Low temperature solid-phase sintering of sintered metal fibrous media with high specific surface area

A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting process were first plated with a coarse copper coating layer by electroless plating process.A low-temperature sintering process was then completed at about 800 °C for 1 h under the protection of hydrogen atmosphere.The results show that a novel SMFM with complex surface morphology and high specific surface area（0.2 m2/g） can be obtained in this way.The effect of sintering temperature on the surface morphology and specific surface area of SMFM was studied by means of scanning electron microscopy and Brunauer-Emmett-Teller.The damage of micro-structure during the sintering process mainly contributed to the loss of specific surface area of SMFM and the optimal sintering temperature was 800 °C.

Metal-Free C_(3)N_(4) with plentiful nitrogen vacancy and increased specific surface area for electrocatalytic nitrogen reduction

As a substitute for synthetic ammonia under mild condition, electrocatalytic nitrogen reduction reaction(NRR) provides a hopeful approach for the development of ammonia. Nevertheless, the current development of NRR electrocatalysts is far from enough and a systematic research is needed to gain a better improvement. This article presents that 2 D C_(3)N_(4)-NV with a large specific surface area and abundant nitrogen vacancies is prepared by a simple and feasible method, and used as a metal-free catalyst for electrocatalytic NRR. Experiment result and density functional theory(DFT) calculation reveal that nitrogen vacancies in 2 D C_(3)N_(4)-NV can act as an efficient active site for catalytic NRR, which is conducive to capturing and activating N_(2), lowering Gibbs free energy(DG) in reaction and inhibiting hydrogen evolution reaction(HER) at the same time. In addition, the larger specific surface area also makes more active site exposed, which is good for the contact between the electrolyte and the active site, thus enhancing its NRR activity. The electrocatalyst shows an excellent catalytic activity for NRR in 0.1 M HCl, including Faradaic efficiency of 10.96%, NH_(3) yields of 17.85 lg h^(-1) mg_(cat)^(-1)., and good stability(over 20 h).

Nickel catalysts supported on MgO with different specific surface area for carbon dioxide reforming of methane

In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.

Study on Preparation of Rice Husk Ash with High Specific Surface Area and Its Chemical Reactivity

Preparation of rice husk ash with high specific surface area and chemical reactivity of the product are reported in this paper. The amorphous rice husk ash with high specific surface area of 311 m2·g-1 was produced by heating acid treated rice husk at 700℃ for 4 h. The isotherms of rice husk ash are similar in shape to type Ⅱof Brunaner's classification with mesopores being predominant. The rice husk ash has a high chemical reactivity,especially that pretreated with acid. This chemical reactivity depends on ashing temperature and pretreatment conditions. There is an exponential relation between the specific surface area of rice husk ash and the change in the conductivity of saturated Ca(OH)2 solution with rice husk ash, from which the specific surface area can be known according to the conductivity change.

Relationship between the specific surface area of rust and the electrochemical behavior of rusted steel in a wet–dry acid corrosion environment

The relationship between the specific surface area（SSA） of rust and the electrochemical behavior of rusted steel under wet-dry acid corrosion conditions was investigated. The results showed that the corrosion current density first increased and then decreased with increasing SSA of the rust during the corrosion process. The structure of the rust changed from single-layer to double-layer, and the γ-FeOOH content decreased in the inner layer of the rust with increasing corrosion time; by contrast, the γ-FeOOH content in the outer layer was constant. When the SSA of the rust was lower than the critical SSA corresponding to the relative humidity during the drying period, condensed water in the micropores of the rust could evaporate, which prompted the diffusion of O_2 into the rust and the following formation process of γ-FeOOH, leading to an increase of corrosion current density with increasing corrosion time. However, when the SSA of the rust reached or exceeded the critical SSA, condensate water in the micro-pores of the inner layer of the rust could not evaporate which inhibited the diffusion of O_2 and decreased the γ-FeOOH content in the inner rust, leading to a decrease of corrosion current density with increasing corrosion time.

Effects of Specific Surface Area and Impurities of Reactive Alumina on Properties of Corundum Based Castables

Effects of specific surface area and tiny amount of impurities of reactive alumina on the workability, sinte- ring and high temperature mechanical strength of corun- dum based castables were investigated. The results show that the presence of reactive alumina with high specific surface area leads to accelerating of the hydration of calcium aluminate cement, thus shortening the working time and setting time of the castables, which can be as- cribed that the critical energy barrier for stable nuclei of hydration products of cement can be reduced by the high specific surface area of reactive alumina. The sintering of the corundum based castables can be accelerated by the reactive alumina with high specific surface area and high amount of impurities, however, the reactive alumina with too high specific surface area and impurities can al- so lead to noticeable shrinkage of castables. In addition, high temperature mechanical strength of corundum based castables can be decreased by the higher amount of trace impurities of reactive alumina due to formation of low- melting phase at high temperatures.

Measurement of Specific Surface Area of Ceramisite Made from River Sediment

Principle and method of measuring Specific Surface Area (SSA) of ceramisite made from dredged river sediment, sewage sludge and adherent materials are discussed. Brunauer-Emmett-Teller Procedure tests SSA of the ceramisite. Influences of sewage sludge content, adherent content and sintering point on the SSA of ceramisite made of river sediment are also analyzed. Results show that with the right sewage sludge content, adherent content and sintering point, the ceramisite can have the highest SSA value and be widely used.

A statistical reappraisal of the relationship between liquid limit and specific surface area, cation exchange capacity and activity of clays

More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2 values ranging between 0.71 and 0.92.Independent data were also used to validate the correlations.Estimated SSA values slightly overestimate the measured SSA up to 100 m^2/g.Regarding the estimated CEC values,they overestimated the measured CEC values up to 20 meq/(100 g).A probabilistic approach was performed for the correlations of SSA,CEC and activity versus LL.The analysis shows that the relations of SSA,CEC and activity with LL are robust.Using the LL values,it is possible to assess other basic engineering properties of clays.

Preparation of activated carbon with low ash content and high specific surface area from coal in the presence of KOH

An activated carbon with ash content less than 10% and specific surface area more than 1 600 m 2 /g was prepared from coal and the effect of K containing compounds in preparation of coal based activated carbon was investigated in detail in this paper. KOH was used in co carbonization with coal, changes in graphitic crystallites in chars derived from carbonization of coal with and without KOH were analyzed by X ray diffraction (XRD) technique, activation rates of chars with different contents of K containing compounds were deduced, and resulting activated carbons were characterized by nitrogen adsorption isotherms at 77 K and iodine numbers. The results showed that the addition of KOH to the coal before carbonization can realize the intensive removal of inorganic matters from chars under mild conditions, especially the efficient removal of dispersive quartz, an extremely difficult separated mineral component in other processes else. Apart from this, KOH demonstrates a favorable effect in control over coal carbonization with the goal to form nongraphitizable isotropic carbon precursor, which is a necessary prerequisite for the formation and development of micro pores. However, the K containing compounds such as K 2 CO 3 and K 2 O remaining in chars after carbonization catalyze the reaction between carbon and steam in activation, which leads to the formation of macro pores. In the end an innovative method, in which KOH is added to coal before carbonization and K containing compounds are removed by acid washing after carbonization, was proposed for the synthesis of quality coal based activated carbon.

Effects of specific surface area of metallic nickel particles on carbon deposition kinetics

Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I（D）/I（G） of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.

Surface distribution of alkalinity and specific alkalinity and their application to water mass tracing in Kuroshio area of the East China Sea

Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea Coastal Current.

Nitrogen and sulfur dual-doped high-surface-area hollow carbon nanospheres for efficient CO2 reduction

The electrochemical reduction of CO2(CO2 RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials(SZ-HCN) as CO2 RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl2 was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area(1510 m2 g–1) exhibited efficient electrocatalytic activity and selectivity for CO2 RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO2-to-CO reduction with a high CO Faradaic efficiency(~93%) at-0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO2-to-CO reduction, thereby enhancing CO2 RR activity.

Allometric equations for estimating leaf area index(LAI) of two important tropical species(Tectona grandis and Dendrocalamus strictus)

Leaf area index（LAI） of Teak（Tectona grandis） and Bamboo（Dendrocalamus strictus） grown in Shoolpaneshwar Wildlife Sanctuary of Narmada District,Gujarat,India was obtained by destructive sampling,photo-grid method and by litter trap method.An allometric equation（between leaf area by litter trap method and canopy spread area） was developed for the determination of LAI.Results show that LAI value calculated by the developed allometric equation was similar to that estimated by destructive sampling and photo-grid method,with Root Mean Square Error（RMSE） of 0.90 and 1.15 for Teak,and 0.38 and 0.46 for Bamboo,respectively.There was a perfect match in both the LAI values（estimated and calculated）,indicating the accuracy of the developed equations for both the species.In conclusion,canopy spread is a better and sensitive parameter to estimate leaf area of trees.The developed equations can be used for estimating LAI of Teak and Bamboo in tropics.

Preparation of High Surface Area, Large Pore Volume Alumina by Using β-Cyclodextrin as a Non-surfactant Template

A series of alumina samples were prepared using β-cyclodextrin as the non-surfactant template. These samples were characterized by XRD, BET and TEM. The results showed that the alumina samples prepared using β-cyclodextrin template had the higher surface areas （124-484 m^2/g）, larger pore volumes （0.7-1.27 mL/g） and more thermal stability than samples prepared without using β-cyclodextrin.

Experimental Study on the Chloride Ion Concentration of Cement Pastes Prepared with Limestone Powder

To investigate the impact of limestone powder on the chloride ion concentration coefficient of cement pastes,various techniques such as scanning electron microscopy(SEM),X-ray diffraction(XRD),thermogravimetric analysis(TGA),and mercury-porosimetry(MIP)were employed in this paper.The findings demonstrate that the creation of Friedel's salt is inversely associated with the addition of limestone powder,that is,Friedel's salt production is lessened by adding more limestone powder,however,the coefficient of chloride ion concentration initially decreased and then increased again,as does the porosity,and most likely the pore size as well.The specific surface area of limestone powder has increased,and the content of Friedel’s salt increased first and then decreased.However,the shifting trend of Friedel's salt and chloride ion concentration coefficient is in direct opposition,and the pore structure was therefore significantly enhanced.The results of this study offer robust theoretical backing for the inclusion of limestone powder in concrete and provide a positive assessment of its potential applications.

Copper oxide foam with high specific surface area for electrocatalytic reduction of CO_(2)to C_(2+)products

The carbon dioxide reduction reaction(CO_(2)RR)for the synthesis of high-energy-density and high-value multi-carbon(C_(2+))products has demonstrated consider-able potential for practical applications.In this work,we design a novel copper oxide foam(OD-Cu foam)catalyst through a high-temperature calcination pro-cess,characterized by a substantial specific surface area.The distinctive three-dimensional structure of the OD-Cu foam catalyst and the metal oxide particles covered on its surface provide abundant active sites.The total Faradaic efficiency of 57.3%for C_(2+)products over the OD-Cu foam is achieved at-0.85 V versus reversible hydrogen electrode(RHE).Furthermore,the partial current density for C_(2+)products over the OD-Cu foam reaches 44.1 mA cm^(-2)at-0.95 V versus RHE,surpassing significantly that both of Cu foam(3.4 mA cm^(-2))and copper oxide foil(OD-Cu foil)(1.6 mA cm^(-2)).In addition,the integrated structure of the OD-Cu foam,which does not require complex preparation processes,facilitates its application in CO_(2)RR.These results underscore the significance of three-dimensional structure and high specific surface area,emphasizing the consider-able potential of this catalyst for effective and sustainable CO_(2)conversion.

Variation of SPAD values in uneven-aged leaves of different dominant species in Castanopsis carlessi forest in Lingshishan National Forest Park

The greenness （SPAD） of uneven-aged leaves of dominant species in the Castanopsis carlessi forest at different altitude gradients in Lingshishan National Forest Park, Fujian Province, China were measured by using portable chlorophyll meter SPAD-502. In addition, the correlation between SPAD value and the concentration of chlorophyll and foliar nitrogen was also investigated. Significant variations in SPAD values were found between the uneven-aged leaves of different dominant species and different altitude gradients. Regression analysis showed that SPAD value was significantly correlated with the concentration of chlorophyll and the content of foliar nitrogen, indicating that SPAD value could be indicators for foliar chlorophyll and nitrogen. It is suggested that SPAD meter is a useful tool for forest assessments in decision-making and operational nutrient management programs.

EXPERIMENTAL STUDY ON ULTRAFINE COMMINUTION IN THEORY OF VERTIGINOUS CURRENT OF BULK MATERIAL

Experiment about ultrafine comminution in theory of vertiginous current of bulk material has successfully performed by a lately developed vertical shaft centrifugal autogenous grinder. The results of tested several materials are analyzed, moreover. the comminution mechanism and the affecting factors of ultrafine comminution are analyzed.

RESEARCH ON CLEANUP AND ACTIVATION OF SEPIOLITE

A simple process of purifying and activating sepiolite is introduced. Impure minerals in sepiolite can be removed by fully agitating the sepiolite suspension to which a few amount of disperser has been added. After being purified and activated, fine sepiolite particles present prior properties such as increased specific area,better dispersiveness and increased adsorptivity, moreover, the pulping ratio can be raised from original 4-5m3/2 to 20m3 /t. The process with simple technique and utilizing cheap chemical agents extends the application of low-grade sepiolite.

Adsorption Isotherm of BET Nitrogen of Concretes with Consolidated Soil by Sugar Cane Molasses

Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the dust.Nitrogen physical adsorption has allowed us to collect information on the state of the accessible total area according to the quantity of sugar cane molasses.The adsorption isotherms,the specific area,the adsorbed quantity of nitrogen on a Qm mono layer,the number of molecules constituting the adsorbed sugar cane molasses(n′)have been examined.The obtained results show that the quantity of sugar cane molasses in the material does not modify the adsorption isotherm of nitrogen of type IV that remains and a hysteria loop of type H4 in all samples,this justifies the monocoat-multicoat adsorption mechanism with capillary condensation and mesopores presence in the structure of materials.Materials with elaborated raw soil by clayey fine soil used are mesoporous materials.More of 50×1018 molecules constituting sugar cane molasses occupy the extreme area accessible to soil clay,without occupying on accessible sites.