Adsorption Capacity For Methyl Orange Research Articles

Combined disposal of methyl orange and corn straw via stepwise adsorption-biomethanation-composting

Agriculture wastes have been proved to be the potential adsorbents to remove azo dye from textile wastewater, but the post-treatment of azo dye loaded agriculture waste is generally ignored. A three-step strategy including sequential adsorption-biomethanation-composting was developed to realize the co-processing of azo dye and corn straw (CS). Results showed that CS represented a potential adsorbent to remove methyl orange (MO) from textile wastewater, with the maximum MO adsorption capacity of 10.00 ± 0.46 mg/g, deriving from the Langmuir model. During the biomethanation, CS could serve as electron donor for MO decolorization and substrate for biogas production simultaneously. Though the cumulative methane yield of CS loaded with MO was 11.7 ± 2.28% lower than that of blank CS, almost complete de-colorization of MO could be achieved within 72 h. Composting could achieve the further degradation of aromatic amines (intermediates during the degradation of MO) and decomposition of digestate. After 5 days’ composting, 4-aminobenzenesulfonic acid (4-ABA) was not detectable. The germination index (GI) also indicated that the toxicity of aromatic amine was eliminated. The overall utilization strategy gives novel light on the management of agriculture waste and textile wastewater.

Sorption behavior of chitosan nanoparticles for single and binary removal of cationic and anionic dyes from aqueous solution.

In this study, chitosan nanoparticles (ChNs) were used as an adsorbent for single and simultaneous uptake of cationic (methylene blue (MB)) and anionic (methyl orange (MO)) dyes. ChNs were prepared based on the ionic gelation method using sodium tripolyphosphate (TPP) and characterized by zetasizer, FTIR, BET, SEM, XRD, and pHPZC. The studied parameters that affect removal efficiency included pH, time, and dyes' concentration. The results showed that in single-adsorption mode, the removal of MB is better in alkaline pH, contrary to MO uptake which presents higher removal efficiency in acidic media. The simultaneous removal of MB and MO from the mixture solution by ChNs could be achieved under neutral conditions. The adsorption kinetic results showed that adsorption of MB and MO for both single-adsorption and binary adsorption systems comply with the pseudo-second-order model. Langmuir, Freundlich, and Redlich-Peterson isotherms were used for the mathematical description of single-adsorption equilibrium, while non-modified Langmuir and extended Freundlich isotherms were used to fit the co-adsorption equilibrium results. The maximum adsorption capacities of MB and MO in a single dye adsorption system were 315.01 and 257.05 mg/g for MB and MO, respectively. On the other hand, and for binary adsorption system, the adsorption capacities were 49.05 and 137.03 mg/g, respectively. The adsorption capacity of MB decreases in solution containing MO and vice versa, suggesting an antagonistic behavior of MB and MO on ChNs. Overall, ChNs could be a candidate for single and binary removal of MB and MO in dye-containing wastewater.

β-Cyclodextrin network crosslinked by novel phosphonium-based tetrakiscarboxylic acid derived from PH3 tail gas: Synthesis and application for rapid removal of organic dyes from wastewater

Organic dyes, such as methyl orange (MO), Congo red (CR), crystal violet (CV) and methylene blue (MB), are common organic pollutants existing in wastewater. Therefore, the exploration of bio-based adsorbents for the efficient removal of organic dyes from wastewater has gained many attentions. Here, we report a PCl3-free synthetic method for the synthesis of phosphonium-containing polymers, in which the prepared tetrakis(2-carboxyethyl) phosphonium chloride-crosslinked β-cyclodextrin (TCPC-β-CD) polymers were applied to the removal of dyes from water. The effects of contact time, pH (1−11), and dye concentration were investigated. The selected dye molecules could be captured by the host-gest inclusion of β-CD cavities, and the phosphonium and carboxyl groups in the polymer structure would respectively facilitate the removal of cationic dyes (MB and CV) and anionic dyes (MO and CR) via electrostatic interactions. In a mono-component system, over 99 % of MB could be removed from water within the first 10 min. Based on the Langmuir model, the calculated maximum adsorption capacities of MO, CR, MB, and CV were 180.43, 426.34, 306.57, and 470.11 mg/g (or 0.55, 0.61, 0.96 and 1.15 mmol/g), respectively. Additionally, TCPC-β-CD was easily regenerated using 1 % HCl in ethanol, and the regenerative adsorbent still showed high removal capacities for MO, CR, and MB even after seven treatment cycles.

High-performance multifunctional porous iron Acetylacetonate/N, O-doped carbon nanospheres for electromagnetic wave absorption at 2–18 GHz and methyl orange absorption

Nowadays, multifunction is regarded as an advanced development direction of new-generation electromagnetic wave absorption (EMWA) materials to fulfill the ever-growing demands in complex environment and situation. Environmental pollution and electromagnetic pollution are all difficult problems for human beings all the time. Now, there is no multifunctional materials for collaborative treatment of environmental and electromagnetic pollution. Herein, We synthesized nanospheres with divinyl benzene (DVB) and N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA), using a simple one-pot method. After calcination at 800 ℃ in N2, porous N, O-doped porous carbon materials were prepared. By regulating the mole ratio of DVB and DMAPMA, the ratio was 5:1 reached excellent EMWA property. Remarkably, the introduction of iron acetylacetonate into the reaction of DVB and DMAPMA was effective in enhancing the absorption bandwidth to 8.00 GHz at a 3.74 mm thickness, which depended on the synergistic effects from dielectric and magnetic losses. Simultaneously, the Fe-doped carbon materials had a methyl orange adsorption capacity. The adsorption isotherm conformed to the Freundlich model. After methyl orange absorption, the EMWA property did not greatly change. Thus, this research paves the way for the creation of multifunctional materials to solve environmental pollution and electromagnetic pollution together.

Adsorption performance and mechanism of mesoporous carbon-doped Al2O3 adsorbent derived from NH2-MIL-53 (Al) for removing Cr(Ⅵ) and methyl orange from aqueous solution

A new porous carbon-doped Al2O3 adsorption material was prepared by calcination at 600 °C with the use of aluminum-based metal–organic framework synthesized by hydrothermal method with aluminum as the metal source to solve the problem of instability of MIL-53 in aqueous solution. It was used to remove methyl orange (MO) from single system and aqueous solution with Cr(Ⅵ). The microstructure of the material was characterized by modern analytical techniques, and its adsorption capacity and mechanism were explored. PXRD, SEM, BET and other characterization methods show successfully synthesized NH2-MIL-53(Al) with porous carbon-doped Al2O3 structure. The precursor NH2-MIL-53(Al) and the calcined derivative porous carbon-doped Al2O3 are similar in morphology, and the specific surface area of porous carbon-doped Al2O3 (180.24 m2/g) is larger than that of NH2-MIL-53(Al) (116.73 m2/g). The maximum equilibrium adsorption capacity of Cr(Ⅵ) and MO by porous carbon-doped Al2O3 material could reach 671.56 and 612.09 mg/g, respectively. The fitting results of the adsorption kinetic model show that the adsorption behavior of porous carbon-doped Al2O3 material for Cr(Ⅵ) is more suitable to Langmuir isotherm model, whereas that of MO is more suitable to Freundlich isotherm model. Both are suitable to pseudo-second-order kinetic model. According to XPS analysis, the contents of Cr(III) and Cr(VI) calculated by C600-6 after adsorption are 56.1 % and 44.9 %, indicating that electrostatic interaction and redox action still play a leading role in the adsorption of Cr(VI), while electrostatic interaction and chelation play a leading role in the adsorption of MO. Studies show that the porous carbon-doped Al2O3 material could be used as a Cr(Ⅵ) and MO removal material to achieve efficient removal of Cr(Ⅵ) and MO. The alumina synthesized by MOF is more stable than the traditional industrial alumina, and its acid and alkaline resistance is more excellent. This material not only solves the problem of instability and uneven distribution of MIL-53 crystal and common alumina materials but also provides more adsorption sites.

Waste organic dye removal using MOF-based electrospun nanofibers of high amine density

The exceptional structural stability of UiO-66 metal–organic framework (MOF) and ligands' functional groups render UiO-66 as a versatile candidate for multiple applications, including wastewater treatment. The possibility of a broad spectrum of post-synthetic modification of UiO-66 further expands its prospective uses. However, commercial applications of UiO-66 have been hindered by the polycrystalline nature of the powder. In this research, modification to obtain UiO-66-NH2 and post-processing with nanofibers comprising chitosan and polyvinyl alcohol (PVA) were applied to faciliate deployment as a suitable option for water decontamination. MOF nanoparticles were post-synthetically modified with 2,4,6-trichloro-1,3,5-triazine (TCT) and 5-phenyl-tetrazole (PT) to produce high-amine containing UiO-66, thus introducing active nitrogen-containing functional groups that enhanced the removal efficiency of targeted molecules from aqueous media. A systematic study was undertaken to optimize the supporting nanofibers and to demonstrate that even a low MOF functionalization, of up to 7- wt%, offered a maximum methyl orange adsorption capacity of 619 mg/g, superior to most adsorbents reported so far. Furthermore, selectivity, regeneration ability, and the effect of ambient conditions were demonstrated.

Methyl Orange Absorption Using Chitosan from Shrimp Skin as an Adsorbent

In the coloring process, the textile industry generally uses synthetic (artificial) dyes, methyl orange (MO). In this study, the adsorption of methyl orange (MO) dye with chitosan was investigated in a series of batch laboratory studies. The adsorption equilibrium study used a MO solution with a concentration of 10 to 50 mg/L with an adsorbent weight of 3 g put into an Erlenmeyer and shaken until the adsorption reached an equilibrium condition. Meanwhile, the adsorption kinetics used a MO solution with an initial concentration of 10 and 20 mg/L with a volume of 100 mL with an adsorbent weight of 3 g and the solution was adjusted to pH 2. Effective operating parameters such as pH, initial concentration of dye (C0) and contact time at adsorption has been investigated. The results showed that the adsorption capacity of methyl orange (MO) dye from chitosan increased with an increasing acid content, and it was found that a solution of pH 2 was the optimal pH value for MO adsorption. The adsorption parameters for the Langmuir and Freundlich isotherms were determined by nonlinear regression and the equilibrium data were best explained by the Langmuir isotherm model, this was indicated by the high value of the correlation coefficient (R2), which was 0.9595. The maximum adsorption capacity was 0.1297 mg/g. Adsorption kinetics can be successfully applied to pseudo second-order kinetic models. The pseudo second-order model results show that the adsorption process is controlled by chemical sorption (chemisorption).

Enhancing methyl orange adsorption capacity via functionalizing ZIF-8 with amphiphilic cetylpyridinium bromide

BackgroundThe precise design or functionalization of metal organic frameworks (MOFs) based on the properties of organic dyes is a promising direction in environment remediation. MethodsHerein, using methyl orange (MO) as the target dye, cetylpyridinium bromide (CPB) functionalized ZIF-8 (CPB@ZIF-8) was fabricated by the post-synthetic modification strategy. Significant findingsThe surface area and the pore volume of CPB@ZIF-8 are greatly reduced compared with pure ZIF-8. However, the introduction of amphiphilic CPB molecules into ZIF-8 can significantly enhance the adsorption performance of MO. This enhanced MO adsorption capacity can be attributed to the incorporation of more positively charged sites, hydrophobic sites and aromatic rings in the CPB-modified ZIF-8 frameworks, which provides the electrostatic attractions, the hydrophobic and π-π interactions that mainly govern the adsorption of MO on CPB@ZIF-8. The pseudo-second-order kinetic model and the Langmuir isotherm model can well represent the adsorption process of MO. The maximum adsorption capacity (195.54 mg/g) has been obtained at 30 °C, outperforming pristine ZIF-8 and various reported absorbents. The prepared CPB@ZIF-8 composite is a superior example of the tunable adsorption affinity of MOFs for anionic dyes.

Fabrication of EVOH/PANI Composite Nanofibrous Aerogels for the Removal of Dyes and Heavy Metal Ions.

Water pollution caused by the leakage and discharge of pollutants, such as dyes and heavy metal ions, can cause serious damage to the environment and human health. Therefore, it is important to design and develop adsorbent materials that are efficient and multifunctional for the removal of these pollutants. In this work, poly(vinyl alcohol-co-ethylene) (EVOH)/polyaniline (PANI) composite nanofibrous aerogels (NFAs) were fabricated via solution oxidation and blending. The aerogels were characterized by a scanning electron microscope, Fourier transform infrared spectrometry, a contact angle measuring instrument and a universal testing machine. The influences of the introduction of PANI nanorods on the structural properties of aerogels were investigated, and the adsorption performance of aerogels was also studied. The results showed that the introduction of PANI nanorods filled the fibrous network structure, reduced porosity, increased surface hydrophilicity and improved compressive strength. Furthermore, EVOH/PANI composite NFAs possess good adsorption performances for dyes and heavy metal ions: The adsorption capacities of methyl orange and chromium ions (VI) are 73.22 mg/g and 115.54 mg/g, respectively. Overall, the research suggests that EVOH/PANI NFAs have great potential as efficient and multifunctional adsorbent materials for the removal of pollutants from water.

Nanoporous hydrogel absorbent based on salep: Swelling behavior and methyl orange adsorption capacity

This study used the gas-blowing method to develop a nanoporous hydrogel using poly (3-sulfopropyl acrylate-co-acrylic acid-co-acrylamide) grafted onto salep. The synthesis of the nanoporous hydrogel was optimized by various parameters for maximum swelling capacity. The nanoporous hydrogel was characterized using FT-IR, TGA, XRD, TEM, and SEM analyses. Images from SEM showed numerous pores and channels in the hydrogel with an average size of about 80 nm, forming a honeycomb-like shape. The change in surface charge was investigated by zeta potential and revealed that the surface charge of the hydrogel ranged from 20 mV at acidic conditions to −25 mV at basic conditions. The swelling behavior of optimum superabsorbent hydrogel was determined under different environmental conditions, such as different pH values, ionic strengths of the environment, and solvents. In addition, the swelling kinetics and the absorbance under loading of the hydrogel sample in different environments were investigated. Moreover, Methyl Orange (MO) dye was removed from aqueous solutions using the nanoporous hydrogel as an adsorbent. The adsorption behavior of the hydrogel was examined under various conditions, and the adsorption capacity of the hydrogel was found tobe 400 mg g−1. The maximum water uptake was obtained under the following conditions: Salep weight = 0.01 g, AA = 60 μL, MBA = 300 μL, APS = 60 μL, TEMED = 90 μL, AAm = 600 μL, and SPAK = 90 μL. Lastly, the adsorption kinetics was studied by employing pseudo-first-order, pseudo-second-order, and intra-particle diffusion models.

Adsorption of Methyl Orange Dyes on Oriented Co/Fe-MOF Bimetallic Organic Framework in Wastewater Treatment

The production of highly efficient and reusable adsorbents that can be used in pigment treatment has been of great scientific interest. Metallic organic frameworks (MOFs) are considered a new type of material with extremely diverse structures and can be used as adsorbents to remove environmental pollutants. The selected Co/Fe-MOF material was synthesized in this study by using the solvent-thermal method. Then, the effects of several influencing factors such as adsorbent dosage, pH, initial concentration of MO, and exposure time on the adsorption capacity of methyl orange (MO) dyes by Co/Fe-MOF were evaluated. Under acidic conditions (pH 4), the effective removal of MO from aqueous solution reached equilibrium after 60 min upon exposure to MO at the concentration of 200 mg/L, and the adsorption capacity was 137.6 mg/g. The two models of adsorption isotherms, Freundlich and Langmuir, showed good compatibility with the experimental data, and the calculated correlation coefficients (R2) were both greater than 0.96. The MO adsorption efficiency was proposed to fit the pseudo-quadratic and pseudo-first-order kinetic models. Therefore, MOF materials can be considered as a potential agent for wastewater treatment, thereby providing a possible solution to solve water pollution.

Novel Cellulose/Silica Microspheres as Sustainable and Efficient Adsorbents for Methyl Orange Removal

The effective removal of organic dyes from aqueous solutions is essential for environmental protection and remediation. Hence, methods for fabricating efficient and sustainable adsorbents for removing toxic dyes are urgently desired. Here, new cellulose/silica microspheres containing amino groups were prepared and applied as functional materials for capturing anionic pollutants. Tosyl cellulose, which has a high degree of substitution, was prepared from cellulose using an ionic liquid as the solvent. Further, (3-aminopropyl)trimethoxysilane was utilized as a silica precursor to prepare the microhybrids via nucleophilic substitution, followed by the sol–gel process. The fabricated microhybrids exhibited an excellent capacity for methyl orange (MO) adsorption. Furthermore, the effects of different pH values, contact times, and initial dye concentrations on the MO adsorption capacity were evaluated. The Langmuir isotherm and pseudo-second-order kinetic models were effective for modeling the adsorption of MO on the cellulose/silica microspheres. Under the established optimal conditions, the cellulose/silica microspheres exhibited a higher adsorption capacity (588 mg/g) than those in previous reports. Therefore, the proposed cellulose/silica microspheres offer a promising platform for the sustainable development of water-purification systems.Graphical

Functionalization of pine sawdust biochars with Mg/Al layered double hydroxides to enhance adsorption capacity of synthetic azo dyes: Adsorption mechanisms and reusability

This study determined that the adsorption of azo dyes, Methyl Orange (MO) and Sunset Yellow FCF (SYF), using the pristine pine sawdust biochar (PSB) and post-modified PSB with Mg/Al layered double hydroxides (PSB-LDHMgAl) was examined to offer valuable information into the differences in their adsorption mechanisms. Although a lower specific surface area of PSB-LDHMgAl (147.2 m2 g−1) than PSB (495.7 m2 g−1), LDHMgAl were successfully functionalized on the PSB surface through co-precipitation, which was highly related to the improvements of adsorption capacity of PSB-LDHMgAl toward MO and SYF. The MO and SYF adsorption kinetics by PSB and PSB-LDHMgAl were confirmed to the pseudo-second-order and considered chemisorption. The adsorption capacity of MO and SYF adsorbed onto PSB-LDHMgAl (MO = 21.8 mg g−1, SYF = 23.6 mg g−1) were significantly higher than that of PSB (MO = 2.2 mg g−1, SYF = 1.6 mg g−1). The adsorption isotherms of MO and SYF by PSB were well fitted by Freundlich isotherm, whereas the MO and SYF via PSB-LDHMgAl were by Langmuir isotherm. Even after 3 adsorption-desorption cycles using desorbents, the PSB-LDHMgAl remained excellent reusability (reuse efficiency: >81.2%). These findings suggest that post-modification with LDHMgAl might accelerate the adsorption performance (i.e., electrostatic interaction) of azo dyes to PSB in water.

Adsorption of Methyl Orange and Amoxicillin from Water using Metal-organic Framework Prepared from Solvothermal Mixing of Zn ions and 1,4-Benzenedicarboxylic Acid Moieties

In this study, we determined the capacity of metal organic framework, which we prepared by the solvothermal mixing of Zn ions and 1,4-benzenedicarboxylic acid (Zn/BDC) moieties to adsorb methyl orange (MO), and amoxicillin (AMX). Results obtained show that MO and AMX adsorption capacity by Zn/BDC (mg/g) was found to increase with increase in solution concentration, for each contaminant type. Three isotherm models were applied to the adsorption data: Freundlich, Langmuir, and Temkin. R2 values obtained for the adsorption of MO, 0.9778, 0.8589 and 0.9038 for Freundlich, Langmuir and Temkin plots respectively, indicates that all three models fit the adsorption data appreciably good, with the Freundlich isotherm providing the best fit. Those for AMX, 0.6737, 0.0616, and 0.5300 indicated a poor fit, but the Freundlich isotherm came out as best fitting isotherm for AMX, an indication of a multilayer adsorption process. Maximum possible amount of contaminant adsorbed per gram of Zn/BDC deduced from the Langmuir isotherm for the adsorption of both contaminants were 93.46 mg/g and 18.41 mg/g for MO and AMX respectively. This, among other indicators, showed the preference of Zn/BDC for MO relative to AMX. Adsorption kinetic models: pseudo first order, pseudo second order, and Weber-Morris intraparticle diffusion models, gave R2 values that indicate that intraparticle diffusion dominated the adsorption of MO, while the adsorption of AMX followed pseudo second order kinetics, an indicator of chemisorptive mechanism. Calculated Qe values, were in close agreement with experimental values.

Porous Cu-based metal organic framework (Cu-MOF) for highly selective adsorption of organic pollutants

In this study, copper based metal organic frame work (Cu-MOF) was synthesized by using different solvents i. e. H2O, Dimethylformamide (DMF) and DMF ​+ ​C2H5OH ​+ ​H2O solutions at various temperatures. Cu-MOF synthesized in different solvents exhibited a large number of properties and advantages including easy synthesis procedure, high porosity, good crystallinity, high surface area, massive pore volume, controllable pore surface properties (zeta potential), rigid and chemical stability. The as-synthesized Cu- MOF was analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, zeta potential, electrostatic attraction and Thermal gravimetric analysis (TGA). A higher BET surface area of 121.1 ​m2 ​g−1 was obtained for Cu-MOF synthesized in DMF ​+ ​C2H5OH ​+ ​H2O compared with H2O (109.3 ​m2 ​g−1) and DMF (115.1 ​m2 ​g−1) solvents. The as-obtained Cu-MOF was used to investigate adsorption kinetic performances of methylene blue (MB) and methyl orange (MO) dye molecules. Compared with other samples, Cu-MOF synthesized in (DMF ​+ ​C2H5OH ​+ ​H2O) has a significantly enhanced adsorption ability for MB but a lower for MO dyes. After 4 ​min, the adsorption co-efficient (k) values were calculated to be 0.506, 0.846 and 1.1915 min−1 for MB and 0.029, 0.024 and 0.005 min−1 for MO dyes for Cu-MOF (H2O), Cu-MOF (DMF) and Cu-MOF (DMF ​+ ​C2H5OH ​+ ​H2O), respectively. It was found that Cu-MOF has a higher adsorption for MB dye but a poor adsorption capacity for MO, which was attributed to the electrostatic attraction/repulsion phenomena. Moreover, compared with Cu-MOF (DMF) and Cu-MOF (H2O), Cu-MOF (DMF ​+ ​C2H5OH ​+ ​H2O) shows an improved stability at 370, 417 and 423 ​°C temperatures. The result obtained through experiment suggested that porous Cu-MOF microstructures synthesized in DMF ​+ ​C2H5OH ​+ ​H2O have potential application for the treatment wastewaters having MB and MO dyes.

Synthesis and testing of polyacrylamide‐grafted waste sand derived composite adsorbent for water purification

AbstractIn this work, waste sand derived polyacrylamide grafted sand particles (PAGSPs) were developed as an effective adsorbent for the adsorption of organic and inorganic pollutants from water. The composite particles were characterized using FESEM, EDX, ATR‐FTIR, XRD, TGA, and BET analyses. The FESEM results revealed the sizes of composite particles were in the micrometer range and BET analysis showed specific surface area of 10 m2 g−1 with average pore radius of 1.22 nm. The adsorption isotherm and kinetics of dyes namely Methyl Orange (MO) and Quinoline Yellow (QY) and Ni(II) and Cr(VI) metal ions were analyzed. The adsorption capacities for dyes MO and QY were 32.25 and 55.55 mg g−1 and for metal ions Ni(II) and Cr(VI) were 75.18 and 125 mg g−1 respectively, at experimental pH conditions. Because of the excellent regeneration capacity, the functional polymer based composite particles exhibit great potential for the removal of any organic and inorganic pollutants from wastewater.

Insights into the pH-Dependent Adsorption Behavior of Ionic Dyes on Phosphoric Acid-Activated Biochar.

Activated biochar is a promising porous carbonaceous adsorbent material for organic pollutant removal, but it remains challenging to obtain high porosity and aromaticity through a simple and low-cost synthetic method. The common adsorption mechanisms of organic dyes on activated biochar should be further investigated in order to guide the synthesis of high-efficiency adsorbent materials. Here, we proposed a high-yield (up to 40 wt %) synthetic method of phosphoric acid-activated biochar from pomelo peel (PPC) with a high specific area of 877.3 m2/g through a facile thermal treatment at a relatively low temperature (250 °C). The specific activation mechanism of H3PO4 in the preparation of the adsorbent was investigated by a range of experiments and characterizations. The kinetic and isotherm experiments are also conducted to evaluate its dye adsorption behavior. According to the adsorption experiment results, PPC exhibits high saturated adsorption capacities for methyl orange (MO, 239.1 mg/g), rhodamine B (RhB, 2821.8 mg/g), methylene blue (MB, 580.5 mg/g), and crystal violate (CV, 396.6 mg/g) according to the Langmuir model. The maximum initial concentration of each dye solution for acquiring 90% removal efficiency is estimated to be 234.55 ppm (MO), 2943.8 ppm (RhB), 633.8 ppm (MB), and 423.6 ppm (CV) at 298 K with an adsorbent dosage of 1 g/L. The characterization results also indicate PPC has a complex synergetic mechanism for ionic dye adsorption behavior. This provides perspectives regarding PPC as a promising biochar adsorbent from biomass waste, which is probably useful for high-efficiency dye removal in water treatment.

Preparation and application of yttrium oxide with a large specific surface area through moderate carbonation in the presence of carbon dioxide

Yttrium oxide with a large specific surface area (SSA) (hereafter called LSSA Y2O3) has high-porosity structure, relatively large interface, and relatively abundant active surface sites, and its optical, chemical and thermal stability properties are greatly improved compared with ordinary yttrium oxide. As a result, LSSA Y2O3 has been applied in various fields as a luminescent, catalytic, and adsorbent material, showing enormous market potential. This study creatively presents a process designed to prepare LSSA Y2O3 powders through moderate carbonation in the presence of CO2. Experimentally, CO2 was used to carbonate a yttrium hydroxide [Y(OH)3] slurry. During the initial stage of carbonation, crystalline yttrium carbonate encapsulated Y(OH)3 through heterogeneous nucleation on its surface. This encapsulation considerably improved the filterability of the carbonation product while allowing it to retain the phase structure and high-porosity morphology of Y(OH)3. Further calcination of the carbonation product produced LSSA Y2O3 with an SSA of approximately 84 m2/g. This Y2O3 powder exhibited a relatively high adsorption capacity for methyl orange and was easy to recycle and reuse, thus showing potential for use as an adsorbent. The process developed in this study for preparing LSSA Y2O3 powders through carbonation in the presence of CO2 is advantageous because it requires only moderate conditions, causes no pollution, produces products with a uniform granularity and morphology, and is easy to scale up to meet industrial demands. Therefore, this process can effectively increase the added value and market competitiveness of Y2O3 powders and provide an experimental basis and theoretical guidance for the synthesis of other rare earth (RE) compounds with large SSAs through carbonation.

A novel pathway based on the comprehensive utilization of oil peony pods into high yield polysaccharides and strong adsorption carbon

The main purpose of the study was to establish a new comprehensive utilization Standard Operating Procedure (SOP) for the oil tree peony pods (OTPP) and realize the green sustainable utilization of agricultural and forestry waste. The OTPP polysaccharide (OTPP-P) was extracted by ultrasonic-assisted extraction (UAE), and the yield was optimized by response surface methodology (RSM). The activated carbon (AC) was prepared by two-step activation using OTPP residue (OTPPR) as raw material, and the structure and adsorption properties of AC were evaluated. The results revealed that the yield of OTPP-P was up to 8.05% by UAE, two polysaccharides were isolated from OTPP-P, and the monosaccharides components were obtained. The PPAC-KOH had a good pore structure (SBET = 1363.39 m2/g and VTotal = 0.81 cm3/g), and had superior adsorption capacity for methyl orange (1113 mg/g), ciprofloxacin (696 mg/g) and norfloxacin (308 mg/g). The adsorption process mainly included electrostatic interaction, π-π interactions, and dominant physical absorption. Adsorption had good applicability and repeatability. This study provided a new way for the comprehensive utilization of OTPP and a reference for the high value-added transformation and sustainable development of waste.

Different Adsorption Behaviors and Mechanisms of Anionic Azo Dyes on Polydopamine–Polyethyleneimine Modified Thermoplastic Polyurethane Nanofiber Membranes

Considering the notable mechanical properties of thermoplastic polyurethane (TPU), polydopamine–polyethyleneimine (PEI) -modified TPU nanofiber membranes (PDA/PEI-TPU NFMs) have been developed successfully for removal of anionic azo dyes. The adsorption capacity of PDA/PEI-TPU NFMs was evaluated using three anionic dyes: congo red (CR), sunset yellow (SY), and methyl orange (MO). Interestingly, it exhibited different adsorption behaviors and mechanisms of CR on PDA/PEI-TPU NFMs compared with SY and MO. With the decrease in pH, leading to more positive charges on the PDA/PEI-TPU NFMs, the adsorption capacity of SY and MO increased, indicating electrostatic interaction as a main mechanism for SY and MO adsorption. However, wide pH range adaptability and superior adsorption have been observed during the CR adsorption process compared to SY and MO, suggesting a synergistic effect of hydrogen bonding and electrostatic interaction, likely as a critical factor. The adsorption kinetics revealed that chemical interactions predominate in the CR adsorption process, and multiple stages control the adsorption process at the same time. According to the Langmuir model, the maximum adsorption capacity of CR, SY and MO were reached 263, 17 and 23 mg/g, respectively. After six iterations of adsorption–desorption, the adsorption performance of the PDA/PEI-TPU NFMs did not decrease significantly, which indicated that the PDA/PEI-TPU NFMs have a potential application for the removal of CR molecules by adsorption from wastewater.