Thomas Model Research Articles

A novel fabrication of graphitic carbon nitride/chitosan composite modified with thiosemicarbazide for the effective static and dynamic adsorption of Pb2+ from aqueous media.

In this work, graphitic carbon nitride (g-C3N4) prepared by thermal treatment, graphitic carbon nitride/chitosan (GCS), and graphitic carbon nitride/chitosan embedded thiosemicarbazide (TGCS) were developed as an effective solid adsorbent. The fabricated adsorbents were characterized by nitrogen adsorption, ATR-FTIR, TGA, XRD, ζ potential, SEM, and TEM, where TGCS composite had a higher surface area (536.79 m2/g), total pore volume (0.4152 cm3 /g), average pore size (3.09 nm), and pHPZC (6.4). TGCS revealed a Langmuir adsorption capacity of 329.61 mg/g for Pb2+ at an adsorbent dosage of 1.5 g/L, pH 5, 45 min of shaking, and 23 °C. The experimental results were applied well by pseudo-second-order kinetic and Langmuir isotherm. Through the first five adsorption-desorption cycles, only 12.2, 6.2, and 5.1 % decline in efficiency were noted for g-C3N4, GCS, and TGCS, respectively. Column adsorption capacity (qo, mg/g) was determined to be 132.24 mg/g at bed height 3 cm, flow rate of 80 mL/min, and 80 mg/L as initial Pb2+ concentration. Based on the lower reduced chi-square values (ꭓ2 × 10-4, 3.8810-12.9000) and the higher correlation coefficients (R2, 0.9917-0.9979), the Yoon-Nelson and Thomas models suggested an acceptable match for the breakthrough curve. Our findings suggested that TGCS had great adsorption capacity, strong selectivity, and quick kinetics, indicating its potential for water treatment applications.

Porous Carbon Fabricated by Microbial Pretreatment of Brewer's Grain for the Improvement of Toluene Adsorption Performance.

Porous activated carbons (AC-AN and AC-AO) for toluene adsorption were prepared starting from brewer's grain biomass pretreated with microorganisms (Aspergillus niger van Tieghem for AC-AN and Aspergillus oryzae RIB40 for AC-AO). The structures and chemical properties of the three activated carbon materials (AC-AN, AC-AO, and AC that was not pretreated with microorganisms) were characterized by N2 adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The adsorption behavior of the three activated carbons for toluene was studied and correlated with the physical and chemical properties of these materials. The results suggested that the activated carbons prepared by microbial pretreatment had a rougher morphology, higher specific surface area, richer pore structure, fewer oxygen-containing functional groups on the surface, and better adsorption performance for toluene (increased by 31.5% and 18.3% with AC-AN and AC-AO, respectively) compared with the untreated activated carbon (AC). The Thomas model was used to fit the toluene adsorption data, indicating that the rich pore structure accelerated the kinetic process of toluene adsorption. Therefore, appropriate microbial pretreatment of the feedstock that is used to prepare activated carbon can effectively improve its adsorption capacity towards toluene.

Six-scroll chaos within the dynamics of the Thomas chaotic system and application to biomedical data encryption

Abstract In this paper, the influence of non-monotonic nonlinearity within the dynamics of the Thomas model
is studied. The system presents various six-scroll chaos over a wide range of parameter values through indepth analysis using conventional nonlinear analysis tools. The new model also reveals multistability with
an elegant configuration of up to nine periodic states. An electronic analog version of the model is designed
and then simulated using PSPICE software to verify the physical implementation of the model. A novel
biomedical image encryption scheme based on the six-scroll chaos system, Arnold transform and diffusion
operation is proposed and its security is analyzed using statistical testing and key space analysis. The results
demonstrate the effectiveness of the proposed system in providing secure and efficient encryption of digital
images.

Continuous packed bed column removal of Cr6+, Cd2+, and Pb2+ ions from synthetic wastewater using polymeric ultra‐permeable and biodegradable ferromagnetic nanocomposite membrane

AbstractWater purification techniques, including membrane technologies, ion exchange and adsorption, chemical/biochemical reduction, and electrochemical processes, have been developed to remove/recover metal ions species from polluted wastewater. This work assessed the efficiency of polymeric, biodegradable, ultra‐permeable and magnetic nanocomposite membrane (CNCs/N6@Fe3O4‐CT) in a continuous packed bed column for the removal of Cd(II), Cr(VI), and Pb(II) metal ions from synthetic wastewaters. The eco‐compatibility of CNCs/N6@Fe3O4‐CT was increased using chitosan biopolymer. Fe3O4 nanoparticles increased the surface area and improved the separation process. CNCs and N6 polymeric materials enhanced their strength, porosity, and additional binding sites. The CNCs/N6@Fe3O4‐CT nanocomposite membrane was employed as packing material in a fixed‐bed lab‐scale column (height 30 cm, diameter 1.5 cm) to constantly remove Cd(II), Cr(VI), and Pb(II) metal ions from synthetic wastewaters and actual hexavalent chromium tannery effluent. The studies were carried out with different initial metal ion concentrations (10, 20, and 30 mg/L), input flow rates (2, 4, and 6 mL/min), and solution pH values (2.0, 5.0, and 8.0). The obtained experimental data from the breakthrough curves was fitted to the traditional dynamic Thomas model, Yoon‐Nelson, and Bed Depth Service Time (BDST) model.

Investigating the efficiency of fixed bed column containing Fe3O4-ZIF8@eggshell membrane matrix in concurrent adsorption of arsenic and nitrate from water.

In the current work, the behavior of a fixed bed column (FBC) containing an innovative nanocomposite, Fe3O4-ZIF8@eggshell membrane matrix (F-ZIF8@EMM), was investigated in the concurrent elimination of arsenic and nitrate, as two potentially harmful elements (PHEs) in drinking water. Flow rate (6-10 mL/min), column height (10-20 cm), reaction time (30-180 min), pH (5-10), primary content of arsenic (25-100 µg/L), primary content of nitrate (100-200 mg/L), and nanocomposite dose (0.25-1 mg/L) were examined as different operational effects on the simultaneous uptake of arsenic and nitrate from actual water via the as-fabricated novel nanocomposite through various experiments. Characteristics of F-ZIF8@EMM were analyzed via X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET) analyses. The consequences illustrated that the optimal parameters were: flow rate (6 mL/min), primary content of arsenic (100 µg/L), primary content of nitrate (150 mg/L), bed height (20 cm), and pH (7). The simultaneous elimination efficiency of nitrate and arsenic was 90 % under optimal conditions. The FBC fed with water containing arsenic and high nitrate could operate for 440 min with a qm of 226 mg/g. After fitting, different models were identified, with the concurrent uptake of nitrate and arsenic was the optimum fit with the Thomas model (R2 = 0.9998). Analysis of the cost of the process displayed that it should be estimated to be approximately 0.005$ per liter of safe drinking water. This study demonstrates the stability and high efficiency of the newly structured adsorbent after 10 consecutive adsorption cycles. It also validates the significant capacity of the as-made composite F-ZIF8@EMM in the concurrent uptake of nitrate and arsenic. Consequently, the application of FBC technology has shown promise in enhancing this process.

Adsorption of Cr(VI) Using Organoclay/Alginate Hydrogel Beads and Their Application to Tannery Effluent.

The tanning industry is among the most environmentally harmful activities globally due to the pollution of lakes and rivers from its effluents. Hexavalent chromium, a metal in tannery effluents, has adverse effects on human health and ecosystems, requiring the development of removal techniques. This study assessed the efficacy of organobentonite/alginate hydrogel beads in removing Cr(VI) from a fixed-bed adsorption column system. The synthesized organobentonite (OBent) was encapsulated in alginate, utilizing calcium chloride as a crosslinking agent to generate hydrogel beads. The effects of the volumetric flow rate, bed height, and initial Cr(VI) concentration on a synthetic sample were analyzed in the experiments in fixed-bed columns. The fractal-like modified Thomas model showed a good fit to the experimental data for the asymmetric breakthrough curves, confirmed by the high R2 correlation coefficients and low χ2 values. The application of organoclay/alginate hydrogel beads was confirmed with a wastewater sample from an artisanal tannery industry in Belén (Nariño, Colombia), in which a Cr(VI) removal greater than 99.81% was achieved. Organobentonite/alginate hydrogels offer the additional advantage of being composed of a biodegradable polymer (sodium alginate) and a natural material (bentonite-type clay), resulting in promising adsorbents for the removal of Cr(VI) from aqueous solutions in both synthetic and real water samples.

Parthenium hysterophorus invasive weed valorization into biochar for removal of pharmaceuticals and personal care products: Competitive adsorption analysis via batch and fixed–bed column systems

The proliferation of invasive weeds and emergence of new contaminants have become significant global concern, threatening human–health and environment. This investigation assesses performance of Parthenium hysterophorus weed–derived biochar (HPC and KPC) for removing acetaminophen (ACT) and metronidazole (MET) in single (ACT/MET) and multi–component (ACT + MET) systems in batch and column modes. Synthesized HPC and KPC were characterized through SEM, EDX, XRD, porosimetry, TGA and FTIR analyses. HPC displayed micropores, featuring surface area of 166.62 m2/g, while KPC exhibited mesopores with 146.16 m2/g surface area. The investigation in batch study includes exploring operating conditions like contact time (0–180 min), concentration (0.5–20 mg/L), biochar dose (0.25–4 g/L) and pH (2–12). At optimal conditions (1 h, pH 6.5 and 1 g/L dose), HPC achieved maximum sorption capacity 48.72 mg/g for MET and 32.10 mg/g for ACT, and KPC exhibited 18.41 mg/g for MET and 16.54 mg/g for ACT in batch mode. According to findings, pseudo–second–order and Langmuir models provided accurate–fit for batch experimental data. Furthermore, study also investigated influence of column operating conditions such as bed depth (3–9 cm), flow rate (0.25–1.00 L/h) and concentration (5–20 mg/L). In column, HPC outperformed KPC in removing ACT and MET, with breakthrough data fitting Thomas model. Both systems exhibit synergistic effect in simultaneously removing ACT and MET from multi–pollutant mixture. In summary, converting invasive weeds into biochar and employing it to remove emerging contaminants provides sustainable approach to protecting aquatic environment and invasive weeds management.

Stabilization of nanoscale zero-valent iron with mordenite for remediation of hexavalent chromium from groundwater in dynamic columns

In this study, mordenite-supported nanoscale zero-valent iron (nZVI@MOR) composites were prepared for the in-situ remediation of Cr(VI) from groundwater. Batch experiments and dynamic column tests were conducted to investigate the adsorption mechanism and long-term removal performance. The batch results revealed that the optimum pH for Cr(VI) adsorption was ∼3 with a capacity of 101.52 mg/g, following an endothermic adsorption process. The dynamic column test results showed that higher seepage velocities resulted in rapid remediation failure, but an increase in adsorption capacity which increased from 9.61 to 15.53 mg/g with the increase of seepage velocity from 3.9 to 15.6 mL/h at Cr(VI) initial concentration of 20 mg/L, which due to the establishment of dominant seepage channels at elevated velocities, facilitating flow circumvention of the nZVI@MOR composites. The experimental breakthrough curve was best fitted by the Thomas model, with the agreement of fit positively correlated with effective remediation time. The mechanism underlying Cr(VI) removal involves the electrostatic attraction of Cr(VI) to the surface of nZVI@MOR, subsequent reduction to Cr(III) by nZVI as an electron donor to form a complex precipitation for remediation. This result suggests that nZVI@MOR can effectively achieve long-term remediation of Cr(VI)-contaminated groundwater by appropriately controlling the flow rate and material filling methods.

Immobilized chitosan as an efficient adsorbent for columnar adsorption of Cr (VI) from aqueous solution

The current effort focuses on creating an effective adsorbent for Cr (VI) adsorption due to the growing need to address Cr (VI) pollution in aqueous solutions. Chitosan, a biopolymer and polysaccharide with several functional sites, is immobilized on alginate using the ion exchange technique. Both prior to and following Cr (VI) adsorption, the material's shape, crystallinity, and functional groups are reported. Immobilized chitosan was employed to adsorb Cr (VI) in a fixed bed column with variable operational parameters (flow rate, initial chromium content, and bed height). The analysis of breakthrough curves showed that at a flow rate of 10 mL/min, Cr (VI) concentration of 50 mg/L and a bed height of 18 cm, a maximum adsorption of 78.41 % was achieved. The adsorption system and the breakthrough curves were thoroughly understood by using Thomas, Yoon-Nelson and Adams-Bohart kinetic models. There is promise for the large-scale use of synthesized immobilized chitosan because the current adsorption process fits the Thomas and Yoon-Nelson model well and confirms the homogenous bed, low mass transfer resistance, and constant operating conditions throughout the experiment. Furthermore, an exploration of the adsorption mechanism is undertaken and the outcomes are compared with existing literature. The regeneration and reuse tests up to four cycles provided insight into the immobilized chitosan's stability, dependability, and potential for scaling up.

One-pot solvothermal synthesis of Ca-Fe-La composite for advanced removal of phosphate from aqueous solutions in a fixed-bed column: Modeling and resource utilization

The Ca-Fe-La composite was synthesized by the one-pot solvothermal method and applied to the advanced removal of phosphate from aqueous solutions in a fixed-bed column. The effects of some important process parameters on the phosphate adsorption were examined. It was found that the maximum equilibrium loading was 121.1 mg g−1 at an influent phosphorus concentration of 30 mg L−1, flow rate of 2.5 mL min−1, adsorbent mass of 0.5 g and pH of 5.14. The Thomas and fractal-like Thomas models were used to analyze the measured breakthrough curves. Their fitting quality was diagnosed by the adjusted coefficient of determination (Adj. R2), the root of mean squared error (RMSE) and the residual plot. According to the Thomas and fractal-like Thomas models, the breakthrough time and the saturation time were solved by the fzero command of MATLAB software. Akaike information criterion (AIC) and Bayesian information criterion (BIC) were adopted to further determine the optimal model. In all cases, the phosphate adsorption on the Ca-Fe-La composite followed the fractal-like Thomas model. The phosphate loaded Ca-Fe-La composite could be used as a slow-release fertilizer and promote tomato plant growth. This work aimed to provide reliable assessment methods for the modeling of the breakthrough curves and allow for waste management and resource utilization of the phosphate loaded Ca-Fe-La composite.

Improved Carboxylate Density in Functionalized Biochar for Methylene Blue Adsorption

AbstractCarboxylate appended biochar BCKA was synthesized by a two‐step functionalization of leached rice straw biochar using ethyl 2‐bromoacetate/K2CO3/DMF and hydrolysis to furnish the modfied biochar. The modified biochar was characterized using proximate analysis, CHNS, SS CPMAS 13C NMR, FESEM, FTIR, XPS, BET, and zeta potential. Biochar BCKA was optimized for pH and dose, respectively, as 7 and 0.2 g/L for methylene blue (MB) adsorption with a contact time of 6 h at 298 K. MB removal up to 98% from 20 mg/L dye solution, using BCKA as adsorbent pH 7, 298 K. The nonlinear fit to Langmuir, Freundlich, Temkin, SIPS, and D‐R adsorption isotherm showed a good fit with correlation coefficients (R2) 0.970, 0.969, 0.988, 0.984, and 0.983, respectively, and maximum MB adsorption (qm) of 261 mg/g. Thermodynamic parameters for the adsorption of MB using BCKA were 38.72 kJ/mol (∆H°), 225.42 J/mole K (∆S°), and negative ∆G° confirming the spontaneity driven by entropy. Kinetic studies showed good nonlinear fit to pseudo‐second order (R2 0.967), intraparticle diffusion (R2 0.977), and Elovich equation (R2 0.958) with chemisorption‐based interaction between BCKA and MB. Chemisorption, particularly ion exchange on the surface of BCKA with MB, is inferred from the D‐R isotherm and kinetic analysis. Column breakthrough studies showed Thomas model fit with qt 267.09 mg/g, and efficiency >80% was retained for two cycles of MB adsorption.

Removal of Fe2+ in coastal aquaculture source water by manganese ores: Batch experiments and breakthrough curve modeling.

Excessive Fe2+ in coastal aquaculture source water will seriously affect the aquaculture development. This study used manganese sand to investigate the removal potential and mechanism of Fe2+ in coastal aquaculture source water by column experiments. The pseudo-first-order kinetic model could better describe Fe2+ removal process with R2 in the range of 0.9451-0.9911. More than 99.7% of Fe2+ could be removed within 120 min while the removal rate (k) was positively affected by low initial concentration of Fe2+, high temperature, and low pH. Logistic growth (S-shaped growth) model could better fit the concentration variation of Fe2+ in the effluent of the column (R2>0.99). The Fe2 breakthrough curve could be fitted by Bohart-Adams, Yoon-Nelson, and Thomas models (R2>0.95). Smooth slices with irregular shapes existed on the surface of manganese sand after the reaction while Fe content increased significantly on the surface of manganese sand after the column experiment. Moreover, FeO (OH) was mainly formed on the surface of manganese sand after the reaction. PRACTITIONER POINTS: Fe2+ in coastal aquaculture source water could be removed by manganese ores. The pseudo-first-order kinetic model better described the Fe2+ removal process. FeO (OH) was mainly formed on the surface of manganese sand after the reaction.

Utilising date palm fibres as a permeable reactive barrier to remove methylene blue dye from groundwater: a batch and continuous adsorption study.

This study aimed to utilise cheap and abundantly available date palm fibre (DPF) wastes for the remediation of methylene blue (MLB) dye-contaminated groundwater. The DPF adsorbents were first prepared, followed by various characterisation analyses, including surface morphology, functional groups, and material structure. Subsequently, the DPF adsorbents were applied in the batch and continuous adsorption studies to assess the MLB dye removal from aqueous environments. The batch adsorption study achieved 98% maximum removal efficiency with a contact time, adsorbents dosage, initial pH, temperature, particle size, initial dye concentration, and agitation speed of 105min, 3g/L, 7.0, 45°C, 0.075mm, 50mg/L, and 150rpm, respectively. Langmuir was the best-fitted isotherm model depending on a higher correlation coefficient (R2 = 0.985), with a maximum monolayer dye adsorption capacity (qmax) of 54.204mg/g. Additionally, the second order was the best-fitted kinetic model (R2 = 0.990), indicating that MLB dye was removed through chemisorption. Besides, the positive enthalpy change (ΔH°) and negative Gibb's free energy (ΔG°) values verified the endothermic process and spontaneous adsorption. According to the impact analysis of initial dye concentrations and flow rates on the permeable reactive barrier (PRB) performance in the continuous adsorption study using the Thomas, Belter, and Yan models, the experimental results and predicted breakthrough curves reflected an excellent agreement (R2 ≥ 0.8767) and a sum of squared errors (SSE) ≤ 0.4834. In short, the results demonstrated DPF as an effective adsorbent material in PRB technology.

Adsorption of Phosphate from Aqueous Solution Using Hydrochar Produced from Agricultural Wastes

Excess phosphorus (P) in agricultural runoff can cause eutrophication in nearby waterbodies. Therefore, it is crucial to remove P from agricultural runoff before it reaches aquatic environments. This study evaluated the P adsorption potential of adsorbents prepared via co-hydrothermal carbonization of multiple agricultural wastes, including dairy manure (DM), corn stover (CS), and eggshell (ES), followed by thermal activation. The performance of the prepared adsorbents was investigated by both batch and column experiments. The activated hydrochar (AHC) with a DM/CS/ES ratio of 1:0:1 showed the highest P adsorption capacity of 209 ± 0.6 and 65.97 ± 9.04 mg/g in batch and column experiments, respectively. The P adsorption mechanism was well described by the Langmuir isotherm model (R2 > 0.8802) and the pseudo-second-order kinetics model (R2 > 0.8989). The adsorbent indicated the longest breakthrough and exhaust time of 210 and 540 min, respectively, with an adsorbent dose of 1 g and an initial concentration of 25 mg P/L. The breakthrough curve was well described by the Thomas model (R2 > 0.971). Thus, this study indicates that AHC with eggshell has high potential for use as an adsorbent for P removal from agricultural runoff.

Treatment of fluoride-contaminated water in a prototype adsorption unit using zirconium-activated carbon nanocomposites

ABSTRACT Zirconium-activated carbon nanocomposites (ZANC) are found to have high fluoride removal capacity and thus used as an adsorbent to perform column studies. The adsorbent was characterised using SEM-EDS and FTIR before and after the adsorption of fluoride. A packed bed adsorber prototype of 1 m length was fabricated to carry out defluoridation studies. The effect of varying initial fluoride concentration (2.5–10 ppm) and bed height (6–14 cm) was studied. The maximum fluoride removal was found to be 29.4% and uptake capacity was 4.72 mg/g at an initial fluoride concentration of 10 ppm, flow rate of 2 LPM, and bed height of 14 cm for synthetic samples. The Thomas, Yoon–Nelson and Bed Depth Service Time (BDST) models were employed and their results confirmed the experimental findings. The maximum fluoride adsorption capacities obtained from the Thomas model are 1.9 mg/g and from the BDST model, the N value was 20.979 mg/cm3. Regeneration studies were performed and found that the adsorbent can be regenerated for three cycles. Column studies were also performed using real-field groundwater samples collected from Pavagada of Tumakuru district. All the tested parameters of the treated water were found to be within the permissible limit.

Sulfonated corn stalk enhanced hydrogel adsorption for heavy metal from metal mine gallery effluent

There are various of abandoned metal mines in China, and a considerable amount of heavy metal contaminated water is generated through water–rock interactions and accumulated within metal mine gallery. Therefore, the effective removal of heavy metals from metal mine gallery effluent holds significant importance. In this study, sulfonated corn stalk (SCS) and acrylic acid was used to prepare the double network hydrogel SCS-gel. The maximum allowable compression force for the SCS-gel was about 3 times than that of raw hydrogel. The SCS-gel exhibited a stable adsorption capacity within the pH range from 2.0 to 6.0. The maximal adsorption capacities of Pb2+ and Cu2+ on the SCS-gel were 111.6 and 370.2 mg/g, respectively. The functional groups of –OH, C-O, C = O, COOH, and −SO3- were participated in the adsorption process through coordination and electrostatic interactions. The SCS-gel exhibited promising reusability as the adsorption efficiency for Pb2+ and Cu2+ remained at approximately 100 % within 10 cycles of adsorption–desorption. The SCS-gel had an excellent removal efficiency for Pb2+ (99.8 %), Cu2+ (99.1 %), Mn2+ (97.4 %), Zn2+ (98.8 %), and Al3+ (95.7 %) from actual metal mine gallery effluent by dosage of 5 g/L with the initial concentrations of Pb2+, Cu2+, Mn2+, Zn2+, and Al3+ were 4.352, 29.20, 13.02, 7.016, and 30.47 mg/L, respectively. In the fixed-bed experiments, the Thomas model has a good description for the breakthrough curves of these heavy metals. These results confirmed the possibility of adopting SCS ethers for hydrogel fabrication and verified its great potential for the practical application for the removal of heavy metals from metal mine gallery effluent.

Development of an ion exchange process for ammonium removal and recovery from municipal wastewater using a metakaolin K-based geopolymer

Ion exchange represents a promising process for ammonium removal from municipal wastewater (MWW), in order to recover it for fertilizer production. Previous studies on ammonium ion exchange neglected the assessment of process robustness and the optimization the desorption/recovery step. This study aimed at developing a continuous-flow process of ammonium removal/recovery based on a metakaolin K-based geopolymer, named G13. Process robustness was assessed by operating 7 adsorption/desorption cycles with two types of MWW. These tests resulted in satisfactory and constant performances: operating capacity at 40 mgN L−1 in the inlet = 12 mgN gdry sorbent−1, bed volumes of treated MWW at the selected breakpoint = 199–226, ammonium adsorption yield = 88–91%. Empty bed contact time (EBCT) was decreased from 10 to 5 min without any reduction in performances. The NH4+ adsorption process was effectively simulated by the Thomas model, allowing a model-based assessment of the effect of EBCT reductions on process performances. An innovative desorption procedure led to high ammonium recovery yields (86–100%) and to a desorbed product composed primarily of KNO3 (54%w) and NH4NO3 (39%w), two salts largely used in commercial fertilizers. The energy consumption of ammonium removal/recovery with G13 resulted 0.027 kWh m−3treated WW, with a relevant reduction in comparison to traditional nitrification/denitrification, whereas the operational cost resulted equal to 60–110% of the cost of the benchmark process. These results show that G13 is a promising material to recover ammonium in a circular economy approach.

Enhanced continuous lithium extraction using self-designed porous nanosorbent fibers in a fixed-bed system: Optimization and mechanistic insights

This study introduced a novel lithium/aluminum layered double hydroxide (Li/Al-LDH) nanosorbent fiber (Li-PNF) engineered for continuous lithium extraction from brine using a fixed-bed system. These fibers featured a three-dimensional interconnected mesh structure and were distinctively encapsulated with needle-like Li/Al-LDH, exhibiting a layer-by-layer configuration. Compared to conventional Li/Al-LDH, Li-PNFs demonstrated abundant mesoporous structure and larger average pore size, facilitating the mass transfer and molecular diffusion of Li+ ions. Li-PNFs possessed a static lithium adsorption capacity of approximately 13.0 mg/g, with notable selectivity against Na+ and K+. Additionally, the Li+ binding energy across three distinct sites within the atomic structure of Li-PNFs proved advantageous, particularly at the Triangle-site-Al-overlapping-O3, which reached −5.72 eV. Fixed-bed adsorption experiments confirmed that lower feed flow rates, higher initial lithium concentrations, and increased bed heights significantly enhanced the Li+ capture efficiency, achieving up to 23.83 % in a single fixed-bed experiment. Based on the prediction of adsorption penetration curves using four empirical models, it was found that the Clark and Thomas models could accurately predict the behavior of Li+ penetration through the bed. Fixed-bed desorption results indicated that optimal lithium recovery was achieved at lower feed rates, reduced lithium concentrations in the desorption solution, and elevated temperatures. Finally, the excellent cyclic adsorption/desorption performance and low preparation cost of Li-PNF further highlighted its potential for real industrial applications, offering a significant advancement in the field of lithium extraction technology.

Fabrication of CNC-AC bionanosorbents from the residual mass of Magnolia champaca l. Bark after methanol extraction for wastewater treatment: Continuous column adsorption study

In this current study, a new class of multifunctional biobased ecofriendly nanosorbents namely crystalline nanocellulose-activated char (CNC-AC) nanosorbents were fabricated by employing a much more innovative and beneficial solvent evaporation induced phase separation (EIPS) technique. While the crystalline nanocellulose (CNC) were extracted from a very much new, innovative, and beneficial agrowaste source namely banana tree (M. oranta) rachis fibers by conducting a series of chemical treatments like scouring, alkali treatment, bleaching, and acid hydrolysis reactions. Additionally, the biochar were synthesized from the residual mass of Magnolia champaca L. barks after methanol extraction and functionalized by 30 % H3PO4 to improve their overall properties. Besides these the fixed-bed continuous column adsorption study were carried out by optimizing the various influential factors such as preliminary concentration and flow rates of the inlet wastewater solution, along with the nanosorbent bed heights into the applied column. For better understanding the overall physicochemical, thermomechanical, and morphostructural behavior of the newly fabricated polyfunctional CNC-AC bionanosorbents the samples were characterized by conducting FTIR-ATR, FESEM, BET, XRD, TGA analysis. Meanwhile the treated and nontreated water specimens were examined by conducting AAS and UV–vis-NIR techniques. The obtained results recommended that the newly produced CNC-AC nanosorbents have contained a quite number of active edges/binding sites along with substantial sp. surface area (around 316.95 m2/g). Additionally, they possessed a crystallinity index about 59.98 ± 0.027 %, greater thermal steadiness up to 600 °C, and outstanding 2D honeycomb-like mesoporous peripheral surface microstructure with a promising spherical shapes and smaller size nearly 5–10 nm. The highest removal capacity were found at 538.91 mg/g and 455.70 mg/g for Pb2+ and CR respectively. Additionally, for better understanding the experimental breakthrough curves (BTC) were evaluated by several well established column models while the maximum R2 value was found around 0.999 for the Thomas model and reduced chi squire (χ2) value was around 0.0001.

Novel versatile 5-aminoisophthalic acid modified chitosan nanofiber pads for adsorption toward Congo red, methyl orange, crystal violet, and methylene blue

To structure novel nanofiber pads for organic dye removal from dye-polluted water, we previously prepared CSP nanofiber pads by chitosan (CS) and polyethylene oxide (PEO) via electrospinning, followed by preparation of CSRP nanofiber pads through partial PEO removal from CSP, and the subsequent fabrication of CS-A nanofiber pads via grafting 5-aminoisophthalic acid (5-AIPA) to CSRP. FTIR, XRD, and elemental analyses confirmed the successful synthesis of CS-A nanofiber pads (crosslinking and crystalline degrees of 36.64 % and 4.57 %). CS-A nanofiber pads had porous nanofiber structures (diameter and pore size of 153.46 and 3.82 nm), high specific surface area (102.06 m2/g), great thermal stability (total mass loss of 50.2 %), excellent hydrophilicity (water contact angle of 12.0°), superior swelling performance (2331 %), good pH stability (pH of 3.0–11.0), and 6.8 of pHpzc, evidenced by SEM, Brunauer-Emmett-Teller (BET), thermogravimetric (TG), differential thermogravimetric (DTG), wettability, swelling, and solid addition tests. Optimum adsorption parameters (e.g., pH, dosage, and initial concentration) were selected by batches of tests on adsorption toward four organic dyes. CS-A’s surfaces were heterogeneous, and the adsorption belonged to spontaneous endothermic chemical adsorption, confirmed by kinetic and isothermal models and thermodynamic results. CS-A nanofiber pads were of great reusability and easy to be separated. Adsorption mechanisms involved electrostatic attractions, hydrogen bondings, π-stacking interactions, and pore fillings. Dynamic adsorption toward Congo red showed the Thomas model well fitted the breakthrough curves (R2 > 0.9971), showing the maximum adsorption capacity of 949.15 mg/g. Totally, CS-A nanofiber pads were effective adsorbents suitable for organic dye-containing wastewater purification.