土壤pH、有机质和含水氧化物对镉、铅竞争吸附的影响

采用一次平衡法(振荡16h)研究了土壤pH值、有机质和含水氧化物(以晶质氧化铁和非晶质氧化铁为代表)对Cd2+、Pb2+在水稻土上竞争吸附的影响。结果表明,pH值是影响土壤吸附Cd2+、Pb2+的主要因素,土壤对金属离子Cd2+、Pb2+的吸附量随pH值的增大而增加。土壤pH值为5.0和6.5时,对Cd2+、Pb2+的吸附量分别达到最大。当土壤去除有机质后,土壤对Cd2+、Pb2+的吸附均降低,与对照相比,分配系数Kd,Cd、Kd,Pb分别下降54%￣64%和36%￣52%;土壤去除非晶质氧化铁后,Kd,Cd、Kd,Pb与对照相比分别下降32%￣45%和15%￣33%。有机质和非晶质氧化铁对Cd2+、Pb2+的选择性为:Pb2+>Cd2+。当土壤晶质氧化铁和非晶质氧化铁均去除后,土壤吸附Cd2+、Pb2+量不但未降低,反而有不同程度的增加,Kd,Cd、Kd,Pb明显高于对照。

某金属氧化物储存容器设计及储存工况优化

某金属氧化物是一种具有高放射性的核工业后处理产物,其在密封储存过程中释放热量并产生氢气和氦气,导致储存容器温度升高、内部压力增大。为了确保某金属氧化物长周期储存安全性,文中深入分析其储存特性演变规律及储存工况参数,设计储存容器采用数值模拟探究储存工况对容器温度、压力的影响,进而验证储存容器结构合理性并优化储存工况。结果表明:提高冷却风速、降低冷却风温、增大堆积密度及适量的含水率有利于金属氧化物在储存过程中传热冷却,其中冷却风速对该金属氧化物温度影响最大;降低含水率、提高冷却风速、增大堆积密度及降低冷却风温有利于避免储存过程中内压过高,其中金属氧化物含水率的升高对容器压力的增加影响显著,在实际储存中需要严格控制金属氧化物中的水分含量。

Physiological characteristics changes of Aesculus chinensis seeds during natural dehydration

A study was conducted to determine the physiological characteristics changes of Aesculus chinensis seeds during natural dehydration in 2003. The results showed that A. chinensis seeds were recalcitrant with being highly desiccation-sensitive. The seed moisture content of fresh fruits was higher than 60%. When the seeds were naturally dried for 30 days, their moisture content declined to 30.2% and their viability was completely lost. The seed germination percentage had a small increase at the beginning of desiccation and then decreased rapidly. The relative electrical conductivity of the A. chinensis seeds increased along with a decrease in seed moisture content. However, there was an abnormal increase in relative electrical conductivity when the seed moisture content was between 53.7% and 50.9%. Superoxide dismutase （SOD） activity decreased rapidly in the period of desiccation except for an abnormality when the seed moisture content was between 53.7% and 50.9%. Malondialdehyde （MDA） content increased slowly at the early stage of desiccation and then rose rapidly after the moisture content was below 50.9%. The soluble sugar content in seeds slowly increased with the increasing period of desiccation. The seed germination percentage was at the high level when seed moisture content was in range of 47%- 60%, which suggests that this was the optimum moisture content for maintaining A. chinensis seed viability.

Studies on the Effects on Growth and Antioxidant Responses of Two Marine Microalgal Species to Uniconazole

Uniconazole, as a plant growth retardant, can enhance stress tolerance in plants, possibly because of improved antioxidation defense mechanisms with higher activities of superoxide dismutase(SOD) and peroxidase(POD) enzymes that retard lipid peroxidation and membrane deterioration. These years much attention has been focused on the responses of antioxidant system in plants to uniconazole stress, but such studies on aquatic organism are very few. Moreover, no information is available on growth and antioxidant response in marine microalgae to uniconazole. In this paper, the growth and antioxidant responses of two marine microalgal species, Platymonas helgolandica and Pavlova viridis, at six uniconazole concentrations(0-15 mg L-1) were investigated. The results demonstrated that 3 mg L-1 uniconazole could increase significantly chlorophyll a and carbohydrate contents of P. helgolandica(P < 0.05). Higher concentrations(≥12 mg L-1) of uniconazole could inhibit significantly the growth, dry weight, chlorophyll-a and carbohydrate contents of P. helgolandica and P. viridis(P < 0.05). Uniconazole caused a significant increase in lipid peroxidation production(MDA) at higher concentrations(≥ 9 mg L-1). The activities of antioxidant enzymes, superoxide dismutase(SOD) and catalase(CAT) were enhanced remarkably at low concentrations of uniconazole. However, significant reduction of SOD and CAT activities was observed at higher concentrations of uniconazole.

Cr(Ⅲ) removal from simulated solution using hydrous magnesium oxide coated fly ash： Optimization by response surface methodology (RSM)

Hydrous magnesium oxide coated fly ash （MFA） has environmental remediation potential by providing a sub- strate for the adsorption of aqueous Cr（Ⅲ）. Aqueous Cr（Ⅲ） adsorption onto MFA was examined as a function of MFA dosage, pH and initial Cr（Ⅲ） concentration with the Box-Behnken approach used for experimental design and optimization using response surface methodology （RSM）. pH and dosage （dosage and concentration） have significant interactive effects on Cr（Ⅲ） adsorption efficiency. Analysis of variance shows that the response surface quadratic model is highly significant and can effectively predict the experimental outcomes. Cr（Ⅲ） removal effi- ciency of 98% was obtained using optimized conditions of MFA dosage, pH and initial Cr（Ⅲ） concentration of 1,5 7 g. L- 1, 4.11 and 126 mg. L- 1, respectively. Cr（Ⅲ） adsorption onto MFA is mainly attributed to the interaction between Or（Ⅲ） and the functional group --OH of the hydrous magnesium oxide, in all probability caused by chemisorptions. The results of this study can conduce to reveal the interactions between Cr（Ⅲ） pollutant and MFA characteristics, posing important implications for the cost-effective alternative adsorption technology in the treatment of heavy metal containing wastewater.

Reflux-synthesized bulk and diluted W-Nb-O mixed oxide bronzes for the valorization of short-chain oxygenates aqueous mixtures

This work reports the preparation of bulk and KIT-6-diluted W-Nb-O mixed oxide bronzes by a reflux method. The influence of the incorporation of Nb and a mesoporous silica on the physicochemical features of the catalysts is studied. The addition of Nb favors the formation of single-phase oxide bronze structure, with improved Lewis acidity;while the incorporation of KIT-6 gives rise to well-dispersed mixed metal oxide particles on the diluter. These diluted W-Nb-O catalysts present enhanced surface areas and mesopore volumes. The materials have been tested in the valorization of an aqueous model mixture (acetol/propanal/ethanol/acetic acid/water weight ratio of 5/25/10/30/30), through C-C bond formation reactions. The increase in the Lewis nature of surface acid sites stands as the key point to maximize the total organic yield during the reaction (C5-C10 products). The best catalysts maintain their catalytic behavior after five consecutive uses.

Physiological and Biochemical Changes Induced by PRD Irrigation in Four Olive Varieties

The present study was conducted to evaluate the effects of partial root-zone drying （PRD） irrigation technique on stomatal conductance （gs）, leaf water potential （qJpd）, leaf relative water content （RWC）, vegetative growth, fruit quality and enzymatic antioxidants of young plants of four Olea europaea L. varieties （Picholine Marocaine, Haouzia, Picholine Languedoc and Manzanilla） grown under arid conditions in Southern Morocco. In this irrigation strategy, a split-root technique was used to divide the root system of the plants in two parts. Two water regimes were used： （1） control, with both root compartments well watered; （2） PRD, with one compartment irrigated （50% of the control）, the other compartment was kept dry switching every 10 days. For all olive varieties studied, gs and the shoot length of the plants subjected to PRD decreased, whereas, Woo and RWC remained higher. The effect of PRD was similar among the four olive varieties, with their stomata closing in response to the water deficit before any significant changes in leaf water status were detectable. At the agronomic level, the benefits of PRD on olive were expressed by an earlier maturity and by higher values of olive fruit weight and dimensions, especially, in Manzanilla, which produced a fruit reaching 7.1 g and 2.6 cm, respectively. The enzymatic activities of soluble peroxidases （POX）, insoluble peroxidases （POXins）, polyphenoloxidase （PPO） and superoxide dismutase （SOD） were up-regulated under PRD. Picholine Marocaine and Haouzia showed higher enzymatic activities revealing that in these two varieties, PRD had possibly induced oxidative stress, which resulted in an up-regulation of the antioxidant activities of POXins, POX, PPO and SOD under water deficit.

Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia(2%, 4%, and 6%, dry matter) and three moisture contents(30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates(50, 65, and 80 g·L-1) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml·g-1(based on per unit volatile solids loaded), with shorter digestion time(T80) of 25 days at the loading rate of 65 g·L-1compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively,while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

STUDY ON SIDE REACTION IN THE SYNTHESIS OF HYPERCROSSLINKED POLYMERS

The systematical study about side reactions have revealed the formation mechanism of oxygen-containing groups of hypercrosslinked polymers. Surface chemistry and functionality of the polymers are characterized by Fourier-transform infrared spectroscopy (FT-IR), solid state nuclear magnetic resonance (NMR) and contact angle. The results showed that the ether groups were from chloromethylated reaction, and the alcohol groups arose from partial hydrolysis of chloromethyl groups during the post-crosslinking reaction, and the carbonyl functionality was formed by further oxidation of the alcohol groups. Catalyst and solvent used in the postcrosslinking reaction would greatly influence the surface chemistry of the polymer.

低温酸性溶液中毒砂和As(Ⅲ)稳定性研究

讨论了铁离子浓度为10^(-2)-10^(-5)mol/kg的Fe2(SO4)3和FeCl3酸性溶液中毒砂和As(Ⅲ)的稳定性.实验研究显示:(1)在所述实验条件下毒砂是不稳定的,它的氧化程度随Fe3+浓度和反应温度升高及pH降低而增加;(2)毒砂氧化时释放的砷以As(Ⅲ)的含水氧化物为主;(3)在FeCl3溶液中,毒砂和As(Ⅲ)向As(V)的氧化速度比在Fe2(SO4)3溶液中快;(4)As(Ⅲ)的稳定性随氧化剂浓度和反应温度的降低而增加,随Cl-浓度的增加及光照而降低.

以超临界CO_2为介质合成环己烯酮的工艺研究

介绍了一种合成环己烯酮的新方法。以超临界CO2 作为反应介质 ,以含水过氧化物 (CH3 ) 3 COOH作为氧化剂 ,研究了反应温度、反应压力、投料比、反应时间对产品收率的影响。结果表明 ,合成环己烯酮的最佳工艺条件为 :环己烯∶含水过氧化物 =1∶1 4 (摩尔比 ) ;反应压力为 16MPa ;反应温度为 95℃ ;反应时间为 4h ,产品收率可达到 6 0 1% ,经过后处理产品纯度达到 99%以上。

CO_2 Sequestration from flue gas by direct aqueous mineral carbonation of wollastonite

Emission of carbon dioxide is considered to be the main cause of the greenhouse effect. Mineral carbonation, an important part of the CCS technology, is an attractive option for long-term CO2 sequestration. In this study, wollastonite was chosen as the feedstock and the feasibility of direct aqueous mineral carbonation in the simulated flue gas was investigated via a series of experimental studies carried in a stirred reactor. X-ray diffraction （XRD）, X-ray fluorescence spectroscopy （XRF）, ion chro- matography （IC） and thermal decomposition were used to determine the carbonation conversion. The influences of various factors, including reaction temperature, reaction pressure, solution composition, heat-treatment and particle size, were dis- cussed. Concurrently, the effects of SO2 and NO presented in simulated flue gas were also investigated and a possible mecha- nism was used to explain the results. Experimental results show that reaction temperature, reaction pressure and particle size can effectively improve the carbonation reaction. Addition of 0.6 M NaHCO3 was also proved to be beneficial to the reaction and heat-treatment is not needed for wollastonite to get a higher carbonation conversion. Compared with carbonation in puri- fied CO2 gas, CO2 sequestration directly from simulated flue gas by mineral carbonation is suggested to have a certain degree of economic feasibility in the conditions of medium and low-pressure. A highest carbonation conversion of 35.9% is gained on the condition of T=150℃, P=40 bar and PS 〈30 μ in distilled water for 1 h.