Redlich-Peterson Isotherm Research Articles

Investigation of the adsorptive capacity of a poly(vinyl alcohol)-based film for sodium diclofenac in aqueous media

Sodium diclofenac (DCF) has been detected in waters worldwide and is considered a micropollutant of emerging concern due to its potential toxicity in aquatic and terrestrial ecosystems. Traditional water treatment methods are unable to remove DCF completely from water, which makes adsorptive films a suitable alternative to address this challenge. In this context, the present study investigated the adsorptive capacities of a poly(vinyl alcohol)-based film for removing DCF from aqueous solutions. The effects of the initial DCF concentration and solution pH on the adsorption performance were evaluated, as well as kinetics and equilibrium isotherms. Regarding the results, DCF precipitation was observed within a pH range of 4.0-7.0, probably due to its limited solubility in acidic media. The optimal DCF concentration was found to be the lowest tested (2.5 mg L-1), yielding an equilibrium adsorption capacity (qe) of 0.511 mg g-1 and a DCF removal percentage (%R) of 23.4% within 90 min. Although the adsorption equilibrium was well described by the Redlich-Peterson isotherm despite the unusual behavior observed, pseudo-first and pseudo-second order kinetic models were satisfactory only at the initial concentration of 2.5 mg L⁻¹. Overall, the data set indicate that the film has a limited adsorption capacity, reaching saturation at low adsorbate concentrations. Nonetheless, these findings support further investigations at lower DCF concentrations to better understand the film’s adsorptive behavior under environmentally relevant conditions.

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.

Synthesis of high-ordered mesoporous aluminosilica monoliths using triblock copolymer and application in the water purification

Mesoporous aluminosilica particulates (MASP) offer a high surface area and specific structural properties that make them effective for adsorbing specific contaminants from drinking water. The MASP’s surface characteristics were studied by SEM, TEM, Mapping-EDX, and BET analysis. Through the use of a batch adsorption approach, this work sought to examine the adsorption behavior of MASP sorbent towards Cd(II) ions at different pH values, time intervals, sorbent doses, and temperatures. MASP’s maximal capacity for Cd(II) ions uptake was 16.5 mg/g at pH 6.5, 25 °C, 0.1 g dose, and 5 h of sorption time. The pseudo-first-order model provided a good description of the uptake process. The best-fitting isotherm was found to be the Langmuir and Redlich–Peterson isotherm. The method came out to be exothermic and spontaneous by thermodynamic analysis. MASP demonstrates durability and reusability during over ten regeneration cycles.

Tailoring of carboxymethyl guar gum hydrogels via gamma irradiation for remarkable removal of cationic and anionic dyes from simulated solutions

Tailoring of carboxymethyl guar gum hydrogels via gamma irradiation for remarkable removal of cationic and anionic dyes from simulated solutions

Ibuprofen Removal by Aluminum-Modified Activated Carbon (AC@Al) Derived from Coconut Shells

In this study, a new composite adsorbent consisting of aluminum-modified activated carbon (abbreviated hereafter AC@Al) was synthesized for the removal of the Ibuprofen compound (IBU), a non-steroidal anti-inflammatory drug (NSAID). Coconut shells were used as a source material for activated carbon, which was then modified with AlCl3 to improve its properties. Adsorbent dosage, pH and initial IBU concentration, as well as contact time and temperature, are some of the factors affecting adsorption that were investigated in this work. Specifically, at pH 2.0 ± 0.1 with the application of 0.5 g/L of AC@Al in 100 mg/L of IBU, more than 90% was removed, reaching 100% with the addition of 1.0 g/L of the adsorbent. The IBU kinetic data followed the pseudo-second-order kinetic model. Non-linear Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models were used to interpret the adsorption. According to the correlation coefficient (R2), the Langmuir model was found to best match the experimental data. The maximum adsorption capacity (Qmax) according to the Langmuir model was found to be as high as 2053 mg/g. The positive values of ΔH0 (42.92 kJ/mol) confirmed the endothermic nature of the adsorption. Due to the increasing values of ΔG0 with temperature, the adsorption of IBU onto AC@Al proved to be spontaneous. Also, the adsorbent was regenerated and reused for five cycles. This study shows that AC@Al could be used as a cost-effective adsorbent.

Anchored Chitosan-Functionalized Magnetite Nanoparticles for Crystal Violet Decolorization from Aqueous Samples.

In this research, 3-(triethoxysilyl)propyl isocyanate (TESPIC) functionalized chitosan was successfully synthesized to fabricate silica-coated magnetite nanoparticles (Fe3O4@SiO2-CS MNPs). The synthesized MNPs were characterized using XRD, FT-IR, SEM, and TEM instruments and were utilized for the decolorization of Crystal Violet cationic dye (CV). The affecting variables controlling CV removal efficiency were investigated using the Taguchi fractional factorial design method (L16 array). Under the optimized removal conditions (adsorbent amount = 0.12 g (4.8 g L-1), pH = 4, ionic strength = 0.05 mol L-1 NaCl, and 30 min stirring), 98.2% of the CV dye was eliminated. The kinetic and equilibrium adsorption isotherms were explained by the pseudo-second-order kinetic (R2 = 0.999) and Freundlich isotherm models, respectively. MATLAB's fmincon function as an efficient solution was applied in order to compare the Redlich-Peterson three-parametric isotherm model with two-parametric models. Moreover, the Fe3O4@SiO2-CS-TESPIC MNPs showed recyclability and reusability for subsequent runs. The findings confirmed that these functional MNPs can be considered as proper adsorbents for the removal of CV dye from the aqueous solutions.

Metal-modified biochars prepared from blue algae and their ability of adsorbing phosphates from water and utilization as soil amendment

The problem of blue algae accumulation can be alleviated by utilizing blue algae as biomass for resource utilization, which can remove excess phosphates from water to alleviate eutrophication. Herein, Magnesium (Mg) and/or lanthanum (La) were used to modify biochar via high-temperature slow pyrolysis with blue algae as the raw biomass. These modified biochars exhibited abundant carbon (18.0 %-50.3 %), oxygen content (17.4 %-49.1 %), along with a high specific surface area (82.26–233.80 m2/g). The surface of metal-modified biochar was enriched with hydroxyl and carboxyl groups and metal elements were efficiently incorporated into biochars. Adsorption kinetic and isotherm experiments were conducted under the optimal pyrolysis temperature of 600 °C, pH of 6.0, and adsorbent dosage of 2.0 g/L. The adsorption kinetics studies by metal-modified biochars for phosphate fitted well pseudo-second-order model Redlich-Peterson isotherm model. Biochar modified by Mg and La exhibited the highest removal efficiency (97.8 %) for phosphate at adsorption equilibrium. The adsorption mechanism involved the electrostatic interaction between hydroxylated metal oxides and negatively charged phosphate ions and the precipitation of phosphate ions through chemical reactions with metal oxides in the solution. After phosphate adsorption, the pristine and metal-modified biochars derived from blue algae were applied as the soil amendment. Biochar adsorbed phosphate apparently improved the germination rate of seeds facilitated the height, width, weight, and chlorophyll content of vegetable seedlings, and induced oxidative stress, which proved that the biochar recovered after adsorption was a high-quality soil amendment. This study provides a new approach for the treatment of phosphate wastewater and the algae application.

Cnicus Benedictus roots as a low-cost adsorbent for methylene blue dye removal from aqueous solution: kinetic and equilibrium studies

In this research, Cnicus Benedictus roots powder (CBRP) was utilized as a low-cost adsorbent for removing methylene blue (MB) as a cationic dye from aqueous solution. Characterization of CBRP by Boehm titration method, Fourier transform infrared (FT-IR) and environmental scanning electron microscope (ESEM) indicates the presence of different types of functional groups and a very rough surface filled with cavities, suitable for MB adsorption. The effect of various parameters such as CBRP dose (0.2–2 g/1L), contact time (0–180 min), initial pH (1–10), coexisting anions/cations and the initial MB concentration (100–500 mg L−1) on MB adsorption were examined, the results showed that MB uptake depends on the pH of solution, the electrostatic attraction forces, the formation of H-bonds and π–π interactions are the possible CBRP–MB interaction mechanisms. Adsorption kinetic of MB on CBRP was best represented by linear and non-linear form of the pseudo-second order model. The experimental equilibrium data were best described by linear and non-linear forms of Langmuir and Redlich–Peterson isotherm models (R 2> 0.98) with a maximum MB adsorption capacity of 85.47 mg g−1 at 25 °C, the adsorption efficiency R (%) was greater than 90 (%). MB adsorption-desorption experiments showed the reusability of CBRP for five consecutive cycles. According to the obtained results, CBRP can be used as a natural adsorbent material for cationic dyes removal from aqueous solution.

Sctudies on adsorption of Brilliant Green from aqueous solution onto nutraceutical industrial pepper seed spent

The study proposed the removal of Brilliant Green, a cationic dye, by adsorption process from wastewater solution utilizing a low-cost adsorbent such as Nutraceutical Industrial Pepper Seed Spent (NIPSS). The study comprises an investigation of the parametric influence on the adsorption process. The parameters identified are pH, dye concentration, process temperature, quantity of the adsorbent, and particle size. The study of statistics found from experiments was carried out by incorporating Freundlich, Brouers-Sotolongo, Langmuir, Toth, Sips, Jovanovic, and Redlich-Peterson isotherm models. The adsorption kinetics were determined by implementing pseudo-first-order and second-order models, diffusion film models, and Dumwald-Wagner and Weber-Morris models. The experimental adsorption capacity qe was found to be about 130 mg/g. This value was closest to the maximum adsorption of 144.6mg/g predicted by the Brouers-Sotolongo isotherm which had a correlation coefficient (R2) of 0.998. The adsorption kinetics data was confirmed to be a pseudo-second-order model. The change in free energy, enthalpy change, and entropy change were vital thermodynamic factors in concluding that adsorption is almost spontaneous and endothermic process. Change in enthalpy (ΔH°) reduced value indicates the physical nature of the process. The adsorption of BG dye on the adsorbent surface was authenticated by FTIR spectroscopy and SEM imaging. A Central Composite Design (CCD) Quadratic model under Response Surface Methodology (RSM) was implemented for statistical optimization of adsorption capacity for the five parameters studied, namely, time, temperature, concentration of the dye, weight of the adsorbent, and pH. Software Design Expert 7.0 was used to evaluate 3D contour plots. The process of optimization yielded a value of 350 mg/g. Thus, incrementing the adsorption process by 84.2 %. The study provides insights on various dye and adsorbent interaction possibilities and derives that NIPSS is an efficient adsorbent to extract BG dye from wastewater solutions.

Synthesis and application of MgCuAl-layered triple hydroxide/carboxylated carbon nanotubes/bentonite nanocomposite for the effective removal of lead from contaminated water

A novel multicomponent adsorbent nano-composite was synthesized by intercalating bentonite clay and carboxylated carbon nanotubes (CNT-COOH) into MgCuAl-layered triple hydroxide (MgCuAl-LTH), abbreviated as LTH/CNT-COOH/Bent. The produced nano-composite, its parental materials, and their binary combinations were characterized using various techniques. Pore filling was noted based on the BET analysis, hence, indicating effective component integration in the nano-composite structure. Further, distinct peaks appearing on the FTIR and XRD spectra of the single materials also appeared on the synthesized composites (including the binary combinations of the parental materials), hence, further indicating the successful synthesis of the targeted adsorbents. The effects of process parameters including pH, adsorbent dose, lead initial concentration and contact time on lead removal, were explored. In general, the application of LTH/CNT-COOH/Bent adsorbent yielded a significant improvement in lead adsorption capacity (∼260.8 mg/g) relative to all parental materials and their binary combinations. It was revealed that the adsorbent dose and lead initial concentration are the most significant factors affecting lead uptake onto the synthesized adsorbent and the adsorption kinetics was fast. The obtained results indicated that the Avrami kinetic and Redlich-Peterson isotherm models best fit the lead adsorption kinetics and isotherm experimental results, respectively. Furthermore, the response surface methodology (RSM) technique was employed for optimization of lead removal, achieving near complete removal (>99 %) at LTH/CNT-COOH/Bent dose of 0.5 g/L, lead initial concentration of 40 ppm and a time of 2 h. Additionally, the machine learning (ML) and the ANN based models for lead removal using LTH/CNT-COOH/Bent nano-composite yielded good predictions.

New hybrid adsorbent based on APTES functionalized zeolite W for lead and cadmium ions removal: Experimental and theoretical studies

Water pollution remains a primary worldwide concern, requiring various treatment technologies for efficient and effective remediation. In recent years, zeolites have gained extensive attention as promising materials and approaches for removing heavy metals from wastewater. This study presents a new hybrid adsorbent based on zeolite W (ZW) chemically modified with aminopropyltriethoxysilane (APTES), demonstrating excellent Pb(II) and Cd(II) removal efficiency, was developed. The prepared zeolites were characterized using several advanced techniques. XPS, NMR, FTIR spectroscopy, elemental analysis and TGA confirmed the successful functionalization via covalent bonds between the zeolite W inorganic surface and the available APTES silanol groups. The adsorption behavior of both metal ions onto the prepared zeolites was well-fitted by the Redlich-Peterson and Langmuir isotherms, and the Pseudo-second order model. Results showed that ZW@APTES provides a larger adsorption capacity than ZW under all studied experimental conditions. The maximum adsorption capacity of ZW@APTES for Pb(II) and Cd(II) reached 421.7 and 253.5 mg/g, respectively. Moreover, batch experiments indicated that ion exchange and surface complexation with weak chemical bonds were the main adsorption mechanisms for Pb(II) and Cd(II). This study demonstrates that APTES-modified zeolite W could be a valuable and promising material for removing heavy metal ions from contaminated water in real-world applications.

Preparation of efficient adsorbent for methylene blue and Congo red by co-hydrothermal of red mud with food waste compost

Herein, a novel red mud-carbon composite (RFBC) was prepared through co-hydrothermal treatment of red mud with food waste compost, and its adsorption property was evaluated on Methylene blue (MB) and Congo red (CR), selected model dyes in aqueous solution. The adsorption process conformed to pseudo-second-order kinetic, intraparticle diffusion, and the Redlich-Peterson isotherm models. RFBC exhibited a maximum sorption of 124.06 mg·g-1 for MB and 2959.35 mg·g-1 for CR at 298 K. Isothermal and thermodynamic studies demonstrated that adsorption of MB and CR by RFBC were spontaneous and exothermic, governed by physisorption and chemisorption. Furthermore, the possible adsorption mechanisms are pore filling, electrostatic attraction, hydrogen bonding, and π-π interactions. After five consecutive adsorption-desorption cycles were completed, the RFBC demonstrated an adsorption efficiency exceeding 70 % in relation to dyes, affirming its exceptional reusability. This study suggested this red mud-carbon composite had high potential as a novel and promising adsorbent for dye removal from wastewater.

Alginate-Based Hydrogel Bead Reinforced with Montmorillonite Clay and Bacterial Cellulose-Activated Carbon as an Effective Adsorbent for Removing Dye from Aqueous Solution.

According to environmental concerns related to water pollution, this study aims to develop a novel hydrogel bead as a biocompatible and efficient adsorbent by integrating bacterial cellulose-activated carbon (BCAC) and montmorillonite (MT) in alginate hydrogel (ALG). The ionotropic gelation method was applied to the fabrication of BCAC/MT/ALG hydrogel beads. The BCAC/MT/ALG hydrogel bead exhibited significantly higher tensile strength, Young's modulus, and thermal stability, with ~1.4 times higher adsorption uptake of methylene blue (MB) from aqueous solution as compared to the pristine ALG bead. The textural properties, including specific surface area and porosity, were beneficial to accommodate the size of cationic MB as the target molecule. This resulted in a remarkable MB adsorption uptake of 678.2 mg/g at pH 7 and 30 °C. The adsorption isotherm showed the best fit for the nonlinear Redlich-Peterson isotherm model. Experimental adsorption data were well-described by the pseudo-second order kinetic model, with R2 values reaching 0.997. In addition, the adsorbent bead demonstrated easy regeneration with high reusability with approximately 75% of MB removal after being used for six cycles. Therefore, BCAC/MT/ALG bead represents an eco-friendly, cost-effective, and highly efficient adsorbent for MB removal from water and could potentially be used for removal of a wide range of cationic dye pollutants from wastewater.

High-performance removal of methylene blue dye using porous lignin extracted from sugarcane bagasse by deep eutectic solvent

This study evaluated the ability of triethyl benzyl ammonium chloride/lactic acid deep eutectic solvent extracted lignin (TEBAC/LA-DES-L) to adsorb methylene blue (MB) without additional functional group modification. The structure and morphology of TEBAC/LA-DES-L were characterized using SEM, BET, FT-IR, and TGA techniques. Various factors influencing MB adsorption, such as extraction temperature, solution pH, adsorbent dose, initial MB concentration, adsorption time, and reaction temperature, were investigated. The Redlich-Peterson isotherm displayed a good fit for the experimental data, with a maximum adsorption capacity of 85.16 mg/g. Kinetic analysis suggested that the adsorption process followed the pseudo-second-order model, with adsorption occurring in <100 min on DES-L-4 h. The mechanism of MB adsorption on DES-L-4 h was attributed to electrostatic attraction, hydrophobic interactions, and hydrogen bonding forces. Overall, DES-L-4 h demonstrated high adsorption capacity and rapid adsorption rate, making it a promising adsorbent for effectively removing cationic dyes from wastewater.

Efficient Removal of Mercury from Wastewater Solutions by a Nitrogen-Doped Hyper-Crosslinked Polyamine.

Mercury, a highly toxic metal and pollutant, poses a significant risk to human health and the environment. This study describes the synthesis of a new nitrogen-doped heteroaromatic hyper-crosslinked polyamine (HCPA) via the polycondensation of 2,6-diaminopyrazine and tris(4-formylphenyl)amine for the efficient removal of mercury ions from aqueous solutions. The HCPA polymer was characterized by solid-state 13C-NMR and FT-IR spectroscopy. A powder X-ray diffraction and thermogravimetric analysis showed that the polymer was semicrystalline in nature and stable up to 500 °C. Adsorption isotherms indicated that mercury adsorption occurred via mono- and multilayer adsorption by HCPA, as depicted by the Langmuir, Freundlich, and Redlich-Peterson isotherm models, with a maximum adsorption capacity of qm = 333.3 mg/g. Adsorption kinetic models suggested that the adsorption process was fast and effective, reaching equilibrium within 20 min. Thermodynamics of the adsorption process revealed that it was endothermic and spontaneous in nature due to the positive ΔH0 of 48 kJ/mol and negative ΔG0 values of -4.5 kJ/mol at 293 K. Wastewater treatment revealed 98% removal of mercury indicating the selective nature of HCPA. Finally, HCPA exhibited excellent performance and regeneration up to three cycles, demonstrating its great potential as an adsorbent for environmental remediation applications.

Tuning surface Mn defects on LaMnO3 perovskite oxides by selective dissolution strategy for enhanced phosphate removal

Selective dissolution is widely used to adjust the surface state of LaMnO3 perovskite oxides. In this study, LaMnO3(LMO) with B-Site vacancies was synthesized using ascorbic acid to selectively remove Mn cations and enhance phosphate adsorption. The optimized LMO with Mn defects (LMO-AA3) presented large surface area, plenty of mesoporosity and suitable electronic structure. Particularly, the adsorption capacity (113.48 mg/g) of LMO-AA3 was about10 times that of LMO. Adsorption experiments showed adsorption occurred both chemically and physically on the heterogeneous adsorption surfaces, as the pseudo-second-order kinetic model and the Redlich-Peterson isotherm model predicted. The stimulated mechanism of LMO-AA3 achieved phosphate absorption through enhancing electrostatic attraction and ligand exchange by –OH groups. Regeneration testing showed that LMO-AA3 can be used for both high and low-concentration purification of phosphate. The selectively remove Mn cations method may offer an appropriate choice for enhancing the material characteristics of effective phosphate capture.

Synthesis and characterization of Fe(III)-doped beta-cyclodextrin-grafted chitosan cryogel beads for adsorption of diclofenac in aqueous solutions: Adsorption experiments and deep-learning modeling

Diclofenac (DCF) is frequently detected in aquatic environments, emphasizing the critical need for its efficient removal globally. Here, we present the synthesis of Fe(III)-doped β-CD-grafted chitosan (Fe/β-CD@CS) cryogel beads designed for adsorbing DCF in aqueous solutions. The beads exhibited an average size of 2.94 ± 0.66 mm and a point of zero charge of 8.03. Adsorption experiments demonstrated that the Langmuir kinetic model provided the most accurate description of the kinetic data, while the Redlich–Peterson isotherm offered the best fit for the equilibrium data. The beads showcased a theoretical maximum adsorption capacity of 712.3 mg/g for DCF, with the adsorption process being identified as exothermic. DCF adsorption on the beads was attributed to hydrogen bonding, metal cation-π interactions, and electrostatic interactions. Reusability tests exhibited that the beads could be regenerated using 0.1 M NaOH. To perform deep learning modeling, adsorption experiments (n = 17), designed utilizing central composite design (CCD), were conducted in duplicate. The CCD framework incorporated input variables such as initial DCF concentration, adsorbent dosage, and solution pH, while the output variable was the DCF removal rate. Utilizing the adsorption data, an artificial neural network (ANN) model was constructed with a topology of 3: 7:10:1, featuring 3 input variables, 7 neurons in the first hidden layer, 10 neurons in the second layer, and 1 output variable. Employing the ANN model data, 3-D response surface plots were generated to elucidate the relationship between input variables and DCF removal rate. Additional adsorption tests were conducted to evaluate the developed ANN model, affirming its reliable predictability for the DCF removal rate. Analysis of the relative importance of the input variables revealed the following order of importance: solution pH (100 %) > adsorbent dosage (75.2 %) > initial DCF concentration (57.7 %).

Comparison of surface adsorption efficacies of eco-sustainable agro/animal biomass-derived activated carbon for the removal of rhodamine B and hexavalent chromium.

Effective management and remediation strategies are crucial to minimize the impacts of both organic and inorganic contaminants on environmental quality and human health. This study investigates a novel approach utilizing cotton shell activated carbon (CSAC), rice husk activated carbon (RHAC), and wasp hive activated carbon (WHAC), produced through alkali treatment and carbonization under N2 atmosphere at 600°C. The adsorption capacities of biomass-derived mesoporous activated carbons (CSAC, RHAC, WHAC) alongside macroporous commercial activated carbons (CAC) were evaluated for removing rhodamine B (Rh B) and hexavalent chromium (Cr6+). The CSAC exhibits remarkable adsorption efficiency (255.4mg.g-1) for Cr(VI) removal, while RHAC demonstrates superior efficacy (174.2mg.g-1) for Rh B adsorption. Investigating various optimal parameters including initial pH (pH 3 for Cr and pH7 for Rh B), catalyst dosage (200mg.L-1), and initial concentration (20mg.L-1), the Redlich-Peterson isotherm model is applied to reveal a hybrid adsorption mechanism encompassing monolayer (chemisorption) and multilayer (van der Waals adsorption) processes. Kinetic analysis highlights the pseudo-second-order and Elovich models as the most suitable, suggesting physiochemisorption mechanisms. Thermodynamic analysis indicates the endothermic nature of the adsorption process, with increased randomness at the solid-solution interface. Isosteric heat investigations using Clausius-Clapeyron, Arrhenius, and Eyring equations reveal a heterogeneous surface nature across all activated carbons. Further confirmation of Rh B and Cr(VI) adsorption onto activated carbons is provided through FTIR, FESEM, and EDAX analysis. This study highlights the innovation and promise of utilizing biomass-derived activated carbons for effective pollutant removal.

High Surface Area Mesoporous Cotton Crop Biochar for Enhanced Confiscation of p-nitrophenol

This research study investigates the efficacy of utilizing biochar obtained from cotton crop residues for the enhanced remediation of p-nitrophenol (PNP). Cotton crop residue-derived biochar (CCB) was prepared using 1N phosphoric acid and subsequently characterized. Batch adsorption experimental analysis were conducted to assess the optimal adsorption capacity of CCB for PNP under various conditions, including temperature, pH, interaction time, initial PNP concentration, and dosage of biochar. The results demonstrated optimal adsorption capacity of 55.38 mg/g at pH 5.0, initial PNP concentration of 100 mg L-1 , and biochar dosage of 200 mg at a room temperature of 298 K. The experimental adsorption data exhibited an excellent correlation with the Redlich-Peterson isotherm model. Analysis of the sorption kinetics revealed that the material's uptake behavior closely followed a pseudo-second-order model. Thermodynamics analysis unveiled that the adsorption of PNP onto CCB was exothermic, spontaneous, and primarily driven by enthalpy. Overall, the findings suggest that CCB exhibits promising potential as an efficient adsorbent for the remediation of aquatic environments afflicted with presence of PNP.

Synthesis of hydrochar from date palm seeds using microwave-enhanced hydrothermal carbonization and its application in dyes removal

This work reports new findings on the preparation of hydrochar from date palm (Phoenix dactylifera) seeds through the application of the microwave hydrothermal carbonization (HTC) method. Optimization investigations involving temperatures and reaction times were conducted to establish the highest yield, achieving a maximum yield of 60.87%. The prepared material was then impregnated in phosphoric acid and carbonized in the tube furnace at 550 °C for 1.5 h with a nitrogen flow of 50 CCM. The samples were characterized via scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) and Fourier transform infrared (FTIR). The samples showed remarkable BET surface areas following activation, reaching up to 992 m2·g−1. The substance was subsequently used to absorb methylene blue with good fitting to the Freundlich and Redlich-Peterson isotherm and achieved a peak adsorption capacity of 196.6 ± 3.9 mg·g−1.