Adsorption Capacity For Methyl Orange Research Articles

One-step coprecipitation synthesis of Cl− intercalated Fe3O4@SiO2 @MgAl LDH nanocomposites with excellent adsorption performance toward three dyes

A magnetic Cl−-intercalated Fe3O4@SiO2@MgAl-Cl− LDH nanocomposite has been successfully synthesized by modified one-step salt-assisted coprecipitation process. The Fe3O4@SiO2@MgAl-Cl− LDH nanocomposite was characterized by FTIR, XRD, XPS, SEM, HRTEM, BET and VSM. The results showed that the Fe3O4@SiO2@MgAl-Cl− LDH particles possessed core (Fe3O4@SiO2) shell (Cl− -LDH) structures and magnetic properties, and Cl− anions were successfully introduced into LDH interlayers. The unique intercalated structure with week interlayer interaction of Fe3O4@SiO2@MgAl-Cl− LDH provide efficient adsorption of methyl orange (MO), Congo red (CR) and methyl blue (MB), leading to its superior performance with much higher uptake capability with the maximum adsorption capacity of MO, CR and MB reaching 733 mg·g−1, 910 mg·g−1 and 385 mg·g−1, respectively. The adsorption process could be well described by pseudo-second-order model for MO, CR and MB. The experimental data of MO and CR could be fitted better with Freundlich model, while that of MB were fitted better with Langmuir model. The adsorption process was spontaneous and exothermic for MO and MB, while spontaneous and endothermic for CR. Moreover, the adsorbent exhibits excellent stability and reusability in the regeneration cycle, and a process called ‘‘post-processing step” is proposed to effectively improve the dye removal ability of the adsorbent in reuse. This study puts forward a new thought for the development of high-performance LDH adsorbents with mesoporous and Cl− intercalation structure for the efficient and rapid removal of dyes.

Adsorption of methyl orange on ZnO supported by seawater-modified red mud

Abstract In this study, a novel adsorbent (SRM-ZnO) was prepared using zinc oxide supported on red mud in a seawater medium and was used for the adsorption of methyl orange (MO). It is expected to solve the recycling of red mud and prepare an economical adsorbent with high efficiency to adsorb dye wastewater. Material composition and morphology analyses showed that hydrotalcite compounds were attached on the surface of SRM-ZnO. The hydrotalcite compounds can increase the surface area of the modified red mud and thus increase the adsorption capacity of MO. The adsorption of MO dye on modified red mud conforms to the Temkin isotherm model and pseudo-second-order kinetic model. The adsorption behavior mainly includes physical interaction, supplemented with chemical interactions. Result also found that the adsorption of MO on SRM-ZnO is a spontaneous exothermic process.

Adsorption characteristics of assembled and unassembled Ni/Cr layered double hydroxides towards methyl orange

The lamella aggregation state of layered double hydroxides (LDHs) may affect their sorption capacity for organic compounds. The dried LDH samples (Ni/Cr LDH-FA-D and Ni/Cr LDH-H2O-D) and the undried samples (Ni/Cr LDH-FA-W and Ni/Cr LDH-H2O-W) were flexibly prepared by a co-precipitation method in formamide (FA) and water, respectively. The results of X-ray diffraction (XRD) and transmission electron microscope (TEM) showed that the undried LDHs were unassembled, which had no the stacking layers but had a pseudohexagonal nanosheet lamella structure. And the unassembled LDH layers can be assembled again during the dry process. Ni/Cr LDH-FA-W and Ni/Cr LDH-H2O-W showed much greater adsorption capacities towards methyl orange (MO) than Ni/Cr LDH-FA-D and Ni/Cr LDH-H2O-D, as well as shorter time to reach equilibrium. The maximum adsorption capacity of MO could be calculated to 806 mg/g and 740 mg/g for Ni/Cr LDH-FA-W and Ni/Cr LDH-H2O-W by Langmuir-type simulation. The greater adsorption capacities of unassembled LDH could be attributed to the loosen structure and much more exposed adsorption sites. It could be concluded that unassembled LDHs were an effective and conducive preparation pathway for the exploration of the adsorption sites of LDHs.

Investigation the adsorption behavior of functional carbon-based composites for efficient removing anions / cations in single and multicomponent systems

A novel pH-responsive carbon-based nano-adsorbent (MGO-CNT@β-CS-CD) for the adsorption of dyes from aqueous solution was prepared by using graphene oxide, Fe3O4, multi-walled carbon nanotubes, β-cyclodextrin and Chitosan as raw materials. The structure and adsorption mechanism of adsorbent were performed by FT-IR, SEM, Raman, TGA, VSM, XPS, BET, XRD and ICP-MS. After that, the adsorption behaviors of MGO-CNT@β-CS-CD towards dyes Methylene blue (MB), Methyl orange (MO), Congo red (CR) and Indigo Carmine (IC) were further systematically investigated. Moreover, kinetic adsorption by MGO-CNT@β-CS-CD was well fitted with the pseudo-second-order model. The adsorption isotherms indicated that the results were fitting well with the Langmuir model, the maximum adsorption capacity of MB, MO, CR and IC reached 1580.50, 269.09, 287.43 and 258.13 mg/g, respectively. Additionally, anionic dyes could be selectively adsorbed when the pH value of the anionic and cationic mixed solution was acidic, whereas, when the pH value of the solution was alkaline, MB could be adsorbed from a mixed anion-cation system. Finally, the results showed that the nanoparticle adsorbent could be used as the packing agent of the adsorption column to realize the series adsorption of anionic - cationic - anionic dye systems, which had a good industrial application prospect.

Production of chitosan nanofibers using the HFIP/acetic acid mixture as electrospinning solvent

Chitosan nanofiber mats are of interest for biotechnological purposes owing to its physical and chemical properties, nonetheless, the production of pristine chitosan nanofibrous mats is challenging due to some of these traits restrict its solubility in most common solvents, thus limiting its electrospun processability. This work presents the production of pristine chitosan electrospun nanofibers using the 1,1,1,3,3,3-Hexafluoro-2-propanol/acetic acid binary mixture as solvent. This binary solvent improves pristine chitosan spinnability and facilitates the one-step fabrication of highly stable nanofiber mats insoluble in water and aqueous media without the need for crosslinking and neutralization, which implies no need for further washing steps, no waste production, less energy consumption, reagents saving and a significant impact on reducing total processing time compared with previously reported methodologies. Moreover, the aqueous adsorption capacity of methyl orange is improved by the microarchitecture of chitosan as-spun nanofibers produced in this work compared with chitosan powder and film, confirming an essential role of the microstructure and highlighting its potential as bioadsorbent for dye removal.

Two-dimensional assembly made up of ZIF-8 particles for the high-efficient capture of the iodine and dyes

The removal of the pollutants from the environment is the need of the environmental protection. ZIF-8 is promising adsorbents, and the construction of ZIF-8 assembly is essential to boost its performance. Here, we showed the easy synthesis of two-dimensional (2D) assembly built by ZIF-8 particles (2D A-ZIF-8) for the high-efficient capture of the iodine (I2) and dyes. The assembly was synthesized by the controllable reaction of 2-methylimidazole (2-MIM) with 2D Zn-glycerol (Zn-GL) precursor. Time-dependent experiments showed the predominant replacement of GL at outer boundary and then basic plane of the precursor by 2-MIM. The assembly can be synthesized with high output and combined the advantage of large accessible surface of 2D sheets, the plentiful pores of ZIF-8 and enhanced stability of assembly, endowing the large potential as adsorbent. The high adsorption capacity of I2 (200 wt%) was achieved on A-ZIF-8, while it is about 128 wt% on traditional dodecahedronal ZIF-8. The assembly also showed the excellent adsorption capacity for methyl orange (MO) (46.3 mg g-1) and methylene blue (MB) (46.5 mg g-1) at a concentration of 50 mg L-1. It can be easily separated for reuse benefited from the large size and enhanced stability of assembly.

Adsorption mechanism study of multinuclear metal coordination cluster Zn5 for anionic dyes congo red and methyl orange: Experiment and molecular simulation

This study aimed to investigate the adsorption behaviors of congo red (CR) and methyl orange (MO) on the coordination cluster Zn5(H2Ln)6(NO3)4 (Zn5, H3Ln = 1,2-bis-(benzo[d]imidazol-2-yl)-ethenol). Due to multinuclear assembly, multinuclear Zn5 possessed higher electrostatic potential and exhibited 3-fold enhancement in removal efficiency, compared with mononuclear Zn (Zn(H3L)2, H4L = 1,2-bis-(benzo[d]imidazol-2-yl)-1,2-ethanediol). The infrared and X-ray photoelectron spectroscopy and the electrostatic potential analysis indicated that the adsorption mechanism was electrostatic interaction and ion exchange interaction. The adsorption kinetics followed both the pseudo first-order and Bangham models. The pore system analysis and Bangham model suggested that CR and MO could diffuse in the snakelike pores of Zn5. The adsorption isotherms complied with the Langmuir isotherm model, and the maximum adsorption capacities for CR and MO are 166.91 and 100.78 mg/g at room temperature. The adsorption process was spontaneous and endothermic, driven by the entropy increase. Based on this research, the multinuclear coordination clusters can be suggested as potential adsorbents for the removal of anionic dyes.

Post-synthetic modification of conjugated microporous polymer with imidazolium for highly efficient anionic dyes removal from water

• A cationic CMP-Im was synthesized by post-synthetic modification. • CMP-Im showed superior adsorption and separation capacity for anionic dyes. • The conjugation, porosity and cation benefit the adsorption results of CMP-Im . • CMP-Im can be used to prepare packed column and beads to remove anionic dyes. Water pollution caused by organic dyes is a severe environmental problem in developing society. Adsorption has been considered as a versatile and simple water-purification method. Therefore, it is desirable to develop adsorbents with high capacity and efficiency to remove dyes. In this work, through two-step post-synthetic modification to introduce imidazolium in a conjugated microporous polymer (CMP), an effective adsorbent ( CMP-Im ) was obtained to study the rational conjugated and cationic skeleton for anionic dyes removal. All these polymers exhibited inherent porous structures and high stability. CMP-Im showed Brunauer–Emmett–Teller (BET) surface area of 533 m 2 g −1 and possessed cationic framework of imidazolium unit favoring interaction with anionic guests. Due to the conjugated, cationic and porous framework, CMP-Im exhibited fast and efficient adsorption of anionic dyes such as methyl orange (MO) and Congo red (CR), and the adsorption capacity for MO and CR were 588 and 2500 mg g −1 , respectively. CMP-Im also exhibited excellent removal ability when it was used as stuffing to prepare packed column and adsorption beads. Hence, CMP-Im can be a promising candidate for dyes removal from water. This work opens up the exploration of post-synthetic CMPs and expands the application of cationic CMPs in dye adsorption.

Soft-template solvent thermal method synthesis of magnetic mesoporous carbon-silica composite for adsorption of methyl orange from aqueous solution.

A facile soft-template solvent thermal strategy was developed to prepare mesoporous carbon-silica composite (MMCS) by using furfuryl alcohol (FA) as carbon precursor, Pluronic copolymer P123 as template, hydrated iron nitrate as iron source, and teraethylorthosilicate as silicon source and it was applied for the removal of methyl orange (MO). The as-synthesized MMCS with abound of hydrophilic groups processed a high specific surface area, large pore volume, and good magnetic response. With the increased amount of FA, the surface area and functional groups increased, promoting the adsorption effect. The maximum adsorption capacity of MO on MMCS can be high to 113.1mgg-1 at pH 4 with 150mg L-1 initial MO concentration. The adsorption isotherm, kinetic, and thermodynamics were all studied and the results showed the adsorption process well fitted Langmuir adsorption isotherm and pseudo-second-order model. Additionally, it was shown that the adsorption process could not be interfered by the co-existence of PO43-, NO3-, CO32-, SO42-, and real water matrix. And the proposed adsorbent can remove MO in three practical water samples with satisfied removal rates ranging from 92.8 to 99.8%. Thus, the MMCS prepared in this study could be utilized as an alternative adsorbent for the removal of methyl orange from practical aqueous solution.

Ultralight and porous cellulose nanofibers/polyethyleneimine composite aerogels with exceptional performance for selective anionic dye adsorption

It is significant to develop new adsorbents with excellent adsorption performance and convenient operation ability for removing pollutants from wastewater owing to the growing environmental problems. In this paper, a novel ultralight aerogel-based adsorbent with highly porous structure and good mechanical integrity was fabricated based on the interaction of amine groups on polyethyleneimine (PEI) and hydroxyl groups on cellulose nanofibers (CNF), with epichlorohydrin (ECH) serving as a crosslinker. The obtained CNF/PEI aerogel showed excellent water stability in harsh conditions, fast water-activated shape recovery, and ultra-fast water transport. The adsorption capacity for methyl orange (MO) in batch can reach to1226 mg g−1 at pH 6. Furthermore, the membrane also exhibited excellent selective adsorption and filtration, and separation performance. Therefore, this paper presents a new strategy to prepare low-cost and highly efficient adsorbents to remove organic dyes from wastewater for potential practical applications.

Highly removal of anionic dye from aqueous medium using a promising biochar derived from date palm petioles: Characterization, adsorption properties and reuse studies

The present work investigates the preparation of promising biochar derived from date palm petioles powder (DPB) via a thermal treatment. DPB was characterized through various techniques to analyze the chemical (FTIR), morphological (SEM) and point of zero charges to investigate changes incorporated through the pyrolysis process. The adsorption of methyl orange (MO) onto the biochar was investigated using batch experiments according to different parameters which influence the adsorption process such as: initial dye concentration, equilibrium time, pH, and temperature. Isothermal and reuse studies of MO adsorption onto DPB were also investigated. Results of MO removal on DPB have demonstrated that the adsorption process was initial dye concentration-dependent, and equilibrium time was occurred in 60 min. The biochar presented high stability of MO adsorption capacity in a large domain of pH. Thermodynamic analysis of this process revealed that methyl orange adsorption was exothermic and spontaneous in nature. The experimental data were analyzed by pseudo-first-order, pseudo-second-order model, and the intraparticle-diffusion for kinetics and Langmuir, Freundlich, and Temkin models for isotherms. Kinetic adsorption followed the pseudo-second-order model and the intraparticle-diffusion within pores controlled the adsorption rate. The experimental data yielded good fits with in the following isotherms order: Langmuir > Temkin > Freundlich, The maximum adsorption capacity of MO on DPB was found 461 mg.g −1 . The reusability study reveals the possibility of the reuse of DPB for three (03) cycles of adsorption–desorption, a slight decrease in the ability of methyl orange adsorption has noticed with the increase of the number of adsorption–desorption cycles : 81.03 %, 67.84 %, and 51.72 %, respectively. The found results of the present study show that the biochar derived from date palm petioles have the potential to be used as a promising adsorbent for the treatment of MO dye.

Synthesis and application of cationized cellulose for adsorption of anionic dyes

Synthetic dyes are commonly used in paper, printing, leather, food, and textile industries. Dyes are non-biodegradable and unstable in the environment causing allergies and hypersensitivity in humans even at low concentrations. Adsorption process is a simple and reliable popular method as it has been extensively used on a variety of contaminants. The availability and use of low-cost adsorbents such as natural cellulose makes it more favorable. In this study, cationized hemp cellulose was used as an adsorbent for the removal of methyl orange (MO), and sunset yellow (SY) from aqueous solutions. The cellulose was extracted from hemp fibers by alkali treatment using 4 %wt NaOH and bleached using 1.7% NaOCl2 in acetate buffer solution. Glycidyl trimethylammonium chloride (GTMAC) was used as a cationizing agent to functionalize cellulose (GT-cellulose). For adsorption studies, the influence of pH, adsorbent dosage, initial dye concentration, contact time, and temperature were investigated using batch experiments. After modification, cellulose showed enhanced adsorption capacity for removal of anionic dyes from aqueous solution. The equilibrium adsorption isotherm data were best described by Langmuir model. The maximum adsorption capacity for MO and SY onto GT-cellulose were found to be 76.9 mgg−1 and 44.9 mgg−1 respectively. The adsorption kinetics were best fit with pseudo-second order for both anionic dyes. The thermodynamic study showed that the adsorption processes for MO and SY were both endothermic and spontaneous in nature. From the resulted, cationized cellulose adsorbents could be effectively applied for removal of anionic dye from wastewater.

Composite aerogels of TEMPO-oxidized pineapple leaf pulp and chitosan for dyes removal

Recycling agricultural and aquacultural by-products into high-value engineering aerogels is a sustainable solution to minimize the negative impacts of these wastes on the environment in case of improper treatment. For the first time, discarded pineapple leaves are processed by a novel two-step procedure involving strong alkali and alkali/hydrogen peroxide treatments to generate cellulose-rich pulp containing 91.66 wt% cellulose. The mediated oxidation catalyzed by 2,2,6,6-tetramethylpiperidinyloxy is performed to introduce more carboxylate groups in the pulp for further physically interacting with amino groups on shrimp-based chitosan to synthesize unique composite aerogels without consuming any crosslinkers. The composite aerogels are ultra-lightweight and exhibit a significant rise in their compressive modulus from 2.46 to 27.25 kPa due to the chitosan addition. At the same initial dye concentration of 300 mg/L, the composite aerogels composed of 0.6 wt% chitosan achieve the equilibrium methyl orange adsorption capacity of 136.64 mg/g in only 6 min, while the highest equilibrium methylene blue adsorption uptake of 31.56 mg/g is witnessed in the samples having the lowest chitosan content (0.2 wt%). The developed composite aerogels display the notable porous structure, remarkable mechanical properties, and high removal efficiency for the two typical dyes, demonstrating the effectiveness of combining the world’s two largest natural sources by a simple and green fabrication. The approach in this study is directed towards multiple goals such as addressing the accumulation and underutilization of solid waste, dealing with water pollution caused by harmful dyes in many developing countries, and providing another solution for the cleaner production of renewable materials.

Adsorption kinetics of simulated mixture wastewaters over porous Bi2MoO6@BiOCl@MOF-199 heterostructure

In this work, we mainly investigate the adsorption properties of the simulated single and mixture wastewaters over porous Bi2MoO6@BiOCl@MOF-199 (BMO@BOC@MOF-199), including methylene blue (MB), rhodamine blue (RhB), methyl orange (MO) and chromium (VI). It is found that BMO@BOC@MOF-199 has a high adsorption capacity for MB, but a poor adsorption capacity for MO. Specifically, for single MB solution, 67%, 80% and 96% of MB are adsorbed by BMO@BOC, MOF-199 and BMO@BOC@MOF-199, respectively. The higher adsorption capacity of BMO@BOC@MOF-199 could be due to its higher surface area and larger pore volume. For single MO solution, nevertheless, only 16%, 13% and 7% of MO are adsorbed by BMO@BOC, MOF-199 and BMO@BOC@MOF-199, respectively. The different adsorption efficiency for MB and MO could be relative to their different molecular structures, which have different electrostatic interactions with adsorbent surface. For single RhB and single Cr(VI) solution, BMO@BOC@MOF-199 has adsorbed 30% RhB and 10% Cr(VI). In RhB-MO mixture solution, 32% RhB and 9% MO can be adsorbed by BMO@BOC@MOF-199, while in Cr(VI)–RhB-MO mixture solution, 7% Cr(VI), 3% RhB and 42% MO can be adsorbed by BMO@BOC@MOF-199. It is seen that in RhB-MO mixture solution, the adsorption efficiencies of RhB and MO by BMO@BOC@MOF-199 do not obviously change as compared to single RhB and single MO solution, while in Cr(VI)–RhB-MO mixture solution, the adsorption efficiency of MO has increased by 5 times, compared to single MO solution; but the adsorption efficiency of RhB has decreased by 9.7 times as compared to single RhB solution, and the adsorption efficiency of Cr(VI) has decreased slightly, compared to single Cr(VI) solution. The results are mainly attributed to the competitive adsorption on the adsorbent surface. This work can help us to understand the adsorption process for practical wastewater.

Physicochemical regeneration of industrial spent activated carbons using a green activating agent and their adsorption for methyl orange

Thermal regeneration of spent activated carbons (SACs) is widely used in industry. However, low specific surface areas (SBET) of regenerated activated carbons (RACs) are achieved after thermal regeneration, constraining the adsorption of contaminants. Herein, a green chemical mixture of K2CO3 and KCl compared to conventional activating agents was used to regenerate SAC1 and SAC2, all prepared from plants and used to adsorb compounds in pharmaceutical and food factory respectively. Two kinds of RAC were used for the adsorption of methyl orange (MO). The SBET value of SAC1 after regeneration increased from 592 m2 g−1 to 1830 m2 g−1 with an abundance of micropores, and the SBET of SAC2 after regeneration increased from 3 m2 g−1 to 1802 m2 g−1 consisting of mesopores. A high carbon yield of 73% for RAC was achieved due to the presence of a KCl activating agent. A maximum MO adsorption capacity (Qm) of 733.73 mg g−1 and 755.73 mg g−1 was achieved for RAC1 and RAC2, respectively. After five cycles of adsorption-regeneration, the Qm of RAC1 and RAC2 was 577.66 mg g−1 and 567.63 mg g−1, and the SBET was 1122 m² g−1 and 1101 m² g−1, respectively. This work shows that the combination of K2CO3 and KCl can be used as an activating agent to achieve high specific surface area and carbon yield.

Quaternization of Poly(2-diethyl aminoethyl methacrylate) Brush-Grafted Magnetic Mesoporous Nanoparticles Using 2-Iodoethanol for Removing Anionic Dyes

Magnetic mesoporous silica nanoparticles (Fe3O4-MSNs) were successfully synthesized with a relatively high surface area of 568 m2g−1. Fe3O4-MSNs were then modified with poly(2-diethyl aminoethyl methacrylate) (PDEAEMA) brushes using surface-initiated ARGET atom transfer radical polymerization (ATRP) (Fe3O4@MSN-PDMAEMA). Since the charge of PDEAEMA is externally regulated by solution pH, tertiary amines in the polymer chains were quaternized using 2-iodoethanol to obtain cationic polymer chains with a permanent positive charge (Fe3O4@MSN-QPDMAEMA). The intensity of the C−O peak in the C1s X-ray photoelectron spectrum increased after reaction with 2-iodoethanol, suggesting that the quaternization process was successful. The applicability of the synthesized materials on the removal of methyl orange (MO), and sunset yellow (E110) dyes from an aqueous solution was examined. The effects of pH, contact time, and initial dyes concentrations on the removal performance were investigated by batch experiments. The results showed that the Fe3O4@MSN-PDMAEMA sample exhibited a weak adsorption performance toward both MO and E110, compared with Fe3O4@MSN-QPDMAEMA at a pH level above 5. The maximum adsorption capacities of MO and E110 using Fe3O4@MSN-QPDMAEMA were 294 mg g−1 and 194.8 mg g−1, respectively.

Preparation of carboxymethyl chitosan/phytic acid composite hydrogels for rapid dye adsorption in wastewater treatment

In recent years, chitosan has been used as a common raw material to prepare hydrogels for wastewater treatment. In this work, a series of carboxymethyl chitosan/phytic acid (CMCS-PA) composite hydrogels with various amounts of PA were prepared to remove methyl orange (MO) and Congo red (CR) dyes from aqueous solution. The composite hydrogels with well-defined structure were characterized by different techniques. The experimental results revealed that the hydrogel possessed stable porous structure with more wrinkles on the surface due to the formation of intermolecular hydrogen bonding between CMCS and PA during the in-situ polymerization process. More importantly, the optimal adsorption conditions of CMCS-PA were obtained by changing different adsorption factors: ratio of two molecules and pH. And the CMCS-PA (3:1) composite hydrogel presented great adsorption capacity for MO (13.62 mg/g) and CR (8.49 mg/g) at pH = 7 at room temperature. In addition, the hydrogel also showed great adsorption reusability and stability. This work promotes further development in composite hydrogels design and their applications of wastewater treatment.

Preparation of sodium alginate/polyvinyl alcohol composite nanofiber membranes for adsorption of dyes

In this research, electrospinning was used to prepare sodium alginate (SA)/polyvinyl alcohol (PVA) composite nanofiber membranes. Effects of electrospinning parameters on the morphology and fiber diameter were investigated, and an orthogonal design was chosen to optimize the parameters. The optimized nanofiber membranes were applied as an adsorbent for the removal of methylene blue (MB), basic fuchsin (BF), and methyl orange (MO). Kinetic and isotherm of adsorption and effects of different experimental conditions such as pH, contact time, and initial dye concentration on adsorption capacity were investigated. It was found that the optimum parameters for the nanofiber membranes were SA/PVA blend ratios (3:7), electric field strength (20 kV), flow rate (0.05 mL/h), and distance (12.5 cm) between the syringe needle and collector, and the mean fiber diameter of the optimized membranes was 99.58 nm. The adsorption of nanofiber membranes was well described by the pseudo-second-order adsorption kinetic model and the Langmuir model, indicating that the adsorption mechanism was chemisorption by a monolayer. Based on the Langmuir model, the adsorption capacities for MB, BF, and MO were 9.25 mg/g, 9.02 mg/g, and 7.35 mg/g, respectively.

Re-utilization of Chinese medicinal herbal residue: waste wormwood rod-derived porous carbon as a low-cost adsorbent for methyl orange removal.

A cost-effective approach was applied to prepare porous carbon samples by the simple carbonization of wormwood rod followed by salt activator (NaCl) activation. The effect of preparation parameters on the characteristics of the wormwood rod-based porous carbons (WWRs) were studied. The properties of these samples were investigated by SEM, BET surface area, X-ray diffraction, FT-IR spectra and X-ray photoelectron spectrometer. The prepared WWRs were applied as new adsorbent materials to remove methyl orange (MO). The experimental results indicated that WWR-800 activated at 800 °C possesses the best adsorption performance. Several factors that affected the adsorption property of the system such as the solution pH, dosing of adsorbent, initial dye concentration and ionic strength were examined. In addition, the thermodynamic parameters and kinetic parameters of MO with WWR-800 were studied. The results indicated that the adsorption of MO on WWR-800 was an endothermic process and non-spontaneous under standard conditions. The maximum equilibrium adsorption capacity of MO on WWR-800 was 454.55 mg/g. After five adsorption/desorption cycles, the adsorption capacity of MO on WWR-800 remained at 94%, which indicated that wormwood rod-based porous carbon possessed good reusability.

Preparation and characteristic of high surface area lignin-based porous carbon by potassium tartrate activation

In order to study the property of lignin-based porous carbon activated by potassium tartrate, the effects of activator types, activator/lignin mass ratio and activation temperature on the surface morphology, specific surface area and pore size distribution of alkali lignin based porous carbon materials were systematically investigated. Meanwhile, the methyl orange adsorption capacity and adsorption kinetics of the lignin-based porous carbon were also evaluated. The N2 adsorption-desorption experiment results showed that the specific surface area value of lignin-based porous carbon materials activated by potassium tartrate (APC-J), KOH (APC-K), and NaOH (APC-Na) are 947, 1113 and 762 m2/g, respectively. Meanwhile, APC-J has a special microporous structure, while the pore structures of APC-K and APC-Na are mainly mesopores. The best specific surface area of lignin-based porous carbon materials was 1911 m2/g obtaining from APC-J-2-8 sample (mass ratio 2:1, activation temperature 800 °C). The adsorption experiment of methyl orange (MO) showed that the adsorption kinetics of APC-J-2-8 conformed to the quasi-second-order kinetic model, mainly chemical adsorption. The isothermal adsorption process conforms to the Langmuir adsorption isothermal adsorption model, which is a single molecular layer adsorption, and the maximum adsorption amounts are 526.31 mg/g.