Single Molecular Layer Research Articles

Synthesis of magnetic chitosan-composite biochar and its removal of copper ions (Cu2+) and methylene blue (MB) dye from aqueous solutions.

This study presents the synthesis and evaluation of a magnetic chitosan-modified biochar (M-BC-CS) composite, developed from waste maize straw, for the efficient removal of copper ions (Cu2+) and methylene blue (MB) dye from aqueous solutions. The composite was characterized using advanced techniques such as SEM, BET, FTIR, XPS, and XRD, confirming its enhanced surface area, porosity, and magnetic properties. The study is aimed at investigating the optimal conditions for adsorption of Cu2+ and MB by M-BC-CS through analysis of the influence of diverse adsorbent dosages, pH levels, reaction times, and initial solution concentrations. The findings demonstrated that the equilibrium duration for the adsorption of Cu2+ and MB by M-BC-CS was 60min, resulting in corresponding equilibrium adsorption quantities of 54.42mg/g and 67.23mg/g, respectively. To elucidate the adsorption mechanism, the present investigation applied the pseudo-second-order kinetic model and the Langmuir isotherm. The outcomes suggested that the adsorption process is attributable to single molecular layer chemisorption. XPS and FTIR analysis determined that ion exchange and electrostatic interactions are the predominant mechanisms responsible for the simultaneous adsorption of Cu2+ and MB, and a competitive relationship exists between these mechanisms. In addition, M-BC-CS exhibited exceptional magnetic separation performance, enabling effortless and effective separation when exposed to an external magnetic field. Furthermore, the results demonstrated that M-BC-CS has good reusability and high adsorption capacity also in real wastewater, thus emphasizing its potential as a promising adsorbent for the elimination of Cu2+ and MB from aqueous solutions.

Facile self-assembled monolayer deposition on copper foil for high-performance lithium-metal batteries

Li metal is widely acknowledged as the optimal negative electrode material for high-energy-density Li rechargeable batteries. However, challenges arise owing to the formation of Li dendrites and poor surface stability, leading to reduced cycle life and energy efficiency, thereby limiting widespread application. In this study, we introduced a novel approach of a molecular single-layer surface modification onto a Cu foil using a self-assembled monolayer with hexamethyldisilane (HMDS) to enhance the performance of Li-metal electrodes. The deposition of a single molecular layer at the Å-level was achieved by a simple combination of precursor casting and heat treatment without greatly affecting the energy and power density. Furthermore, this process was both scalable and cost-effective, making it highly suitable for large-scale battery manufacturing. The molecular deposition of HMDS effectively mitigated electrolyte decomposition and promoted uniform Li deposition by enhancing the surface stability under repeated Li plating–stripping processes. Optical microscopy revealed the homogeneous Li plating even after extended cycling; the first cycle on the modified surface depicted uniform plating without blank spots owing to the reduced gas-phase by-products from electrolyte decomposition. Thus, HMDS modification greatly improved the cycle stability of Li-metal batteries by successfully mitigating polarization due to electrolyte decomposition. Such improvement improved the Coulombic efficiencies and enhanced the energy efficiency, especially over a wide current density range of 1–5 mA cm−2. Furthermore, full cells with LiFePO4 cathodes and HMDS-modified Cu foils exhibited extended cyclability with increased energy efficiencies.

Influence of Supercritical Conditions on Isothermal Adsorption Capacity Calculation of Methane and Model Optimization.

The study of isothermal adsorption models for coal and methane under supercritical conditions helps us to understand the gas content distribution in coal seams and improve gas management in coal mines. Coal samples from the Hebi mine and Longshan coal mine were selected for this research. Using the weight method, isothermal adsorption curves of supercritical methane at temperatures of 308, 313, and 318 K were measured. The adsorption phase density of supercritical methane was obtained by using the intercept method and model fitting, and the absolute adsorption capacity of methane was calculated. Simultaneously, the pore volume and specific surface area of the coal samples were tested, and the isothermal adsorption model for supercritical methane was studied and optimized. The results indicate that using mercury intrusion, low-temperature N2, and low-temperature CO2 adsorption methods for testing coal sample pore structures allows for multiscale characterization of the coal pore structure. Based on the Gibbs excess adsorption theory, the phase density of methane obtained from the intercept method and model fitting effectively represent the isothermal adsorption curve of supercritical methane. By combination of the specific surface area and pore volume distribution of the coal with the absolute adsorption capacity of methane, the number of methane adsorption layers on the coal surface was calculated to be between 1.11 and 1.3 layers. This suggests that the isothermal adsorption model for supercritical methane on coal is not solely micropore filling or single molecular layer adsorption but primarily single molecular layer adsorption with concurrent micropore filling adsorption. Based on this adsorption mechanism, an L-DA isothermal adsorption model for supercritical methane on coal was established. The L-DA isothermal model shows good fitting results and effectively explains the adsorption characteristics of supercritical methane on coal.

Insights into Adsorption Behavior and Mechanism of Br- onto Nickel-Aluminum Layered Double Hydroxides Intercalated with Different Inorganic Anions.

Layered double hydroxides (LDHs) have garnered significant attention from researchers in the field of adsorption due to their unique laminated structures and ion exchange properties. LDHs with various anion intercalation showed different adsorption effects on adsorbing ions, but the corresponding adsorption mechanisms are ambiguous. In this study, three types of NiAl-LDHs were synthesized, utilizing NO3-, CO32-, or Cl- as the interlayer anions. Batch tests were conducted to study their adsorption performances for Br-. Among them, the LDH with a NO3- intercalation layer exhibited the highest adsorption capacity for Br-, reaching up to 1.40 mmol g-1. The adsorption kinetics, mechanism, and renewability of these NiAl-LDHs were systematically compared. As a result, the type of Br- adsorption by all three materials was single molecular layer chemisorption. Moreover, the thermodynamic results of adsorption suggested that the adsorption of Br- was a spontaneous exothermic process. X-ray photoelectron spectroscopy, X-ray diffraction, and point of zero charge analysis collectively indicated that the adsorption of Br- by LDHs primarily occurred through interlayer ion exchange and electrostatic interactions. Structural characterizations of the adsorbents revealed that Br- entered the interlayers of the three LDHs, causing varying degrees of reduction in the interlayer spacing. Density functional theory calculations indicated that the interlayer binding energy of LDH with NO3- intercalation was the lowest, thereby making it more susceptible NO3- to be exchanged with Br-. Finally, the stability of the NiAl-LDHs was studied. The NiAl-LDHs retains a high removal efficiency of Br- even after 5 cycles of adsorption and desorption.

Efficient U(VI) removal by Ti3C2Tx nanosheets modified with sulfidated nano zero-valent iron: Batch experiments, mechanism, and biotoxicity assessment

The MXenes, a new class of two-dimensional layered materials, have found extensive applications in water treatment for its excellent thermal stability, electrical conductivity, and excellent adsorption ability. Sulfidized nano zero-valent iron (S-nZVI) is a good reducing agent, however, the practical application of S-nZVI is currently restricted due to the tendency of nano materials to agglomerate. Herein, MXenes use as a support and in situ loading S-nZVI on it to prepare a new material (S-nZVI/Ti3C2Tx), and applied it to U(VI) removal in water treatment. The microscopic characterization proves that S-nZVI on Ti3C2Tx has good dispersion and effectively alleviates agglomeration. Batch experiments shown that S-nZVI/Ti3C2Tx has a very good effect on U(VI) removal, and the maximum adsorption capacity reaches 674.4 mg/g under the aerobic condition at pH=6.0. The pseudo-second-order kinetic model and the Langmuir isotherm model were found to be more appropriate for describing the adsorption behavior. This indicates that the removal process is a single molecular layer chemisorption. Moreover, the S-nZVI/Ti3C2Tx maintained a removal efficiency of over 85 % for U(VI) even after being reused five times, demonstrating its excellent reusability. It is worth noting that the material can remove 79.8% of 50 mg/L of U(VI) in simulated seawater, indicating that S-nZVI/Ti3C2Tx possessed an excellent uranium extraction performance from seawater. Experimental results and XPS analysis showed that U(VI) was removed by adsorption, reduction and co-precipitation. Moreover, S-nZVI/Ti3C2Tx was a low toxicity material to hyriopsis cumingii. Therefore, S-nZVI/Ti3C2Tx was expected to be a candidate as adsorbent with great potential in removal of uranium from wastewater and seawater.

Efficient capture performance and mechanism of thiadiazole-functionalized covalent organic framework for Pb(II) ion

Covalent organic frameworks (COFs) are very promising adsorbent developed during recent years. Here, a COFs adsorbent (COF@HPLC) for efficient adsorption of lead is designed by post-modification. The adsorption properties were studied by batch adsorption. It is shown that pH 4 is the optimum value for the adsorption of Pb(II) by COF@HPLC. When the temperature is 25 °C, the maximum adsorption capacity of COF@HPLC reaches 251.37 mg/g. The fitting results of adsorption isotherm indicate that the process is a non-uniform adsorption in a single molecular layer. The activation energy fitted by the Dubinin-Radushkevich model are 16.22 kJ/mol, 21.32 kJ/mol, 18.87 kJ/mol and 16.67 kJ/mol, showing that Pb(II) adsorption by COF@HPLC is a chemical reaction. Kinetic studies show also that Pb(II) adsorption is a chemically controlled process. Thermodynamic shows that the adsorption is a spontaneously exothermic process. Finally, COF@HPLC has good adsorption selectivity and reusability. The adsorption mechanism of Pb(II) by COF@HPLC was the electrostatic and chelating interaction between functional groups containing sulphide and nitrogen and Pb(II) based on the zeta potential, XPS and DFT analyses. This work offers guidance toward the design and preparation of functional adsorbents for the treatment and removal of Pb(II).

Synthesis of sodium polystyrene sulfonate resins for the removal of methylene blue from wastewater

BackgroundThe treatment of dye residue water pollution is a hot research topic, so it is necessary to prepare a resin which can adsorb dye efficiently. MethodsThe sodium polystyrene sulfonate (PSSNa) were prepared by the sulfonation reaction of styrene resins with concentrated sulfuric acid and applied for Methylene Blue adsorption in wastewater. The structure of PSSNa was characterized by FT-IR, SEM, XPS and XRD. Significant findingsThe results show that the maximum adsorption capacity is 16.89 mg∙g−1. The adsorption processes of Methylene Blue with PSSNa conforms to the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model, which means that the adsorption process follows single-molecular layer adsorption mechanism. The characteristic group (–SO3−) of the exchange resin interacts electrostatic with MB. Good desorption was achieved with 1 mol·L−1 HCl solution, and the resin retained good adsorption capacity after 5 adsorption-desorption cycles. In practical applications, PSSNa exhibits a good removal efficiency for dyes containing MB in lake water. These results provide a reference for the treatment of printing and dyeing wastewater by resin adsorption materials.

Construction of bismuth based MOF for efficient removal of sodium diclofenac via adsorption and photocatalysis

The mass production and widespread use of Pharmaceuticals and Personal Care Products (PPCPs) have posed a serious threat to the water environment and public health. In this work, a green metal-based Metal Organic Framework (MOF) Bi-NH2-BDC was prepared and characterized, and the adsorption characteristics of Bi-NH2-BDC were investigated with typical PPCPs—diclofenac sodium (DCF). It was found that DCF mainly covered the adsorbent surface as a single molecular layer, the adsorption reaction was a spontaneous, entropy-increasing exothermic process and the adsorption mechanisms between Bi-NH2-BDC and DCF were hydrogen bonding, π-π interactions and electrostatic interactions. In addition, Bi-NH2-BDC also had considerable photocatalytic properties, and its application in adsorbent desorption treatment effectively solved the problem of secondary pollution, achieving a green and sustainable adsorption desorption cycle.

Magnetic alginate supported potassium manganese ferrocyanide for the recovery of uranium from acidic wastewater

Abstract With the rapid development of the atomic energy industry, the demand for nuclear fuel has risen, while the limited resources of uranium mines make it difficult to meet the needs of the future development of nuclear energy. Expanding sources of uranium acquisition is necessary, and the enrichment and recovery of precious uranium from uranium-containing wastewater is invaluable. By synthesizing alginate supported potassium manganese ferrocyanide nanocomposites with magnetic response (KMnFC/MA/Fe3O4), the high efficiency adsorption and separation of uranium in acidic uranium-containing wastewater can be realized conveniently and quickly. The magnetic composite was characterized by a variety of technical means, and the adsorption behavior of the magnetic material on uranium was studied by static adsorption experiments under different environmental conditions. The adsorption kinetics and isotherm of uranium by KMnFC/MA/Fe3O4 were studied by using some common linear adsorption models. The results show that the adsorption rate of KMnFC/MA/Fe3O4 on uranium is fast, and the adsorption equilibrium can be reached within 90 min. The adsorption process conforms to a pseudo-secondary kinetic model and is dominated by chemisorption. The adsorption of uranium by KMnFC/MA/Fe3O4 magnetic material is single molecular layer adsorption, and the maximum adsorption capacity is 425.5 mg g−1 at 35 °C. KMnFC/MA/Fe3O4 is a promising adsorbent in the field of acidic low-concentration uranium wastewater treatment because of its good effect on the treatment of low concentration uranium wastewater, the concentration of uranium in the wastewater reaches the emission standard after treatment and it is easy to be separated magnetically after adsorption.

Preparation of activated carbon from Cephalosporin Mycelia Residue and its adsorption performance for cephalosporin antibiotics

The activated carbon was prepared with the Cephalosporin Mycelia Residue (CMR) obtained from Wichita Pharmaceutical Co., Ltd., and the adsorption kinetics and thermodynamics of Cefoperazone Sodium and Sulbactam Sodium (CS & SS) onto the activated carbon derived from the CMR were investigated. The results of activated carbon characterization showed that the iodine value of the activated carbon derived from the CMR was 1044 mg·g−1, the SBET was 596 m2·g−1, electron microscope scanning showed that the surface of activated carbon was porous and heterogeneous. Four kinds of kinetic models and four kinds of thermodynamic models were used to fit the experimental data of adsorption kinetics and thermodynamics, respectively. In addition, the ΔG0, ΔH0 and ΔS0 was calculated and analysised. The results showed that pseudo-second order model fitted the best to the adsorption kinetic data, indicating that the adsorption rate was proportional to the square of the adsorption site. Redlich-Peterson and Langmuir isotherm model fitted the best to the adsorption thermodynamic data, indicating that CS & SS was mainly adsorbed in single molecular layer on the surface of activated carbon. ΔH0> 0 indicated that the adsorption was endothermic, high temperature was conductive to the adsorption of CS & SS.

Study on the Effect of Nano Pour Point Depressant on Wax Oil Crystallization

The influence of nano pour point depressant (NPPD) on crude oil containing wax is primarily manifested through their interaction with the wax constituents. This study examines the depressant's effects using a polarizing microscope and an atomic force microscope (AFM) to assess morphological and structural changes in the wax crystals within the oil, both before and after the addtion of the NPPD. Additionally, a surface tensiometer measured surface tension, while a rheometer evaluated viscosity and modulus alterations. These methods facilitated insights into NPPD's mechanistic effects. The interaction process between crude oil wax crystal molecules and the main components of NPPD was simulated using JOCTA molecular dynamics simulation software, and the highest interaction strength between benzenesulfonic acid groups and crude oil wax crystal molecules was determined. The findings indicate that the addition of the NPPD alters the growth patterns and crystalline structure of the wax in the oil. Initially, the wax crystals present as flaky, predominantly single molecular layer lamellae with a thickness of approximately 100 nm. Post-treatment, the wax crystals adopt a flattened lamellar configuration, composed of multilayer lamellae, with a reduced thickness of within 10 nm and exhibiting short-range order. AFM height maps reveal an increase in the average roughness of the wax oil correlated with the addition of the NPPD across different sampling lengths. Surface tension measurements demonstrate that the wax oil doped with the NPPD exhibits lower surface tension than undoped oil, with the surface tension decreasing as the temperature increases.

The performance of Adsorbing and Removing gaseous acetic acid by activate carbon

Currently, gaseous molecular contaminants (acetic acid) is one of the main factors that cause defects in semiconductors and wafers, reduce product yields in high-tech process plants. Propylene Glycol Monomethyl Ethyl Ether Acetate (PGMEA) is a versatile solvent with many applications. Solvents used in the solder mask process in the manufacture of printed circuit boards (PCBs). The diluent in photoresist and edge bead removers used in semiconductor and wafer fabrication is PGMEA, which forms acetate contaminants through an acid-catalyzed hydrolysis reaction. The concentration standard of acetic acid pollutants in clean rooms is 1ppb.In order to protect the expensive optical components, the acetic acid generated by PGMEA needs to be controlled.For this purpose, the activated carbon filter in the intake filter prevents acetic acid from contaminating the components and corroding the material. In this study, we used the commercially available activated carbon fabricated filter to adsorption of acetic acid. The effect of adsorption under different face velocity (0.03/0.06/0.09 m/s) and initial acetic acid concentrations (4/6/8/10 ppm) were measured according to the principle of ASHRAE 145.1standard. The experimental data are also evaluated for adsorption performance, adsorption capacity, kinetic model of acetic acid adsorption process, and isothermal model of acetic acid adsorption process.The results of the acetic acid adsorption experiment show that MM3000 activated carbon has the highest adsorption capacity and the longest adsorption saturation time than KPL activated carbon. The higher the inlet acetic acid concentration at a fixed wind speed, the shorter the saturation time and the higher the adsorption capacity; the faster the wind speed at a fixed acetic acid concentration, the shorter the saturation time and the higher the adsorption capacity.The Langmuir (R2) of the MM3000 sample is higher than the Freundlich’s coefficient of determination (R2), which indicates that the adsorption phenomenon of the MM3000 sample is more suitable to be described by the Langmuir isothermal adsorption mode, which is the adsorption of a single molecular layer on a homogeneous surface. The Freundlich R2 of the KPL sample is higher than the Langmuir’s coefficient of determination (R2), which means that the adsorption phenomenon of this KPL sample is more suitable to be described by the Freundlich isothermal adsorption mode, and it is a case of adsorption of multiple layers on an inhomogeneous surface. The adsorption of MM3000 activated carbon and KPL activated carbon is more suitable to be described by the proposed second-order adsorption kinetic model, which is a phenomenon of chemisorption.

The effect of pre-corrosion on corrosion inhibition performance and mechanism of quinoline quaternary ammonium salts

The influence of pre-corrosion on the corrosion inhibition performance and corrosion inhibition mechanism of quinoline quaternary ammonium salt (QQAS) on Q235 carbon steel in 1 wt% HCl solution at 60 °C were investigated by weight loss experiment, molecular dynamics simulation. The results of IR vibrational spectra and NMR hydrogen spectra indicate the successful synthesis of QQAS. The results of weight loss experiments show that the corrosion inhibition performance of the synthesized QQAS increase with the increasing of the concentration under the condition of Q235 carbon steel with and without pre-corrosion. But the pre-corrosion obviously decreases the corrosion inhibition efficiency by 17.28% when the concentration is 50 mg·L−1. Analysis of thermodynamic parameters shows that the adsorption of QQAS on the steel surface is a spontaneous and exothermic process, which conforms to the Langmuir isothermal formula and is mainly based on chemical adsorption. The results of molecular dynamics simulation indicate that pre-corrosion changes the equilibrium adsorption conformations of QQAS molecules, and decreases the adsorption energies, and decreases the density of the film for the different oxidization extent of Q235 carbon steel. As a result, the corrosion inhibition performance of QQAS is decreased by the pre-corrosion. The results are in good agreement with the results of weight loss experiments. The corrosion inhibition performance of QQAS is the best when the number of QQAS molecules is 18. The corrosion inhibition mechanism is a single molecular layer adsorption mechanism. The results of this study can provide a reference for studying the corrosion inhibition performance and corrosion inhibition mechanism of corrosion inhibitors under the action of pre-corrosion.

Extending on-surface synthesis from 2D to 3D by cycloaddition with C60

As an efficient molecular engineering approach, on-surface synthesis (OSS) defines a special opportunity to investigate intermolecular coupling at the sub-molecular level and has delivered many appealing polymers. So far, all OSS is based on the lateral covalent bonding of molecular precursors within a single molecular layer; extending OSS from two to three dimensions is yet to be realized. Herein, we address this challenge by cycloaddition between C60 and an aromatic compound. The C60 layer is assembled on the well-defined molecular network, allowing appropriate molecular orbital hybridization. Upon thermal activation, covalent coupling perpendicular to the surface via [4 + 2] cycloaddition between C60 and the phenyl ring of the molecule is realized; the resultant adduct shows frozen orientation and distinct sub-molecular feature at room temperature and further enables lateral covalent bonding via [2 + 2] cycloaddition. This work unlocks an unconventional route for bottom-up precise synthesis of three-dimensional covalently-bonded organic architectures/devices on surfaces.

Preparation of metal oxide-loaded nickel foam adsorbents modified by biochar for the removal of cationic dyes from wastewater

In this study, metal composite oxides grown on nickel foam were prepared, which were modified by dopamine and biochar to obtain cauliflower-shaped Co2MnO4/[email protected]/BC adsorption material to adsorb cationic dyes from aqueous solutions. The maximum adsorption amounts qmax for methylene blue (MB), malachite green (MG), and crystal violet (CV) were 8.44, 41.03 and 3.39 mg g−1, and the adsorption aligned with the Langmuir isothermal model as single molecular layer adsorption on a homogeneous surface. The adsorption experiments of dyes were conducted using lake water in the environment, and the adsorption rates of MB, MG, and CV were 91.4%, 94.8% and 85.1%, respectively. Meanwhile, the material has wide pH applicability (3–9), and good adsorption-desorption cycle performance. In addition, the synthesized adsorbent Co2MnO4/[email protected]/BC and the control adsorbent were investigated and shown to have good adsorption capacity. In conclusion, the adsorbent materials synthesized in this work have some application prospects in dye wastewater adsorption.

The effects of UiO-66 ultrafine particles on the rapid detection of sulfonamides in milk: Adsorption performance and mechanism.

Nanoscale MOFs particles possess both excellent adsorption and dispersion properties. In this study, ultrafine particles UiO-66 (UP/UiO-66) with a particle size below 50nm were synthesised by a template-controlled method. UP/UiO-66 was able to achieve a maximum adsorption capacity of 139.64mg/g for 5 methoxylated sulfonamides. Adsorption studies showed that UP/UiO-66 adsorption of sulfonamides can be classified as a pseudo-secondary kinetic adsorption model for single molecular layer adsorption. ELISA (validated by Raman and molecular docking) showed that the sulfonamide molecule was still immunoreactive with antibodies after adsorption by UP/UiO-66. In 15min, UP/UiO-66 could be used directly in the ELISA test for sulfonamides in milk without elution and separation. The LOQ (IC20) of UP/UiO-66-ELISA for sulfonamides in milk was 0.21-2.05ng/mL. The ultrafine particle strategy of UiO-66 is expected to be applied to other MOFs and used as a general pretreatment material for residue monitoring in complex matrices.

Molecular simulations of sliding on SDS surfactant films.

We use molecular dynamics simulations to study the frictional response of monolayers of the anionic surfactant sodium dodecyl sulfate and hemicylindrical aggregates physisorbed on gold. Our simulations of a sliding spherical asperity reveal the following two friction regimes: at low loads, the films show Amonton's friction with a friction force that rises linearly with normal load, and at high loads, the friction force is independent of the load as long as no direct solid-solid contact occurs. The transition between these two regimes happens when a single molecular layer is confined in the gap between the sliding bodies. The friction force at high loads on a monolayer rises monotonically with film density and drops slightly with the transition to hemicylindrical aggregates. This monotonous increase of friction force is compatible with a traditional plowing model of sliding friction. At low loads, the friction coefficient reaches a minimum at the intermediate surface concentrations. We attribute this behavior to a competition between adhesive forces, repulsion of the compressed film, and the onset of plowing.

Contrasting effects of a novel biochar-microalgae complex on arsenic and mercury removal

Biochar and algae were commonly used as environmental-friendly adsorbents to treat wastewater contaminated with heavy metals. In the study, we used a biochar-microalgae complex of Coconut shell activated carbon (Csac) and Chlorella to evaluate and compare the adsorption ability of arsenic and mercury. The adsorption kinetic study showed that the adsorption efficiency of the biochar-microalgae complex for mercury was better remarkably than arsenic (about 74.84% higher in initial 1 min and 71.62% higher at adsorption equilibrium), which could be interpreted as the complex had excellent adsorption capacity for mercury. The new biochar-microalgae complex adsorbed up to 46.8 μg·g−1 of mercury at 100 μg·L−1 concentration. FTIR and XPS indicated that the surface of biochar-microalgae complex adsorbent had abundant oxygen-containing functional groups that could provide active sites during the adsorption process, i.e., -COOH, -OH and C-O-C et al. Compared with arsenic, the adsorption peaks of mercury moved or changed significantly, suggesting that the complex strongly adsorbed mercury and the main adsorption mechanisms were the ion exchange and complexation between functional groups and mercury ion. What must be emphasized was arsenic mainly existed as negative ions (AsO2-, AsO23-) in water, which was the reason for the weak adsorption capacity of the biochar-microalgae complex for arsenic. In short, the adsorption efficiency and performance of the biochar-microalgae complex was significantly higher than that of arsenic (p < 0.01), and the adsorption of mercury by biochar-microalgae was chemisorption based on the single molecular layer theory.

Preparation and Adsorption Properties of Lignin/Cellulose Hydrogel.

With the development of global industry, industrial wastewater pollution has caused serious environmental problems, and the demand for green and sustainable adsorbents is increasingly strong in the society. In this article, lignin/cellulose hydrogel materials were prepared using sodium lignosulfonate and cellulose as raw materials and 0.1% acetic acid solution as a solvent. The results showed that the optimal adsorption conditions for Congo red were as follows: an adsorption time of 4 h, a pH value of 6, and an adsorption temperature of 45 °C. The adsorption process was in line with the Langmuir isothermal model and a quasi-second-order kinetic model, which belonged to single molecular layer adsorption, and the maximum adsorption capacity was 294.0 mg/g. The optimal adsorption conditions for Malachite green were as follows: an adsorption time of 4 h, a pH value of 4, and an adsorption temperature of 60 °C. The adsorption process was consistent with the Freundlich isothermal model and a pseudo-second-order kinetic model, which belonged to the chemisorption-dominated multimolecular layer adsorption with the maximum adsorption capacity of 129.8 mg/g.

Adsorption behavior and mechanism of action of magnetic MIL-100(Fe) on MB.

Dye wastewater seriously affects human living environment and human health. This experiment develops green and efficient recyclable Fe3O4@MIL-100(Fe) under room temperature conditions. The microscopic morphology, chemical structure and magnetic properties of Fe3O4@MIL-100 (Fe) were characterized by SEM, FT-IR, XRD and VSM, and the adsorption capacity and adsorption mechanism of the adsorbent on methylene blue (MB) were investigated. The results showed that MIL-100(Fe) was successfully grown on Fe3O4, and the composite had excellent crystalline shape and morphology and good magnetic response. The specific surface area of Fe3O4@MIL-100(Fe) is 1203.18 m2g-1 by N2 adsorption isothermal curve, and MIL-100(Fe) still has high specific surface area after compounding with magnetic particles. The adsorption process follows the quasi-level kinetic equation and the Langmuir isothermal model, according to which the adsorption capacity of Fe3O4@MIL-100 (Fe) on MB can be up to 487.8mgg-1 for a single molecular layer. The thermodynamic experiments show that the adsorption of MB by the adsorbent is a spontaneous heat absorption process. In addition, the adsorption amount of Fe3O4@MIL-100 (Fe) on MB was still maintained at 88.4% after 6 cycles with good reusability, and its crystalline shape did not change significantly, indicating that Fe3O4@MIL-100 (Fe) can be used as an efficient and regenerable adsorbent for the treatment of printing and dyeing wastewater.