Adsorption Technology Research Articles

Adsorbents selection for the enrichment of low-grade methane coal mine emissions by temperature and pressure swing adsorption technologies

This work evaluates the feasibility of common adsorbents (carbonaceous materials, zeolites and metal-organic frameworks) for the adsorption and further methane upgrading of the ventilation air methane (VAM) emissions from underground coal mining (0.57% CH4). Concentration was achieved by adsorption through two different operational procedures based on fixed bed configurations: temperature swing adsorption (TSA) and pressure swing adsorption (PSA). All the combinations have been simulated using a rigorous mathematical model implemented in a commercial simulation package. The main purpose is to evaluate the performance of the different combinations of adsorption technique and adsorbent material, as well as establishing a valid mathematical model able to test a wide range of materials. The comparison has been fulfilled with an economic evaluation of the different combinations. Results show that carbonaceous materials provide the highest concentration factors (C/C0 = 5), with low total methane recoveries (30%) and the lowest cost per kmol of methane recovered (1.5 €/kmol). MOFs can retain substantial amounts of methane, but with lower CH4/N2 selectivities than carbonaceous materials and lower methane concentration factors (C/C0 = 2.6). For this type of materials, a high recovery of methane is achieved, but at expense of the highest costs (80 €/kmol). Finally, zeolitic materials present the lowest methane concentration factor (C/C0 = 2), with intermediate both methane recoveries (58%) and costs (25 €/kmol). Concerning the adsorption technique, TSA has shown higher final methane concentrations for carbonaceous materials and some MOFs, whereas PSA overperforms for zeolitic materials. In addition, TSA is cheaper in all cases than PSA processes. On the other hand, PSA allows higher total methane recoveries and adsorption capacities for all materials, highlighting the high dependence on adsorption pressure, especially in carbonaceous materials (PSA/TSA = 18.3, in the case of Maxsorb).

Diatomite Composited with a Zeolitic Imidazolate Framework for Removing Phosphate from Water.

Adsorption technology based on various adsorbents has been widely applied in wastewater treatment containing phosphate. A novel diatomite adsorbent composited with ZIF-8 (CZD) was developed for removing phosphate from water in this work. The chitosan was used to pre-modify the diatomite so that ZIF-8 could be anchored on the surface of the diatomite solidly and uniformly. The diatomite composited with ZIF-8 was then used to remove phosphate in water by an adsorption process, the process variables such as adsorption time, temperature, pH, and competitive ions were investigated. The electrostatic attraction was the primary mechanism of phosphate removal. The adsorption reached equilibrium within 90 min, and its sorption capacity increased when adsorption time and temperature increased. Especially, CZD had a rapid adsorption rate and 85% of the phosphate in the solution can be adsorbed within the first 10 min. The maximum phosphate adsorption capacities of the modified diatomite reached 13.46, 13.55, and 13.95 mg/g at 25, 35, and 45 °C, respectively. The removal efficiencies of CZD for phosphate were more than 98% and even came up to 100% at 45 °C. The adsorption isotherms fit well with the Langmuir isotherm model. The Freundlich isotherm and Temkin isotherm showed that the adsorption process is physical in nature. The kinetic data of the adsorption process were fitted by the pseudo-second-order kinetics. Thermodynamic parameters indicated that the adsorption process was endothermic. This adsorbent provided an alternative for phosphate removal on account of the high adsorption efficiency in a short time. Therefore, CZD could be a promising and eco-friendly phosphate adsorbent for wastewater treatment.

Efficient phosphate removal and recovery from wastewater with Zn(OH)2@DETA-aminated polyacrylonitrile fibre

The current eutrophication from excess phosphorus (P) discharge and the potential shortage crisis from explosive P demand, have attracted extensive attention from researchers. To solve this dilemma, adsorption technology is a promising method to simultaneously achieve phosphate removal and recovery. However, the difficulty in separation and high cost of adsorbents limit their application in wastewater treatment. Thus, an inexpensive Zn(OH)2 @DETA-aminated polyacrylonitrile (PAN) fibre was prepared to remove and recover phosphate from wastewater. The maximum adsorption capacity reached 108.0 ± 2.8 mg/g with the adsorption equilibrium time of 20 min. The inner sphere complex forming the ZnOP bond was confirmed to be the dominant force, resulting in over 70% anti-interference performance even at a coexisting molar ratio of NO3−, Cl−, SO42−, CO32−, and humic acid (HA) to phosphate of 100:1. Using the Zn(OH)2@DETA-aminated PAN filter column to continuously treat real wastewater, the effluent of phosphate concentration below 0.1 mg/L was obtained with approximately 100% of P-removal. In addition, phosphate in the desorption solution was recovered as P-rich Zn2(PO4)(OH) products. In brief, this study recommends Zn(OH)2@DETA-aminated PAN as a phosphate adsorbent, along with positive prospects for P recovery.

Cr-Based MOF for Efficient Adsorption of Au at Low Concentrations.

The efficient enrichment and selection of Au are crucial for gold recovery. The adsorption technology is considered to have potential due to the advantages of operation simplicity and green processability. Nevertheless, the poor Au selectivity at low concentrations in complex solutions limits the further application of the adsorption technology. In this work, a novel Cr-based MOF adsorbent was successfully synthesized using 1,2,4-triazole and 4-aminobenzoic acid as ligands. Benefitting from the surface positive charge and extensive chelation and reduction sites, the novel Cr-based MOF exhibited a total adsorption capacity of up to 357 mg/g and excellent adsorption selectivity toward Au(III) in the complex metal mixed solutions, such as simulated sewage ash waste liquid and actual e-waste leachate. Furthermore, the adsorption kinetics, isotherms, and thermodynamics were discussed in depth for investigating the adsorption mechanisms of the MOF. The PXRD and XPS analyses reveal that the adsorption process involves complexation, redox, and electrostatic interactions. We believe that this study of novel Cr-based MOF adsorbents for efficient Au adsorption is meaningful for further application in the gold recovery technology from e-waste.

CO2 fixation mechanism of kaolin treated with organic amines at varied temperatures and pressure

CO2 capture and storage is an effective way to control CO2 levels in the atmosphere. However, the adsorption technology is determined by many factors, such as temperature, pressure, and material cost. In this study, a clay-based CO2 adsorbent was designed to monitor the possible factors that affect the geological condensation of CO2 under varied conditions. The effect of molecular chain length on the CO2 adsorption performance of intercalated kaolinite was discussed in detail. The prepared kaolinite/n-hexylamine complex achieved a 17.0 (±0.4) mL/g CO2 adsorption capacity when 6.35% (±0.05) n-hexylamine was loaded, which has significantly improved the utilization rate of organic amines. A higher relative CO2 adsorption capacity (in proportion to the amount of amine) was obtained at lower temperatures and higher pressures. The mechanism of CO2 adsorption of organic amine-intercalated kaolinite was discussed based on Fourier transform infrared spectroscopy and specific surface area measurements. The enhanced relative CO2 adsorption capacity at low-temperature and high-pressure conditions may provide a hint to the geological condensation of CO2 at high latitude positions.

Role of the sedimentary organic matter structure and microporosity on the degradation of nonylphenol by potassium ferrate

In this study, the role of organic matter structure and microporosity in the adsorption and degradation of radioactive nonylphenol in sediments treated with potassium ferrate solutions was investigated. The demineralized fractions and acid non-hydrolyzable fractions were isolated and characterized via advanced solid-state 13C nuclear magnetic resonance and CO2 gas adsorption technology, respectively. Radioactive nonylphenol in the sediments was also fractionated into 14CO2, water-soluble residues, extractable residues, and strongly bound residues after treatment with potassium ferrate. A first-order, two-compartment kinetic model well described the mineralization and degradation kinetics of radioactive nonylphenol in the sediment (R2 > 0.99). The degradation percentages of spiked nonylphenol were highly negatively correlated with aromatic carbon, aliphatic carbon, and microporosity estimated from acid-non-hydrolyzable fractions in the bulk sediments (R2 > 0.82, p < 0.01). The percentages of adsorbed parent nonylphenol residues were highly positively correlated with aromatic carbon, aliphatic carbon, and microporosity estimated from acid-non-hydrolyzable fractions in the bulk sediments (R2 > 0.90, p < 0.01). The parent nonylphenol compound desorbed into the aqueous phase and was completely degraded. This study is the first to demonstrate the important role of aromatic carbon, aliphatic carbon, and microporosity in acid non-hydrolyzable fractions on the degradation of nonylphenol during the potassium ferrate oxidation treatment process.

Performance Improvement of The Radiant Cooling Panel Using Pressure-Vacuum Swing Adsorption with A Solid Desiccant Dehumidification

A growing environmental Impact of global warming and rapidly increasing cost of the electrical energy cause researchers in the field of refrigeration and air conditioning to develop the sustainable cooling technologies. The aim of this study was to investigate and design a radiant cooling panel with solid desiccant dehumidifier which was suitable for tropical climate to achieve thermal comfort. The influence of an interior ventilation fan to thermal comfort assessment was also examined. The designed system with CFD (Computation fluid dynamics) simulation used ANSYS software to compare with the measured data. The total area of the ceiling and wall radiant cooling panels were 16.83 m2 and 16.32 m2 with 26.28 L/min of supplied water by the cooling tower. The solid desiccant dehumidifier was the pressure-vacuum swing adsorption technology with containing 20 kg of silica-gel. The flow rate of supply air was approximately 90 kg/h. The results indicated that the PMV (Predicted mean voted) could be improving with the uses of cooling panel with dehumidifier during the day. The lower temperature and humidity ratio can improve thermal comfort. The patterns of temperature, the relative humidity and the PMV from CFD simulation were in the same agreement with the experimental results. In the case of the ventilation fan installed in the radiant cooling panel with dehumidifier, the average value of predicted mean vote was -0.2. Consequently, the PPD (Predicted percentage dissatisfied) was reduced to 6.2%. The daily electric power consumption was 5.94 kWh which was lower than the conventional air conditioning system about 16.27%.

Porous Adsorption Materials for Carbon Dioxide Capture in Industrial Flue Gas.

Due to the intensification of the greenhouse effect and the emphasis on the utilization of CO2 resources, the enrichment and separation of CO2 have become a current research focus in the environment and energy. Compared with other technologies, pressure swing adsorption has the advantages of low cost and high efficiency and has been widely used. The design and preparation of high-efficiency adsorbents is the core of the pressure swing adsorption technology. Therefore, high-performance porous CO2 adsorption materials have attracted increasing attention. Porous adsorption materials with high specific surface area, high CO2 adsorption capacity, low regeneration energy, good cycle performance, and moisture resistance have been focused on. This article summarizes the optimization of CO2 adsorption by porous adsorption materials and then applies them to the field of CO2 adsorption. The internal laws between the pore structure, surface chemistry, and CO2 adsorption performance of porous adsorbent materials are discussed. Further development requirements and research focus on porous adsorbent materials for CO2 treatment in industrial waste gas are prospected. The structural design of porous carbon adsorption materials is still the current research focus. With the requirements of applications and environmental conditions, the integrity, mechanical strength and water resistance of high-performance materials need to be met.

A novel fabricated polyvinyl alcohol/ bentonite nanocomposite hydrogel generated into colloidal gas aphron

Polyvinyl alcohol/bentonite (PVA- Ben) nanocomposite hydrogel is commonly used as an adsorbent for removing many dye residues in wastewater treatment. In the present study, a novel polyvinyl alcohol/bentonite nanocomposite, (CGA-PVA-Ben) hydrogel, is fabricated by mixing polyvinyl alcohol and bentonite dispersions in the presence of a high shear force via a colloidal gas aphron (CGA) generator. X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and Fourier Transform Infrared (FTIR) spectroscopy methods are used to characterize both the novel (CGA-PVA-Ben) and also conventional (PVA-Ben) nanocomposite hydrogels. The results of EDS, XRD, and FTIR analyses show that the (CGA-PVA-Ben) hydrogel has the same bonds, functional groups, and exact composition as the (PVA-Ben) hydrogel. However, FE-SEM analysis demonstrates that the (CGA-PVA-Ben) has more porous and uneven surfaces. The presence of high shear forces during the mixing of polyvinyl alcohol and bentonite reagents in aphron generator reduces the mass density of hydrogel. Therefore, compared with neat hydrogel adsorbent, i.e., (PVA-Ben), the (CGA-PVA-Ben) has a unique characteristic behavior which is the adsorbent floatability after the adsorption process. This remarkable feature provides an alternative method in adsorption technology and it is an interesting advantage for easy removal of adsorbent from the contaminated effluents. Details of the adsorption characterization of this novel fabricated polyvinyl alcohol/ bentonite nanocomposite hydrogels will be discussed in a follow-up research paper.

Dynamic SPME-SERS Induced by Electric Field: Toward In Situ Monitoring of Pharmaceuticals and Personal Care Products.

The core of the surface-enhanced Raman spectroscopy (SERS)-based techniques for dynamic monitoring is to realize rapid and reversible adsorption. Herein, the integration technology of electro-enhanced adsorption, solid-phase microextraction, and surface-enhanced Raman spectroscopy (EE-SPME-SERS) was developed to obtain sensitive, ultrafast, and reversible SERS response toward in situ monitoring of pharmaceuticals and personal care products (PPCPs). In the EE-SPME-SERS method, a roughened Ag fiber with Au modification (r-Ag/Au fiber) was used as the SERS substrate, SPME sorbent, and working electrode. The r-Ag/Au fiber displayed good SERS sensitivity, ultrahigh photostability, and adsorption properties. The adsorption efficiency of benzidine was 76 times accelerated in EE-SPME-SERS compared to that in static adsorption. The whole process of "sampling and detection" in EE-SPME-SERS can be finished within 1 s. Reversible adsorption and desorption can be achieved in situ by switching the direction of electric field, and the regeneration process takes only a few minutes. Simulated release of benzidine from household wastewater was in situ and dynamically monitored using this strategy. EE-SPME-SERS was proved universal for ionized PPCPs and can detect multicomponents simultaneously. In addition, EE-SPME-SERS showed very good analytical properties. Great potential of EE-SPME-SERS can be expected in environmental monitoring.

Emission characteristics of volatile organic compounds during a typical top-charging coking process

The emission of volatile organic compounds (VOCs) from coking industry severely reduces air quality. Using both offline and online methods, the emissions of 124 VOCs and non-methane hydrocarbon (NMHC) in a typical top-charging coke oven were analyzed during the coking process (emissions form the coke oven flue gas, charging, pushing, coke dry quenching, and topside of the coke oven). The concentrations of VOCs in coke oven flue gas and exhaust gas during charging were the highest, which reached 98.2 mg/m3 and 136.6 mg/m3, respectively. This was followed by the concentrations of exhaust gases sourced from the topside of the coke oven, pushing, and coke dry quenching, which were 12.0 mg/m3, 1.8 mg/m3, and 0.8 mg/m3, respectively. The main components of VOCs for the different exhaust emission sources were significantly different. The ozone formation potentials (OFPs) of coke oven flue gas and exhaust gas during charging were the largest, and unsaturated hydrocarbons such as alkenes and benzenes were the main source of ground-level ozone. These data can support researchers in developing adsorption, catalytic oxidation, and other technologies for the removal of VOCs generated by the coking process.

Investigation of the process of desalination of the concentrate of reverse osmosis plants by energy waste

PURPOSE. To investigate the cleaning process of the reverse osmosis water filtration system (ROWFS) concentrate with energy waste, to obtain and determine its quality indicators, to study the mechanism of sulfate and chloride ions adsorption by sorption material on the basis of energy waste, to consider the process of sulfate and chloride ion adsorption by this sorption material under static and dynamic conditions.METHODS. The method of variable weights was used to determine the adsorption capacity of the sorption material. Methods of titrimetric and photocolorimetric analysis were used during determining of water quality indicators.RESULTS. In this paper the technology of desalination of the ROP concentrate by the adsorption method was studied. Under static conditions the adsorption isotherm has been constructed. On the basis of ground sludge the granular sorption material has been developed. The possibility of using ionexchange filters with granular loading has been considered, the adsorption curve under dynamic conditions has been constructed.CONCLUSION. The sorption based on energy waste - carbonate sludge material for the purification of ROWFS concentrate has been developed. Adsorption isotherms of sulfate and chloride ions were constructed on the basis of experimental data. For investigation the purification of the ROWFS concentrate under dynamic conditions the granular sorption material was obtained. The adsorption technology of ROWFS concentrate purification from sulfate and chloride ions by energy waste is presented.

CONTROLLING OF SO2 BY KMNO4 MODIFIED PLANT MATERIAL BY BIOSORPTION

Adsorption technology has been successfully employed for controlling water pollution. Surface chemistry, surface modification, nature of adsorbent and adsorbate plays a vital role in the Adsorption phenomenon which has been studied by using KMnO4 modified adsorbents. From the present studies the experiments have been carried out by using KMnO4 modified plant materials as bioadsorbents and the order of efficiency of removal of SO2 is found to be Citrus limetta &gt;Abelmoschus esculentus &gt; Hevea brasilensis &gt; Hibiscus sabdariffa &gt; Bacopa monnieri &gt; Aloe barbadensismiller &gt; Psidium guajava &gt; Nelumbo nucifera &gt; Fenugreek &gt; Amaranthus. Keywords: Adsorption; Water pollution; Adsorbent; Adsorbate; Removal of SO2; Surface modification; Plant materials; Bioadsorbents;

Recent trends and advances in biogas upgrading and methanotrophs-based valorization

The global quest for sustainability in industrial activities and waste management has recently boosted biogas production worldwide. However, the rapid decrease in the levelized cost of electricity of renewable energies will soon entail electricity prices from biogas much higher than those from solar or wind power. In this context, the upgrading of biogas into biomethane represents an alternative to on-site biogas combustion. Membrane separation technology is rapidly dominating the biogas upgrading market and displacing scrubbing and adsorption technologies driven by the recent breakthroughs in material science. Similarly, biogas biorefineries have recently emerged as an innovative platform for biogas valorization capable of biotransforming methane into added value products. The limited number of bioproducts naturally synthesized by methanotrophs can be boosted via metabolic engineering of methanotrophs, while novel bioreactor configurations capable of supporting a cost-effective methane mass transfer from the gas phase to the methanotrophic broth are currently under investigation to facilitate the full scale implementation of biogas biorefineries.

A Review of the Removal of Dyestuffs from Effluents onto Biochar

The study provides a review of various applications of biomass-derived biochars, waste-derived biochars, and modified biochars as adsorbent materials for removing dyestuff from process effluents. Processing significant amounts of dye effluent discharges into receiving waters can supply major benefits to countries which are affected by the water crisis and anticipated future stress in many areas in the world. When compared to most conventional adsorbents, biochars can provide an economically attractive solution. In comparison to many other textile effluent treatment processes, adsorption technology provides an economic, easily managed, and highly effective treatment option. Several tabulated data values are provided that summarize the main characteristics of various biochar adsorbents according to their ability to remove dyestuffs from wastewaters.

Adsorbents Used for the Adsorptive Removal of Highly Hazardous Arsenic from Aqueous Solution: A Review

Millions of people worldwide are adversely affected by Arsenic continuing exposure, so providing arsenic-free consumption of water is an immense task for the researchers. The chemistry, content of arsenic-contaminated water as well as adsorption play a big role in arsenic elimination. The mechanism of adsorption technology's elimination of As (V) from the water was simply presented as the elements that govern various adsorption paths. The effects of a variety of adsorbents on As (V) elimination from aquatic were explored in the present research, which classified the materials used as adsorbents based on physical, chemical, and biological processes. When choosing an adsorbent, adsorption capability is an important factor to consider. As a result, developing As (V) elimination from aquatic adsorption strategies includes developing environmentally acceptable materials with effectual adsorption abilities, refining the preparation and alteration procedures of recent adsorbents, and boosting renewal effectiveness. After choosing a particular adsorbent for As (V) elimination from water, regional features of arsenic-polluted water, applied viability of the adsorption process, besides suitable environments of respectively material must be extensively reviewed and analyzed. The current study gives an outline of the adsorption technique to remove arsenic from wastewater, as well as the adsorption capacity of various adsorbents.

Using silver exchange to achieve high uptake and selectivity for propylene/propane separation in zeolite Y

Adsorptive separation of propylene and propane, an important step of polypropylene production, is more energy-efficient than distillation. However, the challenge lies in the design of an adsorbent which exhibits both high selectivity and uptake. Herein, we hypothesise that enhancing the propylene affinity of the adsorption sites while keeping a suitable pore size can address this challenge. To do so, we performed silver exchange of a commercial zeolite Y, thereby making the adsorbent design easily scalable. We characterised the adsorbent using analytical, spectroscopic and imaging tools, tested its equilibrium and dynamic sorption properties using volumetric and gravimetric techniques and compared its performance to those of state-of-the-art adsorbents as well as other silver-functionalised adsorbents. The silver-exchanged zeolite Y (Ag-Y) exhibited one of the best selectivity vs uptake performances reported so far. Ag-Y also displayed fast adsorption kinetics and reversible propylene sorption, making it a promising new benchmark for propylene/propane separation. Synchrotron-based pair distribution function analyses identified the silver cations’ location which confirmed that the silver sites are easily accessible to the adsorbates. This aspect can, in part, explain the propylene/propane separation performance observed. The overall design strategy proposed here to enhance sorption site affinity and maintain pore size could be extended to other adsorbents and support the deployment of adsorption technology for propylene/propane separation.

Evaluation of MBTSA technology for CO2 capture from waste-to-energy plants

Moving bed temperature swing adsorption (MBTSA) is a promising technology for CO2 capture from flue gases. In a MBTSA unit, a selective adsorbent material is circulated between a low-temperature stage where it removes CO2 from the flue gas and a higher-temperature zone where it desorbs CO2 at higher purity. The main benefits of MBTSA are low pressure drops in the adsorption zone and the possibility to heat the adsorbent faster than standard adsorption technologies. This work evaluated via process simulations the use of the MBTSA technology for CO2 capture from an industrial-scale waste-to-energy plant. To assess the technology with realistic parameters, we measured heat transfer coefficients in the heating section of a new MBTSA demonstrator unit using activated carbon spheres. The heating device was produced by 3D printing, and has rectangular channels on the gas-solid side rotated at 45∘ to facilitate solid flow. The heat transfer coefficients increased with the flow rate of activated carbon particles, and the highest value of 120 W/m2K was measured for a sorbent mass flux of 3.5 kg/m2s. This information was used as input for the process simulations, and allowed a tailored and realistic design of an MBTSA unit capturing more than 90% of the exhaust CO2 with a purity above 95%. The rather high specific heat duty of the process (5.7 MJ/kg CO2) can be attributed to the low adsorption capacity of the activated carbon. In this respect, significant improvements can be expected by employing adsorbents with higher adsorption capacity and selectivity, such as zeolites or metal-organic frameworks.

Synergistic Fluoride Adsorption by Composite Adsorbents Synthesized From Different Types of Materials—A Review

The reduction of fluoride concentrations in water is one of many concerns. Adsorption is the most widely used technology for fluoride removal and the center to development of adsorption technology is the improvement of adsorbents. This review classifies the typical fluoride removal adsorbents into four types: metal oxides/hydroxides, biopolymers, carbon-based, and other adsorbents. The exploitation of new materials and the synthesis of composite materials are two ways of developing new adsorbents. In comparison to the discovery of novel adsorbents for fluoride adsorption, research into the composite synthesis of different types of conventional adsorbents has proliferated in recent years. The traditional adsorbents used the earliest, metal oxides, can act as active centers in a wide range of applications for modifying and compounding with other types of adsorbents. This study emphasizes reviewing the research on fluoride removal by composite adsorbents synthesized from different types of metal-modified materials. Seven factors were compared in terms of material characterization, initial fluoride concentration, adsorbent dose, pH, temperature, reaction time, and maximum adsorption capacity. The modification of composite adsorbents is facile and the synergistic effect of the different types of adsorbents significantly improves fluoride adsorption capacity. Metal composite adsorbents are synthesized by facile coprecipitation, hydrothermal, or impregnation modification methods. The adsorption mechanisms involve electrostatic attraction, ion exchange, complexation, and hydrogen bonding. The fluoride adsorption capacity of composite adsorbents has generally improved, indicating that most modifications are successful and have application prospects. However, to achieve significant breakthroughs in practical applications, numerous issues such as cost, separation/regeneration performance, and safety still need to be considered.

Overview of Carbon Monoxide Adsorption Performance of Pristine and Modified Adsorbents

Carbon monoxide (CO) is a key material in C1 chemistry for chemical production and CO2 reduction, whereas in applications, such as H2 for fuel cells, its concentration must be kept below 0.2 ppm. Adsorption technology is useful for both CO removal and production to provide environmental sustainability for the energy and chemical industries. In this review, the CO adsorption performances of various adsorbents, such as activated carbons, zeolites, metal–organic frameworks, activated alumina, mesoporous silicas, and their modified adsorbents, are collected, and their physical and chemical properties and CO selectivities are summarized. Cu+ impregnation is a powerful and widely used modification method to enhance the CO adsorption of adsorbents. Therefore, the preparation methods and their effects on CO adsorption are also compared and reviewed. The data and analysis in this review can provide insights for the development of novel adsorbents and processes for CO removal and production.