反应气氛对绿色合成纳米铁的组分及其活性的影响

成本低廉和无二次污染的"绿色"合成纳米材料是发展原位纳米环境修复技术的前沿研究课题之一.本文以绿茶提取液为还原剂和稳定剂进行"绿色"合成纳米铁,探讨在不同的气氛下"绿色"合成的纳米铁颗粒的主要成分,以期为调控合成纳米铁系材料提供基础研究.首先,利用扫描电子显微镜(SEM)、X射线能谱(EDS)、X射线光电子能谱分析(XPS)和傅里叶变换红外光谱(FTIR)等表征手段对不同反应气氛下合成的纳米铁颗粒的表面微观形貌、尺寸和价态结构进行分析.结果发现,在通入N2情况下,合成的纳米铁颗粒粒径为(84.7±11.5)nm,其主要成分以纳米零价铁为主;在通入空气情况下,合成的纳米铁粒径为(117.8±26.2)nm,其主要成分是纳米零价铁、氧化铁和四氧化三铁的混合物;通入O2时,合成的纳米铁粒径为(141.2±26.3)nm,其主要成分以四氧化三铁为主.其次,评价在不同气氛条件下合成纳米铁颗粒对去除亚甲基蓝(MB)的反应活性.结果表明,在反应温度313 K下降解初始浓度为50 mg·L-1的MB溶液,反应5 min时已达到平衡,通入N2合成的纳米铁降解MB,去除率高达98.7%,而通入O2合成的纳米铁反应效率低,对MB的去除率仅为65.3%.最后,从以上发现提出不同气氛下可以调控"绿色"合成的铁系纳米材料成分,从而导致不同的纳米修复环境中污染物的能力.     

《京都》15年后:分阶段减排政策与“绿色悖论”问题

低碳经济的政策分析,通常囿于单一国家层面的局部均衡结果,较少考虑到全球整体行动的外部影响,但从《联合国气候变化框架公约》建立以来的全球一致减排行动,却产生了一些意料之外的负面效果。本文通过梳理《京都议定书》签订以来,全球低碳经济合作中遇到的新挑战,以及碳交易市场的建设状况,采用制度分析与新古典框架下的市场均衡分析方法,讨论了全球一致减排行动所触发的"绿色悖论"问题。研究发现,造成"绿色悖论"的主要原因,一方面是由于国际合作存在制度设计上的缺陷,《京都议定书》及其关键性的附件一,将重点放在如何限制发达工业国的减排设计上,但却忽视了发展中国家在协议期内有可能出现的增排问题,以及发达国家向发展中国家污染转移的碳泄漏等问题;另一方面,当对不可再生资源的使用征税、以及对其替代品进行补贴时,将会导致在当前期对于化石能源的加速开采,并可能导致对同时期的化石燃料替代品的其他可再生资源的开采速度也大幅度加快,造成了在双重加速开采下的全球绿色福利损失以及CO2排放量的急剧升高,化石能源消费与温室气体排放面临到比协议签署前更为严峻,甚至与全球合作减排框架的设计初衷相悖的结果。研究结果表明,非全局性的减排公约和分阶段的减排政策,是造成"绿色悖论"现象的重要条件,缺少了大量发展中国家和一些重要工业国的缔约,使得负面的环境外部性难以克服;同时,减排任务和责任有所区别的分阶段设计,会把在未来行动期内可预见到的更高地化石能源使用成本转嫁到当前的行动期,造成短时间内资源与环境的迅速破坏。但本文的研究也表明,社会最优经济与对可再生能源进行补贴是克服"绿色悖论"现象的两条可行路径,且需要有与其相匹配的政府政策的支持。由此,本文的主要政策建议是,中国需要加强在国际气候公约中的影响力,提升自身话语权;以碳税政策作为发展低碳经济制度设计的主要政策工具;加快技术进步、提高能源使用效率,对于可再生能源研发进行补贴;根据国情不断优化碳税税率,并适时调整与其相匹配的新能源补贴等相关政策。     

基于低碳经济理论视角的现代循环农业发展战略与对策

随着资源的紧张和环境的恶化,发展现代循环农业对提高资源利用率和环境保护具有至关重要的意义。因此本文从低碳经济理论的内涵与发展、现代循环农业与主要技术对策、绿色农业视野三个层面的资源循环利用来综合分析如何发展现代农业。     

SMART-SREC: A stochastic model of the New Jersey solar renewable energy certificate market

Markets for solar renewable energy certificates (SRECs) are gaining in prominence in many states, stimulating growth of the US solar industry. However, SREC market prices have been extremely volatile, causing high risk to participants and potentially less investment in solar power generation. Such concerns necessitate the development of realistic, flexible and tractable models of SREC prices that capture the behavior of participants given the rules that govern the market. We propose an original stochastic model called SMART-SREC to fill this role, building on established ideas from the carbon pricing literature, and including a feedback mechanism for generation response to prices. We calibrate the model to the New Jersey market and backtest it, analyzing parameter sensitivity and demonstrating its ability to reproduce historical dynamics. Finally, we run simulations to investigate the role and impact of regulatory parameters, thus providing insight into the crucial role played by market design.     

Integration of technologies and alternative sources of water and energy to promote the sustainability of urban landscapes

Recent research has highlighted the positive role of green areas in urban environments, providing numerous social, environmental and economic services, such as mitigation of the urban heat island effect, storm attenuation, increased water infiltration into the soil, reduction of noise and air pollution, among others. However, the maintenance of green areas may result in high consumption of water, reaching 50% of the total consumption in some municipalities, and energy, becoming a reason of concern. The present study aimed to integrate techniques and technologies that promote the automatic and efficient irrigation of urban landscapes, using alternative sources of energy and water, toward its sustainability. The conceptual unit was able to reduce in 64% the water consumed in irrigation. Rainwater met 69% of the demand and the photovoltaic system supplied all the energy required. The economic feasibility analysis showed that the conceptual unit is financially unfeasible, under the conditions of this study. However, with some interventions for reusing the surplus energy and water, and considering the higher fees charged by other cities, the investment became attractive. In this new scenario, the internal rate of return (15 years) was 27.3% and the discounted payback period was 4.9 years.     

Global Trend of Low-carbon Economy and China's Responses

Based on the analysis on the global economic crisis,climate change crisis and their mutual underlying reasons,the authors believe that low-carbon economy has become an inevitable choice to break through the dual crises,coordinate the economic development,and protect the global climate.The global trend of low-carbon economy finds expression in Green Recovery currently,while,in a long run,it will give rise to a new pattern of world competition in politics,economy,technology,trade and finance.The impact of the...     

Biosorption of Direct Yellow 12 from aqueous solution using green alga Ulva lactuca

The potential of commonly available green alga Ulva lactuca was investigated as viable biomaterials for removal of synthetic azo dye (Direct Yellow 12, DY-12) from aqueous solution. The results obtained from the batch experiments revealed that the ability of the U. lactuca to remove DY-12 from its aqueous solution was dependent on the dye concentration, pH, and algal biomass but less dependent on the particle size of the U. lactuca. The equilibrium conditions and kinetics of adsorption were investigated, and the adsorption kinetic was consistent with the pseudo-second-order model (R²=1). The adsorption isotherm followed only the Freundlich model with a correlation coefficient R²=0.99. This study demonstrated that the U. lactuca could be used as an effective biosorbent for the removal of DY-12 from its aqueous solution.     

城市发展质量的综合评价--以江苏省13个省辖市为例

在城市发展质量评价指标体系构建的基础上,依据一定的规则确定各评价指标的目标值,根据综合评价方法,对江苏省13个省辖市2000-2002年各城市发展质量进行综合分析.提出测算城市质量系统间协调发展程度的一般计量模型,根据此模型及城市发展质量综合评价的结论,分别研究了13个城市在近三年的城市化进程中,城市质量系统发展的协调性.     

实时合成水滑石分离模拟放射性核素锶的研究

采用实时合成水滑石的方法从高放废液中分离模拟放射性核素锶,通过单因素实验并借助XRD分析确定了最佳分离实验条件,同时,运用FTIR、SEM等技术手段对合成的含锶水滑石的结构、形貌进行了分析.结果表明,当Sr2+初始浓度为70mg.L-1、pH值为10.5、n(Mg+Sr)/n(Al)为3时,锶的去除率最高可达95%以上;XRD和SEM分析结果表明,锶嵌入了水滑石的晶格中,合成的含锶水滑石形貌为层状六边形;含锶水滑石煅烧产物主要为尖晶石,且煅烧产物中未见氧化锶,表明嵌入到水滑石晶格中的锶在煅烧后存在于尖晶石的晶体结构中.