Solute Adsorption Research Articles

Synthesis of Activated Carbon from Dragon Fruit Peel for Adsorption of Methyl Blue

In this study, activated carbon from dragon fruit peel was synthesized and applied for its ability to adsorb organic pigments in water. The results obtained from the SEM and FTIR analyzes revealed the presence of the characteristic functional groups of activated carbon. The adsorption capacity of synthetic activated carbon was evaluated against methylene blue dye. This study also evaluated factors affecting the adsorption process, including time, content, temperature, concentration, and solution pH. The optimal adsorption conditions were recorded at pH 6, concentration 95 mg/L, time 43 min, and temperature 30 °C. At optimal adsorption conditions, the adsorption capacity predicted from the model is said to be 54.12 mg/g with an efficiency of 27.5%. The experimental data of the study were evaluated using adsorption kinetic models and adsorption isotherm models of the material. The results showed that the activated carbon material from dragon fruit peel is a potential material in the application for adsorbing pollutant dyes in wastewater.

Leaching behavior of arsenic in coal under the action of mine water

Arsenic, a potentially harmful element in coal, has a detrimental effect on the quality of groundwater and the water cycle. There is a significant safety risk to the drinking water and overall health of residents living near mining areas. It is of great significance to explore the leaching pattern of arsenic in coal under the influence of mining and identify the main controlling factors for the prevention and control of groundwater pollution in mining areas. In this paper, we selected long flame coal and non-caking coal from Wulanmulun Mine, along with four types of water samples from the mine area, as the research subjects. Our aim was to investigate the leaching mechanism of arsenic in groundwater under the influence of coal-water interaction in the mine area. To achieve this, we conducted indoor batch coal-water leaching simulation experiments. The results show that: 1) The four leaching solutions, which correspond to four groundwater types at the coal mine production site, exhibit similar trends in the presence of arsenic ions after water-coal interaction. The leaching process can be divided into three distinct zones: a rapid descent zone, a dissolution shock zone, and a dissolution linear stable zone. The initial decline rate of arsenic content in different water samples is proportional to the initial concentration of arsenic in the water samples. 2) The dissolution of arsenic has a strong negative correlation with DO, and the lower the oxygen content in the solution, the higher the arsenic ion content. There is a relatively strong negative correlation with pH value. It has a strong positive correlation with the leaching of Mg, K, V, Cr, and Fe, and a relatively small positive correlation with the leaching of Mn and Cu. The leaching degree of Mg, K, V, Cr and Fe can be used as a sign to explore the leaching or content change of arsenic in actual mining environment. 3) Most arsenic in coal occurs in pyrite in the form of isomorphism or solid solution, and the dissolution of arsenic is related to pyrite content and its oxidative dissolution behavior. The higher the pyrite content, the greater its oxidation degree, and the higher the arsenic content in the solution. 4) Clay minerals, predominantly kaolinite, found in different coal samples demonstrate varying capacities for arsenic adsorption in the leaching solution. The results of this experiment indicate that the adsorption capacity of clay minerals in long flame coal is considerably higher than that observed in non-caking coal, leading to a substantial decrease in the concentration of arsenic ions in the solution. This reduction is associated with a notable decline in the arsenic concentration within the groundwater associated with the coal samples collected on-site. The results suggest that the leaching of arsenic from the coal samples will not lead to arsenic contamination in four distinct categories of groundwater. This finding holds considerable importance for the management and remediation of water pollution in mining contexts.

Enhancing water resistance of metal-organic frameworks

Developing metal-organic frameworks (MOFs) with high water resistance is of high significance because it can largely extend their applications, such as catalysis and adsorption in aqueous solutions. Herein, we present a typical MOF, i.e., CuBTC [Cu3(BTC)2(H2O)3]n (BTC = benzene-1,3,5-tricarboxylate) with high water resistance by post-modification reactions with six commercially available silanes at room temperature, resulting in CuBTC@SILANE. Various techniques demonstrated that the modification successfully incorporates organosilicon moieties on the surface of CuBTC without altering its original structure, significantly enhancing its water resistance. In contrast to pristine CuBTC, CuBTC@SILANE maintains its crystallinity, morphology, and pore structure even after prolonged exposure to water. The modified MOF also exhibits superior stability in various solvents and enhances CO2 adsorption efficiency, retaining high CO2 adsorption capacity even after exposure to water for 1 day. This simple silane modification approach not only addresses the water sensitivity of CuBTC but also holds promise for extending the aqueous applications of other similar MOFs, thereby broadening their potential uses in catalysis and adsorption.

8-hydroxyquinoline directly loaded on graphene oxide for active protective performance of sol-gel coatings on aluminum alloys

The selection of containers and the method of loading corrosion inhibitors are crucial factors in simplifying the preparation process and enhancing the practicality of active protective coatings in the field of corrosion protection research. Using a straightforward solution adsorption method, corrosion inhibitor 8-hydroxyquinoline (8-HQ) was directly loaded onto graphene oxide (GO) to prepare GO@8HQ nanocomposite fillers. On the surface of GO, the adsorption and desorption of 8-HQ were controlled by regulating the pH, enabling the effective loading and release of the inhibitor. This process enhanced the active protective performance of the coating. 8-HQ exhibited a high loading capacity on GO, achieving an adsorption value of 264.1 mg/g at pH=1, and was released from the surface of GO as the pH increased. The GO@8HQ nanocomposite fillers were then applied in sol-gel coatings. Specifically, the coating with GO@8HQ (G@Q) showed minimal surface corrosion after a 72h salt spray test. The impedance modulus at 0.01 Hz (|Z|0.01Hz) of G@Q was an order of magnitude higher than that of the sol-gel coating, owing to the release of 8-HQ upon the occurrence of corrosion. On the surface of GO, two interaction mechanisms—electrostatic adsorption and π-π conjugation—were confirmed through a molecular dynamics simulation of the adsorption of 8-HQ and GO in an aqueous solution. The results demonstrated that the direct loading method of the corrosion inhibitor offered a straightforward and efficient approach for the preparation of practical and active protective coatings.

Estimating in situ prepared alkaline soluble flavan as an advanced adsorbent for rare earth elements

The design and synthesis of organic adsorbents for rare earth element (REEs) separation remain significant scientific aspect and industrial endeavor. In a single-pot reaction, acetone and resorcinol in acidic media over a two-day period facilitated the formation of the 2, 4, 4-trimethyl-7, 2′, 4′ trihydroxy flavan (flavan adsorbent). Under acidic conditions, flavan effectively adsorbs REEs (adsorbate), while under alkaline conditions, flavan rapidly dissolves completely. A series of adsorption experiments was conducted to determine the optimal adsorption conditions, including pH variations (1–5), REEs solution concentrations (250–1000 mg/L), adsorption time (5–60 min), and flavan mass (10–100 mg). The maximum adsorption capacity for flavan under optimal conditions was 258 mg g−1. Various analytical instruments were employed for flavan characterization, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which were essential for analyzing the surface morphology and structural properties of the flavan. Adsorption isotherms suggested that the adsorption of REEs onto the flavan surface followed the Langmuir model, which in turn exhibited a theoretical adsorption capacity of 263.2 mg g−1 better off the Freundlich model. Kinetically, the adsorption of REEs on the flavan is best run in a pseudo-second-order model trajectory, which in turn exhibited an adsorption capacity value of 283 mg g−1. Interference studies revealed that flavan is a selective adsorbent; however, aluminum ions may exert a minor interference effect of 4% (in term of REEs uptake). Other competing elements, including Na, K, Mg, Ba, Mn, Cu, Fe, and Sn, exhibited a minimal decline in flavan uptake for REEs.

Adsorption of Lufenuron 50-EC Pesticide from Aqueous Solution Using Oil Palm Shell-Derived Activated Carbon.

The use of Lufenuron 50-EC pesticide in oil palm crops affects water quality and aquatic life. This study investigated the adsorption of Lufenuron 50-EC from an aqueous solution using activated carbon derived from oil palm shells (OPSs). Activated carbon (AC) was prepared through physical and chemical activation processes in carbon dioxide environments, using potassium hydroxide (KOH) as a chemical activating agent. The resulting AC was characterized using standard techniques. The most favorable operating parameters were physical activation at 900 °C for 2 h, achieving a BET surface area of 548 m2/g. For chemical activation, at 800 °C, 1 h, and an impregnation ratio (KOH/biochar) of 2:1 (w/w), a BET surface area of 90 m2/g was obtained, which was smaller than that achieved by physical activation. The use of KOH reduced the surface area but generated a high presence of functional groups on the AC surface, which is important for adsorption processes. The AC produced achieved high Lufenuron adsorption yields, reaching a maximum of 96.93%. AC produced at 900 °C with 2 h showed the best performance. Therefore, OPS is an excellent precursor for producing AC with favorable characteristics for pollutant adsorption in aqueous solutions, especially for the insecticide Lufenuron.

Adsorption mechanism study of viscoelastic surfactants with various molecular structures on oil and gas reservoir rocks

As clean thickeners used in fracturing fluids or self-diverting acids, viscoelastic surfactants (VESs) have garnered increased attention for their unique properties. While VESs leave little residue, their adsorption on rocks can lead to adverse effects on oil and gas seepage. Herein, sandstone and limestone were utilized as adsorbents to examine a series of VESs with diverse molecular structures. The relationship between adsorption capacity and molecular structure was investigated, along with the impact of salinity and temperature on adsorption capacity through static and dynamic adsorption tests. Experiments were conducted at various temperatures (25 °C–100 °C) and different salinity levels (0–4 wt%) using sandstone and limestone as adsorbents. The wettability alteration caused by each VES solution was assessed to confirm the adsorption capacity of these VESs on sandstone and limestone. Scanning electron microscopy was employed to visually study the microscopic morphologies of rock surfaces after adsorption in VES solutions to investigate the adsorption characteristics. Owing to the differing charges between sandstone and limestone, the adsorption capacity of each VES varied. Cationic VESs tend to be absorbed by sandstone, while zwitterionic VESs are easily adsorbed by limestone. The increase in salinity considerably enhances the adsorption capacity of rocks, with a greater amplification on sandstone compared to limestone. Additionally, the adsorption capacity of cationic VESs on sandstone is highly sensitive to salinity owing to the ease with which their head groups are disrupted by ions. Rising temperatures can weaken adsorption capacity due to the breakdown of hydrogen bonding or van der Waals forces. The wettability changes caused by VES solutions on sandstone are more pronounced than on limestone. By combining experimental results, the mineral content of rocks, molecular structure characteristics of VESs, and adsorption-free energy, the adsorption mechanisms of various VESs with different molecular structures on rocks were examined. This research lays a theoretical foundation for optimizing VES molecular structures for the preparation of fracturing fluids or self-diverting acid.

Performance improvement tactics of sensitized solar cells based on CuInS2 quantum dots prepared by high temperature hot injection

To reveal the ways and causes of conversion efficiency enhancement for quantum dot-sensitized solar cells (QDSSCs), chalcopyrite structure CuInS2 quantum dots (QDs) was synthesized in oil phase by the high temperature hot injection method. Then, QDs were transferred from oil phase to water phase with 3-mercaptopropionic acid as a ligand exchange reagent and loaded inducer of QDs. 3-mercaptopropionic acid coated QDs in water phase were sensitized on TiO2 nanocrystalline thin films to fabricate QDSSCs. The sensitization time of QDs and pH value in QDs solution are two important factors to affect the loading amounts of QDs and performance of the final assembled QDSSCs. Long-time sensitization of QDs on the TiO2 porous thin film will cause QDs to agglomerate and stack on the film. The pH of QDs aqueous solution influences the stable existence in solution of QDs and adsorption on the surface of TiO2. By balancing the influence of the above two factors, the optimal sensitization condition of CuInS2 QDs is adsorption in pH = 11 QDs solution for 2 h. In addition, the interface between QD-sensitized TiO2 porous thin film and FTO is another factor to affect the photoelectric conversion efficiency of QDSSCs. By adding Zn-doped TiO2 compact layer with high conductivity and electron mobility on QDSSCs to modify this interface, the photoelectric conversion efficiency of QDSSCs was further increased by 66.4 %.

Advanced Polymer Composites for Effective Removal of Perfluorooctanoic Acid (PFOA) Pollutants From Aqueous Solutions.

Perfluorooctanoic acid (PFOA) is extensively utilized in industrial applications, posing significant environmental and health risks because of its persistence and toxicity. Effective elimination methods are vital to mitigate its adverse effects on ecosystems and human health. In this study, we investigate the potential of biomass-derived polymer composite for PFOA adsorption in aqueous solution. Due to its unique surface interaction and porosity, the polymer-based composite derived from sustainable biomass sources exhibits favorable adsorption characteristics. The physicochemical properties of polymer composites were characterized using FTIR, XRD, SEM-EDS, XPS, and BET analysis. The polymer composites reached a maximum PFOA adsorption efficiency about 93.3% under optimized conditions determined by Box Behnken Design. The Langmuir isotherm model revealed and provided an adsorption capacity of PFOA about 13.98 mg g-1. Moreover, the polymer-based composites demonstrated reusability, with removal rates of PFOA ranging from 93.3% to 52% over the course of four cycles after desorption. Our findings underscore the possibility of biomass-derived polymer composites as long-term and effective adsorbents for PFOA removal from aqueous environments.

The Ce-modified biochar for efficient removal of methylene blue dye: Kinetics, isotherms and reusability studies

Exploring modification methods for enhancing the adsorption performance of biochar-based adsorbents for effective removal of methylene blue (MB), biochar-loaded CeO2 nanoparticles (Ce/BC) were synthesized by pomelo peels through co-precipitation combined with the pyrolysis method. Ce/BC showed a higher specific surface area and disorder degree than that of BC. The 0.5Ce/BC (mass ratio of Ce(NO3)3·6H2O/BC=0.5/1) showed the best performance to adsorption of MB solution at different reaction conditions (MB concentration, Ce/BC composites dosage, and initial pH). Adsorption kinetics and equilibrium isotherms were well-described with a pseudo-first-order equation and Langmuir model, respectively. In addition, the maximum adsorption capacity of 0.5Ce/BC for MB was 105.68 mg·g−1 at 328 K. The strong adsorption was attributed to multi-interactions including pore filling, π-π interactions, electrostatic interaction, and hydrogen bonding between the composites and MB. This work demonstrated that the modified pomelo peels biochar, as a green promising material with cost-effectiveness, exhibited a great potential for broad application prospectively to dyeing-contaminated wastewater treatment.

Novel Poly(N‐(1‐cyclohexylethyl)Acrylamide‐co‐Styrene‐co‐Ethyleneglycol Dimethacrylate) Synthesis for Efficient Methylene Blue Adsorption from Aqueous Solutions Synthesis

AbstractSynthesis and evaluation of a new polymeric adsorbent for adsorbing methylene blue (MB) from these economical aqueous solutions were investigated. In the first step of the study, N‐(1‐cyclohexylethyl)acrylamide (CEA) monomer was synthesized using S‐(+)‐1‐cyclohexylethylamine and acryloyl and the obtained CEA was analyzed by FTIR, 1H‐NMR, and 13C‐NMR. Then, a poly(CEA‐co‐Styrene‐co‐EGDMA) copolymer was obtained by cross‐linking CEA monomer, ethylene glycol dimethacrylate (EGDMA) and styrene monomers by subsequent radical polymerization episodes. FTIR, solid‐NMR, and elemental analysis methods were used for the characterization of this copolymer. In the last step of the study, the obtained poly(CEA‐co‐Styrene‐co‐EGDMA) copolymer was used as an adsorbent to adsorb MB from aqueous solutions. In the study, various factors such as adsorption properties, adsorbent dose, contact time, initial concentration, and solution pH were investigated. In the study, the most suitable adsorbent dose was determined as 0.1 g, initial solution concentration as 500 mg/L, contact time as 70 min, and pH as 7. Adsorption capacity was determined as 256.4 mg/g at 25 °C. As a result of the analysis of kinetic data, it was found that the model with the highest regression coefficient and the best fit with the experimental data was the pseudo‐second‐order kinetic model.

Synthesis of discrete SSZ-39 zeolite nanosheets by solvent-free seed-assisted route for efficient CO2 capture

Efficient CO2 capture from flue gas and natural gas is highly desirable to reduce greenhouse gas emissions. Discrete SSZ-39 zeolite nanosheets are prepared by the solvent-free seed-assisted route for the first time to capture CO2. Synthesis parameters such as H2O/SiO2 ratio and synthesis time are optimized and the formation mechanism of the SSZ-39 zeolite nanosheets is studied. The nanosheets have a thickness of 30 nm and an aspect ratio of 10. The HR-TEM characterization shows that the base face of the nanosheet corresponds to its (001) plane with a pore size of 3.8 Å × 3.8 Å. The CO2/N2 and CO2/CH4 selectivities of SSZ-39 zeolite nanosheets are as high as 1092 and 136 by Ideal Adsorption Solution Theory (IAST), respectively. Furthermore, breakthrough results indicate that SSZ-39 zeolite nanosheets have great application potential for separating CO2 from flue gas and natural gas.

Combined Toxicity of Multi-Walled Carbon Nanotubes and Cu2+ on the Growth of Ryegrass: Effect of Surface Modification, Dose, and Exposure Time Pattern.

The escalating release of multi-walled carbon nanotubes (MWCNTs) into the environment has raised concerns due to their potential ecotoxicological impacts. However, their combined phytotoxicity with heavy metals such as copper (Cu) is still unclear. This study investigated the individual and combined toxic effects of MWCNTs (MWCNT, MWCNT-OH, and MWCNT-COOH) and Cu2+ on ryegrass (Lolium multiflorum), uniquely considering different addition orders. The results show that Cu severely inhibited the growth of ryegrass while MWCNTs exhibited a hormesis effect on ryegrass. When MWCNT and Cu were combined, the malondialdehyde (MDA) content in ryegrass showed a 32.39% increase at 20 mg/L MWCNT exposure, suggesting reduced oxidative stress. However, at the higher concentration of 1000 mg/L, it led to a significant 75.22% reduction in ryegrass biomass. MWCNT-COOH had the most pronounced effect, reducing the total chlorophyll content by 39.76% compared to unmodified MWCNT and by 10.67% compared to MWCNT-OH (500 mg/L). Additionally, pre-induced MWCNTs might alleviate the Cu in the plant by 23.08-35.38% through adsorption in the nutrient solution. Small molecule organic acids and amino acids primarily mediated the response to environmental stress in ryegrass. This research provides crucial insights into understanding the complex interactions of MWCNT and Cu2+ and their combined effects on plant ecosystems.

Efficient microplastics adsorption in aqueous environments via bidirectional ordered graphene oxide/nanocellulose aerogels

Microplastics not only accumulate various harmful substances but also are ingested by marine organisms and humans, causing immeasurable impacts. Therefore, the removal of microplastics has become a crucial proposition for addressing the issue of microplastic pollution. This study investigated a bidirectional ordered graphene oxide (GO)/nanocellulose aerogels (D-DPGG) to remove microplastics from water bodies. The concentration of microplastics before and after adsorption was measured using a fluorescence spectrophotometer. D-DPGG aerogel exhibited excellent adsorption performance for microplastics (241.56 mg/g) and maintained high adsorption efficiency (>80 %) over 20 cycles of adsorption testing. Additionally, the link between GO and dual-directional treatment significantly improved the aerogel microstructure. It had an apparent layered structure in the transverse direction and improves the mechanical properties. D-DPGG aerogel not only served as an effective solution in adsorption but also held promise as a novel material in directional structural design.

Construction and demolition waste as a low-cost adsorbent for water treatment: kinetics, isotherm, thermodynamics, and Fenton regeneration.

The present study proposes to investigate the feasibility of using construction and demolition waste (CDW) as an aqueous remediation agent through adsorption. The CDW, with and without chemical and thermal pre-activation, was evaluated to remove the methylene blue (MB) dye from the water solution. Variables interfering with adsorption processes, such as adsorbent dosage, solution pH, and particle size, were evaluated. The material was characterized by pHZPC, FTIR, XRD, SEM, EDS, and TG. The kinetic and equilibrium data better fitted the Elovich and Sips models, respectively. A maximum adsorption capacity of 18.62mgg-1 at 60°C was observed. Thermodynamic data indicated that adsorption occurred through a spontaneous and favorable process governed mainly by physical processes. The regeneration studies were carried out using processes based on the Fenton reaction, where the catalytic action of the iron naturally present in the CDW was evaluated. The results showed that the desorption balance was the main limiting factor for the effective regeneration of the saturated material. Adding Fe2+ to the system made this process suitable for the regeneration of the CDW and degradation of the pollutant in the aqueous phase. A regeneration efficiency of 65%, maintained practically constant during five adsorption-regeneration cycles, was observed. These results highlight the high potential of using CDWs as an adsorbent material.

Alkyl polyglycosides derived from α-olefins via Fisher glycosidation and their adsorption and aggregation behavior in aqueous solution

The effective and stable use of α-olefins is a topic of great research interest due to their abundant reserves, and the fact that the hydrolysis and epoxidation reaction of these substances produces hydroxyl group as a key linking group plays an important role in the synthesis of surfactants. Consequently, a series of alkyl polyglycosides (DC08PG, DC10PG, and DC12PG) were synthesized as non-ionic surfactants via the glycosidation reaction of long-chain 1, 2-vicinal diol with different carbon numbers and glucose. The results showed that 1, 2-vicinal diol exhibited increased reactivity in glycosidation due to their unique molecular structure. Furthermore, it was observed that the degree of polymerization (DP) achieved was notably elevated, registering at 1.63, surpassing the DP of 1.37 typically prepared using conventional methods. This enhancement was paralleled by a demonstrable increase in hydrophilicity, as evidenced by the hydrophile-lipophile balance number (HLB), resulting in a substantial improvement in the water solubility of the product, the transmission rate > 90 %. For adsorption and aggregation behavior, DC12PG showed a smaller cross-sectional area (Amin), larger saturation adsorption (Γmax), and could aggregate to form micelles at low concentrations, and short-term dynamic adsorption properties (DST) was prominent. At the same concentration, for foam properties, DC12PG with longer alkyl chains produced higher and more stable foam; for emulsification properties, the emulsification time was 298 s; for wetting properties, the contact angle was 61.59° in 30 s. This analysis will help to reveal the intrinsic connection between the molecular structure and properties of surfactants.

Artificial Neural Network Modeling of the Removal of Methylene Blue Dye Using Magnetic Clays: An Environmentally Friendly Approach

In this study, the effectiveness of Fe3O4-based clay as a cost-effective material for removing methylene blue (MB) dye from aqueous solutions was evaluated. The structural properties of the clay and Fe3O4-based clay were analyzed using SEM, XRF, BET, XRD, FTIR, and TGA techniques. In this research, the effects of various aspects, such as adsorbent amount, contact time, solution pH, adsorption temperature, and initial dye concentration, on the adsorption of Fe3O4-based clay are investigated. The experiments aimed at understanding the adsorption mechanism of Fe3O4-based clay have shown that the adsorption kinetics are accurately described by the pseudo-second order kinetic model, while the equilibrium data are well represented by the Langmuir isotherm model. The maximum adsorption capacity (qm) was calculated as 52.63 mg/g at 25 °C, 53.48 mg/g at 30 °C, and 54.64 mg/g at 35 °C. All variables affecting the MB adsorption process were systematically optimized in a controlled experimental framework. The effectiveness of the artificial neural network (ANN) model was refined by modifying variables such as the quantity of neurons in the latent layer, the number of inputs, and the learning rate. The model’s accuracy was assessed using the mean absolute percentage error (MAPE) for the removal and adsorption percentage output parameters. The coefficient of determination (R2) values for the dyestuff training, validation, and test sets were found to be 99.40%, 92.25%, and 96.30%, respectively. The ANN model demonstrated a mean squared error (MSE) of 0.614565 for the training data. For the validation dataset, the model recorded MSE values of 0.99406 for the training data, 0.92255 for the validation set, and 0.96302 for the test data. In conclusion, the examined Fe3O4-based clays offer potential as effective and cost-efficient adsorbents for purifying water containing MB dye in various industrial settings.

Investigation on mechanism of mechanical activation and chemical reactions in CMP of diamond assisted by hydroxyl free radicals

Chemical mechanical polishing (CMP) is a crucial manufacturing process for diamond substrate applications. However, due to the extremely high hardness and chemical stability of diamond, its CMP efficiency is extremely low. This study aims to achieve microscopic simulation of atomic oxidation removal at the three-phase interface between diamond abrasive particle, diamond substrate, and hydroxyl free radicals (∙OH) aqueous solution. The mechanical activation behavior, microscopic mechanism, and feasibility of elementary reactions in the ∙OH aqueous solution environment was studied using various perspectives of radial distribution function, central atomic coordination state, atomic bonding and removal forms, energy, electron orbitals, and density functional theory (DFT). The simulation results indicate that during the process of diamond atomic oxidation removal, the atomic density at the first adjacent position centered on one atom decreases, and the stable covalent bond structure is disrupted, resulting in an amorphous phase transition. The chemical adsorption reaction generates C-O and C–H bonds. The C atoms mainly separate from the diamond substrate by the forming products such as carbon monoxide (CO), carbon dioxide (CO2), and carbon chains. The mechanical activation behavior indirectly reduces the activation energy of chemical reactions, while increasing the absolute value of adsorption energy and improving the ability of chemical adsorption solution atoms H and O, as well as ∙OH groups. Based on DFT, it has been verified that the intrusion process of ∙OH groups in the elementary reactions involving the typical product C*O2 is an exothermic reaction that can occur spontaneously, and the energy barrier needs to be overcome by the mechanical action of abrasive particles. At the same time, the energetics of the oxidation of diamond C atoms to generate C*O2 have successfully confirmed that the combined action of ∙OH and diamond abrasive particles is expected to achieve efficient oxidation removal and finishing polishing of diamond atoms.

Preparation of chitosan/cellulose nanofibril composite aerogel and its adsorption performance for Cu(II)-MO binary pollutant

Heavy metals and organic dyes commonly coexist in water, which pose a serious threat to human health. Herein, a functional aerogel for adsorption of Cu(II)-methyl orange binary-polluted system was prepared. Cellulose nanofibril (CNF) was prepared by 2,2,6,6-tetramethylpiperidinyloxy (TEMPO)-NaBr-NaClO system using abandoned pineapple leaves as the main raw material, and chitosan/cellulose nanofibril (CS/CNF) composite aerogel was constructed by sol-gel method combined with freeze-drying. The structure of composite aerogel was characterized by XRD, FTIR, TG and SEM. The fabricated aerogels were ultra-lightweight and exhibited a highly porous 3D network structure. The effects of adsorbent dosage, ionic strength, solution pH, adsorbent concentration, adsorption time, and temperature on the adsorption of Cu(II) and methyl orange (MO) by composite aerogel were studied. The adsorption of composite aerogel towards mono-polluted of Cu(II) and MO reached equilibrium after 100 min with a maximum adsorption capacity of 116.69 and 295.86 mg/g, respectively. The adsorption of Cu(II) and MO by CS/CNF aerogel was mainly achieved through electrostatic attraction, metal chelation and hydrogen bonding interactions. More importantly, the adsorption of Cu(II) by CS/CNF aerogel has an inhibitory effect on its adsorption of MO in Cu(II)-MO binary-polluted system.

Characterization optimization of synthesis Chitosanclay/benzoin/Fe3O4 composite for adsorption of Thionine dye by design expert study

A novel composite material, magnetic chitosan-clay/benzoin/Fe3O4 (CS-CY/Benz/Fe3O4), was synthesized for effectively removing thionine dye (TH) from water solutions. The structural integrity and suitability of CS- CY/Benz/Fe3O4 composite for adsorption purposes were validated through extensive characterization techniques including BET, XRD, FTIR, and SEM. The adsorption efficiency was optimized through a Box–Behnken design (BBD) employing response surface methodology (RSM), focusing on variables such as adsorbent dose (A: 0.02–0.08 g), solution pH (B: 4–10), temperature (C: 30–60 °C), and time (D: 5–30 min). Experimental results revealed a maximum TH removal of 99% with significant interactions between temperature (C) and time (D) (p-value = 0.0001). The optimal conditions for TH removal were determined as pH ~ 5.91, adsorbent dosage of 0.08 g, temperature of 54.34 °C, and time of 29.7 min. The investigation of kinetics revealed that the adsorption process conformed to a pseudo-second-order (PSO) model, while the equilibrium data were effectively described by the Freundlich isotherm model. At a temperature of 333.15 K and a TH concentration of 350 mg/L, the adsorption capacity was determined to be 660.86 mg/g. The mechanism of adsorption encompassed various interactions such as electrostatic attractions, n–π interactions, hydrogen bonding, and Yoshida H-bonding. Particularly, the CS-CY/Benz/Fe3O4 composite demonstrated strong magnetic responsiveness, enabling straightforward separation from water using an external magnetic field after adsorption. Particularly, the CS-CY/Benz/Fe3O4 composite demonstrated strong magnetic responsiveness, enabling straightforward separation from water using an external magnetic field after adsorption. This research contributes important findings to the advancement of magnetic chitosan-based composites for efficient removal of TH dye pollutants from water environments.