炭基催化剂用于处理H2S的研究进展＊

介绍了国内外在常温下处理硫化氢等恶臭气体的炭基催化剂的研究进展情况,分析了炭基催化剂中活性炭、活性炭纤维、超级活性炭的特性及国内外应用现状,从工艺技术、成本、环保等几方面总结了此类常温脱硫催化剂的应用情况和优缺点,并对炭基脱硫催化剂未来的应用空间和发展方向进行了展望。     

活性炭烟气脱硫技术研究新进展

研制了新型活性炭脱硫剂－脱硫活性碳纤维。研究表明，脱硫活性碳纤维由于含碳量高、比表面积大、微孔丰富、孔径分布窄、有较多适于吸附ＳＯ２的表面官能团，因而吸附能力及吸附、脱附速度显著大于普通活性炭。在相同工艺条件下，脱硫活性碳纤维吸附容量为粒状疾性炭的４－５倍，空速粒达活性炭的１０倍。采用活性碳纤维脱硫可比普通活性碳脱硫剂用量成倍减少。另外，由于活性碳纤维阻力小，系统能耗可显著降低。活性碳烟气脱硫采用     

水热法合成催化氧化高含硫废水的Ni-MnO2/Al2O3制备条件优化

针对油气田高含硫废水快速氧化处理的需求,以Ni为金属助剂,MnO2为活性组分,采用水热法制备了Ni-MnO2/Al2O3催化剂,通过对高含硫废水催化氧化性能的研究优化了Ni-MnO2/Al2O3的制备条件。BET、XPS、SEM表征结果表明,Ni与Mn摩尔比对催化剂的比表面积变化影响最大,摩尔比为2:10时催化剂的比表面积最大为232.5m2/g,吸附氧和晶格氧的比例高达2.02;水热温度影响催化剂的形貌,低温时以棒状结构为主,110℃时形成有序的片状结构,过高的温度会引起晶粒的团聚;较大的比表面积、丰富的多孔结构及高的吸附氧是催化活性高的主要原因。因此,在Ni与Mn摩尔比为2:10、水热温度为110℃、水热时间为12ｈ、焙烧温度为400℃的条件下制备的Ni-MnO2/Al2O3催化剂具有最高的催化活性,对于硫离子浓度为3000mg/L的废水,90min后的硫离子转化率高达96.6％,对含硫废水的处理效果最好。     

多金属微电解法处理腈纶废水研究

文章通过实验室废水处理实验,研究不同反应条件对纳米化处理的多金属微电解催化剂性能的影响。结果表明：催化剂散装、曝气强度中等、20℃、pH为酸性条件下,反应效果较好,CODc,去除率最高可达60％,TOC的去除率最高可达50％,长时间反应有助于提高废水可生化性。催化剂使用一段时间后,比表面积下降,孔径增大;推测反应机理为污染物首先吸附在催化剂上,在多金属微电解的作用下污染物发生降解反应,长时间烘干有利于催化剂活性的恢复。     

改性椰壳活性炭对工业废水中氨氮的吸附行为研究

为高效去除工业废水中的氨氮化合物,采用椰壳活性炭为原材料,通过碱性溶液改性制备高性能吸附剂。通过表面特征分析发现2 mol/L氢氧化钠改性后的椰壳活性炭孔体积和吸附平均孔径最小,比表面积最大;分析不同体系温度对改性活性炭吸附性能的影响,结果表明：温度对于氨氮的吸附效率影响较大,在35℃时的吸附效果最优,利用等温吸附模型Langmuir方程拟合得到计算理论吸附量为38.8 mg/g;改性椰壳活性炭的吸附行为符合准二级动力学模型,进一步表明椰壳活性炭对废水中氨氮化合物的吸附是易于发生的化学吸附过程。由此可见,改性椰壳活性炭作为一种高性能吸附材料,在去除水中的氨氮化合物方面具有良好的应用价值。     

介孔材料在水处理中的应用

介孔材料由于具有一系列独特的性质,如较高比表面积、较大且连续可调的孔径等,使其在化工、医药、环境保护、纳米功能材料等领域得到了广泛的研究和应用。本文从介孔材料作为吸附剂和催化剂两个方面综述了其在水处理中的应用,并对应用中存在的问题和前景作了分析。     

介孔过渡金属氧化物的合成、改性及在水处理中应用研究

介孔过渡金属氧化物以较大的孔径和比表面积、多变价态和多活性位点等优势得到广泛关注。介绍了介孔过渡金属氧化物的发展现状,简述了以模板法为代表的合成及改性方法,并从催化、吸附和消毒3个方向简述了其在水处理中的应用及研究展望。     

新型L沸石在FCC汽油加氢脱硫催化剂中的应用研究

采用等体积浸渍法,制备了一系列含有相同含量活性组分(MoO3、CoO和NiO)不同USL沸石含量的加氢脱硫催化剂。通过X-射线衍射(XRD)、氮气吸附脱附、吡啶红外(Py-FTIR)和氨气程序升温脱附(NH3-TPD)等分析方法对样品进行了表征。结果表明:与Cat.0(参比剂,仅以γ-Al2O3为载体)相比,添加USL沸石催化剂所得加氢油的烯烃含量、芳烃含量和研究法辛烷值(RON)均增加;仅当催化剂载体中USL沸石加量在0~40m%之间变化时,加氢油的异构烷烃含量呈上升趋势;而当载体中USL沸石添加量在0~20m%之间变化时,催化剂的脱硫率有所升高。综合对比,当载体中USL沸石添加量约为40m%,催化剂具有最佳的综合性能指标,脱硫率达90%,RON损失仅为1.5左右。     

活性炭纤维复合材料的脱硫性能

本实验以粘胶基活性炭纤维和酚醛树脂复合，制备出了一种可用于烟气脱硫的活性炭纤维复合材料（ACFM），考察了制备工艺条件对脱硫性能和比表面积的影响，测试其在填充床的压降。结果表明：粘结剂用量、炭化及活化条件对样品的脱硫性能和比表面积有较大的影响；与其他活性炭材料相比ACFM压降相对较低，只有活性炭纤维的1／20。     

水蒸气活化烟杆制造活性炭及孔结构表征

以烟杆为原料，以水蒸气为活化剂，采用正交实验研究了水蒸气流量、活化时间和活化温度对活性炭得率和吸附性能的影响，最佳工艺条件为活化温度900℃，时间为30分钟，水蒸气流量3．09mL／min，在此条件下制得活性炭产品的碘吸附值为946．52mg／g，亚甲基蓝吸附值为21mL／0，1g，得率为32．64％。同时测定了该活性炭的氮吸附等温线，并通过BET、H-K方程、D-A方程和密度函数理论（DFT）表征了活性炭的孔结构。结果表明：该活性炭为微孔孔型，BET比表面积为1044m^2／g，总孔体积为0．5870mL／g，微孔体积占总孔体积的72．03％，中孔占26．92％。大孔占1．05％。     

Adsorption of pesticides onto quartz, calcite, kaolinite, and alpha-alumina

The fate of pesticides in aquifers is influenced by the small but not insignificant adsorption of pesticides to mineral surfaces. Batch experiments with five pesticides and four minerals were conducted to quantify the contributions to adsorption from different mineral surfaces and compare adsorption characteristics of selected pesticides. Investigated mineral phases included quartz, calcite, kaolinite, and alpha-alumina. Selected pesticides comprised atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine), isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea)], mecoprop [(RS)-2-(4-chloro-2-methylphenoxy)propionic acid], 2,4-D (2,4-dichlorophenoxyacetic acid), and bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide]. Specific surface area and mineral surface charge proved to be important for the adsorption of these pesticides. Detectable adsorption of the anionic pesticides (mecoprop, 2,4-D, and bentazone) was only measured when positive sites were present on the mineral surface. However, when CaCl2 was added as an electrolyte, a detectable adsorption of mecoprop and 2,4-D was also measured on kaolinite (which exhibits a negative surface charge), probably due to formation of Ca-pesticide--surface complexes. Adsorption of the uncharged pesticides (atrazine and isoproturon) was detected only on kaolinite. The lack of adsorption on alpha-alumina indicates that the uncharged pesticides have a greater affinity for the silanol surface sites (=SiOH) than for the aluminol surface sites (=AlOH) in kaolinite. No measurable effect of ionic strength was found for the uncharged pesticides. The results indicate that quartz and calcite play a smaller role than clay minerals.     

Relationship between metal speciation in soil solution and metal adsorption at the root surface of ryegrass

The total metal content of the soil or total metal concentration in the soil solution is not always a good indicator for metal availability to plants. Therefore, several speciation techniques have been developed that measure a defined fraction of the total metal concentration in the soil solution. In this study the Donnan Membrane Technique (DMT) was used to measure free metal ion concentrations in CaCl(2) extractions (to mimic the soil solution, and to work under standardized conditions) of 10 different soils, whereas diffusive gradients in thin-films (DGT) and scanning chronopotentiometry (SCP) were used to measure the sum of free and labile metal concentrations in the CaCl(2) extracts. The DGT device was also exposed directly to the (wetted) soil (soil-DGT). The metal concentrations measured with the speciation techniques are related to the metal adsorption at the root surface of ryegrass (Lolium perenne L.), to be able to subsequently predict metal uptake. In most cases the metal adsorption related pH-dependently to the metal concentrations measured by DMT, SCP, and DGT in the CaCl(2) extract. However, the relationship between metal adsorption at the root surface and the metal concentrations measured by the soil-DGT was not-or only slightly-pH dependent. The correlations between metal adsorption at the root surface and metal speciation detected by different speciation techniques allow discussion about rate limiting steps in biouptake and the contribution of metal complexes to metal bioavailability.     

Effects of alkali promoters on the textural and catalytic properties of mesoporous Fe–Al–Cu catalysts for water gas shift reaction

Mesoporous Fe₂O₃–Al₂O₃–CuO catalysts promoted with alkali oxides were synthesized and used in water gas shift reaction (WGSR) at high temperatures for hydrogen purification. These chromium-free catalysts were characterized using nitrogen adsorption/desorption, hydrogen temperature programmed reduction, X-ray diffraction (XRD), and transmission electron microscopy techniques. The synthesized catalysts with narrow single-modal pore size distribution in mesopore region possessed high specific surface area. The catalytic results revealed that except Cs, the addition of other alkali promoters declined the catalytic activity. However, all catalysts showed higher catalytic performance than the conventional commercial catalyst. The results showed an optimum content of Cs promoter (3 wt.%) for the promoted Fe–Al–Cu catalyst (3 wt.% Cs-FAC), which exhibited the highest activity in WGSR at high temperature.     

HYDROLOGY OF A SMALL IMPOUNDMENT AND WATERSHED IN CENTRAL OKLAHOMA1

ABSTRACT: West Bitter Creek floodwater retarding structure site 3 in South Central Oklahoma was instrumented and records obtained and analyzed to obtain information concerning an impoundment water budget that is useful to landowners and designers of these impoundments. On-site loss of water from the impoundment was only 17 percent of the inflow during three years when the annual precipitation averaged 26 inches and the annual inflow averaged 1.4 inches. Runoff from an eroded area with no farm ponds was about 70 percent greater per unit area than from a portion of the watershed where 71 percent of the drainage area was controlled by farm ponds. A previous study indicated, however, that the ponds were reducing runoff only 13 percent. Loss of top soil increases runoff considerably. Only 24 percent of the total runoff into the impoundment was base flow. The flow rate into the impoundment was less than 0.05 cfs 70 percent of the time, and the inflow rate exceeded 10 cfs only 1 percent of the time. SCS runoff curve numbers varied between 57 and 96 for the impoundment watershed with an inverse relation between precipitation amount and curve number apprently caused by partial area runoff from impervious and semi-impervious areas. A comparison of measured event runoff versus event runoff computed by the SCS curve numbers gave an r² of only 0.44. However, the total computed surface runoff for eight years of record was less than 1 percent below the measured runoff which indicated the curve number method was a good tool for predicting long term runoff for the watershed.     

Performance of a small-scale solar-powered adsorption cooling system

In this study, an experimental investigation on the performance of a small-scale residential-size solar-driven adsorption (silica gel-water) cooling system that was constructed at Assiut University campus, Egypt is carried out. As Assiut area is considered as hot, arid climate, field tests for performance assessment of the system operation during the summer season are performed under different environmental operating conditions. The system consists of an evacuated tube with a reflective concentration parabolic surface solar-collector field with a total area of 36 m², a silica gel-water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water thermal storage tanks of 1.8 and 1.2 m³ in volume, respectively. The results of summer season field test show that under daily solar insolation varying from 21 to 27 MJ/m², the solar collectors employed in the system had high and almost constant thermal efficiency. The daily solar-collector efficiency during the period of system operation ranged from about 50% to 78%. The adsorption chiller performance shows that the chiller average daily coefficient of performance (COP) was 0.41 with the average cooling capacity of 4.4 kW when the cooling-water and chilled-water temperatures were about 31°C and 19°C, respectively. As the chiller cooling water is cooled by the cooling tower in the hot arid area, the cooling water is at a higher temperature than the design point of the chiller. Therefore, an experiment was carried out using the city water for cooling. The results show that an enhancement in the chiller COP by 40% and the chilling power by 17% has been achieved when the city water was 27.7°C.     

Preparation of activated carbons from unburnt coal in bottom ash with KOH activation for liquid-phase adsorption

In this work, unburnt coal (UC) in bottom ash from coal-fired power plants was soaked in KOH solution and activated for 1 h at 780 °C. The yield of activated carbons varied from 47.8 to 54.8% when the KOH/UC weight ratio changed from 2 to 4. Pore properties of these activated carbons including the BET surface area, pore volume, pore size distribution, and pore diameter were characterized based on N₂ adsorption isotherms. It was shown that the isotherms for the adsorption of methylene blue, acid blue 74, and 4-chlorophenol from aqueous solutions on these activated carbons at 30 °C were well fitted by the Langmuir equation (correlation coefficient r² > 0.9968). The adsorption capacities of methylene blue, acid blue 74, and 4-chlorophenol were obtained to be 2.40–2.88, 0.57–1.29, and 2.34–5.62 mmol/g, respectively. Moreover, the adsorption kinetics could be suitably described by the Elovich equation.     

Application of surface molecular imprinting adsorbent in expanded bed for the adsorption of Ni(2+) and adsorption model

A new surface molecular imprinting adsorbent (SMIA) was used in an expanded bed. The expansion ratio and adsorption performance were studied at different volumetric rates, inlet concentrations, and pH values. A model based on the Adams-Bohart adsorption model of breakthrough curves was established. The predicted curves had good agreement with the experimental curves. The breakthrough time (T(1/2)) decreased with increasing inlet concentration when the outlet concentration was half the initial concentration (C/C(0)=0.5). The inlet concentration had little effect on the adsorption rate constant (k(1)) value when the initial concentration (C(0)) was above 150 mg/L. However, T(1/2) values increased with increasing initial pH of the inlet solution, and the k(1) value decreased due to the competition between H(+) and Ni(2+).     

Application of 'waste' wood-shaving bottom ash for adsorption of azo reactive dye

The utilization of wood-shaving bottom ash (WBA) for the removal of Red Reactive 141 (RR141), an azo reactive dye, was investigated. WBA/H(2)O and WBA/H(2)SO(4) were made by treating WBA with water and 0.1M H(2)SO(4), respectively, to increase adsorption capacity. Adsorption of RR141 from reactive dye solution (RDS) and reactive dye wastewater (RDW) by WBA/H(2)O and WBA/H(2)SO(4) involved the BET surface area and pore size diameter. Properties of adsorbents, effect of contact time, initial pH of solution, dissolved metals and elution studies indicated that the decolorisation mechanism involved both chemical adsorption and precipitation with calcium ions. In addition, the WBA/H(2)SO(4) surface might contain sulphate-cation complexes that were specific to enhancing dye adsorption from RDW. The adsorption isotherm had a best fit by the Freundlich model. Freundlich parameters showed that WBA/H(2)O used more heterogeneous surface than WBA/H(2)SO(4) and activated carbon for RDW adsorption. A thermodynamic study indicated that RDW adsorption was an endothermic process. The maximum dye adsorption capacities of WBA/H(2)O, WBA/H(2)SO(4) and activated carbon obtained from a Langmuir model at 30 degrees C were 24.3, 29.9, and 41.5mgl(-1), respectively. In addition, WBA/H(2)O and WBA/H(2)SO(4) could reduce colour and high chemical oxygen demand (COD) of real textile wastewater. According to the difficulty in the elution study, it was an environmentally safe disposal of this waste. Therefore, WBA, a waste from combustion of wood shavings, was suitable to be used as an effective adsorbent for azo reactive dye removal.     

ESTIMATION OF SOIL MOISTURE WITH API ALGORITHMS AND MICROWAVE EMISSION1

Large area soil moisture estimations are required to describe input to cloud prediction models, rainfall distribution models, and global crop yield models. Satellite mounted microwave sensor systems that as yet can only detect moisture at the surface have been suggested as a means of acquiring large area estimates. Relations previously discovered between microwave emission at the 1.55 cm wavelength and surface moisture as represented by an antecedent precipitation index were used to provide a pseudo infiltration estimation. Infiltration estimates based on surface wetness on a daily basis were then used to calculate the soil moisture in the surface 0–23 cm of the soil by use of a modified antecedent precipitation index. Reasonably good results were obtained (R²= 0.7162) when predicted soil moisture for the surface 23 cm was compared to measured moisture. Where the technique was modified to use only an estimate of surface moisture each three days an R² value of 0.7116 resulted for the same data set. Correlations between predicted and actual soil moisture fall off rapidly for repeat observations more than three days apart. The algorithms developed in this study may be used over relatively flat agricultural lands to provide improved estimates of soil moisture to a depth greater than the depth of penetration for the sensor.     

URBANIZATION IMPACT ON WATER QUALITY DURING A FLOOD IN SMALL WATERSHEDS1

ABSTRACT: The impact of various urban land uses on water flow and quality in streams is being studied by monitoring small streams in the Milwaukee urban area. This paper compares the responses of an urban watershed and an agricultural watershed to an autumn rainfall of 2.2 cm. Flow from the urban basin showed a substantially greater response to the rain than that from the rural. Dilution, resulting from the greater quantities of surface runoff in the urban watershed, caused lower concentrations of sodium, chloride, calcium, magnesium, bicarbonate and total dissolved solids in the urban stream. The total quantity of these materials removed per unit drainage area of the urban basin was much greater, however. Road salt was still among the dominant dissolved materials in the urban water chemistry seven months after the last road salting. Sodium was apparently being released from adsorption by clays in the urban basin. Suspended sediment concentrations and total loads were higher in the urban stream.