热回收机焦炉颗粒物排放的监测与评价

使用三套新型便携式气悬颗粒物监测仪,对某焦化厂热回收机焦炉的可吸入颗粒物(PM10)、颗粒物上附着的多环芳烃(PPAHs)和颗粒物活化表面积(AS)的浓度进行了为期5 d的实时监测。初步结果表明,该焦炉的颗粒物排放相当低,PM10平均浓度远低于国家常规机焦炉颗粒污染物排放标准;PPAHs和AS的浓度值也很低,其大气颗粒物污染程度大大低于其他形式的炼焦技术;但在5 min的推焦和装煤过程中,浓度急剧升高,值得进一步改进。

超级活性炭的制备和结构及其性能研究进展

超级活性炭是一种新型高效吸附功能材料 ,由于它具有比表面积高、微孔分布集中且吸附性能优良等优点 ,正越来越广泛地受到重视并在许多领域推广应用 .概述了超级活性炭的制备。

Fibrous activated alumina prepared through phase transformation using dawsonite as a template

Fibrous activated alumina is widely applied in catalysts,adsorbents,and composite materials.This work presents a green approach in preparing the fibrous activated Al_(2)O_(3) with high purity and specific surface area through multistep phase transformation of aluminum-bearing substances using intermediate dawsonite as a template.Thermodynamic calculations and experimental results show that increasing the concentration of Na_(2)CO_(3) and(NH_(4))_(2)CO_(3) is remarkably beneficial to the formation of dawsonite and ammonium aluminum carbonate hydroxide,respectively.Based on determination of dissolution and precipitation mechanism,the ultrafine granular gibbsite is converted to the uniform fibrous dawsonite with a ratio of length to diameter over 50,and the fibrous dawsonite changes into the long fibrous ammonium aluminum carbonate hydroxide with a ratio of length to diameter is about 80 in above 70 g/L(NH_(4))_(2)CO_(3) solution.Furthermore,the activated alumina remains fibrous morphology after roasting ammonium aluminum carbonate hydroxide at a slow heating rate,plentiful open mesopore and weak aggregation of particles,which contributes to the high specific surface area of 159.37 m^(2)/g at 1273 K for the activated alumina.The complete transformation of dawsonite to ammonium aluminum carbonate hydroxide and high specific surface area contribute to the purity of the activated fibrous alumina above 99.9%with low Na and Fe content.

Surface and Hydrogen Sorption Characteristics of Various Activated Carbons Developed from Rat Coal Mine （Zonguldak） and Anthracite

Activated carbon samples were developed from coal samples obtained from a coal mine, rat （Zonguldak, Turkey） and anthracite （Siberia, Russia）, applying pyrolysis in a temperature range of 600-900 ℃ under N2 flow, and activation using chemical agents such as KOH, NH4Cl, ZnCl2 at 650 ℃. Nitrogen adsorption at low temperature （77 K） was used to characterize the activated carbon samples, and their pore structure properties including pore volume, pore diameter and pore size distribution were determined by means of the t-plots and DFT methods. The surface area values were higher for rat coal samples than for anthracite one, and for the rat coal samples treated with KOH ＋ NH4Cl ＋ ZnCl2 at 650 °C [Rat650（2）] there are highest surface area and total pore volume, 315.6 m2·g^-1 and 0.156 ml·g^-1, respectively. The highest value of the hydrogen sorption capacity was found as 0.71% （by mass） for the rat coal sample obtained by KOH ＋ ZnCl2 treatment at 650 °C [Rat650（1）].

Regeneration of waste activated carbon after extracting gold with steam under microwave heating:Optimization using response surface methodology

The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology （RSM） technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 ℃, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m2/g, with total pore volume of 1.242 cm3/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores.

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.

Effects of coal rank, Fe_3O_4 amounts and activation temperature on the preparation and characteristics of magnetic activated carbon

Coal-based Magnetic Activated Carbons （CMAC＇s） were prepared from three representative coal samples of various ranks： Baorigele lignite from Inner Mongolia; Datong bitumite from Shanxi province; and Taixi anthracite from Ningxia Hui Auto- nomous Region. Fe3O4 was used as a magnetic additive. A nitrogen-adsorption analyzer was used to determine the specific surface area and pore structure of the resulting activated carbons. The adsorption capacity was assessed by the adsorption of iodine and methylene blue. X-ray diffraction was used to measure the evolution behavior of Fe304 during the preparation process. Magnetic properties were characterized with a vibrating-sample magnetometer. The effect of the activation temperature on the performance of CMAC＇s was also studied. The results show that, compared to Baorigele lignite and Taixi anthracite, the Datong bitumite is more appropriate for the preparation of CMAC＇s with a high specific surface area, an advanced pore structure and suitable magnetic properties. Fe304 can effectively enhance the magnetic properties and control the pore structure by increasing the ratio of meso- pores. An addition of 6.0% Fe304 and an activation temperature of 880 ℃ produced a CMAC having a specific surface area, an iodine adsorption, a methylene blue adsorption and a specific saturation magnetization of 1152.0 m2/g, 1216.7 mg/g, 229.5 mg/g and 4.623 emu/g, respectively. The coal used to prepare this specimen was Datong bitumite.

Systematic Analysis of Carbon Dioxide Activation of Waste Tire by Factorial Design

In this study, waste tire was used as raw material for the production of activated carbons through pyrolysis. ＇Fire char was first produced by carbomzation at 550℃ under nitrogen. A two tactortal design was used to optimize the production of activated carbon from tire char. The effects of several factors controlling the activation process, such as temperature （.830-930℃）, time （2-6h） and percentage ot carbon dioxide （70%-100%） were investigated. The production was described mathematically as a function of these three factors. First order modeling equations were developed for surface area, yield and mesopore volume. It was concluded that the yield, BET surface area and mesopore volume of activated carbon were most sensitive to activation temperature and time while percentage of carbon dioxide in the activation gas was a less significant factor.

Effect of nanofibers at surface of carbon fibers on microstructure of carbon/carbon composites during chemical vapor infiltration

Before densification by chemical vapor infiltration,carbon or SiC nanofibers were grown on the surface of carbon fibers by catalytic chemical vapor deposition using electroplated Ni as catalyst.The modification and mechanism of nanofibers on the pyrocarbon deposition during chemical vapor infiltration were investigated.The results show that the nanofibers improve the surface activity of the carbon fibers and become active nucleation centers during chemical vapor infiltration.They can induce the ordered deposition of pyrocarbon and adjust the interface bonding between pyrocarbon and carbon fibers during the infiltration.

Characteristics of Chemical Modified Activated Carbons from Bamboo Scaffolding

In this study, bamboo scaffolding was used to produce activated carbon by carbonization at 600 ℃ and 900 ℃with the purge of nitrogen. The 600 ℃ char was then further modified chemically by acids and alkalis by reflux for 6 hours. The produced chars were then characterized by nitrogen adsorption isotherm, He pyncometry, pH, elemental analysis and Boehm titration. For most of the chemically modified carbons, the micropore surface areas and volumes have increased compared with the 600 ~C char, while the mesopore surface areas and volumes slightly decreased, which may have been due to the dissolving of some of the permeated inorganic matter and oxidizing deposited carbon that blocks the pore openings. For the acidic modified carbons, larger amounts of acidic groups were present in the carbons after being activated by phosphoric acid, phosphoric acid furth, er treated with 2 mol-L-1nitric-acid, and calcium hydroxide. Although carbon treated with 2 mol.L-1 and 5 mol·L-1 nitric acid also produced high acidity, the surface areas and pore volumes were relatively low, due to the destruction of pores by nitric acid oxidation. The reduction of porosity may impair the adsorption capacity.

Koutecky-Levich analysis applied to nanoparticle modified rotating disk electrodes： Electrocatalysis or misinterpretation？

The application of naive Koutecky-Levich analysis to micro- and nano-particle modified rotating disk electrodes of partially covered and non-planar geometry is critically analysed. Assuming strong overlap of the diffusion fields of the particles such that transport to the entire surface is time-independent and one-dimensional, the observed voltammetric response reflects an apparent electrochemical rate o constant koapp, equal to the true rate constant ko describing the redox reaction of interest on the surface of the nanoparticles and the ratio,ψ, of the total electroactive surface area to the geometric area of the rotating disk surface. It is demonstrated that Koutecky-Levich analysis is applicable and yields the expected plots of I-1 versus ω-1 where I is the current and ω is the rotation speed but that the values of the electrochemical rate constants inferred are thereof koapp, not ko. Thus, for ψ 〉 1 apparent electrocatalysis might be naively but wrongly inferred whereas for ψ 〈 1 the deduced electrochemical rate constant will be less than ko. Moreover, the effect of ψ on the observed rotating disk electrode voltammograms is significant, signalling the need for care in the overly simplistic application of Koutecky-Levich analysis to modified rotating electrodes, as is commonly applied for example in the analysis of possible oxygen reduction catalysts.

Activated pyrolysed bacterial cellulose as electrodes for supercapacitors

In this paper, the bacterial celluloses(BCs) were pyrolysed in nitrogen and then activated by KOH to form a porous three- dimension-network electrode material for supercapacitor applications. Activated pyrolysed bacterial cellulose(APBC) samples with enlarged specific surface area and enhanced specific capacitances were obtained. In order to optimize electrochemical properties, APBC samples with different alkali-to-carbon ratios of 1, 2 and 3 were tested in two electrodes symmetrical capacitors. The optimized APBC sample holds the highest specific capacitance of 241.8 F/g, and the energy density of which is 5 times higher than that of PBC even at a current density of 5 A/g. This work presents a successful practice of preparing electrode material from environment-friendly biomass, bacterial cellulose.

Investigation of surface morphology and ion activation of aluminium implanted 4H-SiC

Multiple-energy aluminium （AI＋） implantation into 4H-SiC （0001） epilayer and activation anneal with a graphite encapsnlation layer were investigated in this paper. Measurements showed that the implanted Ak＋ box doping profile was formed and a high ion activation ratio of 78% was achieved by 40 rain annealing at 1600℃ using a horizontal chemical vapor deposition （CVD） reactor. The step bunching effect associated with the high temper：lture post implantation activation annealing （PIA） process was dramatically suppressed by using the graphite encapsulation layer. And a flat and smooth surface with a small average surface roughness （RMS） value of around 1.16 nm was achieved for the implanted 4H-SiC after the PIA process. It was demonstrated that this surface protection technique is a quite effective process for 4H-SiC power devices fabrication.

Hierarchical TiO2 photocatalysts with a one-dimensional heterojunction for improved photocatalytic activities

Hierarchical TiO2 photocatalysts with a one-dimensional heterojunction were synthesized via a facile template-free hydrothermal method. The TiO2 photo- catalysts were flower-like microspheres with a 3 μm diameter. The base structure of the flower-like microspheres was a uniform nanowire with a 10 nm diameter. Anatase films were evenly coated onto the surface of the rutile TiO2 nanowires to form a one-dimensional core--shell base structure. This kind of one-dimensional heterojunction is conducive to the separation of charge carriers. In addition, the hierarchical TiO2 microspheres possessed a good mesoporous structure with a high specific surface area of 260 m2/g. Thus, the light scattering and utilization efficiency were improved in this structure. The photocatalysts exhibited better performance in both photocatalytic oxidation and reduction reactions. Moreover, the novel TiO2 photocatalysts displayed excellent stability in these reactions. This kind of hierarchical TiO2 structure has never been reported in the literature. The hierarchical structure and one-dimensional heterojunction were vital to the increase in quantum efficiency. Therefore, these hierarchical TiO2 photocatalysts have potential applications in the environmental and energy fields, such as in photocatalytic degradation, hydrogen production, Li-ion batteries, and dye-sensitized solar cells.

Citric Acid-Enhanced Electroremediation of Toxic Metal-Contaminated Dredged Sediments： Effect of Open/Closed Orifice Condition, Electric Potential and Surfactant

Citric acid(CA), a widely used eco-friendly electrolyte, can be employed as an agent for enhancing toxic metal(TM) removal from contaminated dredged sediment using electrokinetic(EK) technology. In this study, dredged harbor sediments co-contaminated by TMs were subjected to enhanced EK treatment using a mixture of chelating agent(CA) and surfactant as an additive in the processing fluids. Several control conditions that may influence the efficiency of TM removal were tested, including open/closed sediment chamber orifices, electric potential gradients(0.5, 1.0, and 1.5 V cm^(-1)), and electrolyte surfactant. Tween 20(4 mmol L-1) was used as a surfactant within the electrolyte to investigate the extent of TM removal in sediment with high organic matter content. The results showed that an open orifice led to a greater electro-osmotic flow(EOF) with moderate TM removal. In contrast, a closed orifice with a nonionic surfactant electrolyte allowed the highest removal of TMs from the matrix. Moreover, increasing the electric potential gradient led to a higher EOF under the open orifice condition, but no significant increase in TM removal was observed owing to a higher accumulation of TMs in the middle of the matrix, caused by the opposite direction of EOF and electro-migration of metal-citrate complexes.