Adsorption Capacity For Malachite Green Research Articles

A novel surface-oxidized rigid carbon foam with hierarchical macro-nanoporous structure for efficient removal of malachite green and lead ion

This study developed a method to fabricate a surface-oxidized rigid carbon foam (ORCF) with hierarchical macro-nanoporous structure via KOH activation of the carbon foam with two kinds of macropores followed by HNO3 hydrothermal oxidation. The structures of the prepared ORCF were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared (FTIR) spectra, X-ray photoelectron spectroscopy, and N2 adsorption-desorption analyzer. Results demonstrate that the ORCF possesses a fluffy and porous structure with rich oxygen-containing groups. There are numerous through-holes on its pore surfaces connected with two-level macropores forming hierarchical macroporous channels. Meanwhile, the ORCF remains a good bulk structure with a compression strength of 0.74 MPa at a bulk density of 0.09 g cm−3. Batch adsorption experiments for malachite green (MG) and Pb2+ were studied through the single variable method to investigate the effects of different initial conditions on its adsorption process. The ORCF has maximum adsorption capacities for MG and Pb2+ of 587.68 mg g−1 and 157.80 mg g−1 with high partition coefficients of 17.41 mg g−1 µM−1 and 14.86 mg g−1 µM−1, respectively. The experimental data are suitable for Langmuir isotherm and Pseudo-second-order kinetic models, which correspond to monolayer chemisorption. Thermodynamic analysis indicates that the adsorption process is spontaneous and endothermic. Moreover, the removal percentages of MG and Pb2+ by the ORCF could remain above 90% after five cycles, implying that the ORCF is an efficient adsorbent with good adsorption ability and cycling stability.

Green sulfidated iron oxide nanocomposites for efficient removal of Malachite Green and Rhodamine B from aqueous solution.

A green and facile pathway was described using Viburnum odoratissimum leaf extract in the presence of sodium thiosulfate for the synthesis of sulfidated iron oxide nanocomposites (S-Fe NCs) adsorbents. The prepared S-Fe NCs can be used for the efficient removal of Malachite Green (MG) and Rhodamine B (RhB) from aqueous solution. Analytical techniques by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) were applied to understand the morphologies and compositions of S-Fe NCs. The stability of the adsorption capacity on S-Fe NCs was studied. Results from the characterization studies showed that S-Fe NCs were mainly composed of iron oxides, iron sulfides and biomolecules. The S-Fe NCs displayed high adsorption capacity for a wide range of pH values. The Koble-Corrigan isotherm model and Elovich model well described the adsorption process. The maximum adsorption capacity for MG and RhB was 4.31 mmol g-1 and 2.88 mmol g-1 at 303 K, respectively. The adsorption mechanism may be attributed to the electrostatic interaction, the hydrogen bonding, the π-π stacking interactions, the inner-sphere surface complexation or the cation bridging among the S-Fe NCs and dye molecules.

A novel mesoporous Fe-silica aerogel composite with phenomenal adsorption capacity for malachite green

Silica aerogel and Fe doped silica aerogel composite were synthesized by sol–gel method adopting ambient pressure drying method. The crystal structure, surface morphology, pore structure, surface functional groups and elemental composition of silica aerogel prepared with different concentrations of Fe3+ were characterized by XRD, SEM, TEM, BET, FTIR, XPS and Zeta potential analysis. The specific surface area of the composite aerogel was found to decrease with the increase addition amount of FeCl3. The optimal composite aerogel adsorbent had a surface area of 240 m2/g with well-developed mesoporous network, which possessed a maximum malachite green(MG) adsorption capacity of 1592 mg/g, as compared to virgin silica aerogel of 1250 mg/g. Adsorption capacity for large molecules like MG is very low for the most popular adsorbent such as high surface area activated carbon, which is usually the first-choice adsorbent for wastewater treatment. Such high adsorption capacitiy of the silica aerogel composite is highly promising as it is on the classification of low-cost adsorbents, which can serve to be far better alternative for waste water treatment applications.

Superior adsorption and removal of aquaculture and bio-staining dye from industrial wastewater using microporous nanocubic Zn-MOFs

The indirect release of excessive amounts of poisonous dyes into water has drastically affected the environment. Thus, in this work, a method to remove dyes from industrial water was investigated using ecofriendly cubic inorganic–organic Zn metal–organic frameworks (CZM). In particular, the room-temperature one-pot synthesis of inorganic–organic Zn-MOF nanocubes with superior adsorption capacity for the removal of malachite green (MG) dye in wastewater samples was studied. The nanocubes featured intergrowing chains with highly accessible surface areas, and uniform micropores could trap MG dye from wastewater. The inorganic–organic frameworks exhibited excellent adsorption capacity for MG. The adsorption conditions, such as the solution pH, played a significant role in generating an active negatively charged surface throughout the Zn-MOF adsorbent, thereby yielding microporous surfaces with strong ability to interact with and take up MG dye. Adsorption experiments revealed the high capacity of CZM for MG removal (953.14 mg g−1), and this capacity was maintained even after multiple reuse cycles. The microporous CZM adsorbent demonstrated a simple and effective model for water purification and the management of industrial wastewater. To the best of our knowledge, this work is the first to report the usage of Zn-MOF adsorbents for the removal of MG dye in wastewater samples.

Fabrication of magnetically recyclable nanocomposite as an effective adsorbent for the removal of malachite green from water

Herein, a novel magnetic nanocomposite (Fe3O4@ATPA@AMPA) was successfully synthesized for the removal of malachite green (MG) from water. The FT-IR analysis confirmed successful modification of Fe3O4@ATPA with 2-Amino-3-mercaptopropionic acid (APMA). Based on TEM image and XRD pattern, the average particle size of Fe3O4@ATPA@AMPA nanocomposite was ∼ 12.3 nm. The specific surface area of Fe3O4@ATPA@AMPA nanocomposite was 35 m2/g. Elemental analysis exhibited the existence of S, O, C, and N on the surface of Fe3O4 nanoparticles. The influence of time (t: 5–240 min), dose (m: 0.010–0.050 g), pH (2–8.5), initial MG concentration (Co: 25–300 mg/L), and temperature (T: 298–318 K) on the MG adsorption was examined. Experimental results exhibit optimal MG uptake at pH: 6.7, t: 120 min, m: 20 mg, T: 298 K, and Co: 300 mg/L. The non-linear kinetics and isotherm models showed that the adsorption process obeyed pseudo-first-order kinetic and Langmuir isotherm models, respectively. According to Dubinin–Radushkevich (D–R) isotherm, the magnitude of activation energy (Ea) at varied temperatures was in range 0.0116−0.0905 kJ/mol, confirming physical interactions between MG molecules and Fe3O4@ATPA@AMPA nanocomposite dominates during adsorption. The maximum monolayer adsorption capacity for MG was 414.63 mg/g at 298 K. The adsorption process was exothermic, favorable, and spontaneous. Finally, the Fe3O4@ATPA@AMPA nanocomposite exhibited excellent adsorption potential for four consecutive regeneration cycles.

Eco-green C, O co-doped porous BN adsorbent for aqueous solution with superior adsorption efficiency and selectivity

Toxic dyes in wastewater will become a significant hazard to human health if they are not treated effectively. Therefore, it is significant to separate and remove dyes from the aqueous solution. C and O co-doped BN (BCNO) with high adsorption capacity and outstanding cycle efficiency is a simple and efficient adsorbent for the cationic dye malachite green (MG). Glucose is characterized as an eco-friendly and cheap source of C and O. Benefited by the high specific surface area (1515.6 m2/g), the maximum adsorption capacity of MG is 1511.1 mg/g. Besides, the curves of adsorption fitting correspond to the Langmuir model and the pseudo-second-order model, respectively. Moreover, after 5 cycles, the adsorption efficiency reached 78% of the first time and the adsorption capacity remained above 780 mg/g. Furthermore, in the selectivity adsorption study, the cationic dyes (MG, neutral red (NR), methylene blue (MB)) can be removed more effectively in the binary dye system of MG-methyl orange (MO), NR-MO, MB-MO, MG-Orange II (OR), MB-OR, or NR-OR. BCNO-2 has a promising application in the removal of cationic dyes from complex dye wastewaters.

Solvent and catalyst free preparation of sulfonic acid functionalized magnetic covalent organic polymer as efficient adsorbent for malachite green removal

A series of –SO3H functionalized magnetic covalent organic polymer (M-TpBD-SO3H) was synthesized in a few minutes under solvent-free and catalyst-free condition, and their adsorption properties toward organic contaminant were studied by using malachite green (MG) as model. The compositions and microstructures of M-TpBD-SO3H are characterized by TEM, XRD, FT-IR and VSM. M-TpBD-SO3H with a different content of the –SO3H group could be synthesized by adjusting the ratio of benzidine (BD) and 2,2-bissulfonic acid benzidine (BDSA) in the precursor. The results show that with the increase of the BDSA proportion, the adsorption performance of the resulting materials for MG increased. Remarkably, the maximum adsorption capacity for MG was 333.4 mg g‐−1 when all the employed building block was BDSA. In addition, the material can selectively adsorb the MG from the mixed solution of MG and MO. Furthermore, the synthesized M-TpBD-SO3H (100%) also has good magnetic separation ability and excellent reusability, suggesting that the resulting materials can be used as fantastic candidates for environmental water remediation.

Amidoxime modified polymers of intrinsic microporosity/alginate composite hydrogel beads for efficient adsorption of cationic dyes from aqueous solution

Polymers of intrinsic microporosity (PIM-1) has demonstrated great potential in adsorption and separation fields. In this study, PIM-1 was structured into an applicable and efficient adsorbent using a facile way. PIM-1 was first modified by amidoxime, and then the amidoxime modified PIM-1 (AOPIM-1) was mingled into alginate (Alg) hydrogel to obtain composite hydrogel beads. The AOPIM-1/Alg composite beads were further employed for removal of malachite green (MG) from aqueous solution and the effects of doped ratio, adsorbent dosage, contact time, and initial dye concentration on the MG adsorption performance were systematically investigated. The MG adsorption capacity of pure Alg beads was substantially enhanced after incorporating AOPIM-1. Furthermore, isothermal, kinetic and thermodynamic studies were performed to explore the fundamental adsorption behavior. Both Freundlich isotherm and Langmuir isotherm models can fit the adsorption isotherm data well, and the adsorption kinetics is well described by Pseudo-second-order. The adsorption process is feasible, spontaneous and endothermic. In addition, mixed dyes adsorption measurements indicate that AOPIM-1/Alg beads are highly selective to adsorb cationic dyes from anionic/cationic mixed dyes solution. The regeneration test shows that above 90% of the adsorption capacity of the composite beads can be maintained after 10 cycles of MG adsorption/desorption. These findings point that AOPIM-1/Alg composite hydrogel beads are an efficient, up-and-coming and recyclable adsorbent for cationic dyes adsorption from aqueous solution.

One-step fabrication of a new outstanding rutile TiO2 nanoparticles/anthracite adsorbent: Modeling and physicochemical interpretations for malachite green removal

In this study, a facile method was developed to synthesize a new composite via the impregnation of rutile (TiO2) nanoparticles (Rt) into H2O2–modified anthracite (MAn). This new rutile(TiO2)/modified anthracite (Rt/MAn) adsorbent was characterized and employed as an outstanding and cost–effective material to remove malachite green (MG) dye at 25–55 °C. This adsorbent displayed the highest removal efficiency (96.2 %) as compared to its individual components MAn (49.8 %) and Rt (71.4 %) at pH 8.0. The experimental adsorption of MG onto Rt/MAn at equilibrium were satisfactorily fitted to the Freundlich equation and a multilayer statistical physics model at all tested temperatures. The physicochemical parameters (steric and energetic) related to a multilayer adsorption were calculated and interpreted to understand the adsorption mechanism. The theoretical number of adsorbed MG dye molecules per functional group (n) varied from 0.94 to 1.60 indicating a multi-docking adsorption mechanism. The adsorption capacity of MG at saturation (Qsat) increased from 513 to 740 mg/g at 25 and 55 °C and was primarily caused by the density of Rt/MAn functional groups (i.e., the DM parameter). MG adsorption energy with Rt/MAn varied from 13.87 to 29. 96 kJ/mol and was governed by physical interactions. The tested adsorbent was easily reactivated by the dye desorption and reused up to five cycles where it retained>80 % of MG adsorption capacity even after the 5th adsorption–desorption cycle. These results demonstrated that Rt/MAn is an effective adsorbent to remove MG, thus offering outstanding adsorption capacities largely beyond the current state of the art (up to 740 mg/g) and its application could be extended for the adsorption of other organic pollutants from wastewaters.

Isotherm and thermodynamic modelling of malachite green on CO2-activated carbon fibers

We designed porous carbon fibers with the aid of CO2 during activation for effective malachite green (MG) adsorption. The physiochemical mechanisms have been characterized both experimentally and numerically to decipher the underlying relevance of CO2-activation on the MG adsorption capacity. The obtained samples are dominated by micropores, resulting in a high specific surface up to 1012 m2 g−1 via 60 min of CO2-activation. The adsorption isotherm was fitted to Langmuir with the maximum adsorption capacity of 555.56 mg L-1. The regeneration was secured over 80% during 3 trials. Thermodynamics revealed endothermic in nature and the spontaneous adsorption process.

Preparation of Ca/Al-Layered Double Hydroxides/Biochar Composite with High Adsorption Capacity and Selectivity toward Cationic Dyes in Aqueous

Widely reports have evaluated the use of biochar (BC) composites to layered double hydroxide (LDH) to adsorb dyes from wastewater. However, its applicability for adsorbing a mixture of cationic dyes such as Malachite green (MG), Rodhamine-B (Rh-B), and Methylene blue (MB), which causes carcinogenic and mutagenic effects on aquatic life, has not been studied. In this work, we compared the performance of CaAl-LDH/BC adsorbent with or without the addition of BC in the adsorption of cationic dyes. The adsorption study was prepared in a batch system using various temperatures, concentrations, and also contact time. The results of the characterization of Ca/Al-Biochar composite showed the unique diffraction of XRD pattern, and also showed two characteristics of starting materials. Surface area analysis by BET method showed Ca/Al-Biochar composite has a higher surface area than starting material. The results of the adsorption study of MG showed that Ca/Al-Biochar follows the pseudo-second-order kinetic model. The adsorption capacity of MG on Ca/Al-Biochar was up to 71.429 mg/g and shows selectivity toward MG in an aqueous solution. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Activated graphene with fractal structure for the adsorption of malachite green with high removal rate

In this study, the activated graphene (AG) was applied to remove a malachite green (MG) as an adsorbent. The AG with fractal structure was synthesized at high temperature under a nitrogen (N 2 ) environment. The fractal structure is shaped like a branch that extends apart because the AG is created by the rGO with a thin sheet. The fractal structure allows AG to have a high surface area. The surface area of AG was found to be 1885.7 m 2 g −1 . Also, it makes many pores of micro, meso-size which improves the quality as compared to traditional activated carbon (AC). Due to these features, the maximum MG adsorption capacity was 791.27 mg L −1 within the contact time at 40 min. Freundlich isotherm and pseudo-second-order were fitted to AG. Moreover, after cleaning with ethanol and deionized water, the recycled AG maintained a 99.44% removal efficiency which suggesting a good reusability. The AG showed better adsorption capacity than commercial AC showing that AG could be utilized as an excellent adsorbent for next-generation owing to its high removal efficiency, eco-friendly nature, and the long-lasting ability for adsorption of MG. • Activated graphene (AG) was successfully synthesized under N 2 atmosphere. • The AG has the fractal structure owing to the edge. • The fractal structure of AG has micro, meso-size pores with high surface area. • The maximum adsorption capacity of AG is 791.27 mg L −1 for malachite green.

MgO Functionalized Magnetic Activated Carbon Material for Efficient Removal of Malachite Green from Aqueous Solutions

Malachite green (MG) pollution has a negative impact on human health. At present, the method of removing it is inconvenient to operate and the cost is high, which has aroused widespread concern. In this study, MgO functionalized magnetic activated carbon (MgO-mAC) prepared by the sol–gel method was used to remove MG in water. The physical and chemical properties of MgO-mAC were tested by SEM, TEM, FTIR, XRD, BET and VSM. The effects of adsorbent dosage, solution pH, contact time, initial MG concentration and temperature on adsorption were studied by batch experiments. The adsorption kinetics data is well described by a pseudo-second-order model. The equilibrium data fits the Langmuir isotherm well. When the pH is 8 and the contact time is 360[Formula: see text]min, the maximum adsorption capacity of MG is 3809[Formula: see text]mg[Formula: see text]g[Formula: see text]. In thermodynamic studies, [Formula: see text], [Formula: see text], [Formula: see text], MG adsorption is an endothermic and spontaneous adsorption process. The current synthesis method is simple in operation and cheap in raw materials, which can greatly reduce the cost of synthesis. Hence, the MgO-mAC material will be an effective adsorbent for removing MG from aqueous solutions.

Xanthate modified magnetic activated carbon for efficient removal of cationic dyes and tetracycline hydrochloride from aqueous solutions

The removal of cationic dyes and hydrochloride tetracycline from aqueous solutions has attracted more attention. In this paper, magnetic activated carbon (mAC) was first prepared by one-step co-precipitation method, and xanthate was grafted onto the surface of magnetic activated carbon by xanthation reaction, and the x-mAC functionalized magnetic activated carbon material (x-mAC) was successfully synthesized. x-mAC is used to remove cationic dyes and tetracycline hydrochloride. The physical and chemical properties of AC, mAC and x-mAC were characterized by FTIR, SEM, TEM, XRD, BET and VSM. It is found that x-mAC has good removal ability on malachite green (MG), methylene blue (MB), crystal violet (CV) and tetracycline hydrochloride (TC). The adsorption process of x-mAC on cationic dyes and tetracycline hydrochloride obeys Langmuir adsorption model and pseudo-second-order kinetic model. The kinetic data has a good correlation with the pseudo-second-order equation. The Langmuir and Freundlich models are suitable for isotherm data. The calculated adsorption capacities of MG, MB, CV and TC are 595.24 mg/g, 314.3 mg/g, 394.14 mg/g and 210.94 mg/g, respectively. The results of thermodynamic research (△G <0, △H> 0, △S> 0) showed that the adsorption process was endothermic and spontaneous proceeding. The adsorption-desorption process went through five cycles. After five cycles, the removal rates of MG, MB, CV and TC remained above 81.40 %, 91.78 %, 93.69 % and 91.29 %, respectively. The results showed that due to the good adsorption performance and simple preparation process, x-mAC has potential application prospects in the field of wastewater treatment.

Oxygen plasma treated petroleum coke adsorbent: characterization, synthesis, mechanism, and application for enhancement of malachite green removal

ABSTRACT The main purpose of this study is to modify the petroleum coke sample (PCS) for the first time by oxygen plasma treatment (OPT) as an alternative to the existing surface modification methods and to remove the malachite green (MG) colourant from the aqueous medium with the obtained adsorbent. The changes caused by OPT on the PCS surface were observed with photoelectron spectroscopy(XPS), infrared spectroscopy(FTIR), scanning electron microscopy(SEM) and surface area analysis. The atomic percentages of the oxygen for the raw and plasma treated sample were found at 4.021% and 9.363%, respectively. In the light of the obtained results, it was seen that new active groups containing oxygen on PCS increased by OPT. The functional groups such as -COOH, -C-O and -C = O with oxygen plasma on PCS were interpreted to the mechanism possible. The adsorption capacity of MG was 66.66 mg/g at 30°C for the PCS treated with oxygen plasma. The ΔG, ΔH and ΔS values were 168.76 kJ/mol, 84,49 kJ/mol and −278,19 J/mol K.

Facile preparation of robust dual MgO-loaded carbon foam as an efficient adsorbent for malachite green removal

This study developed a facile approach for the fabrication of dual MgO-loaded carbon foam (DMCF) via carbonization of a cured MgO/cyanate ester resin mixture, which underwent self-foaming of the resin followed by the carbothermal reduction of MgO. The features of the prepared DMCF prepared were characterized by FESEM, TEM, XRD, FTIR, XPS and so on, and the effects of adsorption conditions, adsorption isotherms, kinetics, and thermodynamics on malachite green (MG) removal using the DMCF as adsorbents were investigated through batch adsorption experiments. Results demonstrate that the DMCF possesses a unique dual loading of MgO particles which are not only loaded onto its foam walls but also filled within the walls with a graphene-wrapped core-shell structure. The experimental maximum adsorption capacity of MG reaches up to 1874.18 mg/g with a partition coefficient of 10.87 mg/g/μM. The adsorption process can be better described with Langmuir, pseudo-second-order, and intraparticle diffusion models. Moreover, the DMCF exhibits a removal percentage of 84.85% after five reuses, indicating that it is an efficient and promising adsorbent for MG adsorption.

Efficiency of polyurethane elastomer containing sulfonated groups as chain extender in removing Malachite green

A novel type of polyurethane elastomer (PUE) containing nanocomposites of sodium alginate thiacalix[4]arene macrocycles including sodium alginate-thiacalix[4]arene and sodium alginate-tetra-sulfonated thaiacalix[4]arene (SA-TSTCA) was prepared. The key role of these nanocomposites merged into polyurethane elastomers is to function as chain extenders. To provide profound insight into the structural, thermal, mechanical, morphological and hydrophilic properties of the samples, several techniques were employed, namely Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Also the results were compared with the results of polyurethane elastomer based on glycerol (Gly) as chain extender. The results showed that the samples extended with nanocomposites as chain extender have better thermal and mechanical properties and between them the PUE containing SA-TSTCA showed higher thermal and mechanical properties. Furthermore, these elastomers have been used as adsorbent for removal of Malachite green (MG) for investigation of the effect of sulfonated groups introduced on the chain extender. The results revealed that SA-TSTCA-based polyurethane elastomer nanocomposite could well adsorb Malachite green from aqueous media by a batch adsorption method. The pseudo-first-order and pseudo-second-order kinetic models were employed to provide an in-depth study of the adsorption capacity of MG, suggesting that its adsorption onto PUE/SA-TSTCA elastomer was in accordance with pseudo-second-order kinetic process. A possible mechanism of adsorption was suggested where π–π stacking interactions, H-bonding interaction and electrostatic attraction controlled the MG adsorption.

Adsorptive performance of aminoterephthalic acid modified oxidized activated carbon for malachite green dye: mechanism, kinetic and thermodynamic studies

ABSTRACT In this study, aminoterephthalic acid (ATPA) modified oxidized activated carbon (AC) was prepared (AC@ATPA). The (AC@ATPA) composite was applied for removal of malachite green (MG) from aqueous medium. The obtained AC@ATPA composite was characterized by varying techniques such as TGA, FTIR, SEM, EDX, XRD and zeta potential. The results reveal that the optimum parameter conditions for the maximum MG dye ions adsorption were found to be pH- 6, adsorbents amount-30 mg, equilibrium time reached within 240 min at initial concentration 20 mg/L and room temperature. The adsorption process fitted well with Langmuir isotherm and pseudo-first-order kinetic model with the maximum adsorption capacities for MG of 188.7 mg/g.

Synthesis of MgO/Fe3O4 nanoparticles embedded activated carbon from biomass for high-efficient adsorption of malachite green

Fe–Mg bimetallic magnetic activated carbons (Fe–Mg BACs) were synthesized using biomass (peanut shells) as precursor combining the activation mechanism of FeCl3 and MgCl2 to realize high adsorption performance on malachite green (MG) toxic dye. It was observed that MgO nanoparticles were formed and aggregated with the Fe3O4 during activation process under CO2 atmosphere, and then formed MgO/Fe3O4 composite nanoparticles on the surface of the carbon basal plane. A large MG adsorption capacity of 4031.96 mg/g was achieved by Fe–Mg15 (activation using 15 g of MgCl2·6H2O and 10 g of FeCl3·6H2O) at 318 K. Fe–Mg15 still possessed superparamagnetic property while the formation of MgO nanoparticles weakened the magnetic property. The best fit of the Pseudo-first-order kinetic and Freundlich isotherm models suggested that a predominant chemisorption occurred. From the thermodynamic analysis, the high affinity of the MgO active site attracted a large number of MG molecules to the solid-liquid interface, indicating that the randomness was promoted and driven by entropy. Interactions between MG dye and Fe–Mg15 including the H-bonding, π-π stacking and the electrostatic attraction triggered considerable adsorption performance. The dominant interaction should be the H-bonding between Mg–OH and N-containing groups in MG. Chemical regeneration method cannot achieve effective removal of adsorbed malachite green, while the adsorptive properties of Fe–Mg BACs can be well regenerated via thermal regeneration method.

A novel hierarchical stiff carbon foam with graphene-like nanosheet surface as the desired adsorbent for malachite green removal from wastewater

A novel hierarchical stiff carbon foam (HSCF) was successfully prepared via a carbothermal reduction between the carbon foam with two-level pore structure and the Al2O3 from aluminum sulfate, and used as a bulk adsorbent for removing malachite green (MG) dye. The structures of the HSCF were characterized using SEM, XRD, FTIR, BET, and XPS, and the effects of adsorption condition on the MG removal were studied through batch adsorption experiments. Results show that large-sized and complex-shaped HSCF can be easily fabricated with a high compression strength of 1.58 MPa at a low bulk density (0.10 g cm−3). The HSCF possesses a fluffy graphene-like nanosheet surface with a mesoporous structure and meanwhile exhibits good hydrophilicity loaded with aluminum hydroxide. The experimental maximum adsorption capacity for MG reaches 425.2 mg g−1 with a relatively high partition coefficient of 9.38 mg g−1 μM−1 at the optimal condition. The experimental data are in good agreement with Langmuir isotherm and pseudo-second-order kinetic model, and meanwhile, the adsorption of MG onto the HSCF is a spontaneous and endothermic process. Also, the HSCF still exhibits good adsorption ability and stability after seven regeneration cycles.