Review article on alkaline water
104322048
Review of necessary thermophysical properties and their sensivities with temperature and electrolyte mass fractions for alkaline water electrolysis multiphysics modelling
Abstract This article presents an exhaustive review of the transport properties necessary for the multiphysics modelling of alkaline water electrolyzer. This article provides experimental data and the correlations needed to calculate thermos physical properties such as electrical conductivity, density, viscosity, heat capacity, heat and mass transfer diffusion coefficients as a function of temperature and electrolyte mass fraction for two classical alkaline electrolytes (KOH, NaOH) Thus, the different boundary layers growing on the electrodes can be calculated with precision. Different interpolation models from various authors are compared to raw experimental data. The goal of this article is to give to the modeler the correlations needed for the simulation of alkaline water electrolysis.
International Journal of Hydrogen Energy
Damien Le Bideau Philippe Mandin Mohamed El Hachemi Benbouzid Myeongsub Kim Mathieu Sellier
104843556
Recovery of Inorganic Compounds from Spent Alkaline Pulping Liquor by Eutectic Freeze Crystallization and Supporting Unit Operations: A Review
After the kraft or soda pulping of lignocellulosic materials to produce pulp suitable for papermaking, the spent pulping liquor typically has been recovered by multi effect evaporation, followed by incineration in a recovery boiler. This review article considers one unit operation, eutectic freeze crystallization (EFC) that may have potential to save some of the energy that is presently consumed in the evaporation step during recovery of inorganic chemicals from spent pulping liquor. Based on a review of the literature it appears that EFC can be employed to obtain relatively pure sodium sulfate and sodium carbonate, along with relatively pure water (in the form of ice) from the spent liquor, under the assumption that lignin previously has been removed by acidification and precipitation. Issues of inorganic scale formation, during the operation of an EFC process applied to lignin free black liquor, will require research attention. The chemical reactions to regenerate the active pulping chemicals sodium hydroxide and sodium sulfide from sodium carbonate, sodium sulfate, and other compounds isolated by EFC can be carried out either in a separate operation or by returning the materials to the feed of an existing recovery boiler.
Martin A Hubbe Emily Mayer de Andrade Becheleni Alison E Lewis Edward Michael Peters Wei-xing Gan Gu-Zhen Nong Sujata Mandal Sheldon Q Shi
139494876
Low dimensional materials for alkaline oxygen evolution electrocatalysis
Abstract The urge for renewable and clean energy technologies has cultivated the concept of hydrogen economy, in which water electrolysis for hydrogen production is one indispensable component. As the water electrolysis efficiency is primarily restricted by the anodic oxygen evolution reaction (OER) intensive research efforts have been put into this field to acquire good knowledge of the reaction mechanism and obtain active, durable, and cost effective electrocatalyst materials. Many invaluable findings have been achieved in the past years, with some problems being found in the meantime. It is good timing to summarize what have been achieved and identify what to overcome, which would be helpful to unscramble current OER research status and stimulate insightful thoughts in future studies. In this review article, we briefly introduce current understanding of OER electrocatalysis mechanism and the use of catalyst descriptor parameters for correlation with the activity property. We then summarize recent achievements on development of OER catalyst materials, which are categorized and discussed based on their morphological dimension. Perspectives on the existing challenges and future directions in the OER research are also provided.
Materials Today Chemistry
Xiangkai Kong Zhenmeng Peng
89610846
Critical Review Identifying Critical Gaps for Polymer Electrolyte Water Electrolysis Development
Although polymer electrolyte water electrolyzers (PEWEs) have been used in small scale (kW to tens of kW range) applications for several decades, PEWE technology for hydrogen production in energy applications (power to gas, power to fuel, etc. requires significant improvements in the technology to address the challenges associated with cost, performance and durability. Systems with power of hundreds of kW or even MWs, corresponding to hydrogen production rates of around 10 to 20 kg/h, have started to appear in the past 5 years. The thin ~0.2 mm) polymer electrolyte in the PEWE with low ohmic resistance, compared to the alkaline cell with liquid electrolyte, allows operation at high current densities of 1 3 A/cm2 and high differential pressure. This article, after an introductory overview of the operating principles of PEWE and state of the art, discusses the state of understanding of key phenomena determining and limiting performance, durability, and commercial readiness, identifies important 'gaps' in understanding and essential development needs to bring PEWE science engineering forward to prosper in the energy market as one of its future backbone technologies. For this to be successful, science, engineering, and process development as well as business and market development need to go hand in hand. (c) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http:/creativecommons.org/licenses/by/4.0/ which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.1441704jes] All rights reserved.
Ugljesa Babic Michel Suermann Felix N Buchi Lorenz Gubler Thomas J Schmidt
99472598
Pretreatment technologies of lignocellulosic biomass in water in view of furfural and 5 hydroxymethylfurfural production A review
Lignocellulosic biomasses are strongly connected composites of cellulose, hemicelluloses, and lignin. A pretreatment is required in order to make these components available for their later conversion into chemicals. At this point, two strategies have to be considered: to either produce chemicals via microorganism or enzymes (1) or by chemical conversion (2) The focus of this article is the second strategy, which is chemical conversion, performed in water to produce the final products furfural and 5 hydroxymethylfurfural (HMF) Reviewed first is the composition of cellulose and hemicelluloses as well as their degradation chemistry in water. Then, fundamental modes of action and process parameters of pretreatment methods in aqueous solution are summarized. The pretreatment methods discussed here are steam explosion, treatment with hot liquid water, diluted and concentrated acids, as well as alkaline solutions. Finally, the advantages and disadvantages of these pretreatments are discussed for lignocellulosic biomass.
David Steinbach Andrea Kruse Jorg Sauer
105205137
Oxygen reduction reaction on gold in alkaline solutions The inner or outer sphere mechanisms in the light of recent achievements
In this article we present a brief review of the latest publications on the problem of oxygen reduction reactions on gold in alkaline solutions. We focus mainly on the question whether this complex reaction proceeds according to the inner or outer sphere mechanism. Various aspects are discussed, such as an effect of the size, shape and surface characteristics of the metal on its activity towards the oxygen reduction, the strength of adsorption of oxygen molecule on gold, as well as the role of water and hydroxyl anions preadsorbed on the catalyst surface. It is shown that, despite the use of many research techniques and efforts of scientists, some aspects and details of mechanism of the oxygen reduction reaction on gold in alkaline solutions still remain unclear and are subject to scientific disputations.
Current Opinion in Electrochemistry
Anna Ignaczak Elizabeth Santos Wolfgang Schmickler
105202301
Recent Progresses in Electrocatalysts for Water Electrolysis
The study of hydrogen evolution reaction and oxygen evolution reaction electrocatalysts for water electrolysis is a developing field in which noble metal based materials are commonly used. However, the associated high cost and low abundance of noble metals limit their practical application. Non noble metal catalysts, aside from being inexpensive, highly abundant and environmental friendly, can possess high electrical conductivity, good structural tunability and comparable electrocatalytic performances to state of the art noble metals, particularly in alkaline media, making them desirable candidates to reduce or replace noble metals as promising electrocatalysts for water electrolysis. This article will review and provide an overview of the fundamental knowledge related to water electrolysis with a focus on the development and progress of non noble metal based electrocatalysts in alkaline, polymer exchange membrane and solid oxide electrolysis. A critical analysis of the various catalysts currently available is also provided with discussions on current challenges and future perspectives. In addition, to facilitate future research and development, several possible research directions to overcome these challenges are provided in this article.Graphical Abstract
Electrochemical Energy Reviews
Muhammad Arif Khan Hongbin Zhao Wenwen Zou Zhe Chen Wenjuan Cao Jian-hui Fang Jiaqiang Xu Lei Zhang Jiujun Zhang
90074437
A comprehensive review of mathematical modeling of paddy parboiling and drying: Effects of modern techniques on process kinetics and rice quality
Abstract Background Paddy is one of the most important food crops in the world. The major operations of paddy processing are soaking, parboiling/steaming, drying and milling. The paddy processing is an energy intensive process with the substantial wastewater generation. Scope and approach The knowledge of mathematical modeling in different stages of paddy processing helps to improve the final rice quality and reduce the energy consumption. The present article analyzes the results of the recently published research work on different models used in paddy soaking, parboiling and drying operations. In addition, the article discusses the effects of modern methods of parboiling and drying operations on the process kinetics, microstructural changes and rice quality. Key findings and conclusions Hot water soaking (40 80 degC) single steaming, double steaming, pressure cooking and microwave heating are used to parboil or gelatinize the starch in rice. Also, acids/alkaline solutions can gelatinize the rice starch. The open sun (2 4 days) hot air (50 80 degC) superheated steam, vacuum, infrared (0*167 0*625 W cm 2) and microwave drying (2.45 GHz) are employed to dry the parboiled paddy up to 12 14% moisture content (db) Modelling and simulation tools have been used to study these complex processes during paddy hydration, starch gelatinization and drying. Fick's law of diffusion, Peleg model, and exponential equation are used to describe the water sorption in paddy. Arrhenius equation, Ozawa Model and Kissinger equation are useful in understanding the starch gelatinization kinetics. Several empirical and semi empirical models are used to study the drying kinetics of gelatinized paddy. In drying, the models given by Page, Henderson and Pabis and Newton describe the drying kinetics better than other models. The effects of modern methods of the parboiling and drying can be understood from the kinetics and other constants of the models as well as from the change in the microstructure of starch that takes place in the process of gelatinization. The recent developments on the effects of modern methods of hydration, parboiling and drying with limitations have also been focussed in the manuscript. Because of the concerns of wastewater generation during paddy hydration and parboiling, new techniques need to be developed for reducing wastewater generation and its treatment.
Gitanjali Behera P P Sutar
109358865
Heterogeneous Catalysts in Bio DieselProduction A Review
Bio diesel has attracted in recent years as a renewable fuel with less pollutant emissions as compared to diesel fuel on its combustion. Bio diesel fuel is made from vegetable oils, animal fats and microbial oils. The most common method of Bio diesel production is by means of Trans esterification process, where, triglycerides present in the oil reacts with monohydric alcohol in the presence of a catalyst. Synthesis of Bio diesel necessarily needs a catalyst to attain the equilibrium in practical manner. Homogeneous acid catalysts are corrosive in nature and take more time for Bio diesel synthesis, alkaline catalysts requires the thorough rinsing with water to remove the leftover catalyst, resulting in waste water generation and consequently results in the loss of production. In order to overcome these constraints, this review article is focused on finding suitable Heterogeneous catalysts that can be easily separated and gives a high yield
Shripad Diwakar Rana Pratap Reddy
136273297
Alkaline/Surfactant/Polymer (ASP) Flooding
This is a review article on the subject of combining tertiary oil recovery methods like alkaline, surfactant and polymer flooding in order to achieve the synergetic effect out of the different impacts which are caused by these chemicals, affect oil and water filtration in the reservoir and increase oil recovery. In the article the main theoretical concepts of EOR (enhanced oil recovery) are summarized, mechanism of alkaline, surfactant and polymer flooding technologies are explained referring to the research works which had strong contribution to the development of the tertiary oil recovery methods. Formulation of alkaline/surfactant/polymer (ASP) chemical formula for EOR is discussed as well. Importance of numerical simulation and core flood laboratory experiments for the successful implementation of ASP technologies explained in the paper. Finally several examples of ASP flooding applications throughout the world projects are presented.
N Nurxat Iskander Gussenov Gulnur S Tatykhanova T K Akhmedzhanov Sarkyt E Kudaibergenov