A practical approach to CO2 sequestration: Reactions with high salinity water

Carbon dioxide is known to be a major contributor to global warming and climate change and hence has an adverse effect on environmental sustainability. CO2 is emitted by various activities associated with industrial processes and the burning of various types of carbonaceous fuels such as coal, oil and gas. Over the past few years, there has been a considerable amount of interest in carbon capture and storage (CCS) as an option to mitigate the harmful effects of CO2 emissions. This study evaluates a new approach to the capture and sequestration of CO2 through reactions with high salinity water in the presence of an alkaline agent. Processes such as the Solvay process have been successful in utilizing the reactions of CO2 with ammoniated high salinity water to sodium bicarbonate. This process, however, suffers from several drawbacks such as inefficient contact mechanism and the need for the regeneration of ammonia as alkaline catalyst in the process. Such drawbacks have been addressed through developing a new, inert particles reactor system that offers efficient mixing and stable operation. At the same time, carbon dioxide is reacted with high salinity water in the presence calcium hydroxide instead of ammonia to provide the alkalinity needed for the reaction of CO2 and NaCl. The new process and reactor system were able to achieve high CO2 capture efficiency (up to 99%) and effective reduction in water salinity (up to 40%), while storing the CO2 in a stable solid form, namely sodium bicarbonate. The new process can utilize any alkaline solid waste and the inert particles reactor system can be used to capture CO2 from different sources such as natural gas or flue ga

Organic Contaminants in Refinery Wastewater: Characterization and Novel Approaches for Biotreatment

Addressing major environmental issues, such as water pollution, is essential nowadays in realizing sustainable development. The ever-increasing world population and industrial development have led to the introduction of different types of chemicals to the environment, leading to considerable deterioration in environmental quality. A major class of these chemicals is phenolic compounds, which are hazardous pollutants and highly toxic even at low concentrations. In recent years, researchers have realized the importance of extracting new bacterial strains that are effective in treating different types of highly contaminated wastewaters at different severe conditions. They also focused considerable amount of research on developing new types of reactors that would provide efficient mixing and reduce mass transfer limitations. The aim is to develop and evaluate effective reactor systems and biocatalysts for the biodegradation of major contaminants in petroleum refinery wastewater. This chapter examines the different available options for the treatment of refinery wastewater with more focus on novel biotreatment options

CO\u3csub\u3e2\u3c/sub\u3e sequestration using accelerated gas-solid carbonation of pre-treated EAF steel-making bag house dust

© 2015 Elsevier Ltd. Mineral CO2 sequestration is a promising process for the reduction of carbon dioxide emissions to the atmosphere. In this paper, alkaline calcium-rich dust particles collected from bag filters of electric arc furnaces (EAF) for steel making were utilized as a viable raw material for mineral CO2 sequestration. The dust particles were pre-treated through hydration, drying and screening. The pre-treated particles were then subjected to direct gas-solid carbonation reaction in a fluidized-bed reactor. The carbonated products were characterized to determine the overall sequestration capacity and the mineralogical structures. Leaching tests were also performed to measure the extracted minerals from the carbonated dust and evaluate the carbonation process on dust stabilization. The experimental results indicated that CO2 could be sequestered using the pre-treated bag house dust. The maximum sequestration of CO2 was 0.657kg/kg of dust, based on the total calcium content. The highest degree of carbonation achieved was 42.5% and the carbonation efficiency was 69% at room temperature

Bio-regeneration of activated carbon: A comprehensive review

© 2018 Elsevier B.V. The use of microorganisms to regenerate activated carbon (AC), bio-generation, can avert costly and logistically challenging ex-situ steam regeneration of carbon normally required to recover its adsorptive capacity. Bio-regeneration employs microbial metabolism in which the microbes use the available organic substrates (contaminants) to generate energy. During this process, they generate equivalent protons and electrons, which are transferred to the substrates to finally break them down to simpler molecules or ions, such as CO2, methane and Cl−. The optimal microbial conditions depend on the temperature, available nitrogen and phosphorus levels, dissolved oxygen levels, and microbe/substrate stoichiometric ratios and the residence time of the AC particles within the reactor. In this review, the authors highlight the most recent development in bio-regeneration including the regeneration mechanism, the relationship between the reversibility of adsorption and the efficiency of bio-regeneration, the general aspects affecting bio-regeneration, the principle and target compounds for bio-regeneration, different established methods for quantifying the bio-regeneration and the efficiency of bio-regeneration. Few case studies of bio-regeneration of activated carbon loaded with different contaminants are presented. Research on microbiology regeneration has gained considerable attention in recent years, but it still needs more contribution from other disciplines including process engineering, biochemistry and material sciences for optimizing the process performance

Adsorption as a process for produced water treatment: A review

Produced water (PW) is a by-product of oil and gas operations, and its production is foreseen to increase in the upcoming years. Such an increase is justified by various entities through their projection of the expected increase in the demand of oil and gas. The treatment of produced water is a significantly growing challenge for the oil and gas industry that requires serious attention. The first part of this review will present the underlying issue of produced water and relevant practices. With adsorption being defined as the least expensive treatment method, the second part will introduce general adsorption principals. The third part will describe the recent applications of adsorption for the treatment of PW with more focus of categorizing the adsorbents as natural and non-natural adsorbents. The main aim of this review is to shed light on the recent research related to PW treatment using adsorption. This is performed to highlight the shortcomings in PW adsorption research and recommend research pathways that can help in developing the field further.This publication was made possible by GSRA grant, ID# GSRA5-1-0531-18104, from the Qatar National Research Fund (a member of Qatar Foundation) .Scopu

Adsorption of organic water pollutants by clays and clay minerals composites: A comprehensive review

Clays and clay minerals are inexpensive, non-toxic, and naturally occurring minerals that have been utilized in water remediation as adsorbents. However, clays and clay minerals and those modified with heat, surfactants, acids, or organic-inorganic modifiers exhibit low adsorption capacity and re-generation ability towards organic water pollutants. The development of clays and clay minerals composites has gained considerable attention in recent years due to their enhanced adsorption capacity, ease of recovery from aqueous solution and improved physiochemical properties relative to raw and modified clays and clay minerals. This review aims to assess recent literature on clays and clay minerals composites including bentonite, montmorillonite and kaolinite intercalated with carbonaceous, metals, metal oxides, chitosan and polymeric materials and appraise their adsorption performance towards organic water pollutants. The review examines the effect of the composites' physicochemical properties on the adsorption performance and evaluates the adsorption mechanism as well as regeneration methods. The review also attempts to highlight the current progress in this area by assessing the outcomes of recently published articles and outline the research gaps for future research.This publication was made possible by an Award [GSRA6-2-0516-19029] from Qatar National Research Fund (a member of Qatar Foundation). The contents herein are solely the responsibility of the author[s]. Open access funding is provided by the Qatar National Library.Scopu

Catalytic methane decomposition to carbon nanostructures and cox-free hydrogen: A mini-review

Catalytic methane decomposition (CMD) is a highly promising approach for the rational production of relatively COx-free hydrogen and carbon nanostructures, which are both important in multidisciplinary catalytic applications, electronics, fuel cells, etc. Research on CMD has been expanding in recent years with more than 2000 studies in the last five years alone. It is therefore a daunting task to provide a timely update on recent advances in the CMD process, related catalysis, kinetics, and reaction products. This mini-review emphasizes recent studies on the CMD process investigating self-standing/supported metal-based catalysts (e.g., Fe, Ni, Co, and Cu), metal oxide supports (e.g., SiO2, Al2O3, and TiO2), and carbon-based catalysts (e.g., carbon blacks, carbon nano-tubes, and activated carbons) alongside their parameters supported with various examples, sche-matics, and comparison tables. In addition, the review examines the effect of a catalyst's shape and composition on CMD activity, stability, and products. It also attempts to bridge the gap between research and practical utilization of the CMD process and its future prospects.This research was funded by Qatar Shell, grant number QUEX-CENG-SHELL-19/20-1.Scopu