Elovich Kinetic Models Research Articles

Copolymeric hydrogels with high capacities of hydration and methylene blue adsorption in water

Copolymers based on monomethyl hydrogen itaconate (βHI) with 2-hydroxyethyl methacrylate (HEMA) and βHI with 2-hydroxypropyl methacrylate (HPMA) were prepared in different monomer molar ratios. The reactivity parameters of copolymerization (r1 and r2) were determined. The values obtained for r1 and r2 indicate that P(βHI-co-HEMA) exhibits a high tendency towards alternate copolymerization. Structural characterization of the copolymeric hydrogels was carried out using Fourier transform infrared (FTIR) and 1H-NMR spectroscopies, where the characteristic signals of the constituent functional groups were observed. The typical thermal stability of the polymeric systems was observed by thermogravimetric analysis (TGA). In addition, the swelling capacity in water was evaluated, and a swelling percentage over 655 % and 1249 % presented P(βHI-co-HEMA) and P(βHI-co-HPMA) respectively, in a period of 15 days at pH 10, and presence of 0.05 M NaNO3.Additionally, methylene blue (MB) adsorption capacity was studied in batch mode by varying different experimental parameters. MB adsorption capacity of 122.79 mg g-1 and 112.24 mg g-1 were achieved for P(βHI-co-HEMA) and P(βHI-co-HPMA), respectively. The data obtained were fitted to the Elovich kinetic model and to a Redlich-Peterson isotherm. The thermodynamic parameters indicated that the adsorption phenomenon is spontaneous, endothermic and with a high probability of occurrence. The adsorption efficiency decreases by approximately 60% in the presence of interfering ions (Na+, K+, Ca2+ and Cl-). The adsorbents are reusable and achieve high MB adsorption efficiency (90% and 80% for P(βHI-co-HEMA) and P(βHI-co-HPMA) respectively) in a textile-simulated wastewater. Based on the results obtained, it is concluded that P(βHI-co-HEMA) and P(βHI-co-HPMA) show great potential for use in adsorption of water molecules, for MB retention and purification of simulated effluents from the textile industry.

Removal, mechanistic and kinetic studies of Cr(VI), Cd(II), and Pb(II) cations using Fe3O4 functionalized Schiff base chelating ligands.

The Schiff base chelating ligands; (E)-2-(3,3-dimethoxy-2-oxa-7,10-diaza-3-silaundec-10-en-11-yl)phenol (L1), (E)-N-(2-((pyridine-2ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L2) and (E)-N-(2-((thiophen-2-ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L3) were immobilized on Fe3O4 magnetic nanoparticles (MNPs) and utilized in the extraction of Cr(VI), Cd(II) and Pb(II) metal cations from aqueous solutions. The compounds synthesized, denoted as L1@ Fe3O4, L2@Fe3O4, and L3@Fe3O4, were characterized using FT-IR spectroscopy, TEM-SEM, VSM, and BET/BHJ techniques for analysis of functional groups, surface morphology, magnetic properties, and degree of porosity of the adsorbents, respectively. BET/BHJ technique confirmed the mesoporous nature of the compounds as their pore diameters ranged between 15 and 17nm. The initial optimization conditions of pH, adsorbent dosage, initial metal concentration, and contact time on adsorption were studied using L1@ Fe3O4. The optimum efficiencies recorded were 68% and 46% for Cr(VI) and Cd(II), respectively, obtained at pH 3, and a metal concentration of 20ppm while an efficiency of 99% was recorded for Pb(II) cations at pH 7 and a metal concentration of 100ppm. Compounds L2@Fe3O4 and L3@ Fe3O4 were also used in the extraction of metal cations from aqueous solution and gave efficiencies of 22%, 56%, and 78% for L2@ Fe3O4 and 19%, 90%, and 59% using L3@ Fe3O4 for Cr(VI), Cd(II), and Pb(II), respectively. The maximum adsorption capacities of L1@ Fe3O4 for Cr(VI), Cd(II), and Pb(II) cations were obtained from the Langmuir isotherm as 32.84, 41.77, and 450.45mg/g, respectively. The experimental data was analyzed using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. Both linear and non-linear forms of kinetic isotherms; Langmuir, Freundlich, Redlich-Peterson, and Temkin were utilized to investigate the nature of adsorption on L1@Fe3O4. The mechanistic studies deduced that the Langmuir isotherm and pseudo-second-order kinetic model better described the adsorption process both yielding high correlation coefficient values (R2 > 0.98).

Eco-Friendly Green Approach to the Biosorption of Hazardous Dyes from Aqueous Solution on Ragweed (Ambrosia artemisiifolia) Biomass

The presented research includes the preparation, characterization, and implementation of magnetic biosorbent (Fe3O4/RWB), obtained from ragweed (Ambrosia artemisiifolia) biomass. Fe3O4/RWB was examined for the removal of a hazardous dye, malachite green (MG), from an aqueous solution in a batch system. The effects of the experimental parameters—initial dye concentration (10–300 mg/L), contact time (0–120 min), biosorbent dose (1–5 g/L), initial pH (2–10), ionic strength (0–1 mol/L), and temperature (298–318 K) on dye biosorption—were studied. The results showed that increases in biosorbent dose, contact time, and initial pH led to an increase in biosorption efficiency, while the increase in initial dye concentration, the ionic strength, and temperature had the opposite effect. The biosorption kinetics for MG on Fe3O4/RWB were analyzed with pseudo-first-order, pseudo-second-order, and Elovich kinetic models, while the Langmuir, Freundlich and Temkin isotherm models were used for equilibrium data analysis. It was observed that the MG biosorption followed the pseudo-second-order kinetic model, whereas the Langmuir model was the best fit for the equilibrium biosorption data of MG, with a Qmax of 34.1 mg/g. the desorption of MG from Fe3O4/RWB indicated reusability in five adsorption/desorption cycles, good performance, and potential in practical applications.

Fabrication of thiosemicarbazide-modified biochar/carrageenan composite beads based on Eichhornia crassipes for effective removal of Pb (II) from aqueous medium

Several biomasses have been applied as environmentally friendly substitutes to produce biochar, which can be utilized to remediate effluents that contain inorganic chemicals. This study applied water hyacinth (Eichhornia crassipes) as a foundation source for the assembly of thiosemicarbazide-modified biochar (BC), which then was modified with potassium carrageenan (KC). Thiosemicarbazide-modified biochar (BC), potassium carrageenan (KC), and thiosemicarbazide-modified biochar/carrageenan composite beads (BKC) were described by several physicochemical methods. The adsorption of Pb (II) onto the three solid adsorbents was investigated under various experimental conditions. The BKC composite beads revealed a surface area of 687.43 m2/g and a mesoporous structure. The best adsorption conditions were found to be 25 min as an equilibrium time, 1.2 g/L of adsorbent dose, and a solution pH of 5 at a temperature of 15 °C. The pseudo-second-order, Elovich kinetic models, Langmuir, and Temkin isotherms were well familiar to the experimental data, inferring that the progression was physical monolayer adsorption onto the homogenous surface. The highest capacity of Pb (II) adsorption onto BKC was 460.45 mg/g at 15 °C. Thermodynamic measurements proved that adsorption was a spontaneous process and endothermic in the case of BC and BKC while exothermic for KC. Furthermore, BKC showed high reusability conditions.

Comparison of the natural and surfactant-modified zeolites in the adsorption efficiency of sunset yellow food dye from aqueous solutions

The removal of Sunset Yellow (E110) on natural zeolite and zeolite modified with the cationic surfactant cetyl pyridinium chloride (CPC) was studied using the adsorption method. The structural characteristics of the surfactant-modified zeolite (SMZ-CPC) were investigated using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, and the scanning electron microscopy (SEM) images. The effect of different parameters on the adsorption process, such as equilibration time and amount of adsorbent at 298 K, were determined using UV–Vis spectroscopy. The maximum dye removal percentage on SMZ-CPC was obtained with 0.08 g of adsorbent in 30 min. The results show that the zeolite modified with CPC surfactant (SMZ) has a higher adsorption capacity for Sunset Yellow than the unmodified zeolite (natural form). The experimental adsorption data were nonlinearly analyzed using isotherm equations such as Langmuir, Freundlich, Temkin, Langmuir-Freundlich (or Sips), and Extended Langmuir (EL). The experimental data were better fitted with the Sips isotherm. The adsorption kinetic data were analyzed using eight models in nonlinear forms: the pseudo-first-order (PFO), pseudo-second-order (PSO), integrated kinetic Langmuir (IKL), Elovich, intraparticle diffusion (IPD), mixed order rate equation (MOE), fractal-like pseudo-first-order (FL-PFO) and fractal-like pseudo-second-order (FL-PSO). According to the results of the coefficient of determination (R2), Elovich kinetic model well expressed E110 adsorption onto SMZ-CPC. Most of the dye removal takes place in less than 5 min and the maximum adsorption capacity is 5.06 mg/g. The results of this study show that zeolite modified with cationic surfactant is an effective adsorbent for removal anionic dyes from an aqueous solution.

Preparation and characterization of biochar from four different solid wastes and its ampicillin adsorption performance.

The integration of biochar (BC) production from organic waste with ampicillin (AMP), an emerging pollutant, adsorption is a novel and promising treatment approach. In this study, peanut shells, coffee grounds, digestates, and oyster shells were used for BC production. Among these, the use of anaerobic digestate from food waste fermentation to produce extracts for antibiotic adsorption is relatively unexplored. The pyrolysis temperature was determined using thermogravimetric analysis (TGA) and the materials were characterized with BET, SEM, FTIR, and XRD. The TGA results indicate that PSB, CRB, and DSB underwent pyrolysis involving cellulose, hemicellulose, and lignin, whereas OSB underwent crystal formation. Characterization revealed that DSB has more functional groups, a superior mesoporous structure, appropriate O/C ratio, and trace amounts of calcite crystals, which are favorable for AMP adsorption. Adsorption experiments demonstrate that all four materials adhere to the Freundlich and Langmuir isotherm and Elovich kinetic models, indicating predominant physical adsorption, with some chemical adsorption also present. Thermodynamic studies demonstrate that BC is spontaneous during adsorption and is a heat-absorbing reaction. DSB exhibits the strongest AMP adsorption. A 53.81mgg-1 adsorbance was obtained at a dosage of 150mg, pH = 2, and 60°C. This study introduces innovative approaches for managing waste types and provides data to support the selection of suitable solid wastes for the preparation of BC with excellent adsorption properties. Furthermore, it lays the groundwork for future studies aimed at enhancing the AMP treatment efficacy.

Integrated effects of water conditions and aging on chromium speciation and availability in two paddy soils spiked with hexavalent chromium

ABSTRACT Indoor incubation experiment was conducted under flooding (FD), 100% field capacity (100% FC), and alternating wetting and drying (AWD) conditions for 90 days using Guangdong (GD) and Jiangxi (JX) paddy soils spiked with hexavalent chromium [Cr(VI)]. The chromium speciation and availability were investigated usingsequential extraction, diethylene triamine pentaacetic acid (DTPA) leaching, and alkali solution extraction methods. The concentrations of Cr(VI), acid-extractable Cr and DTPA-Cr were reduced by 72%–89%, 48%–81%, and 42%–98%, respectively, at 90 d compared with 1 d. The sequence for acid-extractable Cr and DTPA-Cr concentrations was 100% FC>AWD>FD. While, it was AWD>100% FC>FD for Cr(VI) concentrations. Acid-extractable Cr, DTPA-Cr, and Cr(VI) concentrations in JX soil were higher compared with GD soil. The changes of DTPA-Cr concentrations were well fitted by Elovich kinetic model. These findings revealed water management and aging greatly affected chromium speciation and availability, having potential implications for sustainable agriculture and human health.

Macadamia nut residue-derived biochar: An eco-friendly solution for β-naphthol and Reactive Black-5 removal

The generation of liquid waste containing dyes and complex organic compounds is a problem in the textile industries. In this work, we evaluated the use of macadamia nut residue as a precursor of a biochar for the treatment of these effluents through the adsorption process. The macadamia nut endocarp undergoes a sequential treatment involving pyrolysis at 600 °C followed by physical activation with CO2 and H2O vapor at 700 °C. Characterization of the resulting macadamia nut residue-derived biochar (MB) is accomplished through various techniques, including X-ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), nitrogen physisorption analysis and the pH at the zero charge point (pHZCP). Performance studies reveal that pH exerts minimal influence on the adsorption phenomenon. The Elovich kinetic model effectively describes the adsorption kinetics for both β-naphthol and Reactive Black 5 (RB5), with adjusted coefficients of determination (R2adj) of 0.99 and 0.94, respectively. Further analysis using the intraparticle diffusion model demonstrates that β-naphthol adsorption kinetics involve multiple mechanisms, while RB5 adsorption is predominantly governed by intraparticle diffusion. Equilibrium adsorption data for both adsorbates fit well with the Sips isothermal model, yielding maximum adsorption capacities of qmax β-naphthol = 15.16 mg∙g−1 and qmax RB5 = 3.08 mg∙g−1 at 55 °C. The adsorption process for both compounds is spontaneous and endothermic, based on the enthalpy values, it can be inferred that the β-naphthol adsorption is governed by weak van der Waals forces, indicating physisorption. As for RB5, the enthalpy value suggests that the phenomenon occurs due to electrostatic interactions between the molecule and the surface groups with higher energy involved. This study highlights the potential of macadamia nut residue biomass as a precursor for biochar, demonstrating its favorable attributes for application as an effective adsorbent material in the removal of organic compounds such as β-naphthol and RB5 from wastewater streams within the textile industry.

Enhanced adsorption of Cr(VI) pollutants using CaFe2O4@rGO modified-biochar derived from mixture of black soldier flier exuviae and durian peel

To solve the problem of hexavalent chromium (Cr(VI))-polluted water sources, mixed black soldier flier exuviae (BSFE) and durian peel (DP)-derived biochar modified with CaFe2O4@rGO (BC-CFr) was synthesized to remove Cr(VI) from wastewater. Our findings indicated that the adsorption of Cr(VI) on BC-CFr reached a maximum at a pH of 2.0, biochar dosage of 0.3 g/100 mL, and initial Cr(VI) concentration of 50 mg/L, with a Cr(VI) adsorption capacity of 30.8 mg/g, which was approximately two times greater than that on pristine biochar (PBC). The characterization results showed that the as-prepared modified biochar was rich in surface functional groups, including amine groups (−NH2) and active sites. Cr(VI) adsorption followed the Elovich kinetic and Freundlich isotherm models, illustrating the adsorption process involved multilayer on the heterogeneous surface. The thermodynamic study confirmed the adsorption process was endothermic. The proposed adsorption mechanisms included adsorption-coupled reduction, electrostatic attraction, and pore filling. This study provided a simple method to prepare compositing biochar using abundantly available agricultural by-products that dealt with the dual problems of Cr(VI)-contaminated water and agricultural solid waste. Besides, the BC-CFr exhibited high desorption performance and recyclability over five consecutive adsorption-desorption cycles, suggesting the BC-CFr is a feasible nanocomposite biochar for effectively removing Cr(VI) from wastewater in practice.

Utilization of dragon fruit (Hylocereus undatus) peel-derived biochar for the adsorptive removal of tetracycline from aqueous solution

The peel of Hylocereus undatus was employed in the preparation of biochar and firstly applied for tetracycline removal from aqueous solution. Based on different characterization techniques, the material was found to possess a variety of surface functional groups on a porous structure and a pH point of zero charge (pHpzc) of 9.3. Adsorption of tetracycline (TC) was conducted under varying conditions, revealing significant effects of carbonization temperature, solution pH, adsorbent dose, ionic strength, contact time and initial concentration of TC on the biochar adsorption capacity. Kinetic data on TC adsorption were best described using the Elovich kinetic model, with an initial adsorption rate of 167.3 mg g−1 min−1. Isotherm data on adsorption of the desired biochar showed the best fit with the Temkin isotherm model, followed by the Langmuir model, displaying maximum adsorption capacity at 12.4 mg g−1. The electrostatic interactions between the charged biochar surfaces and certain fractions of TC were proposed as the major mechanism, together with H-bonding, pore-filling effect and π–π interaction. This study demonstrates great potential of H. undatus peel as a starting material to prepare an effective and reusable adsorbent in the removal of TC.

Preparation of CMC-MF/FeO(OH) by growing ferric nanoparticles on melamine foam in-situ for effective phosphate removal

Nanocomposite adsorbents composed of a bulk matrix and metal nanoparticles have garnered significant attention for phosphorus (P) removal. However, many nanocomposite adsorbents have been synthesized in harsh environments involving high temperature or high energy consumption, which do not meet industrial requirements; on the other hand, lots of adsorbents are synthesized by directly depositing metal hydroxides on bulk matrixs, leading to the active components shedding from the matrix due to the lack of chemical anchoring sites to immobilize metal oxide. To overcome the limitations of the existing methods, we synthesized a nanocomposite adsorbent named CMC-MF/FeO(OH) using a facile method in a mild environment. It involved coating an anchoring film prepared with carboxymethyl cellulose sodium (CMCNa) on melamine foam (MF) for in-situ growth of ferric nanoparticles. Our results demonstrated that the CMC-MF/FeO(OH) adsorbent showed promising efficiency in phosphate removal. The adsorption process was effectively described by Elovich kinetic model and Freundlich isotherm model. The adsorption mechanism was ascribed to the chemisorption by inner-sphere complex along with physical adsorption. A maximum adsorption capacity of 31.579 mg P/g which calculated by Langmuir isotherm model was achieved at 45 °C and natural pH condition in experimental range. The adsorbent exhibited effective P adsorption even in harsh environments, with the process being spontaneous and exothermic. In column applications, the CMC-MF/FeO(OH) adsorbent reduce the P content of wastewater from 4 mg P/L to 0.5 mg P/L within a short empty bed contact time of 190.95 s. Furthermore, the adsorption capacity reached 8.87 mg P/g in a column study, and trace P levels in lake water decreased to undetectable levels in a lake experiment, effectively inhibiting algae growth.

Innovative pyrazole–phosphoramidate derivative for effective mercury adsorption and their application for Egyptian industrial waste samples

ABSTRACT Mercury, known for its severe health and environmental impacts even in trace amounts, necessitates effective removal from water systems. This research focuses on preparation of a novel adsorbent of 3,9−bis((4−amino−5−hydroxy−1 H−pyrazol−3−yl)amino)−2,4,8,10−tetraoxa−3,9−diphosphaspiro[5.5] undecane 3, 9−dioxide (PADP) for Hg(II) ions adsorption. To validate functionalization steps and elucidate PADP’s physical and chemical properties, a comprehensive array of assays, including FTIR, surface area, BET, TGA, 13CNMR, Mass spectra, 31PNMR and1HNMR were employed. The study systematically examined several factors controlling mercury sorption, including temperature, adsorbent dosage, pH, interaction time, and mercury concentration using the batch technique. Optimal sorption effectiveness was achieved at pH 5, with an interaction time of 50 min, an 80 mg adsorbent dose, at ambient temperature. The newly devised adsorbent exhibited an impressive adsorption capacity (qe) of 357 mg of Hg(II) per Litre, with empirical data fitting the Langmuir and Dubinin−Radushkevich adsorption isotherm models. The kinetics of mercury sorption followed second-order and Elovich kinetics models. Thermodynamic aspects, including ΔGº, ΔSº, and ΔHº, were also investigated, providing appreciated perceptions into the energetic dynamics of the sorption process. Thermodynamics has shown that the sorption of mercury ions is both endothermic and spontaneous. Additionally, mercury adsorption in the occurrence of other ions was explored, highlighting the selectivity of the modified Pyrazole – Phosphoramidate adsorbent for mercury removal. PADP demonstrates superior performance in removing Hg(II) from wastewater effluents, outshining a range of both natural and synthetic adsorbents previously used for this purpose. This superiority is evident when comparing its adsorption capacity (qo) against those of other adsorbents, showcasing its exceptional efficacy in purifying water from mercury contamination.

MIL-88A(Al)/chitosan/graphene oxide composite aerogel with hierarchical porosity for enhanced radioactive iodine adsorption

To ensure the sustainable development of the nuclear industry, the effective capture of radioiodine from nuclear wastewater has attracted much attention. Herein, a novel MIL-88A(Al)/chitosan/graphene oxide (MCG) composite aerogel was prepared by using crosslinked chitosan and graphene oxide as the 3D network skeleton, and MIL-88A(Al) nanocrystalline particles were introduced into the skeleton by freeze-drying method. MIL-88A(Al) adsorption capacities for volatile and soluble iodine were 2.02 g g−1 and 850.00 mg g−1, respectively. Owing to the synergistic effect of MIL-88A(Al), GO, CS, and the hierarchically porous structures of the MCG aerogel, the adsorption capacities for volatile and soluble iodine by the MCG aerogel were increased to 2.62 g g−1 and 1072.60 mg g−1, respectively. Furthermore, the adsorption performance of the MCG aerogel for volatile and soluble iodine could be maintained at 83 % and 82 % after 5 cycles, suggesting excellent recoverability. Meanwhile, the adsorption mechanism studies showed the interactions between iodine and NH, AlO, and CO in MCG aerogel. Furthermore, the adsorption process is consistent with the Elovich kinetic and Sips isotherm models. MCG aerogels are potential candidates for enhanced radioiodine adsorption due to their high radioiodine capture performance and excellent recyclability.

Adsorption of amitriptyline from aqueous solutions using magnetic graphene-based material: Isotherm, kinetics, and thermodynamic study

Amitriptyline (AMT) is an antidepressant often found in water environments. Due to its toxicity, in this work, AMT adsorption was proposed using graphene oxide (GO) and magnetic GO (GO·Fe3O4 1:1). The adsorbent characterizations were accomplished by FTIR, SEM, EDS, Raman spectroscopy, XRD, and VSM revealed the typical characteristics of the pristine GO and GO·Fe3O4 1:1. In the batch adsorption study, GO·Fe3O4 1:1 showed the highest adsorption capacity (91.84 mg g−1) and removal percentage (92 %) (at pH = 9.0, C0 = 50.0 mg L−1, adsorbent dosage = 0.5 g L−1, the temperature at 293 ± 1.00 K). Moreover, the Sips model showed the best adjustment for isothermal experimental data. This model suggests that the adsorption occurs at heterogeneous surfaces when the qs value increases with the increase in temperature (from 235.57 mg g−1 at 20 ºC to 463.34 mg g−1 at 50 ºC). The thermodynamic study confirms that AMT adsorption onto GO·Fe3O4 1:1 is a spontaneous and endothermic process (ΔH = 32.75 kJ mol−1). Elovich kinetic model presented the best adjustment for experimental data and showed that the adsorption rate (α) and surface coverage constant (β), decrease with the increase of the adsorbate dosage. Additionally, the ionic strength study reveals that a high concentration of NaCl (1.0 M) decreases the qe to 25.74 mg g−1. Lastly, after five consecutive adsorption/desorption cycles, the removal percentage of GO·Fe3O4 1:1 remained elevated (79 %). Overall, this paper reports the efficiency of GO·Fe3O4 1:1 on AMT removal, in addition to investigating the several variables involved in this adsorption.

β-cyclodextrin-functionalized coffee husk biochar for surfactant adsorption

In this study, biochar was produced from coffee husks and further functionalized with β-cyclodextrin to remove sodium dodecylbenzenesulfonate (SDBS) and cetylpyridinium chloride (CPC) surfactants from aqueous solution. The effect of pre-pyrolysis treatment of the coffee husks with NaOH, as well as the type of crosslinking agent, on the functionalization was evaluated. The biochars were characterized by FTIR, Raman spectroscopy, TGA, SEM, EDS, and chemical analysis. Adsorption kinetics and equilibrium isotherms were investigated in aqueous solutions. SDBS adsorption was not favored under all the investigated materials and conditions. The functionalized biochars showed better CPC removal (57.5 mg g−1 for glutaraldehyde functionalized biochar, and 113.6 mg g−1 for epichlorohydrin functionalized biochar) compared with non-functionalized biochars (55.8 mg g−1 for non-treated biochar and 35.1 mg g−1 for NaOH pre-treated biochar). The functionalized materials showed better CPC adsorptive capacity than prior literature reports. The adsorption data of CPC fit best to the Elovich kinetic model and Sips isotherm. Thermodynamic studies revealed that CPC adsorption is an endothermic process. The results indicated that β-cyclodextrin functionalization increased CPC removal, but electrostatic interactions acted as important mechanism for the adsorption. This work extends the range of applications for β-cyclodextrin-functionalized biochars by offering new design strategies for developing biochar-based adsorbents aimed at surfactant wastewater removal.

Fabrication of Nanocellulose/Chitosan Nanocomposite Based on Loofah Sponge for Efficient Removal of Methylene Blue: Thermodynamic and Kinetic Investigations

AbstractWe established three nano-solid adsorbents: nanocellulose based on plant loofah sponge (NC), chitosan (CS), and nanocellulose/chitosan composite (CSC). These substances were employed as solid adsorbents to eliminate methylene blue (MB) dye from wastewater. Various characterization techniques were employed to investigate all the synthesized solid adsorbents, including TGA (thermogravimetric analysis), XRD (X-ray diffraction spectra), (BET) nitrogen gas adsorption-desorption, SEM (scanning electron microscope), TEM (transmission electron microscopy), FTIR (Fourier transform infrared) spectrometer, and zeta potential. According to our results, CSC showed greater thermal stability than LS and NC but lower than CS, mesoporous (2.012 nm), higher total pore volume (0.366 cm3. g− 1), specific surface area (639.3 m2. g− 1), and pHpzc of 7.22. The static adsorption of MB was well described by the Langmuir (R2 > 0.9872), Temkin (R2 > 0.9668), and Dubinin-Radushkevich (R2 > 0.9485) models. The composite of nanocellulose and chitosan exhibited the highest Langmuir adsorption capacity (301.20 mg. g− 1) at 47 °C after a 24 h shaking period at a dosage of 2 g. L− 1 as the adsorbent and pH of 7. The adsorption of MB by the fabricated solid materials fitted well with the linear PSO (R2 > 0.9806) and Elovich (R2 > 0.9574) kinetic model. The enthalpy, entropy, and free energy change for the adsorption of MB onto CSC were determined to be 47.11 kJ. mol− 1, 0.172 kJ. mol− 1. K− 1, and − 3.29 kJ. mol− 1, respectively at 20 °C. Thermodynamic investigation showed that MB adsorption is spontaneous, endothermic, favorable (0 < RL<1, 0.017–0.313), and physisorption (EDR < 8 kJ. mol− 1). Compared to the other eluents, nitric acid produced the highest desorption percentage (98.5%).

A novel approach for modification of montmorillonite using banana peel ash extract for enhanced adsorption efficiency of methylene blue dye

Water contamination from dyes is a major issue that needs to be solved effectively. Addressing this issue, the study aims to improve the adsorption capacity of montmorillonite (MMT) by its modification for removing methylene blue (MB) dye. Powder XRD, FTIR, FESEM, HRTEM, BET, and XPS were employed to analyze the modified materials. Various parameters were studied to optimize the adsorption efficiency of modified MMT. To enhance the removal efficiency of MMT (70.05 ± 0.16 %), this study has modified MMT with banana peel ash extract (BPAE) which achieved maximum MB removal of 98.54 ± 0.31 % under neutral pH, with an equilibrium time of 150 min, initial dye concentration of 120 mg/L, and adsorbent dosage of 1.4 g/L at ambient temperature (32 °C). Among the isotherm models, the Langmuir model showed a maximum adsorption capacity of 100 mg/g. Experimental data fitted well with the Elovich kinetic model. Reusability was efficient up to the third cycle, retaining 56.96 ± 0.39 % efficiency.

Characterization of phosphate modified red mud-based composite materials and study on heavy metal adsorption.

In this paper, Bayer red mud (RM) and lotus leaf powder (LL) were used as the main materials, and KH2PO4 was added to modify the material. Under the condition of high-temperature carbonization, RMLL was prepared and phosphate modified red mud matrix composite (PRMLL) was prepared based on KH2PO4 modification, which can effectively remove Pb2+ from water. The optimum preparation and application conditions were determined through orthogonal experiment: dosage 0.1g, ratio 1:1, and temperature 600 °C. The effects of pH, dosage, and initial concentration on the adsorption of Pb2+ were studied. The pseudo-first-order, pseudo-second-order, and Elovich kinetic models were fitted to the experimental data. It was found that RMLL and PRMLL were more consistent with the pseudo-second-order kinetic model and chemisorption. Langmuir, Freundlich, Timkin, and Dubinin-Radushkevich isothermal adsorption models were used to fit the experimental data. It was found that RMLL and PRMLL were more consistent with Langmuir model. In addition, the maximum adsorption capacity of RMLL and PRMLL was 188.1 mg/g and 213.4 mg/g, respectively. It is larger than the adsorption capacity of their monomers. Therefore, the use of RMLL and PRMLL as the removal of Pb2+ from water is a potential application material.

Using Excel Solver’s Parameter Function in Predicting and Interpretation for Kinetic Adsorption Model via Batch Sorption: Selection and Statistical Analysis for Basic Dye Removal onto a Novel Magnetic Nanosorbent

Magnetic nanosorbents efficiently capture substances, particularly basic dyes, and can be easily recovered using a magnetic field in water treatment. Adsorption is a cost-effective and highly efficient method for basic dye removal. This study compared eight nonlinear kinetic adsorption models using Microsoft Excel 2023, which provided a detailed analysis and statistical results comparable to advanced programs like MATLAB and OriginPro. The Fractal Like-Pseudo First Order (FL-PFO) model showed the best fit for the kinetic adsorption model, closely predicting experimental data at 33.09 mg g−1. This suggests that the diffusion rate of basic dye within the magnetic nanosorbent pores is a crucial factor. The statistical parameters confirmed the suitability of these kinetic adsorption models for describing the observed behavior. Overall, Microsoft Excel emerged as a reliable tool for predicting adsorption behavior using various kinetic models for basic dye removal, offering a wide range of functions for diverse applications, including environmental monitoring and modeling. Corrected Akaike’s information criterion was used to determine the optimal model. It found the lowest AICcorrected value of about −3.8479 for the FL-PFO kinetic model, while the Elovich kinetic adsorption model had the highest AICcorrected value of 29.6605. This indicates that the FL-PFO kinetic model effectively correlated the kinetic data. It can be concluded that Microsoft Excel’s accessibility, familiarity, and broad range of capabilities make it a valuable resource for many aspects of environmental engineering.

Lanthanum and cerium functionalised forestry waste biochar for phosphate removal: Mechanisms and real-world applications

Phosphorus as a diminishing finite resource, yet is an essential element for the growth of biota. However, elevated concentrations in water can imbalance ecosystems and cause eutrophication. To address both problems, two highly efficient biochars, namely La-OB and CeLa-OB were synthesised by lanthanum and cerium doping. The performance of La-OB and CeLa-OB were evaluated in both batch and dynamic regimes with synthetic phosphate (PO43--P) solutions and eutrophic lake water. PO43--P adsorption mechanisms were investigated in terms of pH, kinetics, isotherms, activation energy, thermodynamics and using in-depth characterisation (XPS, FTIR, XRD, BET, pHpzc and SEM-EDX). The feasibility of using such biochar in ‘real life’ situations was studied with column filtration of lake water with low and high PO43--P concentrations. Reusability/desorption and toxicity in the water environment was also considered. The mechanistic study showed that both biochars predominantly had inner-sphere complexes with La and Ce ligands (as a monolayer), while outer-sphere complexation was less common. The exothermic adsorption process followed the Elovich kinetic and Langmuir isotherm models, with a maximum adsorption capacity of 112 mg/g for La-OB and 40 mg/g for CeLa-OB. In column filtration trials the adsorption capacity reached 78 mg/g, while low metal leaching (0.08 mg/L) and low toxicity to Lepidium sativum germination were detected. The results indicated that these biochars, especially La-OB, could be used in circular economy-based water treatment.