scholarly journals Uptake of Methylene Blue from Aqueous Solution by Pectin–Chitosan Binary Composites

2020 ◽  
Vol 4 (3) ◽  
pp. 95
Author(s):  
Dexu Kong ◽  
Lee D. Wilson
Keyword(s):  
Methylene Blue ◽  
Aqueous Media ◽  
Dye Adsorption ◽  
Adsorption Properties ◽  
Point Of Zero Charge ◽  
Cross Linking ◽  
Gravimetric Analysis ◽  
Adsorption Sites ◽  
Biopolymer Composites

To address the need to develop improved hybrid biopolymer composites, we report on the preparation of composites that contain chitosan and pectin biopolymers with tunable adsorption properties. Binary biopolymer composites were prepared at variable pectin–chitosan composition in a solvent directed synthesis, dimethyl sulfoxide (DMSO) versus water. The materials were characterized using complementary methods (infrared spectroscopy, thermal gravimetric analysis, pH at the point-of-zero charge, and dye-based adsorption isotherms). Pectin and chitosan composites prepared in DMSO yielded a covalent biopolymer framework (CBF), whereas a polyelectrolyte complex (PEC) was formed in water. The materials characterization provided support that cross-linking occurs between amine groups of chitosan and the –COOH groups of pectin. CBF-based composites had a greater uptake of methylene blue (MB) dye over the PEC-based composites. Composites prepared in DMSO were inferred to have secondary adsorption sites for enhanced MB uptake, as evidenced by a monolayer uptake capacity that exceeded the pectin–chitosan PECs by 1.5-fold. This work provides insight on the role of solvent-dependent cross-linking of pectin and chitosan biopolymers. Sonication-assisted reactions in DMSO favor CBFs, while cross-linking in water yields PECs. Herein, composites with tunable structures and variable physicochemical properties are demonstrated by their unique dye adsorption properties in aqueous media.

scholarly journals Flax Biomass Conversion via Controlled Oxidation: Facile Tuning of Physicochemical Properties

2020 ◽  
Vol 7 (2) ◽  
pp. 38
Author(s):  
Leila Dehabadi ◽  
Abdalla H. Karoyo ◽  
Majid Soleimani ◽  
Wahab O. Alabi ◽  
Carey J. Simonson ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Pore Structure ◽  
Surface Charge ◽  
Chemical Treatment ◽  
Textural Properties ◽  
Adsorption Properties ◽  
Biomass Composition ◽  
Adsorption Sites ◽  
Modified Forms

The role of chemical modification of pristine linen fiber (LF) on its physicochemical and adsorption properties is reported in this contribution. The surface and textural properties of the pristine LF and its peroxyacetic acid- (PAF) and chlorite-treated (CF) fiber forms were characterized by several complementary methods: spectroscopy (SEM, TEM, FT-IR, and XPS), thermal analysis (DSC and TGA), gas/water adsorption isotherms, and zeta potential (ξ). The results obtained reveal that the surface charge and textural properties (surface area and pore structure) of the LF material was modified upon chemical treatment, as indicated by changes in the biomass composition, morphology, ξ-values, and water/dye uptake properties of the fiber samples. Particularly, the pristine LF sample displays preferential removal efficiency (ER) of methylene blue (MB) dye with ER ~3-fold greater (ER~62%) as compared to the modified materials (CF or PAF; ER~21%), due to the role of surface charge of pectins and lignins present in pristine LF. At higher MB concentration, the relative ER values for LF (~19%) relative to CF or PAF (~16%) reveal the greater role of micropore adsorption sites due to the contributing effect of the textural porosity observed for the modified flax biomass at these conditions. Similar trends occur for the adsorption of water in the liquid vs. vapour phases. The chemical treatment of LF alters the polarity/charge of the surface functional groups, and pore structure properties of the chemically treated fibers, according to the variable hydration properties. The surface and textural properties of LF are altered upon chemical modification, according to the variable adsorption properties with liquid water (l) vs. water vapor (g) due to the role of surface- vs. pore-sites. This study contributes to an understanding of the structure-adsorption properties for pristine and oxidized flax fiber biomass. The chemical conversion of such biomass yields biomaterials with tunable surface and textural properties, as evidenced by the unique adsorption properties observed for pristine LF and its modified forms (CF and PAF). This study addresses knowledge gaps in the field by contributing insight on the relationship between structure and adsorption properties of such LF biomass in its pristine and chemically modified forms.

Metal organic frameworks decorated with free carboxylic acid groups: topology, metal capture and dye adsorption properties

2020 ◽  
Vol 49 (41) ◽  
pp. 14690-14705
Author(s):  
M. Naqi Ahamad ◽  
M. Shahnawaz Khan ◽  
M. Shahid ◽  
Musheer Ahmad
Keyword(s):  
Carboxylic Acid ◽  
Metal Organic Frameworks ◽  
Dye Adsorption ◽  
Adsorption Properties ◽  
Carboxylic Acid Groups ◽  
Metal Capture ◽  
Metal Organic

Elaborating the role of uncoordinated carboxylic acid functions in MOFs in post synthetic modification (PSM) through metal capture and hence in tuning dye adsorption properties.

scholarly journals Tetracycline Adsorption from Aqueous Media by Magnetically Separable Fe3O4@Methylcellulose/APTMS (Isotherm, Kinetic and Thermodynamic Studies)

2021 ◽  
Author(s):  
Sobhan Maleky ◽  
Ali Asadipour ◽  
Alireza Nasiri ◽  
Rafael Luque ◽  
Maryam Faraji
Keyword(s):  
Aqueous Solutions ◽  
Aqueous Media ◽  
Point Of Zero Charge ◽  
Gravimetric Analysis ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Enthalpy Changes ◽  
Isotherm Equations ◽  
Kinetic And Thermodynamic Studies

Abstract This study aimed to synthesize Fe3O4@Methylcellulose/3-Aminopropyltrimethoxysilane (Fe3O4@MC/APTMS) as a new magnetic nano-biocomposite by a facile, fast, and new microwave-assisted method and to be utilized as an adsorbent for tetracycline (TC) removal from aqueous solutions. Fe3O4@MC/APTMS was characterized by Fourier transform-infrared (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), Mapping, X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and vibrating sample magnetometer (VSM). The point of zero charge (pHzpc) value of the nano-biocomposite was estimated to be 6.8 by the solid addition method. Optimum conditions were obtained in TC concentration: 10 mg L−1, adsorbent dosage: 80 mg L−1, contact time: 90 min, and solution pH: 6 with the maximum TC removal of 90% and 65.41% in synthetic and actual samples, respectively. The kinetic and isotherm equations pointed to a pseudo-second order kinetic and Langmuir isotherm optimum fitting models. Based on the values of entropy changes (ΔS) (50.04 J/mol k), the enthalpy changes (ΔH) (9.26 kJ/mol), and the negative Gibbs free energy changes (ΔG), the adsorption process was endothermic, random, and spontaneous. The synthesized adsorbent exhibited outstanding properties, including proper removal efficiency of TC, excellent reusability, and simple separation from aqueous media by a magnet. Consequently, it is highly desirable that Fe3O4@MC/APTMS magnetic nano-biocomposite could be used as a promising adsorbent for TC adsorption from aqueous solutions.

Alternative treatments to improve the potential of rice husk as adsorbent for methylene blue

2016 ◽  
Vol 75 (2) ◽  
pp. 296-305 ◽  
Author(s):  
Dison S. P. Franco ◽  
Eduardo H. Tanabe ◽  
Daniel A. Bertuol ◽  
Glaydson S. dos Reis ◽  
Éder C. Lima ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Rice Husk ◽  
Aqueous Media ◽  
Surface Characteristics ◽  
Organic Fraction ◽  
Alternative Treatments ◽  
Adsorption Sites ◽  
Adsorption Capacities ◽  
Endothermic Process ◽  
Mb Adsorption

Alternative treatments, such as, NaOH, ultrasound assisted (UA) and supercritical CO2 (SCO2), were performed to improve the potential of rice husk as adsorbent to remove methylene blue (MB) from aqueous media. All the treatments improved the surface characteristics of rice husk, exposing its organic fraction and/or providing more adsorption sites. The Langmuir and Hill models were able to explain the MB adsorption for all adsorbents in all studied temperatures. The experimental and modeled parameters demonstrated that the MB adsorption was favored by the temperature increase and by the use of NaOH-rice husk. The maximum adsorption capacities for the MB solutions (ranging from 10 to 100 mg L−1), estimated from the Langmuir model at 328 K, were in the following order: NaOH rice-husk (65.0 mg g−1) > UA-rice husk (58.7 mg g−1) > SCO2-rice husk (56.4 mg g−1) > raw rice husk (52.2 mg g−1). The adsorption was a spontaneous, favorable and endothermic process. In general, this work demonstrated that NaOH, UA and SCO2 treatments are alternatives to improve the potential of rice husk as adsorbent.

scholarly journals Gas and Solution Uptake Properties of Graphene Oxide-Based Composite Materials: Organic vs. Inorganic Cross-Linkers

2019 ◽  
Vol 3 (3) ◽  
pp. 80 ◽  
Author(s):  
Sabzevari ◽  
Cree ◽  
Wilson
Keyword(s):  
Graphene Oxide ◽  
Zeta Potential ◽  
Electrostatic Interactions ◽  
Gas Adsorption ◽  
Aqueous Media ◽  
Adsorption Properties ◽  
Cross Linking ◽  
Supporting Evidence ◽  
Monolayer Adsorption ◽  
Adsorption Processes

This study focused on a comparison of the adsorption properties of graphene oxide (GO) and its composites that were prepared via cross-linking with chitosan (CTS) or Al3+ species, respectively. Comparative material characterization was achieved by several complementary methods: SEM, NMR spectroscopy, zeta-potential, dye-based adsorption, and gas adsorption at equilibrium and dynamic conditions. SEM, solids NMR, and zeta-potential results provided supporting evidence for cross-linking between GO and the respective cross-linker units. The zeta-potential of GO composites decreased upon cross-linking due to electrostatic interactions and charge neutralization. Equilibrium and kinetic adsorption profiles of the GO composites with methylene blue (MB) in aqueous media revealed superior uptake over pristine GO. The monolayer adsorption capacity (mg g−1) of MB are listed in descending order for each material: GO–CTS (408.6) > GO–Al (351.4) > GO (267.1). The gas adsorption results showed parallel trends, where the surface area and pore structure of the composites exceeded that for GO due to pillaring effects upon cross-linking. The green strategy reported herein for the preparation of tunable GO-based composites revealed versatile adsorption properties for diverse heterogeneous adsorption processes.

scholarly journals Cu(II) Ion Adsorption by Aniline Grafted Chitosan and Its Responsive Fluorescence Properties

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1052 ◽  
Author(s):  
Bahareh Vafakish ◽  
Lee D. Wilson
Keyword(s):  
Synergistic Effects ◽  
Fluorescence Emission ◽  
Water Security ◽  
Adsorption Properties ◽  
Metal Species ◽  
Adsorbent Regeneration ◽  
Adsorption Sites ◽  
Adsorption Desorption

The detection and removal of heavy metal species in aquatic environments is of continued interest to address ongoing efforts in water security. This study was focused on the preparation and characterization of aniline grafted chitosan (CS-Ac-An), and evaluation of its adsorption properties with Cu(II) under variable conditions. Materials characterization provides support for the grafting of aniline onto chitosan, where the kinetic and thermodynamic adsorption properties reveal a notably greater uptake (>20-fold) of Cu(II) relative to chitosan, where the adsorption capacity (Qm) of CS-Ac-An was 106.6 mg/g. Adsorbent regeneration was demonstrated over multiple adsorption-desorption cycles with good uptake efficiency. CS-Ac-An has a strong fluorescence emission that undergoes prominent quenching at part per billion levels in aqueous solution. The quenching process displays a linear response over variable Cu(II) concentration (0.05–5 mM) that affords reliable detection of low level Cu(II) levels by an in situ “turn-off” process. The tweezer-like chelation properties of CS-Ac-An with Cu(II) was characterized by complementary spectroscopic methods: IR, NMR, X-ray photoelectron (XPS), and scanning electron microscopy (SEM). The role of synergistic effects are inferred among two types of active adsorption sites: electron rich arene rings and amine groups of chitosan with Cu(II) species to afford a tweezer-like binding modality.

Optimization and kinetic studies on cationic dye adsorption using textile yarn waste/Multiwall carbon nanotube nanofibrous composites

2021 ◽  
Vol 112 (4) ◽  
pp. 333-342
Author(s):  
Subramanian Swaminathan ◽  
Nallammal Muthupaiyan Imayathamizhan ◽  
Andiyappan Muthumanickam ◽  
Pooncholai Moorthi
Keyword(s):  
Methylene Blue ◽  
Thermo Gravimetric Analysis ◽  
Dye Adsorption ◽  
Freundlich Isotherm ◽  
Blue Dye ◽  
Multiwall Carbon Nanotube ◽  
Gravimetric Analysis ◽  
Methylene Blue Dye ◽  
Electrospinning Technique ◽  
Multiwall Carbon

Abstract Polyacrylonitrile yarn hard waste and multiwall carbon nano-tubes nanofibrous mat was prepared by the electrospinning technique. The nanofibrous composite mats were characterized using thermo-gravimetric analysis, Fourier transform infrared spectroscopy, FT-Raman, scanning electron microscopy, and X-ray diffraction. Adsorption studies were conducted with various physical and chemical parameters such as contact time, solution pH and initial dye concentration. The maximum methylene blue dye removal efficiency of nanofibrous composite was found to be 73.4%at optimized pH 10. The pseudo-second order kinetics and Freundlich isotherm are suitable for methylene blue dye adsorption of nanofibrous composite.

scholarly journals Synthesis of bismuth oxyhalide (BiOBrzI(1-z)) solid solutions for photodegradation of methylene dye

2021 ◽  
Vol 4 ◽  
pp. 43
Author(s):  
Robert O. Gembo ◽  
Ochieng Aoyi ◽  
Stephen Majoni ◽  
Anita Etale ◽  
Sebusi Odisitse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Methylene Blue ◽  
Electron Microscope ◽  
Solid Solutions ◽  
Uv Light ◽  
Solar Irradiation ◽  
Point Of Zero Charge ◽  
Adsorption Sites ◽  
Key Species ◽  
Bismuth Oxyhalide

Background: The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties.  In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBrzI(1-z)) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation. Methods: Bismuth oxyhalide (BiOBrzI(1-z)) (0 ≤ z ≤ 1) materials were successfully prepared through the hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) were used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBrzI(1-z) materials was examined through methylene blue (MB) degradation under UV light and solar irradiation. Results: The XRD showed that BiOBrzI(1-z) materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with an increase in the amount of iodide (I-). BiOBr0.6I0.4 materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99% and 88% efficiency under solar and UV irradiation, respectively. The kinetics studies of MB removal by BiOBrzI(1-z) materials showed that the degradation process followed nonlinear pseudo-first-order model indicating that the removal of MB depends on the population of the adsorption sites. Trapping experiments confirmed that photogenerated holes (h+) and superoxide radicals (•O2−) are the key species responsible for the degradation of MB. Conclusions: This study shows that bismuth oxyhalide materials are very active in the degradation of methylene blue dye using sunlight and thus they have great potential in safeguarding public health and the environment from the dye’s degradation standpoint. Moreover, the experimental results agree with nonlinear fitting.

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