Hollow TiO2 spheres with improved visible light photocatalytic activity synergistically enhanced by multi-stimulative: Morphology advantage, carbonate-doping and the induced Ti3 +

Great efforts have been devoted to improve the photocatalytic activity of TiO_2 in the visible light region. Rational design of the external structure and adjustment of intrinsic electronic status by impurity doping are two main effective ways to achieve this purpose. A facile onepot synthetic approach was developed to prepare C-doped hollow TiO_2 spheres, which simultaneously realized these advantages. The synthesized TiO_2 exhibits a mesoporous hollow spherical structure composed of fine nanocrystals, leading to high specific surface area(~180 m~2/g) and versatile porous texture. Carbonate-doping was achieved by a postthermal treatment at a relatively low temperature(200°C), which makes the absorption edge red-shifted to the visible region of the solar spectrum. Concomitantly, Ti~(3+) induced by C-doping also functions in improving the visible-light photocatalytic activity by reducing the band gap. There exists a synergistic effect from multiple stimulatives to enhance the photocatalytic effect of the prepared TiO_2 catalyst. It is not out of expectation that the asprepared C-doped hollow TiO_2 spheres exhibits an improved photocatalytic activity under visible light irradiation in organic pollutant degradation.     

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics, isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.     

Risk and characteristics analysis of the flow-induced vibration of the dip tube in opposed multi-burner gasifier

The vibration of dip tube in multi-burner gasifier changes the stress at the connection, causing flange seal failures and high temperature gas erosions with heavy economic losses and industrial accidents. This work aims to reveal the dip tube vibration mechanism, with special focus on obtaining the effect of operational parameters on the fatigue damage and long-term stable operation of gasifiers. A three-dimensional numerical simulation of the water-scrubbing cooling chamber was conducted to obtain the excitation source in the flow field. Then a FSI (fluid-structure interaction) transient dynamics simulation was carried out to investigate the vibration characteristics. Two major flow forms were found: a vertical annular flow near the dip tube outlet in the water-scrubbing cooling chamber; and a gas-liquid coupled flow caused by the syngas entrained the liquid. These two unstable multiphase flow forms exerted an energy excitation on the dip tube, resulting in a self-excited flutter. The dip tube vibration was similar to the first mode of a cantilever beam. The peak frequency was less affected by the initial liquid level and the syngas stream inlet velocity, which was close to its own first natural frequency. Note that, the alternating load generated by vibration may cause fatigue damage, which needs to be specifically considered in the design and manufacturing process of opposed multi-burner gasifier.     

Advanced treatment of wet-spun acrylic fiber manufacturing wastewater using three-dimensional electrochemical oxidation

A three-dimensional electrochemical oxidation(3D-EC) reactor with introduction of activated carbon(AC) as particle micro-electrodes was applied for the advanced treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under the optimized conditions(current density of 500 A/m~2, circulation rate of 5 mL/min, AC dosage of 50 g, and chloride concentration of 1.0 g/L), the average removal efficiencies of chemical oxygen demand(COD_(cr)), NH3–N, total organic carbon(TOC), and ultraviolet absorption at 254 nm(UV_(254)) of the 3D-EC reactor were 64.5%, 60.8%, 46.4%, and 64.8%, respectively; while the corresponding effluent concentrations of COD_(cr), NH_3–N, TOC, and UV_(254) were 76.6, 20.1, and42.5 mg/L, and 0.08 Abs/cm, respectively. The effluent concentration of COD_(cr) was less than 100 mg/L, which showed that the treated wastewater satisfied the demand of the integrated wastewater discharge standard(GB 8978-1996). The 3D-EC process remarkably improved the treatment efficiencies with synergistic effects for COD_(cr), NH_3–N, TOC, and UV_(254) during the stable stage of 44.5%, 38.8%, 27.2%, and 10.9%, respectively, as compared with the sum of the efficiencies of a two-dimensional electrochemical oxidation(2D-EC) reactor and an AC adsorption process, which was ascribed to the numerous micro-electrodes of AC in the 3D-EC reactor. Gas chromatography mass spectrometry(GC–MS) analysis revealed that electrochemical treatment did not generate more toxic organics, and it was proved that the increase in acute biotoxicity was caused primarily by the production of free chlorine.     

化学合成硫化亚铁(FeS)对三价锑的吸附作用研究

厌氧环境中硫化亚铁(FeS)在重金属元素的地球化学循环中扮演极其重要的角色。然而,厌氧条件下FeS与锑(Sb)之间的相互作用尚未有较为清晰的认识。为了探究厌氧条件下FeS对三价锑(Sb(Ⅲ))的吸附动力学、吸附等温线以及吸附的影响因素,本研究以沉淀法制备的FeS为研究对象,测试了其溶解性以及表面形貌。并通过条件实验,考察不同pH、初始FeS、反应时间等因素对FeS吸附Sb(Ⅲ)的影响。结果表明:吸附过程符合准二级动力学模型的描述;中性条件下Langmuir吸附模型对吸附过程具有较高的拟合度,饱和吸附量为380. 3 mg/g; Sb(Ⅲ)在酸性条件下的吸附可能与硫化矿物Sb2S3的析出密切相关,这可能是与FeS溶解产生H_2S反应的结果;而在中性及碱性条件下,FeS与Sb(Ⅲ)的反应主要与表面吸附反应有关。     

Animal agency in wildlife conservation and management

Wildlife conservation and management (WCM) practices have been historically drawn from a wide variety of academic fields, yet practitioners have been slow to engage with emerging conversations about animals as complex beings, whose individuality and sociality influence their relationships with humans. We propose an explicit acknowledgement of wild, nonhuman animals as active participants in WCM. We examined 190 studies of WCM interventions and outcomes to highlight 3 common assumptions that underpin many present approaches to WCM: animal behaviors are rigid and homogeneous; wildlife exhibit idealized wild behavior and prefer pristine habitats; and human–wildlife relationships are of marginal or secondary importance relative to nonhuman interactions. We found that these management interventions insufficiently considered animal learning, decision-making, individuality, sociality, and relationships with humans and led to unanticipated detrimental outcomes. To address these shortcomings, we synthesized theoretical advances in animal behavioral sciences, animal geographies, and animal legal theory that may help conservation professionals reconceptualize animals and their relationships with humans. Based on advances in these fields, we constructed the concept of animal agency, which we define as the ability of animals to actively influence conservation and management outcomes through their adaptive, context-specific, and complex behaviors that are predicated on their sentience, individuality, lived experiences, cognition, sociality, and cultures in ways that shape and reshape shared human–wildlife cultures, spaces, and histories. Conservation practices, such as compassionate conservation, convivial conservation, and ecological justice, incorporate facets of animal agency. Animal agency can be incorporated in conservation problem-solving by assessing the ways in which agency contributes to species’ survival and by encouraging more adaptive and collaborative decision-making among human and nonhuman stakeholders.     

武汉城市圈土地利用变化系统仿真模拟与驱动力分析

土地利用变化是全球环境变化与可持续研究的重要内容,驱动力研究是土地利用变化研究中的核心问题。现有土地利用变化驱动力研究多针对单一的城市区域展开,无法解释城市群地区,城市一体化战略指导下城市交互作用对土地利用变化的影响。运用系统动力学(SD)方法,综合考虑经济、人口、城市化、政策等主要人文因素,并将城市交互作用因素引入SD,以武汉城市圈为例,构建土地利用变化系统SD模型,运用1997~2006年的历史数据进行检验,并对武汉城市圈2010~2020年不同情景下的土地利用变化进行模拟。结果表明,建立的SD模型是有效的,两种情景下土地利用变化表现出差异性,说明城市交互作用是除经济、人口城市化等社会经济因素外,土地利用变化的又一重要影响因素。     

滑坡灾害孕育-激发过程中的水-岩相互作用

降雨造成的地下水与斜城岩土体之间的复杂作用--水-岩相互作用不仅是滑城灾害的主要激发因素,它的滑坡孕育过程中也发挥着重要作用.以往的相关研究主要集中在滑城激发有关的突隙水压力效应的滑城临界降雨量、地下水富集斜坡的稳定性评价、水-力耦合及地下水对岩石的软化效应等方面.孕育过程在滑城研究中居于重要的基础性地位.以流-固耦合等理论为基础对岩体进行时效变形预测,对于斜坡研究中居于重要的,但是,由于大多数滑城的孕育都是在近地表的侵蚀性地球化学环境中进行的,与深埋地下空间的开挖问题存在明显区别.作为水-岩相互作用主要类型之一的水-岩化学作用是造成这种差别的主要因素.深入开展滑城灾害孕育过程中的水-岩化学作用研究不仅对斜城维护、加固及滑城预报是重要的，而且可以促进水-力双重耦合、水-热-力及水-热-力-化学多重耦合等复杂理论的发展.     

盐度变化对崇明东部河口潮滩氮营养盐循环影响实验模拟研究

以长江口咸淡水交互作用最为典型岸段崇明东部潮滩作为研究区域,运用实验模拟方法,定量地研究了盐度变化对潮滩生态系中无机氮的迁移、转化过程的影响。结果发现,盐度升高有利于沉积物中的NH4-N向上覆水扩散,但NO2-N和NO3-N的界面扩散呈现相反的变化趋势;沉积物中可交换态无机氮含量变化特征显示,在盐度变化剧烈的潮滩生态系统内,硝化作用可能是控制沉积物(尤其是表层沉积物)中无机氮分布的重要因素。     

考虑流固强耦合效应的深水桥墩地震反应分析

基于任意拉格朗日-欧拉(Aribitrary Lagrange-Euler,ALE)描述的Navier-Stokes方程,建立了考虑流固强耦合效应(Fluid-structure interaction,FSI)的深水桥墩地震反应分析整体有限元模型,分析了流固强耦合效应对桥墩墩身相对位移、剪力和弯矩反应的影响,讨论了不同水位下的流固耦合效应及其影响。算例结果表明:流固强耦合效应将使墩身位移和内力反应明显增大,增大幅度与输入地震波的频谱特性存在相关性;输入地震波的位移峰值越大,流固耦合效应对位移反应的影响越大,对内力反应的影响越小;水位对深水桥墩内力反应的影响较对位移的影响显著。