Original Sorbent Research Articles

Regularities in mercury cation sorption by a lignin-based sulfur-containing sorbent

The unfavorable environmental situation in the town of Usolye-Sibirskoye (Irkutsk Oblast, Russia) determines the relevance of investigating and applying a new lignin-based sulfur-containing sorbent for purification of groundwater from mercury compounds. The sorbent was synthesized on the basis of waste products of epichlorohydrin (1,2,3-trichloropropane), sulfur, and lignin. The IR spectrum of the sorbent under study showed the presence of an S–S bond in the region of 445–465 cm-1. Intensive absorption of Hg2+ ions in the regions of 2800–2950 cm-1 (valence vibrations of C–H bonds in CH and CH2 groups) and 1460 cm-1 (deformation vibrations in CH2 group) was observed. Absorption of Hg2+ ions by lignin fragments was accompanied by a change in the vibration band of S–S bonds, which splits into two bands of higher frequencies than the νS–S band in the original sorbent. The optimum sulfur content, which ensures the maximum sorption activity of the sorbent, was found to be 53.25%. The mercury sorption isotherms at 20 and 60 °C are described by parabolic dependencies with determination coefficients of 98.9 and 98.6 %, respectively. The kinetic curve at 20 °C and 40 °C is approximated by a hyperbola and a cubic polynomial with determination coefficients of 97.9 and 96.2 %, respectively. The reaction order (first order at 20 °C and second order at 40 °C) and the reaction rate constant (0.0876 min-1 at 20 °C and 0.00014 min-1 at 40 °C) were determined. At 20 °C, the sorption rate of Hg2+ was established to be significantly higher and the sorption time to be faster than those at 40 °C. Therefore, mercury sorption by the proposed sorbent should be carried out at 20 °C in order to reduce energy consumption.

Application of high-frequency plasma modification to obtain protective materials with improved sorption properties

In sorption technologies, surface modification of coals is widely used in order to increase their sorption capacity. The most promising method for improving the properties of materials of various structures is high-frequency plasma treatment. It was revealed that after the treatment of sorbents with low-pressure high-frequency capacitive plasma, materials are obtained with properties different from the original sorbent, characterized by increased sorption properties. Processes that affect the kinetics of adsorption and increase the sorption activity of activated carbon have been studied by FTIR spectroscopy.

Analysis of sorption capacity of natural sorbents in relation to aqueous solutions of heavy metal compounds

The main preconditions emergence of an environmental crisis in the country due to surface water pollution include irrational use of water resources in violation of the environmental requirements, discharge of untreated and insufficiently treated industrial and municipal wastewater into water bodies and inflow of polluting substances from agricultural lands as a result of surface water drainage. The whole set of considered factors leads to depletion and pollution of surface water of Ukraine, reduction of their self-cleaning capacity, degradation, impoverishment and collapse of aquatic ecosystems.
 Excessive content of heavy metal ions in surface water has a negative impact on the environment, causing acute and chronic diseases. Ingress of such pollutants into surface water is almost entirely due to anthropogenic economic activity. Wastewater from chemical, ferrous and nonferrous metallurgy brings a great amount of such pollutants.
 Among various methods used for removing heavy metal ions from aqueous media, sorption methods remain one of the most effective and popular, mainly due to the fact that they ensure a high degree of purification at relatively low costs. Along with the adsorbents traditionally involved in these processes, a number of studies and practical implementations with use of natural dispersed minerals as adsorbents were conducted lately.
 The research aims at studying the sorption capacity and efficiency of natural and modified sorbent such as bentonite clay for purification of aqueous solutions containing heavy metal ions in the form of dissolved compounds and justifying its potential application.
 It studies the efficiency of wastewater treatment aimed at removing heavy metal ions by the natural clay sorbent of bentonite clays of the Cherkaskyi Deposit (Dashukovskyi deposit).
 The paper presents a technique for modification of bentonite clay in order to increase its adsorption capacity for heavy metal ions using the following three methods: physical (thermal), chemical (processing with application of Iron(III) chloride solution) and combined (thermal processing of the original sorbent followed by processing with application of Iron(III) chloride solution).
 It has been experimentally proved that a natural sorbent modified via thermal and chemical processing is characterized by a high absorption capacity to heavy metal ions contained in water solutions, in particular to chromium(VI) ions, copper(II) ions and aluminum(III) ions with the purification degree ranging from 5% to 83%. The highest adsorption rate, 83%, is demonstrated by the combined method of bentonite clay modification, therefore proving the effectiveness of application of environmentally friendly natural sorbents for wastewater treatment processes aimed at removing heavy metal ions. The paper indicates the advantages of wastewater treatment sorption methods allowing removal of pollutants of different origin and any concentration.

Prospects of the Use of New Carbon Sorbents with Antimicrobial Properties in the Intensive Care Medicine

The purpose is to study antibacterial and antimycotic properties of produced granular carbon sorbents. Material and methods. A VNIITU-1 carbon sorbent was used as a starting material, which was modified with polyvinylpyrrolidone and lactic and glycolic acids oligomers. Microbiological bench tests were carried out to determine the antibacterial and antimycotic activity of these granulated carbon hemosorbents. Antibacterial properties of sorbents were studied in relation to pathogenic and conditionally pathogenic microorganisms: Staphylococcus aureus, Pseudomonas aeroginosa, Klebsiella pneumonia, Escherichia coli, Streptococcus agalactiae as well as their mixtures: mixture No. 1 — S. aureus and E. coli; mixture No. 2 — S. aureus and P. aeruginosa. Results. Presented data demonstrate that the modified VNIITU-1 exhibits significant antibacterial and antimycotic activity against most of the studied microorganisms compared to original sorbent. Conclusion. Modified sorbents as antimicrobial and detoxifying drugs may further be employed in treatment of obstetrical-gynecological and surgical diseases. The carbon sorbents are promising materials for medicine, as they expand the potential of sorption therapy in clinical practice.

Control of microimpurities emitted from polymer construction materials based on polyvinyl chloride

The aim of this article is to improve the degree control of microimpurities emitted from polymeric construction materials into the environment. It is proposed to do this through the modification of the physicochemical nature of the original (source) sorbent and, as a consequence, the improvement of the sorption capacity and the extraction ratio of highly volatile toxic substances. The proposed concentrator columns can be widely used in the analysis of microimpurities of polar organic substances released into the environment from polymeric construction materials based on polyvinyl chloride.

Functionalized three-dimensional graphene sponges for highly efficient crude and diesel oil adsorption.

Modified Hummer's method has been used in this study to synthesize graphene oxide (GO) solution that was utilized for the fabrication of three-dimensional (3D) graphene sponges and their subsequent functionalization through a low-cost and facile vapor-based surface enhancement approach. The functionalized 3D-graphene sponge is an excellent absorbent, which can remove more than 3300wt.% of crude oil (calculated with respect to the original sorbent mass). The functionalization of the obtained graphene sponges with trichloro (1H,1H,2H,2H-perfluorooctyl)silane enhanced their wettability properties due to the super-hydrophobic nature of the resulting materials characterized by the contact angles in water greater than 150°. Furthermore, their elastic compression modulus (estimated by conducting a series of compression tests) was about 22.3kPa. The equilibrium modeling of the oil removal process, which was performed by plotting Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, confirmed the properties of the fabricated 3D graphene sponges as exceptional absorbents for crude and diesel oil, which could be attributed to the oleophilic nature of graphene. Moreover, the obtained 3D graphene sponges could be regenerated via heat treatment, which was conducted to release the adsorbed species. After five adsorption-desorption cycles, the sorption capacity of the produced 3D graphene sponges towards crude oil reached 95% of the initial value.

Development of stabilized Ca-based CO2 sorbents supported by fly ash

The rapid decay of CO2 capture capacity during the calcination/carbonation cycles is one major problem of the calcium looping technology. To improve and maintain excellent CO2 capture performance of sorbents is of significance, especially in an environmental friendly and cost effective way. Using fly ash, the solid waste captured by collectors from coal combustion systems to modify calcium based sorbents is a potential application to enhance CO2 capture capacity. Sorbents modified with fly ash presented great reactivity and achieved enhancement in CO2 capture capacity. After 15 cycles, the modified sorbents achieved a CO2 capture capacity of 0.27 g CO2/g sorbent, 5 times as high as that of the original sorbent (calcium carbonate) under severe calcination conditions. The modified sorbent maintained a capacity of 0.180 g CO2/g sorbent over 80 cycles. The increased surface area and pore volume enabled enhanced CO2 capture capacity of the modified sorbents. The carbonation kinetics of the modified sorbents was highly increased compared with the original sorbents. The formation of Ca3Al2O6 and CaAl2O4 in the modified sorbents enhanced the sorbents’ sintering resistant and slowed the decay in CO2 capture capacity during the multiple cycles. A promising route to enhance CO2 capture performance with waste reutilization is highlighted.

Application of sorption technologies for infected burn wounds treatment in the experiment

The frequency of infectious complications in patients with burn is still an actual problem of modern medicine. Endogenous and exogenous intoxication leads to disruption organs and systems functions in general. That's why more attention should be paid to such a direction of medicine as application sorption. Purpose: The aim of this study was the evaluation of antibacterial activity and wound-healing properties of the sorbent applicator based on highly dispersed nanosilica with immobilized antimicrobial mixture for the treatment of experimental Pseudomonas infection. Materials and м ethods : The research was carried out on 90 6-month male mice NMRI line weight 18–20 grams. All animals were divided into 5 groups. We used a model of the contact thermal burn. After burning experimental animals were infected by daily agar culture of multidrug resistant clinical strain of P. aeruginosa 3101, obtained from a patient with burns. Microbiological studies of burn wounds were carried out. The rate of wound healing was carried out using the following parameters: the average rate of wound surface decrease (cm² per day) and reduction of wound surface area (percent per day – Popova’s index). Results. It has been found that the application of new original applicator sorbent for 3 days decrease the number of microbial cells in the wound below the critical level (10 5 ). In this experimental group the amount of purulent discharge from the wounds, swelling, redness and infiltration of tissues were reduced in comparison with the other groups. Earlier cleansing of wounds and acceleration of reparative processes were observed. Conclusions. The findings suggest that the applicator sorbent exhibits antibacterial and wound healing properties and can be a prospective complex drug for the topical treatment of Pseudomonas infected burns.

Trace Na2CO3 Addition to Limestone Inducing High-Capacity SO2 Capture

Although the literature has reported enhanced indirect sulfation of limestone by adding Na2CO3, the amount of Na2CO3 additive required to achieve high CaO conversion is typically high (∼4.0 mol %), which commonly results in adverse effects in fluidized-bed combustion boiler systems and increased cost of sorbents. In this work, we demonstrate for the first time that trace Na2CO3 (0.1 mol %) can significantly enhance the sulfate conversion of limestone. This enhanced sulfation is attributed to the increased surface area and optimized pore size distribution. The trace Na2CO3 additive splits the pores of the original sorbents peaking at ∼70 nm into pores peaking at ∼4 nm and ∼140 nm due to the slight promotion of sintering. This well-developed pore structure results in a relatively high reactivity for sulfation. Thus, the Na2CO3 additive influences the sorbent reactivity in two ways: (1) at less than 0.5 mol %, tuning its pore structure; (2) at more than 0.5 mol %, promoting the product layer diffusion. We also find that trace amount of other metal salts, such as CaCl2 and NaCl, clearly enhance the sulfation of limestone. The strategy of enhancing limestone sulfation by the addition of trace amount of metal salts offers evident engineering and economic advantage.

Characterization of polyaniline-coated stationary phases by using the linear solvation energy relationship in the hydrophilic interaction liquid chromatography mode using capillary liquid chromatography.

A polyaniline coating was used to modify the surface of bare silica gel and octadecyl silica stationary phases to characterize the properties of altered materials. It was assumed that the mixed-mode retention was established on the basis of the polyaniline chemical structure and its combination with the original sorbents. Polyaniline was deposited onto the original surfaces during the chemical polymerization of aniline hydrochloride. The prepared materials were slurry packed into capillary columns and systematic chromatographic characterization was performed using the linear solvation energy relationship, also employing descriptors that allow inclusion of ionic interactions in the proposed retention mechanism. The retention times of 80 solutes with various chemical structures were measured in the hydrophilic interaction liquid chromatography mode. The obtained results demonstrated the significant contribution of the polyaniline coating to the retention mechanism under the given conditions; the assumed mixed-mode retention was confirmed. The dominant retention interaction for both modified stationary phases was based on the protonation of nitrogen atoms in the polyaniline structure, leading to suitable retention and selectivity for the hydrophilic analytes, especially anionic and zwitterionic species. Thus, especially, the polyaniline-coated bare silica gel sorbent seems to be promising for potential applications related to the separation of polar compounds.

Experimental Study of the Biocompatibility of Soft Tissues and a Finely Dispersed Sorbent Containing Silver

The physicochemical and biological properties of a new finely dispersed Si- and Al-containing sorbent are presented. Its modification using silver nanoclusters immobilized on the sorbent-particle surface is described. The parameters of the sorbent porous structure, its sorption activity, and the rate of silver release from the sorbent surface in contact with a liquid medium are determined. Both the sorbent matrix and the original silver-modified sorbent are well tolerated by experimental animals upon intramuscular administration and cause no changes in the behavior, weight, and appearance of the animals. Results from studies of the leukocyte, platelet, and red-blood-cell pools of peripheral blood also confirm that the sorbents are biocompatible with body tissues.

Regeneration Effect of Fluoride-Rich Granular Activated Alumina on Desorption Regent NaOH Solution

As an effective adsorbent, granular activated alumina (GAA) has been widely used in defluoridation. In order to reduce cost and operate environment-friendly, the adsorbent should be regenerated. In this paper, column experiment was done to characterize the fluoride removal properties and to develop an optimal method to regenerate fluoride-rich modified activated alumina (MGAA). The MGAA can be regenerated by utilizing sodium hydroxide solution desorption, deionized water washing and ferric sulfate reactivation and then used for futher defluoride operation. The influence of the concentration of desorption agent (NaOH solution) and desorbing time on desorption rate and the adsorption capacity of regenerated MGAA were studied. The optimal desorption condition was: 1% NaOH solution for desorption agent, desorbing time in 1.5h.In addition, when the regenerated MGAA was used again for column adsorption test, its adsorption capacity reached 94% of that of original sorbent in 1mg/L outlet fluoride concentration.

Reuse of Spent Sorbents from FBC for SO2 Capture by Simultaneous Reactivation and Pelletization

Sorbent utilization of CaO-based sorbents for in situ SO2 capture in fluidized bed combustion (FBC) is far from quantitative, and in consequence FBC residues contain a significant amount of unreacted CaO. Treatment of bed materials by hydration with liquid water or steam can reactivate the spent sorbent for further SO2 capture, although, to date, the costs of such processes have deterred its practical use. By contrast, fly ash is already very reactive, but given its short residence time in the combustor, direct reuse of fly ash appears to be an ineffective strategy. This is significant as fly ash often accounts for the majority of solid waste streams discharged from FBC systems. This paper describes a new technique for reactivation of FBC spent sorbent and preparation of pellets suitable for SO2 capture, which can also incorporate the fly ash into the pellets so that it has an adequate residence time in the primary combustion loop of a CFB to realize improved sulfur capture. Reactivation and pelletization of the spent sorbent were achieved simultaneously in a mechanical pelletizer with the addition of spray water. Four types of pellets were prepared with various proportions of bed ash and fly ash. Quick lime (CaO) powders were also tested as a useful additive for the pelletization process. The effectiveness of the reactivation technique was tested by the nitrogen physisorption, which confirmed that a more suitable pore surface area and pore volume distribution for sulfation were developed. The SO2 capture potential of the pellets was also examined in a thermogravimetric analyzer. The reactivated pelletized sorbents showed an improved sulfation rate in comparison to both the original sorbent and the spent sorbent, particularly during the diffusion-controlled reaction stage.

Novel Optimized Process for Utilization of CaO-Based Sorbent for Capturing CO2 and SO2 Sequentially

Calcium oxide (CaO) based sorbents, used for CO2 capture in calcination/carbonation cycles, reduce in activity with increasing numbers of cycles, thus reducing the economic benefits of this capture process, generating a significant amount of spent sorbent and raising the potential for pollution from its disposal. This paper presents research into the use of this spent sorbent for the prior capture of sulfur oxides (SOx), as required when the cycle is used with coal-derived flue gases. Using a thermogravimetric analyzer (TGA), the sulfation behaviors of two limestones from Hebei Province (named LA and LB) were examined after different numbers of calcination/carbonation cycles. The results show that the sulfation conversions for spent sorbent of the LA and LB after 40 cycles were, respectively, about 4% and 14% less than that of the original sorbent, indicating that spent sorbents from CO2 capture cycles remain active for SO2 retention. As the number of cycles increased, there was a difference in the sulfation conversions between LA and LB, probably due to the difference in pore structure development for the two limestones as the sulfation reaction progressed. The surface morphology and pore structure of sorbents after different numbers of cycles were examined by scanning electron microscopy (SEM) and nitrogen adsorption/desorption spectroscopy. It was found that the pore size distributions show two peaks in all cases, and as the number of cycles increased, the larger pores fuse together while the number of small pores was not markedly diminished, which is not consistent with the existing sintering model. The observed sintered pore structure provides greater product growing space for reactions to occur in the pore inner surface, which benefits sulfation more than carbonation due to their different product molar volumes, helping to explain why cycled sorbent samples remain active in sulfation.

Development of CaO-Based Sorbent Doped with Framework Materials for CO2 Capture

Calcium looping technology is an attractive method for CO2 capture in dual fluidized bed combustion (FBC) reactors. The major limit for this technology is that the capture capacity of CaO-based sorbents sharply decreases with increasing cycle numbers. Attrition and consequent elutriation of CaO-based sorbents from FBC reactors also limit its application. In order to overcome these shortcomings, doping with framework materials is shown as a promising potential solution. Therefore, this work looks at a review of the CO2 capture capacities of CaO-based sorbents doped with different framework materials, such as aluminate cements, kaolin, aluminum oxides, magnesium oxide, titanium dioxide, and lanthanum salt. The synthetic sorbents have a better performance in CO2 capture capacities than the original sorbents in long term carbonation/calcination cycles.

Optimization of magnetic powdered activated carbon for aqueous Hg(II) removal and magnetic recovery

Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 μg/L while being magnetically recoverable. Magnetic recapture allows simple sorbent separation from the waste stream while an isolated waste potentially allows for mercury recycling. MPAC Hg-removal performance is verified by mercury mass balance, calculated by quantifying adsorbed, volatilized, and residual aqueous mercury. The batch reactor contained a sealed mercury–carbon contact chamber with mixing and constant N 2 (g) headspace flow to an oxidizing trap. Mercury adsorption was performed using spiked ultrapure water (100 μg/L Hg). Mercury concentrations were obtained using EPA method 245.1 and cold vapor atomic absorption spectroscopy. MPAC synthesis was optimized for Hg removal and sorbent recovery according to the variables: C:Fe, thermal oxidation temperature and time. The 3:1 C:Fe preserved most of the original sorbent surface area. As indicated by XRD patterns, thermal oxidation reduced the amorphous characteristic of the iron oxides but did not improve sorbent recovery and damaged porosity at higher oxidation temperatures. Therefore, the optimal synthesis variables, 3:1 C:Fe mass ratio without thermal oxidation, which can achieve 92.5% (±8.3%) sorbent recovery and 96.3% (±9%) Hg removal. The mass balance has been closed to within approximately ±15%.

Cyclic CO2 Capture Behavior of Limestone Modified with Pyroligneous Acid (PA) during Calcium Looping Cycles

In this work, pyroligneous acid (PA) was used to modify limestone, and the CO2 capture capacity in calcination/carbonation cycles was consequently strengthened. The cyclic CO2 capture behavior of PA-modified limestone was investigated in a thermogravimetric analyzer and a dual fixed-bed reactor. The main component of the PA-modified limestone was found to be calcium acetate hydrate. The optimum ratio of PA to limestone was found to be 20 mL/g. The PA-modified limestone was found to retain a higher CO2 capture capacity for carbonation at 700 °C. The carbonation conversion of the PA-modified limestone achieved 0.33 after 103 cycles, whereas, for the original sorbent, the conversion was just 0.078 under the same reaction conditions. The modification of limestone increased the surface area and pore volume of the calcined material during cycles. Furthermore, the calcined form of the modified limestone had more pores in the ranges of 1.8–4.6 and 18–155 nm, and as a result, its surface area and pore volume were both expanded.

Experimental Study on Abrasion Characteristics of Rapidly Hydrated Sorbent for Moderate Temperature Dry Flue Gas Desulfurization

A rapidly hydrated sorbent for moderate temperature (600−800 °C) dry flue gas desulfurization (FGD) was developed with the fine calcium-containing particles formed by hydrating the lime adhering to the fly ash particles to increase the residence time of these fine particles in the circulating fluidized bed (CFB) reactor to increase the desulfurization efficiency. Abrasion of the rapidly hydrated sorbent was investigated by sieving the sorbent for 1 h with a sieving displacement of 1.5 mm. The abrasion ratio, Ra (%), which is the percentage of calcium (Ca) mass below the sieve to the original sorbent mass, was used to represent the sorbent abrasion characteristics. The sorbent desulfurization ability, Rd (mg/g), was represented by the mass of sulfur dioxide (SO2) absorbed per gram of sorbent. The experimental results show that Ra decreased from 7.35% to 3.16% as the fly ash particle size increased from 74 to 182 μm, while Rd of sieved sorbent increased from 124 to 139 mg/g, indicating that sorbent made from larger fly ash particles had a lower abrasion ratio and retained higher desulfurization ability after sieving. The sorbents prepared by firing, alkali, and acid modified fly ash particles had lower abrasion ratios and higher desulfurization abilities than those of sorbent prepared from the original fly ash.

SO2 Retention by CaO-Based Sorbent Spent in CO2 Looping Cycles

CaO-based looping cycles are promising processes for CO2 capture from both syngas and flue gas. The technology is based on cyclical carbonation of CaO and regeneration of CaCO3 in a dual fluidized-bed reactor to produce a pure CO2 stream suitable for sequestration. The main limitation of natural sorbents is the loss of carrying capacity with increasing number of reaction cycles, resulting in the need for extra sorbent, and subsequent spent sorbent waste. Use of spent sorbent from CO2 looping cycles for SO2 capture is investigated in this study. Three limestones were investigated: Kelly Rock (Canada), La Blanca (Spain), and Katowice (Poland, Upper Silesia). Carbonation/calcination cycles were performed in a tube furnace with both the original limestones and samples thermally pretreated for different times (i.e., sintered). The spent sorbent samples were sulfated in a thermogravimetric analyzer (TGA). The changes in the resulting sorbent pore structure were then investigated using mercury porosimetry. It has been shown that the sulfation rates of both thermally pretreated and spent sorbent samples are lower in comparison with those of the original samples. However, final conversions of both spent and pretreated sorbents after longer sulfation time were comparable or higher than those observed for the original sorbents under comparable conditions. Maximum sulfation levels strongly depend on sorbent porosity and pore surface area. The shrinkage of sorbent particles during calcination/carbonation cycling resulted in a loss of sorbent porosity on the order of ≤48%, which corresponds to maximum sulfation levels of ∼55% for spent Kelly Rock and Katowice. This is ∼10% higher than that seen with the original samples after 15 h of sulfation. By contrast, La Blanca limestone had more pronounced particle shrinkage during pretreatment and cycling, leading to porosities lower than 35%, which resulted in sulfation conversion of spent samples <30%, which is significantly lower than that for the original sample (45%). These results showed that spent sorbent samples from CO2 looping cycles can be used as sorbents for SO2 retention in cases where significant porosity loss does not occur during CO2 reaction cycles. The higher conversions of spent samples are explained by a shift in pore size distribution toward larger pores that reduce the reaction rate and pore plugging near the particle’s outer surface, with formation of either unreacted core or unreacted network patterns. In the case of spent Kelly Rock and Katowice samples, sorbent particles are practically uniformly sulfated, achieving final conversions that are determined by the total pore volume available for the bulky CaSO4 product.

Cyclic calcination/carbonation looping of dolomite modified with acetic acid for CO 2 capture

The dolomite modified with acetic acid solution was proposed as a CO 2 sorbent for calcination/carbonation cycles. The carbonation conversions for modified and original dolomites in a twin fixed-bed reactor system with increasing the numbers of cycles were investigated. The carbonation temperature in the range of 630 °C–700 °C is beneficial to the carbonation reaction of modified dolomite. The carbonation conversion for modified dolomite is significantly higher than that for original sorbent at the same reaction conditions with increasing numbers of reaction cycles. The modified dolomite exhibits a carbonation conversion of 0.6 after 20 cycles, while the unmodified sorbent shows a conversion of 0.26 at the same reaction conditions, which is calcined at 920 °C and carbonated at 650 °C. At the high calcination temperature over 920 °C modified dolomite can maintain much higher conversion than unmodified sorbent. The mean grain size of CaO derived from modified dolomite is smaller than that from original sorbent with increasing numbers of reaction cycles. The calcined modified dolomite possesses greater surface area and pore volume than calcined original sorbent during the multiple cycles. The pore volume and pore area distributions for calcined modified dolomite are also superior to those for calcined unmodified sorbent during the looping cycle. The modified dolomite is proved as a new and promising type of regenerable CO 2 sorbent for industrial applications.