Alginate Gel Beads Research Articles

Removal of Cr(VI) by polyaniline embedded polyvinyl alcohol/sodium alginate beads − Extension from water treatment to soil remediation

Efficient nano-scale chromium (Cr) remediating agents used in the water industry may find their application in soil difficult because of the strong aggregation effect. In this study, a millimeter-sized PANI/PVA/SA composite (PPS) was synthesized by embedding polyaniline (PANI) into polyvinyl alcohol (PVA)/sodium alginate (SA) gel beads. Additionally, the PPS was used to recover hexavalent chromium (Cr(VI)) contaminated water and soil to study the remediation impacts and mechanism. Results showed that the PPS was an irregular sphere with a pore size of 24.24 nm and exhibited strong adsorption capacity (83.1 mg/g) for removing Cr(VI) in water. The Cr(VI) adsorption by PPS could be well described with the pseudo-second-order kinetics and the Redlich-Peterson isotherm model, indicating that the chemical reactions were the controlling step in the Cr(VI) adsorption process. PPS also exhibited excellent physicochemical properties (< 13 mg/L TOC release) and reusability (efficiency of 95.25% after four runs) for Cr(VI) removal. Soil incubation results showed that the 5% PPS (5PPS) treatment could efficiently remove 24.17% of total Cr and 52.47% of Cr(VI) in the contaminated soil after 30 days. Meanwhile, the water-soluble and the leaching Cr contents were decreased by 43.37% and 61.78% in the 5PPS group, respectively. Elemental speciation by XPS revealed that Cr(VI) removal from solution and soil proceeded mainly by electrostatic attraction, reduction, and complexation/chelation. The study implied that PPS could be a useful amendment to remediate both the Cr(VI)-contaminated water and soil.

Aggregation enhances the activity and growth rate of anammox bacteria and its mechanisms

The aggregation of anaerobic ammonium oxidation (anammox) bacteria is important for the start-up and biomass retention of anammox processes. However, it is unclear whether it is beneficial to the activity, growth and reproduction of anammox bacteria. In this study, four reactor systems were developed to explore the effects of aggregation on anammox activity, growth and reproduction, after excluding the contribution of aggregation to sludge settling and retention. Results demonstrated that (i) compared with free-living planktonic bacteria, the aggregated bacteria had a higher volumetric nitrogen removal rate (0.75 kg-N/(m³·d)) and specific nitrogen removal activity (1.097 kg-N/VSS/d). And after 67 days cultivation, it had the higher sludge concentration and relative abundance (92.4%); (ii) compared with acidic polysaccharides and α-d-glucopyranose polysaccharides, β-d-glucopyranose polysaccharide play more essential roles of anammox aggregation; (iii) norspermidine triggered the secretion of α-d-glucopyranose polysaccharides to combat the toxicity, and inhibited biomass growth rate; (iv) immobilization in polyvinyl alcohol (10%) or sodium alginate (2%) gel beads was better than sodium alginate-chitosan gel beads and norspermidine (biofilm inhibitor) for the cultivation of free-living planktonic anammox bacteria. This is the first comparative study of three methods for cultivating free-living anammox bacteria. In conclusion, we found that the aggregation of anammox sludge not only facilitates biomass retention but also enhances the bioactivity, relative abundance, growth, and reproduction rate of anammox bacteria. The work is helpful to understand the formation of anammox granular sludge and contribute to the fast start-up and stable operation in anammox application.

The impact of pH on mechanical properties, storage stability and digestion of alginate-based and soy protein isolate-stabilized emulsion gel beads with encapsulated lycopene

In alginate-based emulsion gels containing protein-coated droplets, pH can influence the gelation mechanism of alginate gels, and the interactions between alginate molecules and protein-coated droplets, and thus properties of emulsion gels. This study investigated the impact of pH 3–7 on the properties (e.g., surface structures of droplets, mechanical properties, storage stability, digestion behavior) of alginate gel beads containing soy protein isolate(SPI)-stabilized oil droplets. Emulsion droplets were SPI-coated droplets at pH 6–7 and alginate/SPI-coated droplets at pH 3–5. Emulsion droplet flocculation only occurred in emulsions at pH 7.0. Emulsion gel beads at pH 3.0 had lower mechanical strength, higher storage stability, faster release of encapsulated lycopene during in-vitro digestion, and higher bioaccesibility of lycopene after 2 h of intestinal digestion than those at pH 7.0 and 5.0. The findings of this study are crucial to emulsion gel beads with controlled release and improved storage stability of encapsulated compounds by changing the pH of emulsions.

Development of Shuttle Adsorbents between the Bottom and Surface of Water for the Adsorption of Pollutants

For various pollutants with different specific gravity values, adsorbents having similar specific gravity values as those of target pollutants are necessary to achieve enough contact time. The purpose of this work is to introduce a self-vertical migration system to adsorbents for wastewater treatment. An alginate hydrogel composite with controlled specific gravity and buoyancy was successfully developed, which can first sink to the bottom of water and then float up on the surface after the adsorption. The alginate hydrogel composite was prepared using an alginate solution containing both glucose and yeast. In an experiment, the obtained beads first sank. However, 30 min later, most of them floated up to the water surface, where carbon dioxide was generated in the fermentation process. This behavior was repeated several times during the fermentation process, causing the beads to float. To confirm the efficiency of this unique property, the removal of cesium ions was demonstrated in a water column using Prussian Blue modified alginate gel beads with a repeated vertical migration system. The adsorbent showed a faster removal of cesium than the other adsorbents without the proposed system. We believe that the proposed system can be applied to treat large volumes of wastewater that cannot be stirred or pumped. Therefore, the novel adsorbent developed in this study is expected to significantly contribute to environmental remediation.

A novel and oral colon targeted isoliquiritigenin delivery system: Development, optimization, characterization and in vitro evaluation

The aims of the study were to prepare oral colon targeted gel beads loaded with isoliquiritigenin (ISL) which exhibited a variety of biological activities with a low solubility and oral bioavailability. ISL loaded sodium alginate and pectin gel beads (SA-P gel beads) were prepared by ionic gel technique, and Uniform Design method was used to optimize the formulation. To decrease the leakage in simulated gastric juice and simulated intestinal juice, the Eudragit S-100, sodium alginate and pectin gel beads (EU-SA-P gel beads) were prepared based on the SA-P gel beads. The EU-SA-P gel beads were characterized for size, shape, morphology, encapsulation efficiency, drug loading percentage, swelling degree and in vitro release. The size and shape results showed that the EU-SA-P gel beads were yellow and spherical with a size of 1.22 ± 0.19 mm, and a roundness degree of 72.78% ± 8.25%. It could be confirmed by DSC and FTIR analysis that the drug was not chemically modified but physically dispersed in the gel beads. The swelling degree of EU-SA-P gel beads in simulated gastric juice was 1.13 ± 0.14 at 3 h and remained almost unchanged until 6 h indicating the beads would not dissolve in simulated gastric juice. In simulated intestinal juice, the swelling degree reached the maximum (22.73 ± 3.27) at 3 h which was 20.11 times of that in simulated gastric juice and decreased to 1.85 ± 0.19 at 6 h indicating the gel beads swelled in simulated intestinal juice. As for in simulated colonic juice, the maximum swelling degree was 16.63 ± 3.52 at 3 h which was 0.73 times of that in simulated intestinal juice, then the swelling degree decreased to 1.93 ± 2.33 at 6 h indicating the beads dissolved in simulated colonic juice. The results of in vitro evaluation tests revealed that the cumulative drug release percentage of EU-SA-P gel beads exposure to simulated gastric juice and simulated intestinal juice was only 12.74% ± 3.55% for 5 h. However, the cumulative drug release percentage in simulated colonic juice was 50.64% ± 2.22% from 5 h to 12 h which was 3.97 times of that in pre-colon. These results revealed that the EU-SA-P gel beads was a promising isoliquiritigenin delivery system for colon targeting.

Addition of disaccharides and dimethyl sulfoxide to sodium alginate gel improves viability of immobilized Saccharomyces boulardii after cryopreservation

Gel-immobilized microorganisms are increasingly used in microbiological industries. Currently, the problem of developing technologies for long-term storage of microorganisms immobilized in gel carriers remains urgent. Low-temperature storage is the most effective method of preserving microorganisms. The viability of immobilized cells is affected by cryoprotective properties of gel matrix as well as cooling regimes. Therefore, the effects of incorporation of cryoprotective agents in alginate gel and cooling regimes on the viability of immobilized Saccharomyces boulardii cells after cryopreservation were studied. Incorporation of non-permeable cryoprotectants (sucrose, lactose, and trehalose) and permeable one dimethyl sulfoxide (DMSO) in alginate gel beads promoted an increase in the viability of immobilized cells after freeze-thawing. The highest viability rates of the gel-immobilized cells were observed in the alginate gel beads incorporating combinations of DMSO (5 – 10 % v/v) and one of the disaccharides (10 – 20 % w/v). In all experiments, slow cooling provided significantly higher viability if compared to the rapid immersion of the samples into liquid nitrogen.

Strong adsorption properties and mechanism of action with regard to tetracycline adsorption of double-network polyvinyl alcohol-copper alginate gel beads

In the present study, glutaraldehyde was used as a hydrophobic modifier to crosslink polyvinyl alcohol (PVA), and copper ion was immobilized by sodium alginate (SA). Polyvinyl alcohol-copper alginate (PVA-CA) gel beads were prepared by a one-step process, and were used to adsorb and remove tetracycline (TC) from an aqueous solution. The beads were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) measurement, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The adsorption experiment showed that the optimal pH value of the beads was 5, and that their adsorption met pseudo-second-order kinetic and Langmuir isothermal models. The adsorption thermodynamics experiment showed that the adsorption process was spontaneous and endothermic. Under optimal adsorption conditions, the maximum adsorption capacity for TC of the beads was 231.431 mg/g, which was much higher than that of a single copper alginate matrix. After 5 adsorption-desorption cycles, the adsorption capacity remained high. FTIR and X-ray photoelectron spectroscopy (XPS) revealed that the cation bonding bridge reaction was the main driving force behind the adsorption mechanism. Compared with other reported adsorption materials, the PVA-CA gel beads have high adsorption capacity, a simple preparation process, and excellent recovery performance.

The optimization of U(VI) removal by a novel amidoximated modified calcium alginate gel bead with entrapped functionalized SiO2 nanoparticles

Adsorption of U(VI) ions from aqueous solution onto a novel amidoximated modified calcium alginate bead with entrapped functionalized SiO2 nanoparticles, (alginate/SiO2/TMPTMS/PAO), with variation in SiO2 and 3-mercaptopropyltrimethoxysilane (TMPTMS) contents was studied. In order to synthesis of the composite adsorbent, SiO2 nanoparticles were first modified via TMPTMS and then applied to prepare the alginate gel beads. The adsorption capacity of U(VI) ions by alginate/SiO2/TMPTMS/PAO beads at 5 wt % of SiO2 and 30 wt % of TMPTMS (with respect to the alginate weight) was 3.6 times greater than that of the blank one (alginate/PAO). The characterizations of adsorbent were carried out using FTIR, SEM-EDX and BET analyses. The equilibrium and kinetic data were well described by the Langmuir isotherm and Pseudo-second order kinetic models, respectively. The effect of operating variables, including initial pH of solution, initial concentration of U(VI) solution and the dosage of adsorbent on the adsorption capacity of uranium ions were investigated by central composite design (CCD) of response surface methodology (RSM). The effect of presence of copper, cadmium and nickel ions on the adsorption of uranium ions in binary systems was investigated. In this work, for the first time, modified SiO2 nanoparticles with –SH group, have been added to the calcium-alginate gel beads to increase the mechanical, thermal and radiative resistance of alginate as well as to increase the uranium adsorption capacity. The results showed that alginate/SiO2/TMPTMS/PAO composite adsorbent was effective in removal of U(VI) ions from aqueous solutions.

Construction of a Drug Release Evaluation System: Application of Mitochondrial Respiration to Monitor Drug Release.

Efficient drug encapsulation and regulation of drug release are important factors for sustained drug release and application for release-controlled anti-cancer and anti-inflammatory drug delivery. In the present study, a direct evaluation system for drug-release from model carrier (e.g., alginate-gel beads) was examined using the mitochondrial oxygen consumption rate as an index. Alginate-gel beads were coated with the uncoupler SF6847 (SF beads) and used as a model microparticle-type drug. The real-time monitoring of SF6847 release from prepared alginate-gel beads was performed using the mitochondrial oxygen consumption rate. Release profiles of nonsteroidal anti-inflammatory drugs [NSAIDs, mefenamic acid (MEF) and diclofenac (DIC)] from alginate-gel beads as well as SF beads were investigated using the real time monitoring system. SF6847 release from alginate-gel beads was clearly detected using the rat liver mitochondrial oxygen consumption rate. The release features of MEF and DIC from alginate-gel beads were defined by the present trial monitoring system, and these NSAIDs exhibited different release profiles. The present drug monitoring system detected released drugs, and the release profile reflected the molecular properties of the test drugs. This system may be applied to the design and development of precise sustained drug release systems (e.g., anti-cancer and anti-inflammatory drugs).

Amylase Production by Aspergillus niger immobilized in Microporous Calcium Alginate Gel Beads

Microporous calcium alginate gel beads were investigated as potential solutions to mass transfer limitations in immobilized cultures. The beads were prepared by gelling mixtures of sodium alginate and fillers (starch or granulated sugars) in calcium chloride solution. The resulting beads were cured in the same solution, during which the fillers leached out of the beads thereby creating micro-pores in the beads (microporous beads). The effectiveness of the microporous beads in improving amylase production by Aspergillus niger LC 269109 was investigated. Spores of A. niger were immobilized in the microporous beads and used for batch alpha amylase and gluco amylase production. Amylase production by the A. niger immobilized in the microporous beads were significantly higher (p&lt;0.01) than the values obtained with the conventional calcium alginate gel beads. Under all the conditions investigated, gluco-amylase activities were significantly (p&lt;0.01) higher than the alpha-amylase activities. Under the optimum conditions of inoculum concentration (1.0 × 105 spores/ml), pH (6), temperature (35°C), bead diameter (3 mm) and calcium chloride concentration (1.5%), the gluco-amylase and alpha amylase activities were 11.98 U/ml and 6.7 U/ml respectively, which were significantly higher (p&lt;0.05) than the 7.8 U/ml and 3.2 U/ml obtained with the conventional gel beads.

Denitrification potential of sodium alginate gel beads immobilized iron–carbon, Zoogloea sp. L2, and riboflavin: Performance optimization and mechanism

A kind of gel beads loaded with iron–carbon powder (Fe–C), Zoogloea sp. L2, and riboflavin (VB2) were prepared through cross–linking of sodium alginate (SA) to establish an immobilized bioreactor. The optimal ratio of SA beads was adjusted by orthogonal experiment. The change of oxidation–reduction potential (ORP) and the concentration of Fe2+ and Fe3+ showed that the addition of VB2 as a redox mediator can promote denitrification. Under the optimal conditions (carbon to nitrogen (C/N) ratio = 2.0, pH = 7.0, and hydraulic retention time (HRT) = 8 h), the nitrate removal efficiency (NRE) of bioreactor reached 98.48% (1.99 mg L–1h−1). Furthermore, Fourier transform infrared spectrometer (FTIR), Fluorescence excitation–emission matrix (EEM), X–ray diffraction (XRD), and gas chromatography (GC) analysis revealed that the immobilization and denitrification of the immobilized bioreactor were excellent. High throughput sequencing also showed that Zoogloea played a vital role in nitrate removal.

Modulation effect of glycerol on plasticization and water distribution of vacuum-dried calcium alginate gel beads encapsulating peppermint oil/β-cyclodextrin complex

Gel beads are prone to texture hardening after the drying treatment, which limits its application. The purpose of the present work was to investigate the influence of glycerol addition on the morphology, encapsulation characteristics, texture, water distribution, and moisture status of vacuum-dried gel beads encapsulating peppermint oil/β-cyclodextrin complex. The results showed that the hardness of the dried gel beads was significantly reduced from 1719.45 g to 359.02 g by adding 5% glycerol. The analysis of transverse relaxation time showed that the proportion of tightly bound water in the dried gel beads increased from 23.69% to 34.70%, and the proportion of free water decreased from 72.76% to 59.60% when the addition of glycerol ranged from 0 to 5%. The results of infrared spectroscopy revealed that the hydrogen bond interaction between glycerol and alginate could stabilize the gel network structure and improve the tolerance of gel beads to drying.

Development of Multi-Cellular Gel Droplets Using κ-Carrageenan Composited Alginate for Controlled Release of Hydrophobic Components

Biopolymer gels have considerable potential because of their ability to encapsulate, protect, and release bioactive components. In the present study, κ-carrageenan composited alginate gel beads were prepared and tested for use as potential delivery vehicles for the encapsulation and controlled release of capsanthin, an antioxidant ingredient contained in red pepper. By varying the weight ratio of κ-carrageenan, as well as the concentration or type of the crosslinking agent and outer organic phase, different sustained release characteristics of capsanthin from κ-carrageenan composited alginate gel beads were obtained. In the case of sustained release experiments using κ-carrageenan composited alginate gel beads, for a mass ratio of κ-carrageenan in the polymer (1wt%) of 50%, the sustained release ratio for a predetermined time was suppressed to about 80% of the maximum value for Ca2+ and about 40% for K+ at 120 min. When the KCl concentration of the crosslinking agent for gelation was increased, the start time of the sustained release was delayed. These were discussed on surface structure of the gel beads by scanning electron microscopy. Also, as the hydrophobicity of the outer organic phase increased, the beads shrank in volume, and the sustained release ratio decreased. These results indicate that the encapsulation of bioactive components using κ-carrageenan composited alginate polymer could provide an effective means for the controlled release of capsanthin.

Mechanical properties of starch-filled alginate gel particles

The aim of this work was to investigate the mechanical behaviour of alginate-based composite particles. Alginate gel beads with entrapped starch were used as the replicates of storage cells of plant tissue. Beads were formulated using different ratios of both ingredients and were produced using two methods, resulting in particles in the macro- and micro-scale size range. Compression tests revealed an effect of bead size on mechanical properties and a dominant role of the alginate on the material properties. Starch was successfully encapsulated as native granules in the beads and once encompassed, it suffered restricted swelling, up to 45 % of its original size, after undergoing heating. Force versus displacement data were fitted to both an empirical and the Hertz model and Young’s modulus was found to increase only with heated starch inclusions. Microscopy was deemed crucial for the interpretation of mechanical measurements.

Effect of temperature shifts and anammox biomass immobilization on sequencing batch reactor performance and bacterial genes abundance

Implementation of anaerobic ammonium oxidation (anammox) below its optimal temperature, known as “cold anammox”, may lead to its common use in wastewater treatment plants, reducing the operational costs of wastewater treatment. Thus, we investigated the effects of immobilization in polyvinyl alcohol–sodium alginate gel beads on anammox performance at temperatures of 30 °C, 23 °C, and 15 °C in laboratory-scale sequencing batch reactors. We determined the relative gene abundance of the nitrogen removal bacterial groups, which are considered as the key functional microbes of nitrogen cycle in activated sludge: denitrifies, ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and anammox bacteria. Nitrogen removal efficiency was higher for immobilized anammox sludge in comparison with non-immobilized anammox biomass at each investigated temperature. At 30 °C, nitrogen removal efficiency was 83.7 ± 6.46% for immobilized reactor, and 79.4 ± 7.83% for the control reactor, while at 15 °C was remained at the level of 50 ± 2.5% for immobilized reactor, and fluctuated from 13.2 to 45.3% for the control one. During temperature shifts, the process was also more stable in the case of the reactor with immobilized biomass. A statistically significant correlation was found between nitrogen removal efficiency and hydrazine oxidoreductase gene abundance.

Synthesis of quercetin-encapsulated alginate beads with their antioxidant and release kinetic studies

In this present study, different forms of quercetin encapsulated beads were synthesized, namely ionic cross-linked gel beads and cryogel beads. Fourier Transform Infrared (FT-IR) spectra of the beads were used to characterize and prove quercetin encapsulation in alginate beads. Swelling and drying profiles were studied. Besides, release kinetics of quercetin molecules from gel beads and cryogels were carefully investigated in two different solvent/media; dimethyl sulfoxide (DMSO) and Roswell Park Memorial Institute Medium (RPMI-1640). Based upon the release kinetic studies, it is found that quercetin release from alginate cryogel beads fits the first-order release model in DMSO and it depends on the concentration of quercetin in the beads. The release of quercetin from alginate gel beads was described by the Higuchi release model, which highlights the release of quercetin molecules through the pores of the matrix. In RPMI-1640, the release of quercetin from both forms of alginate beads fits zero-order release model and it indicates a constant release of quercetin per unit time. Finally, the radical scavenging activity of the quercetin quantities was tested by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, and successful results were obtained compared to reference material.

Saccharomyces cerevisiae and Lactobacillus rhamnosus cell walls immobilized on nano-silica entrapped in alginate as aflatoxin M1 binders

Aflatoxins are common fungal toxins in foods that cause health problems for humans. The aim of this study was to use Saccharomyces cerevisiae and Lactobacillus rhamnosus cell walls immobilized on nano-silica entrapped in alginate as aflatoxin M1 (AFM1) binders. In this study, microbial walls were disrupted using a three-step mechanical technique including autoclave, thermal shock, and ultrasound. Dynamic light scattering (DLS) results proved size reduction in microbial walls ranging 75.8–91.4 nm. Disrupted walls were immobilized on nano-silica to enhance the efficiency of AFM1 adsorption. Then, to prevent the release of the nano-silica or cell walls into the reaction medium, they were entrapped into alginate gel beads. Fourier transform infrared spectrometer (FT-IR) and scanning electron microscopy (SEM) micrographs confirmed the immobilization and entrapment process. Individual and mixtures of free cell walls, immobilized-entrapped walls, alginate bead and nano-silica were contacted with AFM1 for 15 min and 24 h. AFM1 reduction ability was evaluated using high performance liquid chromatography (HPLC). The results showed an AFM1 reduction ranging 53–87% for free cell walls mixture at 15 min and alginate bead respectively. Also, it was possible to reuse immobilized-entrapped walls as binders with an efficiency of about 85%.

Rotating-liquid-based hydrogel bead generator

Hydrogel beads are widely used in various applications, but producing such beads often requires complicated devices. Instead, we propose an easy-to-adopt, cost effective, open source hydrogel bead generator. This generator consists of two modules. The first module rotates two immiscible liquids in rigid body motion: mineral oil as the continuous phase (CP) liquid on top, and a hydrogel cross-linking (CL) liquid at bottom. The second module injects a hydrogel pre-polymer solution as the dispersed phase (DP) liquid into the rotating CP liquid. As the DP liquid flows out of a syringe needle, its drops are pinched off by the shear force from the CP liquid, and move with the CP liquid while settling down. When the drops enter the CL liquid, they become hydrogel beads. Experiments using water and mineral oil showed that the size of produced drops could be controlled by adjusting the flow speed of the CP and DP liquids. A demonstration using alginate showed that the proposed generator could successfully create alginate gel beads of uniform size and shape.

Al2O3 Nanoparticles Promote the Removal of Carbamazepine in Water by Chlorella vulgaris Immobilized in Sodium Alginate Gel Beads

The roles of Al2O3 nanoparticles on the removal of carbamazepine (CBZ) by Chlorella vulgaris immobilized in sodium alginate gel beads were for the first time investigated. The optimum conditions to prepare immobilized C. vulgaris beads with addition of Al2O3 nanoparticles were determined as follows: C. vulgaris density was 3.0 × 106 cells for 1 mL sodium alginate solution, Al2O3 nanoparticle concentration was 0.5 g/L, and concentrations of sodium alginate and CaCl2 were 1.6% and 1%, respectively. The results showed that the proposed algae beads achieved the highest CBZ removal rate of 89.6% after 4 days of treatment, relative to 68.84%, 48.56%, and 17.76% in sodium alginate-immobilized C. vulgaris, free microalgae, and Al2O3 nanoparticle alginate beads, respectively. The results also showed that the CBZ removal rate increased with more proposed algae beads, while decreased with increased bead diameter. The algae beads exhibited excellent CBZ removal ability even after three recycles. This work provided an economical and effective approach to remove CBZ from water.

Nitrogen-doped hierarchically porous carbon spheres for low concentration CO2 capture

Synthesis of spherical carbon beads with effective CO2 capture capability is highly desirable for large scale application of CO2 sorption, but remains challenging. Herein, a facile and efficient strategy to prepare nitrogen-doped hierarchically porous carbon spheres was developed via co-pyrolyzation of poly(vinylidene chloride) and melamine in alginate gel beads. In this approach, melamine not only serves as the nitrogen precursor, but also acts as a template for the macropores structures. The nitrogen contents in the hierarchically porous carbon spheres reach a high level, ranging from 11.8 wt% to 14.7 wt%, as the melamine amount increases. Owing to the enriched nitrogen functionalities and the special hierarchical porous structure, the carbon spheres exhibit an outstanding CO2 capture performance, with the dynamic capacity of as much as about 7 wt% and a separation factor about 49 at 25 °C in a gas mixture of CO2/N2 (0.5:99.5, v/v).