Conventional processes and membrane technology for carbon dioxide removal from natural gas:A review

Membrane technology is becoming more important for CO,_ separation from natural gas in the new era due to its process simplicity, relative ease of operation and control, compact, and easy to scale up as compared with conventional processes. Conventional processes such as absorption and adsorption for CO2 separation from natural gas are generally more energy demanding and costly for both operation and maintenance. Polymeric membranes are the current commercial membranes used for CO2 separation from natural gas. However, polymeric membranes possess drawbacks such as low permeability and selectivity, plasticization at high temperatures, as well as insufficient thermal and chemical stability. The shortcomings of commercial polymeric membranes have motivated researchers to opt for other alternatives, especially inorganic membranes due to their higher thermal stability, good chemical resistance to solvents, high mechanical strength and long lifetime. Surface modifications can be utilized in inorganic membranes to further enhance the selectivity, permeability or catalytic activities of the membrane. This paper is to provide a comprehensive review on gas separation, comparing membrane technology with other conventional methods of recovering CO2 from natural gas, challenges of current commercial polymeric membranes and inorganic membranes for CO2 removal and membrane surface modification for improved selectivity.

Integration of biological method and membrane technology in treating palm oil mill effluent

Palm oil industry is the most important agro-industry in Malaysia, but its by-product-palm oil mill effluent （POME）, posed a great threat to water environment. In the past decades, several treatment and disposal methods have been proposed and investigated to solve this problem. A two-stage pilot-scale plant was designed and constructed for POME treatment. Anaerobic digestion and aerobic biodegradation constituted the first biological stage, while ultrafiltration （UF） and reverse osmosis （RO） membrane units were combined as the second membrane separation stage. In the anaerobic expanded granular sludge bed （EGSB） reactor, about 43% organic matter in POME was converted into biogas, and COD reduction efficiency reached 93% and 22% in EGSB and the following aerobic reactor, respectively. With the treatment in the first biological stage, suspended solids and oil also decreased to a low degree. All these alleviated the membrane fouling and prolonged the membrane life. In the membrane process unit, almost all the suspended solids were captured by UF membranes, while RO membrane excluded most of the dissolved solids or inorganic salts from RO permeate. After the whole treatment processes, organic matter in POME expressed by BOD and COD was removed almost thoroughly. Suspended solids and color were not detectable in RO permeate any more, and mineral elements only existed in trace amount （except for K and Na）. The high-quality effluent was crystal clear and could be used as the boiler feed water.

The opportunity of membrane technology for hydrogen purification in the power to hydrogen (P2H) roadmap:a review

The global energy market is in a transition towards low carbon fuel systems to ensure the sustainable development of our society and economy.This can be achieved by converting the surplus renewable energy into hydrogen gas.The injection of hydrogen(£10%v/v)in the existing natural gas pipelines is demonstrated to have negligible effects on the pipelines and is a promising solution for hydrogen transportation and storage if the enduser purification technologies for hydrogen recovery from hydrogen enriched natural gas(HENG)are in place.In this review,promising membrane technologies for hydrogen separation is revisited and presented.Dense metallic membranes are highlighted with the ability of producing 99.9999999%(v/v)purity hydrogen product.However,high operating temperature(≥300℃)incurs high energy penalty,thus,limits its application to hydrogen purification in the power to hydrogen roadmap.Polymeric membranes are a promising candidate for hydrogen separation with its commercial readiness.However,further investigation in the enhancement of H2/CH4 selectivity is crucial to improve the separation performance.The potential impacts of impurities in HENG on membrane performance are also discussed.The research and development outlook are presented,highlighting the essence of upscaling the membrane separation processes and the integration of membrane technology with pressure swing adsorption technology.

Membrane science and technology

Membrane science and technology has been developed very fast in recent years in China.The Zhong Ke Membrane Re-search & Development Centre of Beijing(its predecessor is the Polymer Division of Research Centre for Eco-EnvironmentalSciences,Chinese Academy of Science)is one of the main institutions on membrane research and development,has been de-voted itself to the study and application of the membrane science and technology and has obtained great achievements since1975.More than ten kinds of polymers or their blend have been used for manufacturing ultrafiltration(UF)membranes withmolecular weight cut off from 3000 to 150000 dalton for plate membrane and from 6000-100000 dalton for hollow fiber

Application of Whole Membrane Water Treatment Technology in Environmental Protection

In the current social development of our country,environmental protection has become a key content,and water treatment process is a key step to achieve environmental protection.This paper analyzes the application of whole membrane water treatment technology in environmental protection.It is hoped that this analysis can be helpful for the rational application of the whole membrane water treatment technology and the improvement of environmental protection quality.

Treatment of a dyeing wastewater from a woolen mill using an A/O membrane bio-reactor

An anaerobic/oxic membrane bioreactor (A/O MBR) was used for treatment of dyeing wastewater from a woolen mill. COD and color of the wastewater were 54—473 mg/L and 40—400 dilution time (DT) respectively. The ratio of BOD 5/COD was less than 0.13. By the A/O MBR process, the average removal of COD, BOD 5, color and turbidity was 82%, 96%, 71% and 99%, respectively. The average COD, BOD 5, color and turbidity of effluent was 37 mg/L, 0.8 mg/L, 40 DT and 0.44 NUT respectively. The effluent COD met the local standard of reuse water in Beijing, China. The average COD volume load of the anaerobic biological tank was 0.0483 kgCOD/(m 3·d) and that of the aeration tank of the MBR was 0.3589 kgCOD/(m 3·d). The sludge load of the MBR was 0.19 kgCOD/(kg·MLSS·d) on average and the maximum of that was 0.4 kgCOD/(kg·MLSS·d). The flux of the A/O membrane bioreactor could be remained at larger than 50 L/(h·m 2·0.1MPa). The results indicated that A/O membrane bioreactor has technical feasibility for treatment of woolen mill wastewater.

Efficiency of Advanced Membrane Wastewater Treatment Plant towards Removal of Aspirin, Salicylic Acid, Paracetamol and p-Aminophenol

The efficiency of membrane separation technology for wastewater treatment was employed to check its efficiency in removing pharmaceuticals, their degradation products and their metabolites from wastewater. Aspirin and paracetamol were found to degrade in wastewater furnishing salicylic acid and p-aminophenol, respectively. The kinetics for the degradation reactions of both drugs were investigated in wastewater environment and both have shown first order kinetics with rate constants 0.845 × 10^-8 Ms^-1 and 1.0 × 10^-8 Ms^-1 at room temperature, respectively. These values are an order of magnitude larger than those obtained in pure water under the same conditions. The over all performance of the plant has shown complete removal of these compounds from spiked wastewater within the detection limit of the analytical method. The most effective components for removing those drugs within the plant were activated carbon and clay micelle filters. The adsorption isotherms for these compounds have been studied using both activated carbon and newly developed adsober named clay-micelle complex. All studied isotherms were found to fit Langmuir isotherm. The Langmuir constant and the adsorption capacity were evaluated and discussed.

Treatment of submerged hollow fiber ultrafiltration membrane for reuse of sludge water

To lower the costs of wastewater treatment, the submerged hollow fiber ultrafiltration membrane was employed to reuse the filter backwash water and settling tank sludge water. Experimental study indicates that the submerged hollow fiber uhrafihration membrane can condense the concentration of sludge from 0. 1% -0. 3% to 2.5%. At 20 ℃, the system can operate continuously for 80 clays with daily online backwashing with chemical additions only once, and the membrane flux can be recovered up to 97% by using NaClO and NaOH as chemical additions. The results show that the membrane flux is mainly affected by temperature,and has a positive lin- ear relation to temperature with a slope of 0. 368. After treated by submerged hollow fiber uhrafihration membrane, the effluent can reach the National Standard for Drinking Water（ GB5749 -85 ） , especially for the sludge water from sedimentation tanks and the backwashing Water from filters in water supply plants.

Design and synthesis of Al-MOF/PPSU mixed matrix membrane with pollution resistance

To enhance the performance of the polyphenylene sulfone(PPSU) membrane,a novel mixed matrix membrane with hydrophilicity and antifouling properties was prepared.Using PPSU as the ba sic membrane material,polyvinyl pyrrolidone(PVP) as the porogen,N-Methyl pyrrolidone(NMP) as the solvent,and MOF-CAU-1(Al_(4)(OH)_(2)(OCH_(3))_4(H_2 N-BDC)_(3)·xH_(2) O) as the filler,PPSU/CAU-1 mixed matrix membrane(MMM) was prepared by an immersion precipitation and phase transformation technique.By changing the amount of MOF-CAU-1,the properties and performance of the MMM membrane were investigated in terms of hydrophilicity,pore morphology,surface roughness,and dye removal.The results show that the highest pure water flux of the mixed reached 47.9 L·m^(-2)·h^(-1), when the CAU-1 addition amount was 1.0 wt%, which was 23% higher than that of the pure PPSU membrane.Both the rejection rate and the antifouling performance of the MMM membrane also noticeably improved.

Sprayed separation membranes: A systematic review and prospective opportunities

Membrane separation technology has been taken up for use in diverse applications such as water treatment,pharmaceutical,petroleum,and energy-related industries.Compared with the design of membrane materials,the innovation of membrane preparation technique is more urgent for the development of membrane separation technology,because it not only affects physicochemical properties and separation performance of the fabricated membranes,but also determines their potential in industrialized application.Among the various membrane preparation methods,spray technique has recently gained increasing attention because of its low cost,rapidity,scalability,minimum of environmental burden,and viability for nearly unlimited range of materials.In this Review article,we summarized and discussed the recent developments in separation membranes using the spray technique,including the fundamentals,important features and applications.The present challenges and future considerations have been touched to provide inspired insights for developing the sprayed separation membranes.

Stability and Removal of Commonly Used Drugs in Environmental Water and Wastewater

Introduction:Pharmaceuticals are regarded as emerging contaminants in the environment.In recent years,their destiny and removal have piqued people’s interest.Methods:Examine how well conventional wastewater treatment facilities and cutting-edge technologies(ultrafiltration and reverse osmosis)can remove specific pharmaceutical compounds from water,with a focus on the compounds'environmental status,their origin,deterioration,metabolites,and the capacities of these facilities.Results and discussion:the ability and efficacy of sophisticated treatment technologies such as membrane separation,adsorption,and AOPs(Advanced Oxidation Processes)in eliminating chosen commonly used drugs from water are explored.Batch adsorption experiments were integrated with appropriate adsorption isotherms and appropriate kinetic models to predict the final extent of pollutant removal by this method.Continuous filtration mode was also investigated.Combining filtration(using AC(Activated Carbon)and micelle-clay granule complexes)with AOPs improves the economy of treating wastewater,which contains recalcitrant PhACs(Pharmaceutical Compounds).

An Alternative to Flare Gas Processing:A Feasibility Study of Natural Gas to Liquid Processes

The quantities of gas released into the environment during the extraction and processing of crude oil,by flaring,constitute a vast source of mineral wealth which can be used to produce other useful products.The processes studied in this paper,as alternatives to the above problem,are the ones used in Shell Pearl Qatar project and Oryx GTL project.Both projects produce liquid fuels,mainly naphtha and diesel,in addition to more special fuel such as kerosene.This paper is a feasibility study of a project that makes use of the flare gas from the State of Texas,U.S.A.,as a feedstock to a process similar to either Shell Pearl Qatar project,or Oryx GTL project.The objective of this study is to determine the price range for crude oil over which an investment to similar projects can be profitable.An MS Excel Model was developed in order to perform calculations having as a variable the crude oil price and taking into account all the process and project’s financial data.The results of this model showed that a project similar to Shell Pearl Qatar remains profitable in crude oil price above$57.76/barrel,while a project similar to Oryx GTL remains viable for crude oil price over$31.4/bbl.In the price range$55-$60/barrel,the payout of the corresponding to Shell Pearl Qatar project will be in about 15.2 years and 3.3 years for a project similar to Oryx GTL.Finally,using the financial principles of this study we can apply them to any process in order to determine under what conditions will remain viable.

A review of removal technology for antimony in aqueous solution

Antimony(Sb)and its compounds,toxic metalloid,have been classified as high-priority pollutants.Increasing Sb released into the water environment by natural processes and anthropogenic activities,which exposure threatens to human health and ecosystems.Therefore,it is of unquestionable importance to remove Sb from polluted water.Keeping in view the extreme importance of this issue,we summarize the source,chemistry,speciation,distribution,toxicity,and polluted situation of Sb about aqueous solution.Then,we provide the recent and common technology to remove Sb,which are based on adsorption,coagulation/flocculation,electrochemical technology,membrane technology,ion exchange,etc.In this review,we focus in detail on the adsorption method,researchers at present have been investigating to discover more advanced,cost-effective,eco-friendly,reusable adsorbents.However,to date the Sb-containing wastewater treatment technologies are not sufficiently developed and most of research have been tested only in controlled lab conditions.Few reports are available that include field studies and applications.We critically analyzed the salient features and removal mechanisms,evaluating benefits and limitations of these technologies,hoping to provide more references for further research.Finally,we considered the Fe-or Mn-based technologies was the most promising technique to remove Sb for field application.

Advances in graphene oxide membranes for water treatment

Graphene oxide(GO),a derivative of graphene,is a novel carbon material that has attracted a lot of attention in the field of membrane materials as its ability to achieve layer-by-layer stacking and the formation of nanochannels between the lamellae makes it excellent for selective separation of substances.In this paper,the separation mechanism of the GO membrane is summarized.According to the different separation substances,the separation mechanism of graphene oxide membrane is reviewed from two aspects of metal ions and organic pollutants.Next,the preparation methods of graphene oxide membranes is introduced,such as spin-coating,vacuum filtration,dip-coating,spraying,and layer-by-layer self-assembly,followed by a review on the structural regulation of GO.Finally,this paper concludes with an overview of the potential development prospects and challenges of GO membranes.

Membrane bioreactors for hospital wastewater treatment: recent advancements in membranes and processes

Discharged hospital wastewater contains various pathogenic microorganisms,antibiotic groups,toxic organic compounds,radioactive elements,and ionic pollutants.These contaminants harm the environment and human health causing the spread of disease.Thus,effective treatment of hospital wastewater is an urgent task for sustainable development.Membranes,with controllable porous and nonporous structures,have been rapidly developed for molecular separations.In particular,membrane bioreactor(MBR)technology demonstrated high removal efficiency toward organic compounds and low waste sludge production.To further enhance the separation efficiency and achieve material recovery from hospital waste streams,novel concepts of MBRs and their applications are rapidly evolved through hybridizing novel membranes(non hydrophilic ultrafiltration/microfiltration)into the MBR units(hybrid MBRs)or the MBR as a pretreatment step and integrating other membrane processes as subsequent secondary purification step(integrated MBR-membrane systems).However,there is a lack of reviews on the latest advancement in MBR technologies for hospital wastewater treatment,and analysis on its major challenges and future trends.This review started with an overview of main pollutants in common hospital wastewater,followed by an understanding on the key performance indicators/criteria in MBR membranes(i.e.,solute selectivity)and processes(e.g.,fouling).Then,an in-depth analysis was provided into the recent development of hybrid MBR and integrated MBR-membrane system concepts,and applications correlated with wastewater sources,with a particular focus on hospital wastewaters.It is anticipated that this review will shed light on the knowledge gaps in the field,highlighting the potential contribution of hybrid MBRs and integrated MBRmembrane systems toward global epidemic prevention.

Pore Engineering for Covalent Organic Framework Membranes

Membrane technology is of particular significance for the sustainable development of society owing to its potential capacity to tackle the energy shortage and environmental pollution.Membrane materials are the core part of membrane technology.Researchers have always been pursuing predictable structures of advanced membrane materials,which provides a possibility to fully unlock the potential of membranes.Covalent organic frameworks(COFs),with the advantage of controllable pore microenvironment,are considered to be promising candidates to achieve this design concept.The customizable function of COF membranes through pore engineering does well in the enhancement of selective permeability performance,which offers COF membranes with great application potentials in separation and transportation fields.In this context,COF-based membranes have been developed rapidly in recent years.Herein,we present a brief overview on the strategies developed for pore engineering of COF membranes in recent years,including skeleton engineering,pore surface engineering,host-guest chemistry and membrane fabrication.Moreover,the features of transmission or separation of molecules/ions based on COF membranes and corresponding applications are also introduced.In the last part,the challenges and prospects of the development of COF membranes are discussed.

Recovery of Sc^(3+) from one certain deposit of rare earth

The extraction of scandium from one certain deposit was studied by the liquid membrane emulsion technique using P507-Span80-sulphonating kerosene-HCl.The emulsion conditions,the technological factors such as ratios of oil to the internal aqueous phase and water to emulsion,and the extraction time etc.were investigated.