Application of Multilayer Thin Film Technology in Desalination Membrane

Membrane‐based desalination is the fastest growing technology in the area of desalination. Reverse osmosis (RO) and nanofiltration (NF) have been established in the last couple of decades; meanwhile, forward osmosis (FO) has begun to find its own place in the field of desalination. Typical commercial polyamide (PA) thin film composite (TFC) membrane has been mostly used in those membrane processes, but it has no drawback. Recently, a versatile, robust technique in preparing ultra‐thin films, so‐called layer‐by‐layer assembly (LbL), was adopted in fabrication of desalination membrane. This chapter highlights the most important literatures in the application of LbL assembly for preparing RO, NF and FO membranes, the obstacles and future works, which are essential for those who wish to work in the field

Carbon Dioxide Conversion to Methanol: Opportunities and Fundamental Challenges

Greenhouse gases mitigation is one of most important challenges facing societies nowadays. Therefore, the way to reduce greenhouse gas emissions should be using carbon free sources that do not generate extra CO2 to the atmosphere. However, there is a great potential in energy carriers and other materials from CO2, with many challenges to overcome. It has been suggested that the reduction of CO2 and conversion to renewable fuels and valuable chemicals may be considered as a promising solution to reduce the greenhouse gas emissions. This chapter discusses the recent developments and remaining challenges of CO2 utilization for the efficient production of methanol. This includes novel technologies, approaches, and current barriers for the conversion of CO2 to methanol through heterogeneous catalysis, homogenous catalysis, electrochemical, photochemical, and photoelectrochemical conversion, which will contribute to the economic growth and mitigate the hazardous emissions for cleaner environment. A review of various state-of-the-art technologies for CO2 conversion to methanol was carried out aiming to establish the advances in this area and present an overview of the recent research trend for future development of new ideas for CO2 reduction into methanol in a large scale

Economic Analysis of Liquid drop-out Minimization in Natural Gas Pipelines

The main goal of this research work is to provide an economic evaluation about the controlling of natural gas liquid dropout. The devloped idea is to minimize the natural gas losses in pipeline integrity management companies for the sake of controlling Un-accounted for gas (UAFG). The main idea is to possibly recover those valuable liquids to convert them in a liquid fuel. The econoimc analysis of the overall problem has been discussed.  The overall associated cost with the adsorber unit is calculated. Finally the Net present value, Pay back period, Accounting rate of return and Internal rate of return has been calculated.    Key words: Economic Analysis, Hydrocarbon Natural Gas Liquids (HNGL’s), Natural Gas Pipeline

Photodegradation of Organic Pollutants Using an Efficient Molybdate Intercalated Mg2+/Fe3+ Layered Double Hydroxide (LDH)

Organic pollutants dyes are the highly toxic major waste products causing severe harmful environmental pollution. From the viewpoint of environmental issues, the removal of harmful organic dye compounds is of great interest and importance1. Traditionally physical and biological methods are generally used to decompose many organic pollutants. However, these methods suffers from certain disadvantages and are time-consuming process. 2,3 Visible-light photocatalysis has been renewable "green" technologies which can harvest solar energy in the environmental remediation capable of removing harmful heavy organic contaminations4. This presentation is focused on the design of a novel kind of photocatalyst that cover entire solar spectrum i.e. from ultraviolet to infrared (IR) regions to decolorize and degrade the organic dye such as rhodamine 6G in an effective way. Now a days, the use of layered double hydroxides (LDHs) as active photo-catalysts has been receiving considerable attention over the layered metal oxides. A number of photocatalysts have been reported for the photocatalytic degradation of organic pollutants. Among the new generation photocatalyst, LDH was very much promising material for pollutant degradation5. However, designing novel visible light active LDH catalysts to meet present technical requirements is a great challenge. Intercalation of different polyoxometalic anionic species into inorganic layered materials like layered double hydroxide (LDH) offers a technique in which altering the properties of the two components are combined into a single modified material. By intercalating different anions, the characteristics of the layered double hydroxide (LDH) can be improved. Layered double hydroxide basically called Hydrotalcite consist of a cationic brucite like sheets with anionic moieties in the interlayer through electrostatic interaction. The unique structure, surface hydroxyl groups, interlayer spaces with intercalated anions, swelling properties, oxo-bridged linkage and high chemical stability are some of the added advantages of this group of materials. To harvest solar energy efficiently a series of Mg/Fe Layered double hydroxide materials has been synthesized by hydrothermal method and modified by intercalating molybdate anion by ion exchange. These materials have been characterized by various techniques and tested for their photocatalytic activity for the pollutant removal. The broad absorption band in case of Mg/Fe LDH was found due to the metal ligand charge transfer band of O2p ?Fe3+ and the metal-metal-charge-transfer spectra of Mg2+-O-Fe3+. The metal to metal charge transfer (MMCT) for an oxo-bridged bimetallic system with different oxidation states was defined to be an excitation transition of an electron from one metal to the other, which is known to absorb visible light and even near-IR light. 6,7 In the case of Mg/Fe/Mo LDH, the absorption edge shifted towards near IR is due to the HOMO-LUMO OMCT of Interlayer Molybdate where the HOMO is mainly derived from the O 2p orbitals and the LUMO is from the Mo 4d orbitals. These materials show enhanced photoactivity for the degradation of organic dyes such as rhodamine 6G. The enhanced photoactivity is due to edge shared metal oxygen octahedron of (MO6) of brucite sheet, visible light absorbing species, low recombination of charge carriers', metal-metal charge transfer spectra (MMCT) of the oxo-bridged bimetallic Mg2+-O-Fe3+ system, long life time of photogenerated charge carriers and HOMO-LUMO oxygen metal charge transfer spectra of intercalated Molybdate anions. These modified photo catalysts can be reused easily with several times without substantial loss of catalytic activity, which is green alternative material for practical applications for degradation of organic dyes like rhodamine 6G.qscienc

Highly efficient photocatalytic z-scheme hydrogen production over oxygen-deficient WO3-x nanorods supported Zn0.3Cd0.7S heterostructure

The demand for clean renewable energy is increasing due to depleting fossil fuels and environmental concerns. Photocatalytic hydrogen production through water splitting is one such promising route to meet global energy demands with carbon free technology. Alternative photocatalysts avoiding noble metals are highly demanded. Herein, we fabricated heterostructure consist of oxygen-deficient WO3-x nanorods with Zn0.3Cd0.7S nanoparticles for an efficient Z-Scheme photocatalytic system. Our as obtained heterostructure showed photocatalytic H2 evolution rate of 352.1 ?mol h-1 with apparent quantum efficiency (AQY) of 7.3% at ? = 420 nm. The photocatalytic hydrogen production reaches up to 1746.8 ?mol after 5 hours process in repeatable manner. The UV-Visible diffuse reflectance spectra show strong absorption in the visible region which greatly favors the photocatalytic performance. Moreover, the efficient charge separation suggested by electrochemical impedance spectroscopy and photocurrent response curves exhibit enhancement in H2 evolution rate. The strong interface contact between WO3-x nanorods and Zn0.3Cd0.7S nanoparticles ascertained from HRTEM images also play an important role for the emigration of electron. Our findings provide possibilities for the design and development of new Z-scheme photocatalysts for highly efficient hydrogen production. 1 2017 The Author(s).Scopu

A High-Energy-Density Magnesium-Air Battery with Nanostructured Polymeric Electrodes

The greenhouse emissions are biggest challenge of the present era. The renewable power sources are required to have characteristics of good charge capacity, energy density with proven charging discharging cycles for energy storage and applications. Mg-air batteries (MABs) are an alternative renewable power source due to their inexpensive cost. In particular, the previous reports presented the metal-air battery structure, with a specific energy overall output of 765 W h kg(−1). This paper is focused mainly on the MAB, which employed nanocomposite polymeric electrodes with a proven energy density of 545 W h kg(−1) and a charge capacity of 817 mA h g(−1) when electrolyzed at a cycling current density of 7 mA cm(−2)

A New Class of Electrocatalyst Materials for Direct Methanol Fuel Cell Applications

Direct methanol fuel cell (DMFC) has been attracting lots of attention as a power source for transportation, stationary and portable electronic devices due to the high energy density of methanol and ease of handling compared to gaseous fuels such as hydrogen and natural gas. However, the commercialization of DMFC is still limited due to some technical challenges such as methanol crossover and low methanol electro-oxidation kinetics. In order for fuel cells to be a feasible and viable option amongst clean energy technologies, innovations in the materials developments are required for efficient operation of fuel cells. Many efforts have been made in various research laboratories to develop high-performance catalysts that will enhance the methanol electro-oxidation. Compared to any single-metal catalyst, Pt has shown the highest activity for the electro-oxidation of methanol in an acid environment. However, Pt is expensive and during the methanol electro-oxidation reaction, COads and other organic intermediates such as formaldehyde, formic acid and methyl formate are formed on the Pt surface, which results in poisoning of the Pt catalyst. Many binary and ternary catalysts for methanol electro-oxidation have been investigated and reported in the literature, most of them based on modification of Pt with some other metal(s). The aim is to accelerate the oxidation of the intermediates and decrease their accumulation so as to improve the catalyst performance. Among the various catalyst formulations, PtRu alloy has shown the best results for the methanol electro-oxidation. Diverse methods have been used to prepare the PtRu-based catalysts for methanol electro-oxidation. Catalyst composition and method of preparation are known to immensely affect the physical property es and electrochemical performance of a catalyst. Thus, there is the need to use a carefully selected approach in order to prepare a catalyst with the highest attainable performance. Incorporation of transition metals into the PtRu catalysts to form ternary catalysts in order to improve the performance of the PtRu catalysts is one of the techniques attracting a lot of interest. In this work, a novel approach have been used for synthesizing a new class of electrocatalyst nanomaterials for electro-oxidation of methanol by incorporation nano-oxides of transition metals. The prepared nanomaterial catalysts were characterized using FESEM, BET surface area, EDX, FT-IR and XRD. The catalysts performance was studied using cyclic voltammetry and compared with the commercial Pt-Ru/C.qscienc

Tungsten-molybdenum oxide nanowires/reduced graphene oxide nanocomposite with enhanced and durable performance for electrocatalytic hydrogen evolution reaction.

Hydrogen has attracted huge interest globally as a durable, environmentally safe and renewable fuel. Electrocatalytic hydrogen evolution reaction (HER) is one of the most promising methods for large scale hydrogen production, but the high cost of Pt-based materials which exhibit the highest activity for HER forced researchers to find alternative electro-catalyst. In this study, we report noble metal free a 3D hybrid composite of tungsten-molybdenum oxide and reduced graphene oxide (GO) prepared by a simple one step hydrothermal method for HER. Benefitting from the synergistic effect between tungsten-molybdenum oxide nanowires and reduced graphene oxide, the obtained W-Mo-O/rGO nanocomposite showed excellent electro-catalytic activity for HER with onset potential 50 mV, a Tafel slope of 46 mV decade-1 and a large cathodic current, while the tungsten-molybdenum oxide nanowires itself is not as efficient HER catalyst. Additionally, W-Mo-O/rGO composite also demonstrated good durability up to 2000 cycles in acidic medium. The enhanced and durable hydrogen evolution reaction activity stemmed from the synergistic effect broadens noble metal free catalysts for HER and provides an insight into the design and synthesis of low-cost and environment friendly catalysts in electrochemical hydrogen production

Highly efficient sustainable photocatalytic Z-scheme hydrogen production from an α-Fe2O3 engineered ZnCdS heterostructure

We present an α-Fe2O3/Zn0.4Cd0.6S heterostructure that shows visible light photocatalytic H2 production as high as 536.8μmolh−1 with apparent quantum efficiency of 11.2% at 420nm. The UV–vis diffuse reflectance spectra of as-synthesized α-Fe2O3/Zn0.4Cd0.6S heterostructure reveal efficient absorption in the visible region, which is a key factor in the enhanced catalytic activity. Moreover, the increase in charge separation efficiency of α-Fe2O3/Zn0.4Cd0.6S suggested by electrochemical impedance spectroscopy and photocurrent response also results in enhanced photocatalytic H2 production. The interface contact between α-Fe2O3 and Zn0.4Cd0.6S ascertained from HRTEM images promotes the recombination of photogenerated electrons from the conduction band of α-Fe2O3 and holes from the valence band of Zn0.4Cd0.6S, thus enhancing the utilization of solar light and increasing the efficiency. Our coupling approach to synthesizing an efficient Z-scheme photocatalyst provides insight into the design of further solar energy utilization photocatalysts.- USTC/Anhui Government Scholarships programme - CAS-TWAS President's Fellowship programme. - Qatar National Research Fund (a member of the Qatar Foundation) - grant # NPRP [9—219-2-105]