Arsenic is a widely occurring geogenic contaminant in groundwater in many places around the globe. The incorporation of high-adsorption iron oxides into activated carbon is an important area of research for arsenic removal. The present study describes an activated carbon-based iron-oxide nanocomposite (AC-IONC) synthesized via co-precipitation and evaluated for the removal of arsenic from aqueous systems. The characterization of AC-IONC using BET, SEM-EDS, FTIR, FESEM, and XRD confirmed the successful integration of iron oxide nanoparticles onto the porous activated carbon matrix, yielding a high surface area (947.97 m 2 /g), structural stability, and abundant functional groups, all of which are favorable for adsorption. Batch adsorption experiments were conducted to assess the influence of pH, adsorbent dosage, kinetics, and initial arsenic concentration. The kinetics of adsorption at various pH levels were investigated. The modeling studies using kinetic adsorption models revealed that the adsorption process followed a pseudo-second-order kinetics model (R 2 = 0.98, NAPE = 2.6%). The adsorption equilibrium datasets were best fit by the Langmuir isotherm model (R 2 = 0.99, NAPE = 2.81), suggesting monolayer adsorption on a homogeneous surface, with a maximum adsorption capacity of 8.08 mg/g. The combined adsorption kinetic and equilibrium (CAKE) model was used to predict the adsorption kinetics and equilibrium at various initial concentrations and times. The regeneration studies showed a modest decrease in adsorption capacity after repeated adsorption-desorption cycles, indicating the AC-IONC’s moderate regeneration efficiency. A spiked study conducted with real water samples showed a marked reduction in adsorption capacity, which suggested that adsorption was reduced in the presence of other co-existing ions. In summary, the AC-IONC demonstrated strong potential as an efficient method for arsenic remediation in water treatment applications.
Phenolic compounds are hazardous pollutants that threaten aquatic ecosystems and human health, necessitating effective removal from industrial effluents. This study evaluates phenol adsorption using raw Jacaranda biomass (BJ) and phosphoric acid-activated biochar (H-BJ). Activation at 600 °C produced a highly porous adsorbent with a Brunauer–Emmett–Teller (BET) surface area of 791 m 2 /g and enriched surface functionalities, as confirmed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, X-ray diffraction analysis, pH point of zero charge (pH pzc ), and BET analyses. FTIR indicated the formation of additional hydroxyl groups that enhanced phenol interaction. Adsorption behavior followed Langmuir and Freundlich isotherms and pseudo-second-order kinetics, indicating uniform and predominantly physical adsorption. Maximum capacities reached 40.127 mg/g for BJ and 61.732 mg/g for H-BJ at 600 °C. Thermodynamic parameters confirmed a spontaneous, exothermic process with increased entropy. Application of H-BJ600 (2% dosage) to olive mill wastewater achieved 74% phenolic removal with a q e of 45.42 g/g. These findings demonstrate the potential of Jacaranda -derived activated biochar as an efficient adsorbent for phenol remediation and wastewater treatment.
Pharmaceutical contamination of water sources presents serious risks to environmental sustainability and public health, requiring the development of affordable and effective wastewater treatment methods. Common treatment technologies often fail to fully remove pharmaceutical residues and are hindered by high energy use, operational costs, and the production of harmful by-products. Recently, research has increasingly focused on repurposing industrial wastes such as fly ash and sludge as low-cost, high-surface-area adsorbents for removing pharmaceuticals. This review thoroughly examines pharmaceutical pollutants, including their sources, environmental impacts, and concentration levels in wastewater. It assesses both traditional and emerging removal methods, with a particular emphasis on adsorption. The potential of raw and modified industrial waste materials as sustainable adsorbents is critically analyzed, considering key factors influencing adsorption, such as pH, temperature, initial concentration, as well as adsorption kinetics and isotherms. The review also emphasizes how these materials can be integrated into the circular economy by repurposing them for water purification. Recommendations for future research include enhancing adsorbent stability, reusability, and selectivity through modifications like magnetization, acid treatment, chitosan addition, and zeolitization, along with verifying their scalability. The results reinforce the importance of waste-based adsorbents in achieving sustainable water management.
The continuous rise in atmospheric CO 2 concentration is a major driver of climate change, underscoring the urgent need for efficient capture technologies. Activated carbons (ACs) are among the most promising adsorbents because they are inexpensive, structurally tunable, and exhibit excellent moisture resistance. This review critically examines recent advancements (2022–2025) in AC-based sorbents for CO 2 capture by integrating findings from 30 representative studies covering biomass- and waste-derived precursors, heteroatom-doped carbons, and composite materials. Under near-ambient conditions, ultramicropores (<0.7 nm) dominate CO 2 adsorption, with uptake capacities ranging from 6 to 9 mmol g −1 despite wide variations in brunauer-emmett-teller surface area. Surface chemistry further enhances performance: pyridinic and pyrrolic nitrogen species, as well as oxidized sulfur functional groups, strengthen interactions with CO 2 and significantly improve both uptake and CO 2 /N 2 selectivity, reaching values up to 161 in olive-stone-derived carbons. Thermodynamic analyses indicate an optimal isosteric heat of adsorption (Qst) window of 20–35 kJ mol −1 , ensuring a balanced trade-off between adsorption affinity and regenerability. Stability assessments consistently demonstrate that physisorption-dominated ACs retain more than 90–99% of their initial capacity across multiple cycles, supporting their potential for industrial deployment. Nevertheless, challenges remain related to large-scale production, sustainable precursor selection, performance in humid or impurity-rich conditions, and energy-efficient regeneration processes. Future research directions include the utilization of green and waste-derived precursors, precise pore engineering, targeted heteroatom doping, and the development of hybrid AC/metal–organic framework or AC/oxide composite sorbents. Overall, ACs—particularly those derived from renewable or waste resources—offer a robust and versatile platform for CO 2 capture. Through combined structural, chemical, and thermodynamic optimization, these materials can transition from promising laboratory prototypes to scalable solutions for post-combustion and direct air capture applications.
Biocomposite beads (AC-SA) were prepared utilizing sodium alginate and activated carbon from a mix cultivar of date palm (Phoenix dactylifera) pits in order to study the removal of methylene blue (MB). Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and pH of zero point of charge (pH zpc ) investigations were used to evaluate the produced beads physiochemically. Numerous factors, such as adsorbent dosage, temperature, initial dye concentration, pH, and contact time, were taken into consideration while evaluating adsorption performance. The optimization method showed that, with a basic pH, 8.5 and 0.080 g bead weight, equilibrium was reached in 120 min. Several isotherms and kinetic models were used to evaluate the adsorbent capacity. The results showed that the greatest removal efficiency of MB onto AC-SA beads was 23.529 mg/g. Adsorption occurred via the pseudo-second order kinetic model and the coulombic forces adsorption mechanism. The Langmuir and Freundlich isotherms were determined to best suit the experimental data for the AC-SA beads. These findings demonstrate the potential of AC-SA biocomposites as economical and effective dye removal adsorbents.
Phenolic compounds are hazardous pollutants that threaten aquatic ecosystems and human health, necessitating effective removal from industrial effluents. This study evaluates phenol adsorption using raw Jacaranda biomass (BJ) and phosphoric acid-activated biochar (H-BJ). Activation at 600 degrees C produced a highly porous adsorbent with a Brunauer-Emmett-Teller (BET) surface area of 791 m2/g and enriched surface functionalities, as confirmed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, X-ray diffraction analysis, pH point of zero charge (pHpzc), and BET analyses. FTIR indicated the formation of additional hydroxyl groups that enhanced phenol interaction. Adsorption behavior followed Langmuir and Freundlich isotherms and pseudo-second-order kinetics, indicating uniform and predominantly physical adsorption. Maximum capacities reached 40.127 mg/g for BJ and 61.732 mg/g for H-BJ at 600 degrees C. Thermodynamic parameters confirmed a spontaneous, exothermic process with increased entropy. Application of H-BJ600 (2% dosage) to olive mill wastewater achieved 74% phenolic removal with a qe of 45.42 g/g. These findings demonstrate the potential of Jacaranda-derived activated biochar as an efficient adsorbent for phenol remediation and wastewater treatment.
Mercury pollution in aquatic systems poses a critical environmental challenge due to its high mobility, toxicity, and bioaccumulation potential. In this study, the synthesis of floating alginate–bentonite (FAB) and floating alginate– β -zeolite (FAZ) composites was optimized using a central composite design, with buoyancy as the key functional parameter to facilitate material recovery and large-scale applicability. The composites were comprehensively characterized by X-ray diffraction, attenuated total reflectance–Fourier transform infrared spectroscopy, thermogravimetric and differential thermogravimetric analysis, field emission scanning electron microscope, N 2 adsorption–desorption isotherms, and pH p zc analysis (point of zero charge), and subsequently evaluated for Hg(II) adsorption. The optimized formulations, FAB 1.0 and FAZ 1.0 , exhibited buoyancies above 98% and adsorption capacities of 33 and 28 mg g −1 , respectively, under single-cycle operation. Notably, both materials showed a marked improvement in removal efficiency upon reuse, reaching 93% for FAB 1.0 and 71% for FAZ 1.0 after three adsorption–desorption cycles. Spectroscopic and thermal analyses revealed specific interactions between alginate carboxylate groups and aluminosilicate surface sites, which enhanced structural cohesion, thermal stability, and resistance to repeated regeneration. The integration of design-of-experiments with the synthesis of floating, regenerable alginate–aluminosilicate composites provides a sustainable and operationally advantageous strategy for Hg(II) removal from mining-impacted waters. The high buoyancy, reusability, and ease of recovery without energy-intensive separation steps position FAB 1.0 in particular as a competitive candidate for scalable and environmentally responsible water treatment applications.
In this study, a ternary MgO-impregnated eggshell–kaolin (EKM) composite was synthesized and evaluated for fluoride removal from water under fixed-bed column adsorption. The composite, prepared by co-precipitation and wet impregnation, was characterized using XRD, FTIR, SEM–EDX, and Brunauer–Emmet–Teller analyses. Results confirmed successful integration of the three components, yielding a mesoporous structure with a surface area of 158.5 m 2 g −1 . The composite exhibited good defluoridation performance under varying operational conditions. Higher bed depth and lower flow rate enhanced adsorption capacity, achieving up to 6.35 mg g −1 at 10 mg L −1 influent fluoride concentration. Breakthrough data were well described by the Thomas, Clark, and Yoon–Nelson models ( R 2 ≥ 0.94 ) at lower influent concentration, moderate flow rate, and greater bed depth, while the bed depth service time model confirmed a linear increase in service time with bed depth. The adsorbent maintained good regeneration ability across four cycles. Co-existing anions showed interference with the uptake of F − , with inhibitory effects following the order: PO 4 3 − > SO 4 2 − > NO 3 − > Cl − . The study estimated that 11.11 g of EKM composite yields 2 L of safe water for less than USD1. These results highlight the EKM composite as an efficient and sustainable adsorbent for practical defluoridation applications.
Octafluoropropane (C 3 F 8 ) is widely used as etching agent in refrigeration, air conditioning and semiconductor industries. However, due to its long lifespan and strong infrared absorbing ability, once C 3 F 8 is emitted, the atmospheric radiation absorbing ability will be permanently altered, which will result in a serious greenhouse effect. Therefore, the efficient removal technology of C 3 F 8 is crucial in protecting the environment and alleviating the greenhouse effect. In this work, a series of X-ETS-4 (X: Mg, Ca, Sr, Ba) molecular sieves were synthesized by solvothermal and ion-exchange method. The morphology and structure of the prepared X-ETS-4 were characterized by FT-IR, XRD, and SEM, etc. The adsorption performance of the X-ETS-4 on C 3 F 8 are determined by fixed-bed adsorption breakthrough experiments and single-component isothermal adsorption experiments. The adsorption mechanism was investigated using different adsorption theoretical models. The results show that Ba-ETS-4 exhibits high adsorption capacity and high adsorption selectivity for C 3 F 8 , achieving C 3 F 8 adsorption separation at very low concentration (C 3 F 8 /N 2 volume ratio = 1:400). The saturated adsorption capacity of Ba-ETS-4 on C 3 F 8 reaches 155.17 mg/g (298 K, 170 kPa), which is 15.49 times more than that of Na-ETS-4. In addition, the ideal adsorption solution theory (IAST) separation selectivity of C 3 F 8 /N 2 reaches 341–941 in the pressure range of 0–170 kPa.
The reduction and resource recovery of waste incineration fly ash represent a central focus of current research initiatives. In this study, Ca-Al-layered double hydroxides (LDHs) were prepared via a coprecipitation method using waste incineration fly ash as a calcium source combined with aluminum chloride. Their Pb 2+ adsorption capacities were compared with commercial LDHs and LDHs synthesized from chemical reagents. Results indicate that the optimal Ca/Al molar ratio for both fly ash-derived LDHs and reagent-synthesized LDHs was 2:1. The Pb 2+ adsorption capacities of fly ash-derived LDHs (FCA2), reagent-synthesized LDHs (CA2), and commercial LDHs (CL) were 1149.78 mg·g −1 , 1024.00 mg·g −1 , and 1069.34 mg·g −1 , respectively. After five regeneration cycles, FCA2 maintained stable adsorption performance, with Pb 2+ removal efficiency exceeding 95%. The synthesized LDHs were characterized by SEM, XRD, FTIR and BET, revealing that the dominant adsorption mechanisms included ion exchange, surface complexation, and precipitation. This study not only proposes a method for high-value resource utilization of waste incineration fly ash but also provides insights for aquatic heavy metal pollution control and hazardous waste management.
The development of low-energy and sustainable materials for carbon capture is critical to climate change mitigation. In this study, activated carbon was synthesized from tea twigs waste ( Camellia sinensis ) via pyrolysis at 300 °C followed by KOH chemical activation at an ultra-low temperature of 200 °C. The optimized sample (AC-A 2 B 4 ) exhibited a high BET surface area of 542 m 2 g −1 , narrow average pore diameter (1.936 nm), and a CO 2 adsorption capacity of 2.867 mmol g −1 at 25 °C—surpassing many adsorbents produced under conventional high-temperature conditions. Characterization using BET, FTIR, XRD, and SEM-EDX confirmed the presence of abundant polar surface functionalities (e.g. –OH, C = O), high carbon content (83.5%), and an amorphous mesoporous structure conducive to CO 2 physisorption and chemisorption. Although the initial N 2 uptake at low P/P 0 (< 0.1) suggests the presence of narrow pores, the overall isotherms exhibited Type IV characteristics, indicative of dominant mesoporosity. Isotherm modeling showed strong agreement with the Langmuir model (R 2 = 0.994), indicating monolayer adsorption on a surface with uniform high-affinity sites. Regeneration experiments over five cycles demonstrated minimal capacity loss (<5%), while life cycle analysis revealed ∼70% lower energy consumption compared to traditional activation routes. This study introduces a novel, energy-efficient pathway to produce mesoporous, high-performance CO 2 adsorbents from agro-industrial waste under mild processing conditions, offering scalable potential for decentralized carbon capture and sustainable manufacturing.
Chromium (VI) contamination in water presents significant environmental and public health challenges, demanding efficient and sustainable remediation strategies. This study explores the use of biochar (BC) derived from the invasive plant Mimosa pigra, modified with hydroxyapatite (HAp), to form a composite (BC@HAp) for effective Cr VI removal. HAp is known for its high adsorption capacity and biocompatibility, and its incorporation into BC enhances heavy metal removal through synergistic effects. BC and BC@HAp were synthesized via the sol–gel method and tested under various conditions including pH, adsorbent dosage, Cr VI concentration, contact time, and temperature. Structural and morphological analyses confirmed improved surface characteristics of BC@HAp. The composite exhibited a significantly higher Cr VI adsorption capacity (67.68 mg/g) compared to unmodified BC (39.95 mg/g), attributed to increased surface area and new functional moieties. The adsorption mechanism was facilitated by electrostatic attraction between Cr VI anions (HCrO 4 − , Cr 2 O 7 2− ) and positively charged Ca 2+ sites, ion exchange with surface carbonate and phosphate groups, and surface complexation involving hydroxyl (–OH) and carboxyl (–COOH) groups. Adsorption followed the Freundlich and Temkin isotherms, indicating heterogeneous surface interactions, and was best described by the Elovich kinetic model. Thermodynamic parameters revealed the process to be spontaneous and endothermic, favoring higher temperatures. The enhanced performance of BC@HAp demonstrates its potential as a cost-effective and eco-friendly solution for both Cr VI remediation and invasive species utilization.
The discharge of organic pollutants has become a significant environmental concern, posing serious threats to aquatic ecosystems. In this study, an iron-based metal–organic framework (Fe-MOF) was synthesized using ferric nitrate and 1,2,4-benzenetricarboxylic acid (BTC) through a solvothermal method and evaluated for its dual functionality in dye removal and antibacterial activity. Unlike the commonly used 1,3,5-BTC, the 1,2,4-BTC linker positions two carboxylic groups adjacent to each other, which enables intramolecular hydrogen bonding and alters the coordination geometry, thereby enhancing framework stability and providing interaction sites for pollutant binding. The morphology and surface characterizations of the Fe-MOF were confirmed by FTIR, XRD, SEM, TEM, EDX, XPS, vibrating sample magnetometer, Raman spectroscopy, and zeta-potential analysis, confirming its successful formation and surface charge. The Brunauer-Emmett-Teller analysis showed that the surface area of Fe-based MOFs was 157 m 2 /g, confirming the presence of mesopores and facilitating dye diffusion to the active sites. The batch adsorption experiments showed high efficiency in removing tropaeolin OO and sunset yellow dyes with maximum removal efficiencies of 89% and 96%, respectively. According to isothermal modeling, kinetic studies, and thermodynamic analysis, the adsorption process favored multilayer adsorption behavior and spontaneous dye removal. Statistical analysis, including regression modeling and one-way analysis of variance, revealed the significant influence of operational parameters, such as pH, temperature, and adsorbent dose. Fe-MOF presented antibacterial activity, achieving a 96.47% reduction in colony-forming units. Regeneration studies confirmed the reusability of the Fe-MOF, preserving over 92% of its efficiency after two cycles.
Low-cost activated carbon electrodes derived from Moringa oleifera seeds were developed for the efficient removal of Arsenic from contaminated water by capacitive deionization (CDI). The electrodes were synthesized using a carbon slurry composed of Moringa oleifera powder (MOP), poly(vinylidene fluoride), and carbon black. Scanning electron microscopy was used to analyze the surface morphology. In contrast, their electrochemical properties, including capacitance and electrical conductivity, were analyzed through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The capacitance values, as determined from CV and EIS measurements, were 201.3 Fg −1 and 122.62 Fg −1 for MOP (MOP-1:1 and MOP-1:2), respectively. The Arsenic removal efficiency was evaluated under optimized electrochemical conditions, achieving an efficiency of 89.38% when treating a 100 mg/L arsenite solution at an applied voltage of 1.2 V and pH 9. These findings highlight the potential of Moringa oleifera seeds-derived carbon electrodes as sustainable, cost-effective materials for Arsenic removal through CDI.
The increasing CO 2 emission leads to significant ecological changes, and the control of CO 2 emissions has been a major concern worldwide. Solid adsorbents are a highly promising carbon capture technology; the regeneration energy, visually representing the operating cost, is a key parameter to judge the merit of different solid adsorbents. In this paper, a uniform energy consumption calculation method was proposed to compare the characteristics of CO 2 adsorbents in temperature swing adsorption process. The results showed that, for chemisorbents with strong interactions with CO 2 (e.g. alkali and alkaline earth metal-based adsorbents), due to the high adsorption heat and the high regeneration temperature required, their energy consumption in CO 2 capturing was quite high. It could be even higher than that of 30% monoethanolamine solution. Adsorption heat plays an important role in the cyclic regeneration of adsorbents; a very low adsorption heat (<25 kJ/mol) will make it difficult to form the difference in adsorption capacities between low and high temperatures. Among all the adsorbents, metal–organic frameworks, zeolites, and amine-functionalized adsorbents perform best, all of which possess moderate adsorption heats and large adsorption capacities at relatively low regeneration temperature.
Paraquat (methyl viologen, PQ 2 + ) is a persistent cationic contaminant that remains difficult to remove from water. This study shows that the composition of the synthesis gel, specifically the balance of water and basicity, governs phase purity, crystallinity, and microporosity in zeolite products and, consequently, their adsorption performance. Using as-synthesized Na-form materials, we varied gel composition, characterized the resulting solids (scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared, and N 2 sorption), and measured paraquat isotherms in water at room temperature. High-water gels produced phase-pure, highly crystalline NaY (faujasite) that followed Langmuir behavior with strong affinity and high capacity. The best NaY sample, named 210H 2 O, synthesized from a gel with a molar composition of 6.01Na 2 O : 1.00Al 2 O 3 : 11.75SiO 2 : 210H 2 O gave the largest surface area (880 m 2 /g), highest relative crystallinity, and paraquat adsorption capacity (233 mg/g). Lower water content promoted NaP formation, reduced microporosity, and shifted the isotherm to the Freundlich, indicative of weaker and heterogeneous binding. These results establish a clear synthesis–structure–performance relationship and provide practical guidance: controlling gel water and basicity enables preparation of NaY adsorbents with maximized accessible Na + exchange sites for effective paraquat removal.
This study examines the influence of surfactants with varying hydrocarbon chain lengths—tetradecyltrimethylammonium bromide (TDAB), octadecyltrimethylammonium bromide (ODAB), and docosyltrimethylammonium bromide (DKAB)—on the structure and properties of montmorillonite (a bentonite clay) with a cation exchange capacity of 101 mmol/100 g. Structural modifications were analyzed using X-ray diffraction (XRD), infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and microscopy techniques. Intercalation of these surfactants increased the interlayer spacing of montmorillonite from 1.24 nm (raw) to 1.98 nm, 2.17 nm, and 2.32 nm for TDAB-, ODAB-, and DKAB-modified samples, respectively. IR spectral analysis confirmed the incorporation of the hydrocarbon chains and a resulting decrease in clay hydrophilicity. TGA demonstrated enhanced thermal stability in the modified clays, with the highest residual mass (17.43%) observed for DKAB-modified bentonite. The decrease in the point of zero charge (pH p zc) of the clay from 9.6 (raw bentonite) to approximately 9.0 in the modified samples reflects a change in the electrochemical state of the surface. Water vapor adsorption decreased from 0.183 g/g (raw clay) to 0.086 g/g in modified samples, while benzene vapor adsorption increased. Adsorption studies with organic dyes showed a maximum sorption capacity of 10.6 mg/g for methylene blue on ODAB-modified clay and 13.6 mg/g for Congo red on TDAB-modified clay, reflecting enhanced affinity due to interlayer expansion and improved surface properties. These findings highlight the potential of surfactant-modified bentonites for improved adsorption applications.
13X molecular sieve (MS) was modified with diethylenetriamine (DETA) using a high-gravity rotating adsorption bed, and subsequent carbon dioxide (CO 2 ) adsorption experiments were conducted in a high-gravity rotating adsorption bed. The results indicate that high-gravity technology significantly enhances the DETA loading in 13X MS and ensures excellent dispersion, offering clear benefits over conventional impregnation modification methods. Furthermore, the adsorption capacity for CO 2 in the high-gravity modified 13X MS increased by 23.81% compared to the unmodified 13X MS under identical conditions. The efficacy of the high-gravity rotating adsorption bed for CO 2 capture was enhanced by 16.48% compared to that of the fixed bed. Overall, this study demonstrates that high-gravity technology considerably strengthens both the modification and CO 2 adsorption processes in 13X MS, markedly improving performance. This research validates the novel application of high-gravity technology in this domain and suggests new avenues for advancement in related industrial sectors.
Coal seam water injection is a coal mine safety technology used to inhibit coal dust and reduce the potential risk of gas explosions, but its effectiveness is limited by the wettability of the coal seam. Anthracite coal, due to its strong hydrophobicity, is difficult to fully combine with injected water. To improve the wettability of anthracite coal, this study systematically investigates the regulatory effects and wettability mechanisms of the non-ionic surfactant dodecyl β- d -maltoside (DDM) on anthracite coal, combining physical experiments and molecular simulations from both macroscopic and microscopic perspectives. The contact angle experiments indicated that DDM significantly reduced the contact angle of anthracite and enhanced its wettability. XPS and FTIR spectral analysis showed that DDM improved the chemical composition of the coal surface by decreasing the content of hydrophobic functional groups and increasing the content of hydrophilic functional groups on the coal surface. Molecular dynamics simulations further revealed the adsorption characteristics and microscopic wettability mechanism of DDM on the surface of anthracite coal. The results showed that the hydrophobic tail chain of DDM adsorbed onto the coal surface, while the hydrophilic head group oriented toward the water phase, significantly enhanced the interactions between water molecules and the coal surface, increased the number of hydrogen bonds and the contribution of electrostatic energy, thereby greatly improved the hydrophilicity of anthracite coal. This study provides theoretical support and technical references for improving the wettability of anthracite coal in coal seam water injection.
In this research, Casuarina equisetifolia fruit-based-activated carbon (CAC) was employed to investigate the simultaneous removal of crystal violet (CV), Naphthol Black Blue (NBB), and methyl orange (MO) in one mixture from aqueous solutions. The efficacy of adsorbent removal was studied concerning adsorption characteristics such as pH, dose of CAC, initial dye concentration, and adsorption time. Fourier transform infrared (FTIR), scanning electron microscope (SEM), and UV-visible analysis all showed that the dye mixture stuck to the CAC surface at the same time. Results revealed the best simultaneous adsorption efficiencies for the investigated dyes were attained in the pH range of 3–10, with a CAC dose of 0.08 g. The optimal initial concentration for the dye mixture was found to be 40 mg·L −1 . The optimal contact time for CV, NBB, and MO was 45 min. Kinetic studies revealed a pseudo-second-order adsorption mechanism for the dye mixture. The Freundlich isotherm model best described the equilibrium data. The maximum adsorption capacities were CV (239.23 mg·g −1 ), NBB (134.95 mg·g −1 ), and MO (45.93 mg·g −1 ). Thermodynamic analysis suggests these adsorption processes to be endothermic and spontaneous. The findings of high adsorption capacities highlight the practical applicability of this approach in addressing complex dye pollution challenges.
