Dynamic Adsorption Properties Research Articles

Experimental study on dynamic adsorption properties of methylene blue onto coal-based activated carbon using a hydrocyclone

To address the issues of low adsorption efficiency of activated carbon in dyeing wastewater treatment, a dynamic adsorption process using activated carbon for wastewater treatment was proposed. A hydrocyclone was used as the carrier, and the adsorbent separation process was integrated into the same single device. Methylene blue (MB) was used to simulate printing and dyeing wastewater. The effects of initial concentration of MB solution, ratio of activated carbon quality to wastewater flow, and adsorption temperature on the adsorption efficiency were investigated. The results showed that the optimal adsorption efficiency of MB by activated carbon was 95.2 % when the initial concentration of MB solution was 12 mg/L, the ratio of activated carbon quality to wastewater flow was 0.5 mg/mL, and the adsorption temperature of MB solution was 44.5 °C. In addition, compared with the water bath oscillation method, the removal efficiency of MB was increased by 731 % under the same adsorption conditions. The research shows that it is feasible to treat printing and dyeing wastewater by using a hydrocyclone to enhance activated carbon adsorption. The research aims to provide a practical basis for future optimization of the structure and operation parameters of hydrocyclone and to reveal their wide application prospects.

Functional properties and continuous adsorption process of Arenga pinnata shell and its porous biochars for aqueous methylene blue removal

Arenga pinnata shell, an agricultural-processing residue, was used as an alternative precursor for synthesizing Arenga pinnata shell particles (ASP), Arenga pinnata shell biochar (ASB), and Arenga pinnata shell activated biochar (ASAB) for methylene blue (MB) adsorption. Optimized adsorbent was observed for ASAB fabricated via an impregnation ratio of KOH to ASP of 0.5:1 (w/w) at 700 °C for 30 min of activation time under N2 pyrolysis, with a surface area, pore volume, and average pore diameter of 967 m2/g, 0.572 cm3/g, and 2.47 nm, respectively. The adsorbent also possesses the largest carbon constituent (90.4 %), negative surface charge (−36.4 mV), and abundant oxygen-containing functional groups. Dynamic MB adsorption properties on the adsorbents from the aqueous environment under continuous mode at 25 °C were determined using the Thomas and Yoon-Nelson models. Although the ASP and ASB presented comparatively favorable adsorption properties, the optimum adsorption performance was observed for the ASAB. Its superior functional features contributed to the largest adsorption capacity of 203.86 mg/g. The elemental composition analysis indicated the presence of sulfur on the ASAB surface, which supported the findings. This research demonstrates the utility of Arenga pinnata shell as an eco-friendly precursor for high-performance adsorbent fabrication with excellent MB adsorption properties.

Directly synthesized high-silica CHA zeolite for efficient CO2/N2 separation

Carbon dioxide capture is an effective method to mitigate climate change. Highly CO2-selective and highly moisture-resistant absorbent is essential for energy-efficient carbon capture by absorption. Herein, a highly CO2-selective and high-silica CHA zeolite in a pure lithium form (Li-SSZ-13) was synthesized using a direct synthesis method for the first time. The effects of gel n(SiO2)/n(Al2O3) ratio, gel n(SiO2)/n(Li2O) ratio and synthesis time on the crystallinity, yield, micropore volume and CO2 loading of the crystals were systematically investigated. The adsorption isotherms of CO2 and N2 were measured for directly synthesized Li-SSZ-13, conventional Na-SSZ-13 and ion-exchanged Li-Na-SSZ-13 zeolites. The dynamic breakthrough adsorption properties were measured for Li-SSZ-13 in comparison with Na-SSZ-13 and Li-Na-SSZ-13. The obtained Li-SSZ-13 exhibited a high CO2 adsorption capacity of 4.48 mmol/g and a high CO2/N2 IAST selectivity of 310 at 100 kPa and 273 K, which were 45.0% and 441% higher than Na-SSZ-13 zeolite, 24.8% and 179% higher than Li-Na-SSZ-13 zeolite, respectively. It suggests that directly synthesized Li-SSZ-13 zeolite has great potential for efficient CO2 capture from flue gas.

Synthesis of high hydrophobicity USY zeolite with excellent VOCs adsorption performance under humid condition: Combined strategy of high temperature steam and acid treatment

Y Zeolite and its ultra-stabilized hierarchical derivative (USY) as absorbents have low adsorption capacity for VOCs under humid conditions thus limits their industrial applications. It is well known that high SiO2/Al2O3 ratio (SAR) can improve the hydrophobicity of zeolite, and the increase of pore volume can enhance the adsorption performance. In the present work, SAR and the pore size of CY were enlarged by oxalic acid-high temperature steam-citric acid treatment, as the framework aluminum in the zeolite was removed and maintaining its structural integrity. The surface morphology and structure of samples were characterized by XRD, BET, TEM, SEM and TG. 27Al MAS NMR, XPS and Pyridine infrared analysis the mechanism of aluminum removal from the CY framework. The dynamic adsorption properties of the samples were systematically investigated with toluene selected as representative volatile organic compounds. The hydrophobicity of the samples was investigated by static water adsorption, and the adsorption kinetics model of the samples were plotted to study their adsorption characteristics. N2 adsorption-desorption results showed that the modified CY material has larger surface area, wider pore size and larger microporous volume than the raw material. On the other hand, with the improved SiO2/Al2O3 ratio and hydrophobicity, the modified USY also exhibited excellent adsorption performance under humid conditions, with 4.2 times more capacity to adsorb toluene. Therefore, this method can provide effective adsorption of VOCs in humid environments.

In-situ confined growth of defective MIL-100(Fe) in macroporous polyacrylate spherical substrate at room temperature for high-efficient toluene removal

The hazard caused by toluene has attracted worldwide attention, and it is of practical significance to study the efficient adsorption of toluene for environmental governance. In this work, a hierarchical metal–organic framework (MOF), MIL-100(Fe), was crystallized on the surface of a macroporous polyacrylate (PAA) spherical substrate at room temperature through an in-situ confinement growth strategy to form MIL-100(Fe)@PAA composite. By decreasing the nucleation energy barrier, the average size of MIL-100(Fe) crystals was reduced from 400 nm to 55 nm and defects as adsorption sites for toluene were able to install in the crystal lattices. Therefore, the composite provided excellent static and dynamic adsorption properties for toluene, much better than the pristine MIL-100(Fe). The potential mechanism for crystal defects to significantly improve the adsorption performance was subsequently explored through kinetic fitting and density functional theory (DFT) calculation. All results indicated that the innovative MIL-100(Fe)@PAA prepared using defect engineering and effective molding technology was potent in both toluene removal and regeneration, which was expected to provide a new avenue for the facile synthesis of molded MOF composites.

A Fixed-Bed Column with an Agro-Waste Biomass Composite for Controlled Separation of Sulfate from Aqueous Media

An agro-waste composite with a pelletized form was prepared and characterized via IR and 13C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization of the sulfate adsorption properties under equilibrium and dynamic conditions. The sulfate monolayer adsorption capacity (qe = 23 mg/g) of the prepared agro-waste pellets was estimated from the adsorption isotherm results by employing the Langmuir model, and comparable fitting results were obtained by the Freundlich model. The dynamic adsorption properties were investigated via adsorption studies with a fixed bed column at pH 5.2. The effects of various parameters, including flow rate, bed height and initial concentrations of sulfate, were evaluated to estimate the optimal conditions for the separation of sulfate. The experimental data of the breakthrough curves were analyzed using the Thomas and Yoon–Nelson models, which provided satisfactory best-fits for the fixed bed kinetic adsorption results. The predicted adsorption capacities for all samples according to the Thomas model concur with the experimental values. The optimum conditions reported herein afford the highest dynamic adsorption capacity (30 mg/g) as follows: 1100 mg/L initial sulfate concentration, 30 cm bed height and 5 mL/min flow rate. The breakthrough time was measured to be 550 min. This study contributes to a strategy for controlled separation of sulfate using a sustainable biocomposite material that is suitable for fixed-bed column point-of-use water treatment systems.

Effectiveness and mechanisms of the adsorption of phenol from wastewater onto N-doped graphene oxide aerogel

Phenol, as a representative toxic substance in coking wastewater, will cause harm to the ecology and human beings. Therefore, advanced treatment of phenol is urgently needed. However, most adsorbents have the problems of low adsorption capacity and difficult recovery in water dephenolization. It is imminent to develop a recyclable and effective adsorbent. Herein three-dimensional (3D) N-doped graphene oxide aerogel (NGOA) was synthesized by using ammonium citrate as reductant and nitrogen source. NGOA exhibits large specific surface area, developed pores, excellent hydrophilicity and mechanical properties. The static and dynamic adsorption properties of NGOA were investigated. NGOA has good adsorption performance and reusability. The static saturated adsorption capacity of NGOA for phenol reached 108.19 mg g−1, which was obviously higher than most adsorbents. Furthermore, the dynamic adsorption capacity of NGOA was 43.69 mg g−1, which illustrates that NGOA has immense potential in the uptake of phenol for industrial application. Importantly, monolithic NGOA could be easily separated and recovered after adsorption saturation. The adsorption behavior conforms to the endothermic physical adsorption process, which is matched with the Pseudo-first-order kinetic model and Langmuir-Freundlich isotherm model. This work has good scientific research value and practical application prospect.

Study on the Properties of the Sodium Lauroyl Glycinate and Sodium Lauroyl Lactylate Composite System.

The scientific community has shown a great deal of interest in sodium lauroyl glycine (SLG) and sodium lauroyl lactylate (SLL), two sustainable and eco-friendly substances that are considered as potential bio-friendly alternatives for petrochemical-based amphiphiles. In the present work, the formation of mixed micelle for SLG and SLL surfactant in water was investigated. Meanwhile, the surface interaction and thermodynamic parameters were calculated according to the surface tension curves. The results indicated that at certain ratios, SLG/SLL surfactant mixtures had synergistic effects that could yield higher surface activity and improve application performance. When the mole fraction of SLL (αSLL) was 0.4, γcmc achieved a minimum of 22.6 mN m-1 and displayed the best foaming properties. The mixed solution exhibited the best wetting ability when αSLL was 0.6. While αSLL was 0.8, the mixed solution showed the optimum dynamic adsorption properties. And it was found that the antibacterial property of SLG and SLL could be partially preserved after compounding. These results demonstrated for the first time that the mixed environmentally friendly surfactant SLG and SLL has a promising prospect for use in the personal care, detergent, and cosmetic industries.

HKUST-1 infused woven cotton filter for enhanced adsorptive removal of toluene vapor from gaseous streams

The utilization of metal–organic frameworks (MOFs) has recently increased in air/gas purification, especially for the adsorptive removal of volatile organic compounds (VOCs). However, the dynamic adsorption properties of fine powdery porous MOFs (e.g., HKUST-1) tend to suffer from a number of defects, especially a significant space velocity/pressure drop upon being loaded in a packed-bed adsorbent system. To overcome such shortcomings, a new fibrous MOF-based woven fiber sorbent filter was prepared via in-situ growth of HKUST-1 crystals on woven cotton substrates (thickness ≈1mm, diameter = 4.3 cm) at five different mass ratios of infused MOFs (i.e., 2.4, 6.6, 9.5, 31.2, and 41.8 wt/wt%). The adsorption efficacy of this filtration system was studied in reference to the packed bed sorbent using 1 Pa toluene vapor at near-ambient conditions. The relative adsorption performance of toluene was accounted for by the combined effects of the content of infused HKUST-1 (e.g., 41.8 > 31.2 > 9.5 > 6.6 > 2.4 wt/wt%) and the surface availability (m2 [g∙HKUST-1]−1) (e.g., 432 < 527 < 534 < 679 < 852, respectively: e.g., in relation to the increases in surface active sites). Based on the kinetics modeling, the adsorption mechanism was controlled dominantly by physisorption phenomena that consist of surface and pore diffusion as a rate-limiting step. This research offers valuable insights into the significance of morphological features of MOFs-based filtration media when employed for air purification by adsorption technique.

Dynamic Adsorption Properties of Insoluble Humic Acid/Tourmaline Composite Particles for Iron and Manganese in Mine Wastewater.

Iron- and manganese-contaminated mine water is widespread around the world, and economical and efficient remediation has become a priority. Insoluble humic acid/tourmaline composite particles (IHA/TM) were prepared by combining inorganic tourmaline (TM) with the natural organic polymer humic acid (HA), and the effects of different calcination temperatures and calcination times of TM and IHA on the adsorption of Fe2+ and Mn2+ were analyzed. Based on the microscopic characterization of Scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Brunnauer–Emmet–Teller (BET), X-ray diffractometer (XRD) and Fourier transform infrared (FTIR), the simultaneous adsorption performance of IHA/TM on Fe2+ and Mn2+ was studied through dynamic adsorption tests, and a dynamic adsorption model was established. Adsorption regeneration experiments were carried out to further investigate the effectiveness of the composite particles in practical applications. The results show that, when the calcination temperature was 330 °C and the calcination time was 90 min, the removal rates of iron and manganese by the IHA/TM composite particles reached 99.85% and 99.51%, respectively. The curves for penetration of Fe2+ and Mn2+ ions into the IHA/TM composite particles were affected by the bed height, flow rate and influent concentration. Decreasing the flow rate, decreasing the influent concentration, or increasing the bed height prolonged the operation time of the dynamic column. If the bed height was too low, the penetration point was reached before the expected treatment was achieved, and when the bed height was too high, the removal of Fe2+ and Mn2+ was slow, and the utilization rate of the adsorbent was also reduced. If the flow rate was too low, longitudinal remixing easily occurred in the column. However, when the flow rate was too high, the speed of Fe2+ and Mn2+ ions passing through the adsorption layer increased, which reduced the total amount of adsorption. The increase in influent concentration not only reduces the removal rate, but also greatly shortens the total operation time of the dynamic column and reduces the treatment water. The dynamic process for the adsorption of Fe2+ and Mn2+ by IHA/TM was fitted best by the Thomas model. The adsorption column was continuously regenerated five times, and the results show that the IHA/TM composite particles were suitable for iron and manganese removal from mine wastewater. The research results will provide a reference for the effectiveness of the IHA/TM composite particles in practical applications.

Design of Sustainable Biomaterial Composite Adsorbents for Point-of-Use Removal of Lead Ions From Water

The uncontrolled release of contaminants into aquatic environments has created the need for improved adsorbent materials for point-of-use (POU) treatment applications to address water security. The goal of this study was to prepare a low-cost sustainable adsorbent material with tailored Pb(II) adsorption properties in aqueous media. Several types of ternary composite adsorbents were prepared that contain chitosan, kaolinite, and a biomass additive (oat hulls or torrefied wheat straw), along with spectral characterization and thermal analysis of the adsorbents. The adsorption properties of the ternary composites with lead nitrate were studied at equilibrium using batch mode and dynamic conditions with a fixed bed column under variable experimental settings [flow rate, bed height, and Pb(II) concentration]. The adsorption capacity at equilibrium in synthetic or tap water was found to depend on the relative composition (wt.%) of additive components in the composite. The optimal composite adsorbent for maximum Pb(II) removal had the following composition (wt.%): chitosan (50%) + kaolinite (10%) + oat hulls (40%). Using this adsorbent, the dynamic adsorption properties with lead nitrate were studied in a fixed bed column at pH 6.5 and 295 K to reveal optimized Pb(II) removal that concur with the results obtained from batch studies. The sustainability of the biocomposite adsorbent was demonstrated with the use of relatively low-cost and locally available materials, whilst achieving favorable Pb(II) adsorption properties. The facile preparation of the optimal biocomposite adsorbent herein is proposed for use as a disposable POU filter media technology for the removal of lead and other multivalent heavy metal cations, including organic contaminants such as cationic dyes and agrochemicals.

Counterion Effects in Metal Hybrid Biopolymer Materials for Sulfate Adsorption: An Experimental and Computational Study

Modification of biomaterials is an active research area in materials and environmental science, where the controlled removal of sulfate is a key goal toward achieving global water security in regions with saline aquifers. In this study, biopolymer-based ternary metal composites (TMCs) were prepared that contain alginate/chitosan/Al(III) with variable counterions: chloride (C), nitrate (N), and sulfate (S), denoted as TMC-C, TMC-N, and TMC-S, respectively. The structure and physicochemical properties of the TMCs were characterized by spectroscopy (NMR, FT-IR, Raman, and XPS) and other complementary methods (thermal gravimetry, potentiometry, and zeta potential) to gain insights on the role of counterion effects related to the adsorption properties of TMCs with inorganic and organic anions in aqueous media. Both equilibrium and dynamic adsorption properties of the TMCs were evaluated with inorganic sulfate (Na2SO4) and two types of anionic organic dyes (methyl orange, MO,; and reactive black-5, RB5) at pH 7 and 295 K. A computational study was carried out to evaluate the structural features of the TMCs related to the coordination of sulfate with the TMC-N system. The charge state of the TMCs for the various counterion systems was estimated according to the pHPZC (5.0 to 5.9) and zeta potential (+8.31 to +35.7 mV) of the composites in aqueous media. The presence of variable counterions (chloride, nitrate, and sulfate) revealed the effects on the equilibrium and kinetic uptake of sodium sulfate and RB5. The Sips isotherm model for sulfate adsorption revealed a value of Qe from 87 to 120 mg/g, which depends on the counterion. The uptake of RB5 (Qm = 77 to 208 mg/g) by the TMCs varied over a wider range due to the role of secondary biopolymer adsorption sites. The incorporation of switchable counterions in TMCs offer a low-cost and bottom-up approach for the design of tailored biopolymer adsorbents with tunable anion uptake properties toward organic and inorganic anions in aqueous media.

Developing a simple box–behnken experimental design on the removal of doxorubicin anticancer drug using Fe3O4/graphene nanoribbons adsorbent

This paper aims to develop a Box–Behnken experimental design system to optimize the removal process of doxorubicin anticancer drugs. For this goal, Fe3O4/graphene nanoribbons was selected as adsorbent and removal of doxorubicin anticancer drug optimized using Box–Behnken experimental design with a selection of four effective factors. A three-level, four-factor Box–Behnken experimental design was used to assess the relationship between removal percentage as a dependent variable with adsorption weight (0.0015–0.01 mg), pH (3–9), temperature (15–45 °C) and time (1–15 min) as independent variables. Optimized condition by Behnken experimental design (pH = 7.36; time = 15 min; adsorbent weight = 0.01 mg and temperature = 29.26 °C) improved removal of doxorubicin anticancer drug about 99.2% in aqueous solution. The dynamic behavior, adsorption properties and mechanism of doxorubicin molecule on Fe3O4/graphene nanoribbon were investigated based on ab initio molecular dynamics (AIMD) simulations and density functional theory calculations with dispersion corrections. A closer inspection of the adsorption configurations and binding energies revealed that π-π interactions were the driving force when the doxorubicin molecule adsorbed on Fe3O4/graphene nanoribbon. The observed negative adsorption energy signifies a favourable and exothermic adsorption process of the various adsorbate-substrate systems. Besides, AIMD and phonon dispersion calculations confirm the dynamic stability of Fe3O4/graphene nanoribbon.

The Effects of Hydrophobicity and Textural Properties on Hexamethyldisiloxane Adsorption in Reduced Graphene Oxide Aerogels.

To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (SBET), micropore volume (Vmicro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with SBET, Vmicro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas.

Dynamic adsorption properties of activated carbon for radioactive noble gas treatment in offshore floating nuclear power plant

Offshore floating nuclear power plant (OFNPP) is a significant solution for marine electricity shortage. In this study, the optimized activated carbon for decay technology was studied in the experiment bench and engineering prototype respectively. The results show that ZLCYK001 activated carbon has better properties. The adsorption coefficient for krypton can be improved when the pressure is increased, the temperature and relative humidity are decreased and the flow velocity is controlled between 0.12 and 5 cm/s. The adsorption property has good reliability and stability in engineering prototype which is significant for the design and operation of the waste gas treatment system.

Acid gas adsorption on zeolite SSZ‐13: Equilibrium and dynamic behavior for natural gas applications

AbstractIn developing new adsorption separation processes, it is necessary to study both the equilibrium and dynamic adsorption properties of potential materials. Experimental determination of isotherms and dynamic breakthrough properties aid in the development of modeling new adsorption systems toward process development. Here, the equilibrium adsorption properties of a small‐pore zeolite, Na‐SSZ‐13, are studied for its natural gas separation potential. Using volumetric, gravimetric, and dynamic column breakthrough adsorption techniques, the adsorption properties of CO2, CH4, C2H6, H2S, and H2O are determined. High‐pressure breakthrough experiments demonstrate the mixed gas separation performance of Na‐SSZ‐13 in mixtures containing CO2, CH4, C2H6, and H2S. Simulations of these breakthrough experiments show that ideal adsorbed solution theory adequately describes the mixed gas adsorption modeling for this zeolite. In gas mixtures containing both CO2 and H2S, there is an observed acid gas reaction that results in elution of carbonyl sulfide, COS.

Importance of PCDD/F molecules’ polarizability and steric hindrance on their adsorption onto zeolites in a standard EN1948-1 sampling device for incinerator emission monitoring

Currently, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) monitoring at stationary sources uses short- and long-term sampling methods compliant with EN1948 standard. The XAD-2 resin is exposed to gas stream for 3–4 weeks (long term), and subsequently analysed in an accredited laboratory for 2 weeks. With the aim of developing an on-line mass spectrometer device using adsorption onto a set of different zeolites as specific adsorbents prior to mass analysis, the paper proposes to firstly test zeolites within the methods compliant with EN1948 standard.In addition to the non-specific external surface adsorption, zeolites possess micropores for adsorbing molecules specifically. Zeolites allowing selective adsorption of only tetra- and penta-chlorinated toxic congeners (TeCDD/F, PeCDD/F) were exposed to the gas flow of a household waste incinerator. As the extraction method of EN 1948 standard does not allow us to discern the two types of adsorption, the adsorbents have been tested at a sampling point located before the last filter. With high congener concentrations, it is expected that the dynamic adsorption properties of the zeolites can be deduced from the breakthrough of some congeners.The electronic interactions between zeolite surface area and PCDD/F involve the polarizability of the molecules. Thanks to the congener breakthrough comparing two zeolite structure types, it has been deduced that toxic TeCDD/F and PeCDD/F were adsorbed in the micropores of FAU-NaX zeolite due to steric compatibility of these congeners. Moreover, the partition of congeners between the condensate and gas phase was elucidated by considering the polarizability of PCDD/F molecules.

Dynamic interfacial properties of sugar-based surfactants: Experimental study and modeling

Careful investigation about dynamic adsorption properties of surfactant molecules has a tremendous interest for their practical applications. The intention of this article is to study the dynamic adsorption properties at air/water interface for 16 nonionic sugar-based surfactants with gradual structure variation. Based on obtained results the dynamic surface tension (DST) behaviour of glycolipids was found to depend on both hydrophobic chain length and bulk concentration of surfactant. Interestingly, the plot of the maximum rate of surface tension decrease against the surfactant bulk concentration showed a linear trend for all studied surfactants independently of their structure. Furthermore, it was confirmed that all molecules were gathered on one unique curve representing a plot of the limit elasticity versus the relative surface concentration of surfactant. The using approach provided further insight into the anticipation of the dynamic surface properties of sugar-based amphiphiles.

Preparation of Multicomponent Biocomposites and Characterization of Their Physicochemical and Mechanical Properties

This work focused on a mutual comparison and characterization of the physicochemical properties of three-component polymer composites. Binary polyaniline–chitosan (PANI–CHT) composites were synthesized by in situ polymerization of PANI onto CHT. Ternary composites were prepared by blending with a third component, polyvinyl alcohol (PVA). Composites with variable PANI:CHT (25:75, 50:50 and 75:25) weight ratios were prepared whilst fixing the composition of PVA. The structure and physicochemical properties of the composites were evaluated using thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and spectroscopic methods (infrared (IR), nuclear magnetic resonance (NMR)). The equilibrium and dynamic adsorption properties of composites were evaluated by solvent swelling in water, water vapour adsorption and dye adsorption isotherms. The electrical conductivity was estimated using current–voltage curves. The mechanical properties of the samples were evaluated using dynamic mechanical analysis (DMA) and correlated with the structural parameters of the composites. The adsorption and swelling properties paralleled the change in the electrical and mechanical properties of the materials. In most cases, samples with higher content of chitosan exhibit higher adsorption and mechanical properties, and lower conductivity. Acid-doped samples showed much higher adsorption, swelling, and electrical conductivity than their undoped analogues.

Preparation of GO/PAM Continuous Adsorption Medium and its Dynamic Adsorption Properties for Methylene Blue

A continuous and structured porous adsorbent named GO/PAM was synthesised by one-step copolymerization of graphene oxide (GO) and acrylamide (AM) in amorphous region initiated by redox agent consisting of hydrogen peroxide (H2O2) and ascorbic acid (VC) at -20°C. The dynamic adsorption characteristics of methylene blue (MB) in GO/PAM structured adsorption medium were investigated. With the introduction of GO which rich in —OH and —COOH groups, the adsorption capacities were 178.65 mg/g~201.58 mg/g. Structured continuous adsorption medium was prepared by one-step polymerization of crystallization, in order to replace traditional bulk resin and ion exchange resin in the treatment of printing and dyeing wastewater.