108 research outputs found
Synthesis And Characterization Of Titanium Dioxide Nanotubes For Sonocatalytic Degradation Of Organic Dyes In Wastewater
Get PDFThe sonocatalytic degradation of Rhodamine B was studied using titanium dioxide nanotubes (TiO2 NTs) with various annealing temperatures ranging from 300 oC to 900 oC for 2 h. Characterizations of the catalysts were performed using SEM, TEM, EDX, EA, AAS, XRD, Raman spectroscopy, FT-IR, nitrogen adsorption-desorption, UV-vis DRS, TGA-DTA, zeta potential measurement and XPS. The effect of catalytic activity for TiO2 nanoparticles (NPs) or various annealed TiO2 NTs and various experimental parameters including the use of various organic dyes (Congo Red, Reactive Blue 4, Methyl Orange, Methylene Blue and Rhodamine B), initial concentration of Rhodamine B of 50−150 mg/L, catalyst dosage of 0.5−2.5 g/L, solution pH of 1−11, ultrasonic frequency of 35 or 130 kHz, ultrasonic power of 20−100 W, hydrogen peroxide (H2O2) dosage of 4−20 mM, solution temperature of 25−50 oC and the presence of dissolved air at 1 L/min were examined to determine the optimum conditions. The optimum conditions for sonocatalytic degradation of Rhodamine B (88.47 % after 2 h) occurred when the initial concentration of the dye was 50 mg/L, 2 g/L of TiO2 NTs-300, solution pH of 7, ultrasonic power of 50 W, ultrasonic frequency of 35 kHz and H2O2 dosage was 8 mM at 45 oC ± 2. The as-prepared TiO2 NTs was modified by introducing urea on TiO2 NTs at molar ratios of N: Ti between 0.1–1.0. Urea doping at N: Ti equals to 0.3 led to an increment in the sonocatalytic degradation of Rhodamine B up to 86.75 % after 1 h. Meanwhile, Fe-doped TiO2 NTs at molar ratios of Fe: Ti between 0.001−0.02 were prepared. Fe doping at Fe: Ti equals to 0.005 gave the highest sonocatalytic activity (91.19 %) after 1 h
Quan qiu zi ben zhu yi xia de ling lei fa zhan: Dayushan Meiwo 1997-2013
No full text香港作為「全球城市」，過去數十年城市核心的空間布局不斷轉變。建築物相繼推倒再建，道路工程也無日無之。資本主義生產模式的壓迫需求，把空間（重新）組織、理性化，務求令效率極大化，加速資本價值生產和社會過程。然而，距離香港城市心臟地帶不足一小時小輪航程的大嶼山梅窩，卻馬上讓人感受不一樣的故事。當地居民以單車作為主要代步工具；村落裏穿插的是彎彎曲曲的小路；時間與空間的感知和經驗方式，許多方面都與香港大都會大不相同。如果說，香港核心商業區不斷的推倒、建設已屬「常識」，也代表了全球資本主義之下的發展，我們該如何理解梅窩的「非尋常」發展？如果說，核心商業區所出現的代表了主導的發展形式，這又是否我們唯一可以依循的道路？我在本研究批判全球資本主義下的發展，如何在跨國資產階級的力量和政府干預的推動之下，令空間同質化，使資本可以從空間搾取最大的剩餘價值。通過討論梅窩發展的獨特性和異質性，我的論點是，梅窩展示了全球資本主義下另類發展的可能；也就是說，不受資本宰制的發展方式是可能、也是可行的。還有，世上並非只有一條放諸四海皆準的金光發展大道。梅窩的邊緣性和鄉村傳統，為我們提供資源和啟發，詰問資本主義發展背後的種種假設。本研究特別聚焦於一九九七至二零一三年這段時間。一九九七年，青馬大橋通車，令梅窩失去作為大嶼山「窗口」的地位。在隨後的超過十年期間，梅窩失去昔日的繁華，卻造就了另一條道路，讓市區基層人士也能體驗一種有別於大都會的生活方式。一些獨立藝術家也憑借梅窩的鄉村文化，同時受到當地人、動植物、田野提供的資源所啟發，發展出獨特的藝術和生活觀。這些藝術家與梅窩的邊綠性就如大都會核心的一面批判鏡子，反映社會及主流文化的問題。更重要的是，我希望通過梅窩這個具體例子，說明另類發展這條道路儘管又彎又小，而且十分艱難，但它並非僅是浪漫的白日夢，而是可以發生的現實。As a ‘global city’, Hong Kong has been undergoing endless transformations in the spatial organisation of its core districts over the past few decades. Building after building is demolished and built; road works also go on incessantly. Due to the exigencies of the capitalistic mode of production, space is (re-)organised and rationalised in ways so as to maximise efficiency and to speed up capital value production and social processes in general. Less than an hour’s ferry ride from the heart of urban Hong Kong, however, people disembark at the pier of Mui Wo, Lantau Island to find another story. There, residents rely on cycling as the main means of transport; winding, small paths weave through inland villages; time-space is perceived and experienced in ways distinct from the metropolis.If the destructions and constructions in the Central Business District (CBD) of Hong Kong are ‘common sense’ and epitomise development in the era of global capitalism, how should I make sense of the ‘uncommon’ development of Mui Wo? If what is unfolding in the CBD represents the dominant form of development, is it the only path that we could follow? In this thesis, I critique capitalistic development in the age of global capitalism which, with the agent of the transnational capitalist class and the intervention of government, is leading to the homogenisation of space such that capital can extract its maximum surplus value possible out of space. By discussing the specificity and heterogeneity of the development of Mui Wo, I argue that it provides a case of how development is pursued in an alternative way in the age of global capitalism, that there exists the possibility of pursuing development that is not governed by capital. The marginality and rural traditions of Mui Wo provide resources and inspirations for us to interrogate the assumptions behind capitalistic development, and to see that there are other possibilities. I am particular interested in the period between 1997 and 2013. My argument is that Mui Wo had been spared from the frenzy of capitalistic development by the opening of Tsing Ma Bridge in 1997 which ended its status as the ‘gateway’ to Lantau Island. For more than a decade, a less busy Mui Wo provided an alternative road to urbanites of the lower classes to experience a way of living that is different from the metropolis. Some independent artists took this opportunity to develop a unique philosophy of arts and living out of the resources and inspirations provided by Mui Wo, including its rural culture, and the people, animals, vegetation, farmlands and nature there. The marginality of these artists, together with the marginality of Mui Wo, is like a critical reflection on the metropolitan core, informing us all is not right in the wider society and the dominant culture. More importantly, through my discussions of this concrete case of Mui Wo, I seek to argue that an alternative path of development, though small, winding and difficult, is not merely a romantic dream, but can actually be reality.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Tang, Kin Ling.Thesis (Ph.D.) Chinese University of Hong Kong, 2014.Includes bibliographical references (leaves 317-328).Abstracts also in Chinese.Tang, Kin Ling
Sonocatalytic degradation of Rhodamine B in the presence of iron-doped TiO2 nanotubes: Characterizations and reaction kinetic studies
No full textSynthesis of seaweed based carbon acid catalyst by thermal decomposition of ammonium sulfate for biodiesel production
No full textThree-dimensional flow structures modelling based on a depth-integrated method in a sharply curved open channel over topography
Get PDFIn this study, we introduce the bottom velocity calculation (BVC) technique, a depth-integrated approach for modeling three-dimensional flow systems in the two-dimensional (2D) river management model framework. The method has been expanded to a general coordinate system and its applicability to flow in bends and meanders for the applications to rivers. The method was validated to a laboratory experiment conducted in a sharply curved channel over topography. The pattern of water surface elevation and vertical velocity distribution can be replicated by the BVC method’s models, which also show strong qualitative agreement with the experimental dataset and 3D model. The benefit of using the BVC technique instead of the 2D model is verified; the 2D model is unable to replicate the profile since it does not take into account three-dimensional flow structures. As seen above, the BVC method is helpful in evaluating the river environment because it can account for the complicated material transports caused by three-dimensional flows in the meandering sections of the river channel
Comparative study on the process behavior and reaction kinetics in sonocatalytic degradation of organic dyes by powder and nanotubes TiO2
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Nanocellulose: Recent advances and its prospects in environmental remediation
No full textAmong many other sustainable functional nanomaterials, nanocellulose is drawing increasing interest for use in environmental remediation technologies due to its numerous unique properties and functionalities. Nanocellulose is usually derived from the disintegration of naturally occurring polymers or produced by the action of bacteria. In this review, some invigorating perspectives on the challenges, future direction, and updates on the most relevant uses of nanocellulose in environmental remediation are discussed. The reported applications and properties of nanocellulose as an adsorbent, photocatalyst, flocculant, and membrane are reviewed in particular. However, additional effort will be required to implement and commercialize nanocellulose as a viable nanomaterial for remediation technologies. In this regard, the main challenges and limitations in working with nanocellulose-based materials are identified in an effort to improve the development and efficient use of nanocellulose in environmental remediation
Review on sonochemical methods in the presence of catalysts and chemical additives for treatment of organic pollutants in wastewater
No full textOptimization of sonocatalytic degradation of Rhodamine B in aqueous solution in the presence of TiO2 nanotubes using response surface methodology
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