon for the <i>in Situ</i>Treatment of Groundwater

The use of in situ technologies for the treatment of groundwater containing various compounds of concern are widely accepted. These technologies include chemical reduction, chemical oxidation, anaerobic and aerobic bioremediation, and adsorption, among others. One requirement for the successful application of these technologies is the delivery of the remedial reagent(s) to the compounds of concern. A rapidly evolving in situ technology is the injection of adsorptive media such as activated carbon and ion-exchange resin including powdered or colloidal activated carbon. Activated carbon has a long-demonstrated history of effectiveness for the removal of various organic and inorganic compounds in above ground water treatment systems. However, due to constraints related to the particle size and physical properties of the activated carbon, the in situ application of activated carbon has been limited. Recent developments in the manufacturing of activated carbon have created a smaller particle size allowing activated carbon to be applied in situ. To evaluate if powdered and colloidal activated carbon can be effectively distributed in aquifers, the two types of carbon were injected using direct push technology adjacent to each other at four sites with varying geology. Evaluation of distribution was completed by sampling the aquifer prior to and post-injection for total organic carbon. The results of the studies indicated that both forms of activated carbon were effectively delivered to the targeted injection zones with both carbon types being detected at least seven meters away from the point of injection. The colloidal form of the activated carbon showed good distribution throughout the four targeted zones of injection with 93 percent of the samples collected having colloidal activated carbon present within them whereas the powdered activated carbon cells were more susceptible to aquifer heterogeneity with only 67 percent of the samples collected having activated carbon present. Preferential accumulation of activated carbon was observed in high horizontal hydraulic conductivity seams, especially within the powdered activated carbon cells. These results suggested that the powdered form of activated carbon was more suspectable at the four sites to heterogeneity within the aquifer than the colloidal form of activated carbon. Sampling of monitoring well screens installed prior to the injection of the two forms of activated carbon showed preferential accumulation of powdered activated carbon within the sand pack, which could result in sampling bias.