Adsorption Of Rhodamine B Research Articles

Hydrophilic magnetic molecularly imprinted resin in PVDF membrane for efficient selective removal of dye

Selective removal of contaminants from water by membranes is of practical importance for water purification and environmental protection. In the present study, through an in-situ polymerization process, a novel composite of Fe3O4/molecularly imprinted resorcinol -formaldehyde-melamine resin (Fe3O4/MIRFMR) was synthesized. Then, the novel membrane was prepared from a tea filter bag (TFB) as a base substrate which was subsequently coated by a casting solution containing polyvinylidene fluoride (PVDF) matrix, Prunus scoparia gum as a hydrophilic agent and Fe3O4/MIRFMR as selective filler by phase inversion technique. Resorcinol as functional monomers with multiple hydrophilic groups such as –OH, –NH2 and –NH–, were used for selective removal of Rhodamine B (RhB) as target molecule. The Fe3O4/MIRFMR/PVDF/TFB membranes were characterized by FE-SEM, XRD, FTIR, BET, VSM, water contact angle (WCA) and mechanical analysis. The filtration and adsorption of RhB on the prepared membrane was investigated parameters in a cross-module filtration setup. Casting solution containing 0.01 g of Fe3O4/MIRFMR as optimum value showed good wettability, high water flux (42.5 L/m2 h), flux recovery ratio (88.9%), RhB removal efficiency (95.8%). The selectivity of 4.9, 3.3, 2.1 and 2.5 was found to be for RhB compared to AB, MG, EB, and TB dye. It seems that the fabricated membrane could be an effective and selective option for wastewater containing pollutants. The high removal efficiency, fouling resistance, good wettability and stability of the fabricated membrane are promising for use in practical water filtration, especially for selective removal of dyes.

Sustainable approaches for removing Rhodamine B dye using agricultural waste adsorbents: A review

Rhodamine B (RhB) is among the toxic dyes due to the carcinogenic, neurotoxic effects and ability to cause several diseases for humans. The adsorption with agricultural waste adsorbent recorded high performance for the RhB removal. The current review aimed to explore the efficiency of different adsorbents which have been used in the few last years for removing RhB dye from wastewater. The data of adsorption of RhB using agricultural wastes were collected from the Scopus database in the period between 2015 and 2021. The use of agricultural wastes and adsorbents as a replacement for the activated has received high attention among researchers. The RhB removal methods by microbial enzymes and biomass occurred between 76 and 90.1%. In comparison, the adsorption with agricultural wastes such as activated carbon white sugar reached 98% within 12 min. The adsorption process has a wide range of pH (3-10) due to the zwitterionic forms of RhB. Gmelina aborea leaf activated carbon is among the agriculture wastes absorbents that exhibited 1000 mg g−1 of the adsorption capacity. It appeared that the agricultural wastes adsorbents have a high potential for removing RhB from the wastewater.

Adsorptive performance of MWCNTs for simultaneous cationic and anionic dyes removal; kinetics, thermodynamics, and isotherm study.

Disposal of contaminated wastewater causes many serious problems especially when it gets mixed with the ground and seawater. It is, therefore, important to apply any remedial action to eradicate dangerous pollutants from the aqueous effluents and to avoid exposure of this wastewater to aquatic life. The research results discussed herein deal with the removal of Rhodamine B (RhB) and Congo Red (CR) dye from wastewater by using multi-walled carbon nanotubes (MWCNTs) as an adsorbent. Different factors like solid dosage, initial pH and concentration, time, and temperature were studied to understand the behavior and mechanism of adsorption. The maximum adsorption capacity in case of a single component system was found to be 302 mg/g and 300 mg/g for Congo Red and Rhodamine B, respectively. Moreover, the mechanism of adsorption was best described by a pseudo-second-order kinetic model. Thermodynamic parameters showed that adsorption of CR and RhB was exothermic when these were removed from a single dye system. However, the overall process became endothermic for concurrent removal of both dyes from the solution. The research results showed that the MWCNTs could successfully be utilized to remove the dye from the industrial wastewater.

Characterization of the Physical, Chemical, and Adsorption Properties of Coal-Fly-Ash–Hydroxyapatite Composites

(1) Hydroxyapatite (HAp), which can be obtained by several methods, is known to be a good adsorbent. Coal fly ash (CFA) is a commonly reused byproduct also used in environmental applications as an adsorbent. We sought to answer the following question: Can CFA be included in the method of HAp wet synthesis to produce a composite capable of adsorbing both heavy metals and dyes? (2) High calcium lignite CFA from the thermal power plant in Bełchatów (Poland) was used as the base to prepare CFA–HAp composites. Four types designated CFA–HAp1–4 were synthesized via the wet method of in situ precipitation. The synthesis conditions differed in terms of the calcium reactants used, pH, and temperature. We also investigated the equilibrium adsorption of Cu(II) and rhodamine B (RB) on CFA–HAp1–4. The data were fitted using the Langmuir, Freundlich, and Redlich–Peterson models and validated using R2 and χ2/DoF. Surface changes in CFA–HAp2 following Cu(II) and RB adsorption were assessed using SEM, SE, and FT-IR analysis. (3) The obtained composites contained hydroxyapatite (Ca/P 1.67) and aluminosilicates. The mode of Cu(II) and RB adsorption could be explained by the Redlich–Peterson model. The CFA–HAp2 obtained using CFA, Ca(NO3)2, and (NH4)2HPO4 at RT and pH 11 exhibited the highest maximal adsorption capacity: 73.6 mg Cu/g and 87.0 mg RB/g. (4) The clear advantage of chemisorption over physisorption was indicated by the Cu(II)–CFA–HAp system. The RB molecules present in the form of uncharged lactone were favorably adsorbed even on strongly deprotonated CFA–HAp surfaces.

Fabrication of graphene oxide/polydopamine adsorptive membrane by stepwise in-situ growth for removal of rhodamine B from water

Polyethersulfone-sulfonated polyethersulfone (PES-SPES) membranes were prepared by non-solvent immersion precipitation method, and then the graphene oxide-polydopamine (GO-PDA)/PES-SPES adsorptive membranes were fabricated by the stepwise in-situ growth method, and employed for the removal of rhodamine B (RhB) from aqueous solutions. The static adsorption thermodynamics, the effects of pH values, adsorption kinetics, and dynamic adsorption/desorption were investigated. The results showed that, the adsorption of RhB on the membrane can be well described by the Langmuir model and the pseudo-second-order kinetic model, and the maximum adsorption capacity of the GO-PDA layer is 87.03 mg g−1, indicating a chemisorption dominated adsorption process. The GO adsorbents and PDA crossslinker contributed to the synergistic adsorption. The adsorptive membranes also exhibited good reusability in dynamic adsorption/desorption cycles.

Parametric and modeling studies of Rhodamine-B adsorption using coconut coir-based materials as eco-friendly adsorbents

The present study aimed to optimize the adsorption process of Rhodamine B (Rh-B) on crude and organosolv-based coconut fibers using a full factorial experimental design and response surface modeling. The modification of the fiber was carried out using an aqueous formic acid solution (85% wt.) at 100 ⁰C during 1 h. The crude and modified coconut fibers (CCF and MCF) were characterized regarding their chemical composition, water contact angle, scanning electron microscopy and X-ray diffraction and point of zero charge. The batch adsorption tests were performed to evaluate how the biosorbent dosage ([CCF] and [MCF]), contact time, temperature and initial concentration of Rh-B ([Rh-B]) would influence the removal efficiency of Rh-B and their adsorption capacity. Factorial designs of 3² type were carried out for each biosorbent. For the independent variables, the following levels were used: biosorbent concentration (2–4 g L−1), contact time (10–60 min), initial concentration of Rh-B (50–100 mg L−1) and temperature (298–318 K). The effects and interactions caused by the studied variables were statistically significant in the adsorption of Rh-B, based on the values obtained by the ANOVA test. The parameters that provided maximum adsorption of Rh-B onto CCF and MCF were 4 g L−1, 60 min, 318 K and 100 ppm, yielding qmax values of 13 mg g−1 and 22 mg g−1, respectively. The formosolv process enhanced the performance of coconut coir as biosorbent, while the parametric study was capable of optimizing and designing the parameters involved in Rh-B adsorption for both biosorbents.

Enhanced Adsorption of Rhodamine B on Modified Oil-Based Drill Cutting Ash: Characterization, Adsorption Kinetics, and Adsorption Isotherm.

In this paper, phosphoric acid (H3PO4), hydrochloric acid (HCl), and hydrogen peroxide (H2O2) were employed for the modification of oil-based drill cutting ash (OBDCA) for the first time. The adsorption of rhodamine B (RhB) on modified oil-based drill cutting ash (MOBDCA) in an aqueous medium was investigated. H2O2-modified OBDCA had the optimal adsorption efficiency for RhB. The physical and chemical properties of MOBDCA were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ζ-potential, N2 adsorption–desorption isotherm, and pore size distribution. The effect of the pH value (3–11), reaction time (10–720 min), and initial RhB concentration (10–200 mg/L) on RhB adsorption was discussed. The adsorption kinetics highly fitted with the pseudo-second-order model (R2 > 0.99), which indicated that the adsorption process was dominated by chemisorption. The adsorption isotherm fitted well with the Langmuir and Freundlich models (R2 > 0.97), which indicated the monolayer adsorption process and the heterogeneous adsorption process, respectively. The theoretic adsorption capacity (50 mg/g) for RhB was achieved by H2O2-modified OBDCA. This paper provides a promising method of resource utilization of OBDCA to treat organic pollutants.

Various Adsorbents for Removal of Rhodamine B Dye: A Review

Lately, there has been an increase in dye manufacturing, resulting in increased environmental pollution. Recent studies show a wide availability of usage adsorbents, including banana peels, potatoes, algae, etc. Food and Drug Administration prohibited the use of Rhodamine B (RhB) for its toxicity and harmful effects. Therefore, this study presents a wide range of non-conventional low-cost alternative adsorbents to remove RhB dye from wastewater. It has been observed that the mechanism of the dye adsorption is focused on kinetics, isotherm, and thermodynamics models, which depend on the chemical nature of the materials and various physicochemical experimental conditions such as solution pH, initial dye concentration, adsorbent dosage, and temperature of the system. The kinetic data of adsorption of RhB dye usually follow the pseudo-first-order and pseudo-second-order kinetic models. Several studies revealed that Langmuir and Freundlich adsorption isotherm models are frequently used to evaluate the adsorption capacity of the adsorbents. Furthermore, thermodynamic examination showed that RhB adsorption was endothermic and unconstrained in nature. Thus, both photocatalytic degradation and adsorption methods offer good potential to remove RhB dye from industrial effluents. The work is in progress to evaluate the possibility of using other modified waste biomass for industrial pollution control.

Efficient Removal of Organic Contaminants from Aqueous Solution by Highly Compressible Reusable Three-Dimensional Printing Sponges.

Adsorption is considered to be one of the most effective and economically viable technologies for removing contaminants from the environment. However, the disadvantages of its high-cost complicated process and difficulty in efficient recycling limit its practical application. Herein, a thermoplastic elastomer-polyvinyl alcohol composite (LAY-FOMM 60) sponge three-dimensional structure (3D printing sponge) was fabricated by the fused filament fabrication combined with water erosion technique. The size and shape of the resultant sponge were tailored, and the batch of adsorption/desorption experiments of Rhodamine B (RhB) onto the sponge was performed. The results show that the adsorption of RhB on the 3D printing sponge was mainly via physical adsorption, and pseudo-second-order and Langmuir models exhibited good correlation with the adsorption kinetic and isotherm data, respectively. Thermodynamic parameters suggest that the adsorption is an endothermic and spontaneous process. It is worth to note that the adsorption/desorption efficiency can be raised by compression. This results in high efficiency and low cost for adsorption/desorption process and benefit for regeneration of the adsorbent. The adsorption capacity was maintained over 85% of the initial capacity after being used for five cycles. The approach provides a simple strategy for manufacturing customizable porous adsorbent materials that meet various water treatment requirements.

Performance of activated carbons prepared from spent tyres in the adsorption of rhodamine B in aqueous solutions.

Activated carbons were produced from spent tyre pyrolysis char by steam or CO2 activation and evaluated for their performance in rhodamine B (RhB) adsorption in aqueous solutions. The effect of RhB starting concentration (80-150 mg L-1), contact time (0-80 min), temperature (298-318 K) and initial pH on the adsorption process was examined. Pseudo-first-order and pseudo-second-order models were carried out to fit the experimental data to derive RhB adsorption kinetics. Langmuir, Freundlich and Temkin isotherm models were applied to depict RhB adsorption behaviour of the prepared activated carbons. Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were calculated. It has been found that the activated carbons can effectively adsorb RhB due to high mesoporosity and RhB equilibrium adsorption capacity (qe) increased almost linearly with increasing total mesopore volumes, regardless of the activation agents. When BET surface areas are similar, CO2-activated carbon obtained higher qe than steam due to higher mesoporosity of CO2-activated carbon. The results show that pseudo-second-order well fitted the experimental data. RhB starting concentration increased from 80 to 150 mg L-1 causing qe increased from 158 to 251 mg g-1 but RhB removal decreased from 99.7 to 84.5%. The RhB adsorption process follows the Langmuir model and thermodynamic calculation, indicating RhB adsorption is an endothermic, spontaneous process, dominated by both chemisorption and physisorption.

Electrospun graphene oxide/MIL-101(Fe)/poly(acrylonitrile-co-maleic acid) nanofiber: A high-efficient and reusable integrated photocatalytic adsorbents for removal of dye pollutant from water samples

The electrospun graphene oxide/MIL-101(Fe)/poly(acrylonitrile-co-maleic acid) nanofibers (E-spun GO/MIL-101(Fe)/PANCMA NFs) were fabricated by a facile electrospinning method and used as integrated photocatalytic adsorbents (IPAs) to remove dye pollutant from water samples. Compared with E-spun GO/PANCMA and E-spun MIL-101(Fe)/PANCMA NFs, the fabricated E-spun GO/MIL-101(Fe)/PANCMA NFs exhibited higher adsorption ability and excellent photocatalytic activity towards a model pollutant Rhodamine B (RhB). Under the optimized conditions, the as-prepared IPAs achieved almost complete adsorption of RhB within 15 min with the maximum adsorption capacity of 10.46 mg/g. Under visible-light irradiation, 93.7% of RhB in 20 mL water sample was degraded within 20 min, and the degradation kinetics of RhB fitted well with the first-order kinetic model. In addition, LC-MS analysis of the RhB degradation products confirmed the degradation pathways, and the generated •OH radicals played important roles in the degradation process. Importantly, the E-spun GO/MIL-101(Fe)/PANCMA NFs exhibited good reusability and could be reused for consecutive 20 cycles, which make them promising candidate materials in the field of industrial applications and environmental remediation.

Enhanced adsorption of Rhodamine B over Zoysia sinica Hance-based carbon activated by amminium chloride and sodium hydroxide treatments

A Zoysia sinica Hance-based activated carbon (ZBAC) was synthesized via two-step method combining NH4Cl-assisted hydrothermal pretreatment and NaOH activation for the removal of Rhodamine B (RhB) in aqueous. The physical and chemical properties of the as-prepared activated carbon were investigated through the usage of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) analysis. A series of batch experiments have been used to visually evaluate the various parameters (pH, dosage, reaction time and actual water condition) affecting the adsorption experiments. Results revealed that the aimed activated carbon exhibited superior adsorption capacities for RhB (1375.8 mg/g) due to its specific surface area (1307 m2/g) and available porosity. In addition, the adsorption of RhB could well-fitted by the Langmuir isotherms model and pseudo-second-order kinetic model, corresponding to monolayer and chemical adsorption respectively. As for the study of adsorption mechanism, ion exchange interactions and hydrogen bonding may be dominant for adsorbing RhB molecules by the activated carbon. The findings of the present work could provide a promising strategy to develop high-performance adsorbents for dye removal from wastewater using biochar derived from waste grass cuttings.

Synthesis of large pore sized mesoporous carbon using alumina-templated strategy for high-performance RhB removal

Abstract The mesoporous carbon dye adsorption materials were synthesized through a simple alumina-templated strategy. The morphology and structure were characterized by Xray diffraction, transmission electron microscopy, nitrogen adsorption–desorption and adsorption capacities of rhodamine B (RhB) were also tested. The results showed that the mesoporous carbon materials exhibit large BET surface area (1093.1 m2·g−1), large pore volume (3.03 cm3·g−1) and large pore size (21.9 nm) due to the consistence pore structure of carbon material and the template nanosheet γ -alumina. Therefore, the mesoporous carbon had high equilibrium adsorption amounts (374.3 mg·g−1) and fast adsorption rate of RhB (317.8 mg·g−1 at 5 min). We also explore the kinetic studies of carbon materials for RhB adsorption, indicating that the kinetics module fit the pseudo-second-order kinetic model and Langmuir model for isothermal adsorption theory. This study promotes a high efficient material for RhB dye adsorption and a promising candidate for toxic dye wastewater treatments.

High-efficiency adsorption of Cr(VI) and RhB by hierarchical porous carbon prepared from coal gangue

Coal gangue (CG) is one of the largest industrial solid wastes in the world produced during the process of coal mining. The accumulation of CG is easy to cause ion leakage, which is harmful to the environment and human body. The recovery and utilization of CG are imminent. In the process, a hierarchical porous carbon (HPC) adsorbent with excellent adsorption property for Cr(VI) and rhodamine B (RhB), was prepared from CG by a two-step method and characterized by SEM, TEM, XRD, XPS, TPD and BET. The results revealed that the specific surface area of HPC is up to 2012.7 m2 g−1, and its adsorption capacities for Cr(VI) and RhB are reached 320.51 and 3086.42 mg g−1. The adsorption mechanism of RhB was the synergetic effect of physics and chemistry. While XPS results suggested that hierarchical porous carbons (HPCs) only have a chemisorption effect on Cr(VI). This study provided an idea for the preparation of HPCs from CG to remove inorganic and organic pollutants such as heavy metal Cr(VI) and RhB in water.

Facile Green Synthesis of Copper Oxide Nanoparticles and Their Rhodamine-b Dye Adsorption Property

Adsorption has gained more popularity in wastewater treatment because the process is non-toxic, cheap, and highly efficient. Environmental and human-friendly adsorbents specifically have a vast prospective. Hence, in the present study, copper oxide nanoparticles (CuONPs) synthesized with Wedelia urticifolia leaf extract were used as adsorbents for Rhodamine-b (RhB) dye. The biomolecules responsible for the synthesis were predicted from Fourier transform infrared (FT-IR) analysis while UV–Visible (UV–Vis) spectroscopy, Dynamic laser spectroscopy (DLS), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) techniques were used for particle characterization. The results revealed that the synthesized nanoparticles are crystalline and spherical with a size of less than 40 nm. The dye adsorption characteristics from the aquatic environment were investigated at room temperature under different doses of CuONPs, initial concentration of RhB dye, and contact time, and over 99% of RhB dye removal was achieved. The adsorption process of RhB dye onto the as-synthesized CuONPs was accurately described by the Freundlich isotherm and pseudo-second-order kinetic models. In summary, the as-synthesized nanoparticles possess an excellent ability for RhB adsorption, and hence these nanoparticles can be used as inexpensive, promising, and potential alternatives to traditional wastewater treatment techniques.

Molecular dynamic simulations and quantum chemical calculations of adsorption process using amino-functionalized silica

Present study focused on the adsorption behavior of two cationic dyes (Neutral Red (NR) and Rhodamine B (RB)) on mesoporous silica (MPS) and amino-functionalized MPS with N1-(3-Trimethoxysilylpropyl) diethylenetriamine linker (TAF/MPS). In order to provide more details about adsorption mechanism of dyes on the adsorbents surface, the molecular dynamics (MD) simulations were employed. A very promising simulation approach for adsorption of NR and RB dyes by functionalized and bare MPS adsorbents were obtained by MD results. The obtained results of quantum chemical calculations confirmed the highest adsorption energy for TAF/MPS-water-RB configurations, while the MPS-water-NR had the lowest adsorption energy. According to the results, functionalization of MPS with amino groups led to improvement in adsorption affinity of both dyes. The Sigma profiles demonstrated higher RB adsorption on both adsorbent while lower HOMO–LUMO energy gap was observed for RB dye compared to NR dye. Based on the energies of the HOMO and LUMO, other quantum chemical descriptors were calculated for different dyes, water and adsorbent configurations. These descriptors include: hardness (η), softness (σ), chemical potential (μ), nucleophilicity (ɛ) and electrophilicity index (ω). It was observed that the chemical reactivity, softness, and polarizability of RB dye were more than that of NR dye. The results of this study provide deeper atomic/molecular understanding into the adsorption mechanism of dye molecules on adsorbent surface which could help to get new insights about interactions of molecules. Moreover, MD simulation can be a very useful approach in term of cost-efficient and time saving for predicting the adsorption behavior of structures.

Adsorption and photocatalytic performance of Au nanoparticles decorated porous Cu2O nanospheres under simulated solar light irradiation

In this work, pristine Cu2O and Au nanoparticle modified Cu2O (Au/Cu2O) spherical nanocomposites were prepared by a simple redox method at room temperature. The as-prepared Cu2O nanospheres with diameters of 150–200 nm show relatively large surface area. The dye removal abilities of the pure Cu2O and the Au/Cu2O nanocomposites were tested by evaluating their adsorption and photocatalytic activities towards different aromatic molecules (e.g., Congo red (CR), Methyl orange (MO), Methyl blue (MB), Rhodamine B (RhB)). The experimental results indicate that the Au/Cu2O nanocomposites exhibit much superior adsorption and photocatalytic properties to the pristine Cu2O nanospheres. Among the catalysts, 1 wt% Au/Cu2O nanocomposite shows the best removal abilities to various dyes. Besides, the removal abilities towards these dyes are quite different from each other. For deep understanding of the adsorption mechanism, molecular dynamics (MD) caculations were conducted to investigate the adsorption energy of the Cu2O spheres by simulating the porous structure and Au modification. The calculation results indicate that CR and MO are chemically adsorbed on the Cu2O materials while the adsorption of MB and RhB are physical adsorption, which are well consistent with the experimental results. This study demonstrates the porous Cu2O based nanocomposites are promising materials with high adsorption and solar light-photocatalytic performance. In the meanwhile, the underlying mechanism on the superior dye removal abilities of Au modified Cu2O nanospheres were systematically discussed.

Kinetic and thermodynamic approaches on Rhodamine B adsorption onto pomegranate peel

In the present study, the adsorption potential of pomegranate peel for the removal of Rhodamine B (RhB) was investigated in a batch system. Kinetic and thermodynamic studies of adsorption were conducted. The rate adsorption of RhB was rapid, attained equilibrium at about 120 ​min, at which the adsorption capacity is close to 30,47 ​mg/g, and this in the initial dye concentration of 100 ​mg/L. The kinetic modeling of RhB adsorption was investigated using four celebrated models: pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion. According to the values of R2, RMSE, ARE, and χ2 it was found that the pseudo-second order model provided a better fit to kinetic data. The results also show that intraparticle diffusion is not the only rate-limiting step on RhB adsorption onto pomegranate peel. Moreover, the thermodynamic study revealed no-spontaneous and endothermic nature of the adsorption process.

Mg-Cr Layered Double Hydroxide Intercalated Oxalic Anion to Remove Cationic Dye Solutions: Rhodamine B and Methylene Blue

A MgCr-based layered double hydroxide (LDH) was synthesized by a coprecipitation method, followed by an intercalation process using an oxalic anion. The materials were characterized using X-ray diffraction analysis, FT-IR spectroscopy, and pH pzc measurement. The materials were then applied as adsorbents for removal of methylene blue (MB) and rhodamine B (RhB) from aqueous solution. Pristine Mg/Cr LDH exhibited RhB adsorption capacity of 32.154 mg g⁻1, whereas the use of intercalated Mg/Cr LDH caused an increase in the capacity (139.526 mg g⁻1). Kinetic studies indicated that the dye adsorption using both LDHs followed a pseudo-second-order kinetic model; the K2 values of pristine and modified Mg/Cr LDH for RhB and MB were 6.970, 0.001, 0.426, and 2.056 g mg⁻1 min⁻1, respectively. The thermodynamic study identified that the adsorption of both dyes onto the LDHs was a spontaneous process and can be classified as physical adsorption with adsorption energies of <40 kJ/mol. Moreover, the desorption and regeneration experiments indicated the high economic feasibility and reusability of the LDHs. By using HCl as the optimal solvent, the LDHs could desorb as much as 98% of the dye and could be used as adsorbents with high adsorption capacity over three cycles.

Surface oxidized nano-cobalt wrapped by nitrogen-doped carbon nanotubes for efficient purification of organic wastewater

Dyes and antibiotics in the wastewater discharged by factories have caused immeasurable harm to natural water bodies. It is of great significance to remove the organic pollutants from wastewater. Herein, a novel magnetic nanomaterial of surface oxidized nano-cobalt wrapped by nitrogen-doped carbon nanotubes (Co@CoO/NC) was prepared through a one-step annealing method and used as efficient adsorbing material for tetracycline (TC) and rhodamine B (RhB). The maximum adsorption capacity of the optimal Co@CoO/NC for RhB and TC was 679.56 mg·g−1 and 385.60 mg·g−1, respectively. As a kind of magnetic recyclable and reused adsorbent, Co@CoO/NC could respectively maintain 75% and 84% of absorption capacities for TC and RhB after four repetitions. The adsorption processes were well matched with the pseudo-second-order kinetic model and the Langmuir model. The Zeta potential, XPS, FT-IR and theoretical calculation results showed that the hydrogen bonding and π-π electron donor-acceptor interaction dominated the adsorption of TC and RhB. Due to the presence of CoO on the surface of Co nanoparticles, cation exchange and surface complexation also played an essential role in the adsorption of TC. This work provides a new opportunity for the rational design and construction of efficient, stable and easily recyclable adsorbents in environmental remediation.