Dubinin-Radushkevich Isotherm Research Articles

Biosorption of Cd(II), Co(II), and Cu(II) onto Microalgae under Acidic and Neutral Conditions

The biosorption of Cd, Co, and Cu onto three microalgae species (Chlorella vulgaris, Scenedesmus sp., and Spirulina platensis) was compared to determine the microalgae’s capability for heavy metal adsorption in acidic and neutral environments. The Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models were used to characterize the adsorption of the heavy metals onto microalgae. The maximum adsorption capacity (qmax) determined using the Langmuir and D-R model showed results in the order of Cu > Co > Cd in both acidic and neutral conditions. A shift from acidic to neutral conditions increased the microalgae’s adsorption affinity for heavy metals, as determined using the Freundlich parameter (KF). The adsorption affinity of the biomass for Cd and Co was in the order S. platensis > C. vulgaris > Scenedesmus sp. while that of Cu was in the order C. vulgaris > Scenedesmus sp. > S. platensis. In addition, it was found that the adsorption of Cd and Co enhanced the production of Dissolved Organic Content (DOC) as a byproduct of biosorption, whereas the adsorption of Cu appeared to suppress the generation of DOC. The mean adsorption energy (E) values computed by the D-R model were less than 8 (kJ/mol), indicating that physisorption was the primary force of sorption in both acidic and neutral settings. The findings of this study suggest that microalgae may be used as a low-cost adsorbent for metal removal from industrial effluent.

Studies on Sorption and Release of Doxycycline Hydrochloride from Zwitterionic Microparticles with Carboxybetaine Moieties.

The aim of this study was to examine the use of zwitterionic microparticles as new and efficient macromolecular supports for the sorption of an antibiotic (doxycycline hydrochloride, DCH) from aqueous solution. The effect of relevant process parameters of sorption, like dosage of microparticles, pH value, contact time, the initial concentration of drug and temperature, was evaluated to obtain the optimal experimental conditions. The sorption kinetics were investigated using Lagergren, Ho, Elovich and Weber-Morris models, respectively. The sorption efficiency was characterized by applying the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The calculated thermodynamic parameters (ΔH, ΔS and ΔG) show that the sorption of doxycycline hydrochloride onto zwitterionic microparticles is endothermic, spontaneous and favorable at higher temperatures. The maximum identified sorption capacity value is 157.860 mg/g at 308 K. The Higuchi, Korsmeyer-Peppas, Baker-Lonsdale and Kopcha models are used to describe the release studies. In vitro release studies show that the release mechanism of doxycycline hydrochloride from zwitterionic microparticles is predominantly anomalous or non-Fickian diffusion. This study could provide the opportunity to expand the use of these new zwitterionic structures in medicine and water purification.

Experimental design of polymer synthesis applied to the removal of Cd2+ ions from water via adsorption

Cadmium is a highly toxic metal, and its presence can have adverse effects on both human health and aquatic ecosystems. The efficient removal of cadmium from wastewater is therefore of crucial importance, but traditional methods have proved to be inadequate. Thus, technologies for the treatment of wastewater containing cadmium, including adsorption, have been developed. The aim of this study was the preparation of a polymeric material by the grafting reaction of κ-carrageenan and its use as an adsorbent for cadmium removal. This was performed to study the removal capacity of cadmium ions in synthetic solutions, as well as the effects of pH and ions on adsorption capacity, adsorption kinetics, isotherms, and reusability. Additionally, the disinfectant potential of the solution was evaluated for the inactivation of total coliforms and E. coli in river water. The best adsorption capacity was 75.52 ± 1.325 mg g−1, with the kinetics described by the pseudo-second order model. Maximum adsorption capacity (127.6 ± 1.833 mg g−1) and RL (0.0113) were determined using the Langmuir model, the Freundlich model was the one that best fits the experimental data and indicated cooperative adsorption, and the Dubinin-Radushkevich isotherm was used to obtain the adsorption energy and identify that it is physical. The presence of ions K+, Na+, Mg2+, and Ca2+ in a concentration of 0.5% decreased the adsorption capacity, and that at pH 2.0, the adsorption capacity was drastically reduced. The study indicates that the polymer has potential as an adsorbent for removing cadmium from aqueous solutions and exhibits self-disinfecting properties.

Methylene blue dye removal by adsorption with coconut coir and acid-treated forms: adsorption-desorption study, MPR and modeling using artificial intelligence

A batch study is conducted to remove methylene blue (MB) dye from an aqueous solution using coconut coir and its acid-treated forms. The sulfuric acid-treated coconut coir (SCC), phosphoric acid-treated coconut coir (PCC) and untreated coconut coir (UCC) were prepared. Adsorbents were characterized via BET, SEM, pHPZC, FTIR, and FT-Raman analysis. Adsorbent’s total organic carbon (TOC) and the number of oxygen-containing functional groups like carboxylic, lactonic and phenolic, total acidic, and basic groups were also estimated. FTIR and FT-Raman studies establish functional groups responsible for dye removal. The operating parameters were optimized through experiments. Dye was removed maximally at the lowest temperature, 303K. Langmuir and Temkin isotherm models use linear equations, and the Pseudo-second-order kinetic model uses a nonlinear equation, which fits well. The adsorption capacity of SCC, PCC and UCC adsorbents was 88.18 ± 0.63 mg/g, 92.68 ± 2.74 mg/g and 76.39 ± 0.36 mg/g, respectively, for 303K. Intraparticle diffusion dominated more than film diffusion. Physisorption was estimated by applying the Dubinin-Radushkevich (D-R) isotherm model. Thermodynamic study indicates a spontaneous, favorable, exothermic process. 75% glacial acetic acid and 100% methanol are the best solvents for desorbing dye-loaded adsorbents. Porous coir and non-covalent interactions like hydrogen bonding, van der Waals force and π-π interaction between dye and coir are vital in the dye removal process. The regression equation has been successfully formulated, and the application of a genetic algorithm has predicted the percentage removal of methylene blue dye.

Seaweed Superheroes: Cystoseira barbata-Incorporated Electrospun Fibers for Lead Ion Sequestration.

The efficient removal of lead ions at low concentrations is paramount in combating the significant threat posed by water pollution resulting from industrial activities and population growth. In this study, electrospun C. barbata/PAN fibers were developed to efficiently remove lead(II) ions from water. The morphology, structure, and mechanical properties of the fibers were examined, highlighting that the augmentation of the surface area through the conversion of C. barbata into the polymer fibers facilitates increased metal bonding sites during sorption. C. barbata/PAN fibers exhibited superior characteristics, including higher surface area, smaller pore size, and increased pore volume, compared to powdered C. barbata. The effects of factors such as shaking time, algae percentage, sorbent amount, pH, metal concentration, and temperature on Pb(II) sorption were investigated by the batch method. At an initial ion concentration of 100 μg L-1 and pH 4.0, C. barbata (5 wt %)/PAN fiber demonstrated a notable sorption efficiency of 89-90% (270 μg/g) after 60 min. The equilibrium data align with the Freundlich and Dubinin-Radushkevich isotherm models, whereas the pseudo-second-order kinetic model provides the most suitable description. The characterization of fibers after sorption revealed that carboxyl, hydroxyl, and sulfonyl groups play an active role in Pb(II) sorption.

Assessment of the Detoxification Potential of Modified Biochar from Annona senegalensis Stem Bark on Cr6+ and Cu2+ in Aqueous Solution: An Equilibrium, Kinetic and Thermodynamic Studies

Background: Environmental contamination of the air, water, soil, and food has become a threat to the continued existence of many plant and animal communities in the ecosystem. The chemically activated stem bark of Anonna senegalensis was examined for equilibrium sorption. Methods: This study aimed to assess the adsorption of Cr6+ and Cu2+ onto Annona senegalensis carbon (ASC) according to the following parameters: pH, solution temperature, starting metal ion concentration, agitation duration, dose of adsorbent, particle size, and carbonization temperature using a simultaneous batch adsorption method. Pseudo-first order, pseudo-second order, intra-particle diffusion kinetic, Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich isotherm models were all fitted using the equilibrium sorption data that were produced. Thermodynamic parameters of the adsorption studies were also evaluated. Results: The physicochemical analysis of ASC showed ash content of 7.21 ± 0.02%, moisture content of 11.73 ± 0.29%, and porosity of 0.99 ± 0.08 with bulk density of 0.18 g/cm3. The heavy metalloaded scanning electron microscope (SEM) micrograph showed a filled pit, and the XRD diffractogram, as well as FTIR spectra, revealed peaks that were different from the raw spectra, implying functionalization. The sorption data gave optimum conditions of the adsorption process to be pH of 6, agitation time of 88 minutes, adsorbent dose of 2.5 g/g, initial metal ion concentration of 5 mg/L, temperature of 30°C, particle size of 0.154 mm and carbonization temperature of 400°C. Conclusion: The Langmuir isotherm was found to give the best-fit conformation of all the models based on superior R2 (R2 ≥0.99). Dubinin-Radushkevich proved the mechanism to be physisorption. The pseudo-second-order kinetic model best fits the data with R2 of 0.998 and 0.986 for Cr6+ and Cu2+. Thermodynamic results of the study revealed that ΔHᵒ for Cr6+ and Cu2+ were 32.78 and 27.14 KJ/mol and are all positive, implying an endothermic process and confirming the physisorption mechanism. The entropy change, ΔSᵒ, was also positive, revealing a high degree of disorderliness at the sorbate/sorbent interphase. The standard Gibbs free energy, ΔGᵒ, were all negative, showing spontaneity and feasibility.

Synergistic adsorption of methylene blue using ternary composite of phosphoric acid geopolymer, calcium alginate, and sodium lauryl sulfate.

The removal of dyes from the aquatic ecosystem is necessary being a major threat to life. For enhanced remediation of methylene blue (MB) dye, a new ternary biopolymer-geopolymer-surfactant composite adsorbent is synthesized by combining phosphoric acid geopolymer (PAGP), calcium alginate (Alg), and sodium lauryl sulfate (SLS). During the synthesis of the composites, PAGP and SLS were mixed with the alginate matrix, producing porous hybrid beads. The PAGP-SLS-alginate (PSA) beads prepared were characterized using different analytical tools, i.e., scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR), X-ray diffractometry (XRD), surface area and porosimetery (SAP), and thermogravimetric analysis (TGA). To ascertain the ideal conditions for the adsorption process, a batch reactor procedure was used to investigate the effects of several parameters on MB adsorption, including pH (2, 4, 6, 8, 10), PSA adsorbent dosage (0.06-0.12 g), MB concentration (50-500 mg/L), contact time (15 to 300 min), and temperature (25, 35, and 45 °C). The SEM investigation indicated that ~ 1860 μm-sized PSA beads with 6-8 μm voids are generated. Based on XRD, FTIR, and SAP examinations, the material is amorphous, having numerous functional groups and an average pore size of 6.42 nm. Variation of pH has a little effect on the adsorption process, and the pH of 7.44 was found to be the pHpzc of the PSA beads. According to the findings of the batch study, equilibrium adsorption was obtained in 270-300 min, showing that the adsorption process was moderately slow-moving and effective. The dye adsorption linearly increased with initial dye concentration over concentration range of 50-500 mg/L and reciprocally decreased with rise in temperature. 0.06 g adsorbent dose, 25 °C, pH10, and 270 min were found to be the better conditions for adsorption experiments. Langmuir isotherm fitted well compared to Freundlich, Temkin, and Dubinin-Radushkevich (DR) isotherm models on the experimental data, and the maximum adsorption capacity(qmax) calculated was 1666.6 mg. g-1. Pseudo-second-order (PSO) kinetics model and multi steps (two) intra particle diffusion (IPD) model fitted well on the adsorption kinetics data. The system's entropy, Gibbs free energy, and change in enthalpy were measured and found to be -109.171 J. mol-1. K-1, - 8.198 to - 6.014 kJ. mol-1, and - 40.747 kJ. mol-1. Thermodynamics study revealed that adsorption process is exothermic, energetically favorable and resulting in the decrease in randomness. Chemisorption is found to be the dominant mechanism as confirmed by pH effect, Langmuir isotherm, PSO kinetics, IPD model, and thermodynamics parameters. PSA beads were successfully regenerated using ethanol in a course of 120 min and re-used for five times. To sum up, the PSA adsorbent's impressive adsorption capability of 1666.66 mg/g highlights its potential as a successful solution for methylene blue removal. The results of this study add to the expanding corpus of information on sophisticated adsorption materials and demonstrate PSA's potential for real-world uses in wastewater treatment and environmental clean-up.

Artificial neural network-based modeling of Malachite green adsorption onto baru fruit endocarp: insights into equilibrium, kinetic, and thermodynamic behavior

In this study, artificial neural network (ANN) tools were employed to forecast the adsorption capacity of Malachite green (MG) by baru fruit endocarp waste (B@FE) under diverse conditions, including pH, adsorbent dosage, initial dye concentration, contact time, and temperature. Enhanced adsorption efficiency was notably observed under alkaline pH conditions (pH 10). Kinetic analysis indicated that the adsorption process closely followed a pseudo-second-order model, while equilibrium studies revealed the Langmuir isotherm as the most suitable model, estimating a maximum adsorption capacity of 57.85 mg g−1. Furthermore, the chemical adsorption of MG by B@FE was confirmed using the Dubinin–Radushkevich isotherm. Thermodynamic analysis suggested that the adsorption is spontaneous and endothermic. Various ANN architectures were explored, employing different activation functions such as identity, logistic, tanh, and exponential. Based on evaluation metrics like the coefficient of determination (R 2) and root mean square error (RMSE), the optimal network configuration was identified as a 5–11-1 architecture, consisting of five input neurons, eleven hidden neurons, and one output neuron. Notably, the logistic activation function was applied in both the hidden and output layers for this configuration. This study highlights the efficacy of B@FE as an efficient adsorbent for MG removal from aqueous solutions and demonstrates the potential of ANN models in predicting adsorption behavior across varying environmental conditions, emphasizing their utility in this field.

Modified powder of Corchorus capsularis as a new adsorbent for removal of tetracycline group antibiotic from water

AbstractThis study prepared a novel adsorbent from Corchorus capsularis modified powder for the removal of the tetracycline group (tetracycline ‐TC, oxytetracycline ‐OTC, chlortetracycline ‐CTC) in aqueous solution. Corchorus capsularis powder was pre‐treated with 15% sodium hydroxide (COC), then reformed by a mixture of 0.15 mol L−1 sodium bisulfide (SB) and 0.2 mol L−1 ammonium peroxydisulfate (APS). This adsorbent was embedded with monoacrylamide (AM) at ratio AM/COC = 1/1 at 60 °C for 2.5 h. After modification with AM (BTA), the surface area of the adsorbents increased from 1.53 to 2.79 m2 g−1, while the pore size of the adsorbents decreased from 36.95 to 11.85 nm. The study also investigated the effects of pH, adsorbent dose and temperature on the adsorptive removal process. Tetracycline concentrations were determined using liquid chromatography–tandem mass spectrometry (LC–MS/MS). The kinetics and isotherms of adsorption performance were examined using a variety of models, including pseudo‐first‐order kinetic (PFO), pseudo‐second‐order kinetic (PSO), Freundlich, Langmuir, and Dubinin–Radushkevich isotherms (DRM). The experimental data fitted very well with the pseudo‐second‐order kinetic model. The maximum adsorption bulks of TC, OTC, CTC following Langmuir isotherm model were 1.25, 0.83, 1.43 mg g−1, respectively. The adsorption constants Kp of TC, OTC, and CTC from the Freundlich isotherm model were 15.36, 21.80, and 22.08 mg1−nLng−1, respectively. The mean free energy E (kJ mol−1) of TC, OTC, and CTC from DRM was 4.35, 4.20, and 4.57, respectively. The results indicated that modified Corchorus capsularis powder had significant potential as a new adsorbent material for removing antibiotics from aqueous solutions.

Adsorption isotherms and kinetic studies for the defluoridation from aqueous solution using eco-friendly natural adsorbent like Terminalia Chebula

A practical technique for removing fluoride from aqueous solutions by adsorption was created using the natural adsorbent known as Terminalia Chebula with a primary emphasis on adsorption isotherms and kinetic studies. The experimental results showed the best conditions for removing fluorine ions as follows: the dosage of the natural adsorbent: 50 mg/L, contact reaction time: 40 min, shaking speed = 120 rpm, temperature = 32 °C. The amount of removal of fluorine ions was found to be >98 % fluoride within a shorter time and reached adsorption equilibrium within 40 min with a maximum defluoridation capacity of 20.92 mg/g. At lower solution pH (3 to 5), there is higher fluoride adsorption on the adsorbent surface and as the pH becomes alkaline (pH > 7) the adsorption capacity decreased. The two co-ions namely NO3− and Cl− removed the fluoride 79 % whereas, the phosphate ions did not have any marked effect on the defluoridation. The pseudo-second-order kinetic order such Langmuir, Empirical Freundlich, Temkin and Dubinin–Radushkevich isotherms can well predict the adsorption equilibrium rate to be at 0.044 mg/L with contact time (t) of 30 min. In addition to that the adsorption is characterized by SEM, X-ray diffraction and FTIR techniques. This study has ultimately found that the Terminalia Chebula is a workable, natural material for fluoride elimination.

Innovative Plant-Derived Biomaterials for Sustainable and Effective Removal of Cationic and Anionic Dyes: Kinetic and Thermodynamic Study

The aim of this study is to purify industrial textile effluents by treating two types of commonly encountered dyes: blue maxilon (BM), of cationic nature, and black eriochrome (NE), of anionic nature. We intend to employ an innovative approach based on the adsorption of these dyes onto a novel vegetal biomaterial derived from Aleppo pine fibers (FPAs). A kinetic and thermodynamic study was conducted. The effect of some physicochemical parameters on both dye adsorption and FPAs was also evaluated. The modeling of the adsorption results was performed using Langmuir, Freundlich, Temkin, and Dubinin Radushkevich (D-R) isotherms. The results indicate that the equilibrium time strongly depends on the initial concentration of the two dyes, being 60 min with pseudo-second-order adsorption kinetics for both dyes. Adsorption isotherms under the optimal conditions of adsorbent mass, temperature, medium pH, and dye concentration were used to determine the maximum adsorption efficiency, which was close to 93% and 98% for BM and NE, respectively. The results also show that the adsorption of both dyes on FPAs fits well with Langmuir’s model. The thermodynamic study indicates that the adsorption of both dyes on FPAs is spontaneous and exothermic in nature for BM and endothermic for NE.

UPTAKE OF Co(II), Pb(II) AND Ni(II) IONS BY Annona senegalensis STEM BARK BIOCHAR FROM AQUEOUS SOLUTION: OPTIMIZATION, KINETIC AND THERMODYNAMIC STUDIES

The concern for heavy metal pollution in the environment is especially so since they are non-biodegradable. The use of agro materials in the removal of these heavy metal pollutants has been recognized as a low-cost alternative to the costly conventional remediation techniques. The equilibrium sorption of the chemically activated Anonna senegalensis stem bark was investigated. Using standard techniques, the physicochemical properties of activated carbon (MAASC) were ascertained. By using a simultaneous batch adsorption approach, the adsorption of Co2+, Pb2+, and Ni2+ onto MAASC was examined as a function of pH, solution temperature, initial metal ion concentration, agitation time, adsorbent dose, particle size, and carbonization temperature. The equilibrium sorption data generated were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models as well as pseudo first-order, pseudo-second-order and intraparticle diffusion kinetic models. From the obtained results, it was discovered that the Langmuir isotherm provided the best match conformation of all the models, except for Pb2+, which was best for Freundlich with an R2 of 0.95. Physisorption was shown to be the mechanism by Dubinin-Radushkevich. For Co2+, Pb2+, and Ni2+, respectively, the pseudo second-order kinetic model had R2 values of 0.997, 0.999, and 0.999 that best matched the data. Both intraparticle diffusion and the boundary layer effect also contributed to regulating the rates of the adsorption process. The study's thermodynamic results showed that Ho for Co2+, Pb2+, and Ni2+ were 27.51, 19.70, and 13.37 KJ/mol, respectively. These values are all positive and suggest an endothermic reaction, supporting the physisorption mechanism.

Trace cisplatin adsorption by thiol-functionalized sponge (TFS) and Sn/SnO2-coated TFS: Adsorption study and mechanism investigation

To remove trace cisplatin from aqueous solution, commercial sponges were functionalized by esterification with 3-mercaptopropionic acid, followed by reduction with Na2S·9H2O or SnCl2·2H2O. The resulting thiol-functionalized sponges (TFSs), TFS_1 and TFS_2, were tested for the removal of cisplatin (235 μg L−1) achieving maximum removal of 95.5 ± 0.8% and 99.5 ± 0.1% respectively, which were significantly higher than the non-functionalized counterpart. The successful grafting of thiol groups, verified through FTIR, elemental analysis, SEM-EDS, and XPS characterization, facilitated Pt−S complexation during adsorption. The aqua-derivatives of cisplatin, formed through hydration, complexed with thiol sites through ligand displacement. Additionally, the presence of Sn/SnO2 coating on TFS_2 further enhanced the adsorption process. The rapid adsorption process conformed to pseudo-second-order kinetic model, involving both diffusion and chemisorption. While the Langmuir isotherm model generally described the monolayer adsorption behavior of cisplatin, the aggregation of Sn/SnO2 onto TFS_2 at 343 K introduced surface heterogeneity, rendering the Freundlich model a better fit for the adsorption isotherm. Differential pH dependence and the evaluation of mean free energy, derived from the Dubinin-Radushkevich isotherm model, indicated that cisplatin adsorption onto TFS_1 involved physisorption, including electrostatic attraction, while chemisorption predominated for TFS_2. Increasing the temperature notably promoted adsorption by facilitating the thermal-favored formation of Pt−S bonds.

Chitosan‐nTiO2 Nanocomposite Synthesis and its Adsorptive Removal Capacity for Methylene Blue from its Aqueous Solution: Batch Adsorption Study and Modeling

AbstractThe current work used chitosan (CS)‐nTiO2 nanocomposites (CTNCs) prepared with different CS:nTiO2 mass ratios toward the MB dye removal from an aqueous medium in batch method at variable experimental conditions. The stability and competence of the nanocomposites were checked through characterization by SEM, FTIR, XRD, TGA, and BET. The highest removal of MB was 78 % with the adsorbent CS without nTiO2 (CWT), 94.5 % with CS:nTiO2=1 : 1 weight ratio (CTNC1‐1) and 80 % with CS:nTiO2=2 : 1 weight ratio (CTNC2‐1) with 10 mgL−1of MB and 5 gL−1 adsorbent dosages. The experimental observations obeyed the pseudo‐2nd‐order model, and rate‐limiting steps were film diffusions for CWT, CTNC1‐1 and intraparticle diffusion for CTNC2‐1. Monolayer adsorption was established from the isotherm model. Langmuir adsorption capacities for MB were presented as CTNC1‐1 (qL=34.31)>CTNC2‐1 (qL=32.87)>CWT (qL=21.32). The sorption energy, as derived from Dubinin–Radushkevich isotherm model, showed physisorption for all three adsorbents. The scale‐up design is reported. The statistical (R2>0.98) and GA modeling (R2>0.98) successfully predicted the percentage elimination of MB. Thus, CS‐nTiO2 nanocomposites are prepared as novel and environment‐friendly adsorbents for dye removal.

Reactive Blue 19 Adsorption on Activated Carbon From Pumpkin (Cucurbita Pepo) Seed Waste: Kinetic, Isotherm and Thermodynamic Studies

In this study, the removal of Reactive Blue 19 dyestuffs in aqueous systems was investigated by adsorption method using activated carbon obtained from the pumpkin seed waste. Activated carbon obtained from pumpkin seed waste functionalized with ZnCl2 was used as an absorbent. Pumpkin seed hydrochar was characterized by FT-IR, SEM, TGA-DTA, BET, and XPS. In the experimental stages, the adsorption equilibrium time was determined as 45 minutes, the adsorbent dosage was 0.8 g and the optimum pH was 6.0. After this step, the adsorption parameters of Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms were investigated. It has been pointed out that the adsorption process fits better with the Freundlich isotherm model, and the adhesion occurs in a multilayered manner and on a heterogeneous surface. Freundlich and Dubinin-Radushkevich isotherms support that the bonding mechanism is realized by physical interactions. When the kinetic data were evaluated, it was found to be compatible with the pseudo-second-order kinetic model. The thermodynamic parameters of adsorption indicate that the system is endothermic, and the adsorption of Reactive Blue 19 on activated carbon is a spontaneous process.

Norfloxacin adsorption by urban green waste biochar: characterization, kinetics, and mechanisms.

Biochar, as a potential adsorbent, has been widely employed to remove pollutants from sewage. In this study, a lignin-based biochar (CB-800) was prepared by a simple high-temperature pyrolysis using urban green waste (Cinnamomum camphora leaves) as a feedstock to remove norfloxacin (NOR) from water. Batch adsorption test results indicated that CB-800 had a strong removal capacity for NOR at a wide range of pH values. The maximum adsorption achieved in the study was 50.90 ± 0.64mg/g at 298K. The pseudo-first and second-order kinetic models and the Dubinin-Radushkevich isotherm fitted the experimental data well, indicating that NOR adsorption by CB-800 was a complex process involving both physi-sorption and chemi-sorption. The physical properties of CB-800 were characterized by SEM and BET. The mesoporous structures were formed hierarchically on the surface of CB-800 (with an average pore size of 2.760nm), and the spatial structure of NOR molecules was more easily adsorbed by mesoporous structures. Combined with Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis, it was showed that the main NOR adsorption mechanisms by CB-800 included ion exchange, π-electron coordination, hydrogen bonding, and electrostatic adsorption. Meanwhile, the reduction of C = O and pyridine nitrogen, and the presence of C-F2, also indicated the occurrence of substitution, addition, and redox. This study not only determined the reaction mechanism between biochar and NOR, but also provides guidance to waste managers for the removal of NOR from water by biochar. It is envisaged that the results will broaden the utilization of urban green waste.

Iron-lanthanum supported on graphite sheets for As(III) removal from aqueous solution: kinetics, thermodynamic and ecotoxicity assessment.

Graphene-based material is widely used to remove arsenic from water due to its layered structure with high surface area. Here, we have successfully synthesized Fe-La bimetallic modified graphite sheet materials to more efficiently remove As(III) from aqueous solution. The results showed that Fe-La-graphite sheets (FL-graphite sheets) have a larger specific surface area (194.28 m2·g-1) than graphite sheets (2.80 m2·g-1). The adsorption capacity of FL-graphite sheets for As(III) was 51.69mg·g-1, which was higher than that of graphite sheets (21.91mg·g-1), La-graphite sheets (26.06mg·g-1), and Fe-graphite sheets (40.26mg·g-1). The FL-graphite sheets conformed to the Freundlich and Dubinin-Radushkevich isotherm, and the maximum adsorption capacity was 53.62mg·g-1. The removal process obeys intra-particle diffusion and pore diffusion for As(III). The results of batch adsorption experiments and characterization analyses demonstrated that oxidation, ligand exchange, and inner sphere complexation mechanisms involved in the adsorption of FL-graphite sheets to As(III) in comparison with graphite sheets. In addition, electrostatic attraction mechanism was found vital in the adsorption. Ecotoxicity assessment revealed that FL-graphite sheets have little influence on rice germination and growth, but reduced the toxicity of As(III) to rice. Therefore, the FL-graphite sheets have good practical application value in purifying As(III) polluted water with litter ecotoxicity.

Ecofriendly Application of Calabrese Broccoli Stalk Waste as a Biosorbent for the Removal of Pb(II) Ions from Aqueous Media

A new biosorbent obtained from Calabrese broccoli stalks has been prepared, characterised and used as an effective, low-cost and ecofriendly biomass to remove Pb(II) from aqueous solutions, without any complicated pretreatment. Structural and morphological characterisation were performed by TGA/DGT, FTIR and SEM/EDX; the main components are hemicellulose, starches, pectin, cellulose, lignin and phytochemicals, with important electron donor elements (such as S from glucosinolates of broccoli) involved in Pb(II) sorption. The biosorbent showed values of 0.52 and 0.65 g mL−1 for bulk and apparent densities, 20.6% porosity, a specific surface area of 15.3 m2 g−1, pHpzc 6.25, iodine capacity of 619 mg g−1 and a cation exchange capacity of 30.7 cmol kg−1. Very good sorption (88.3 ± 0.8%) occurred at pH 4.8 with a biomass dose of 10 g L−1 after 8 h. The Freundlich and Dubinin–Radushkevich isotherms and the pseudo-second-order kinetic models explained with good fits the favourable Pb(II) sorption on the heterogeneous surface of broccoli biomass. The maximum adsorption capacity was 586.7 mg g−1. The thermodynamic parameters evaluated showed the endothermic and spontaneous nature of the Pb(II) biosorption. The chemical mechanisms mainly involved complexation, ligand exchange and cation–π interaction, with possible precipitation.

Blighia sapida Waste Biochar in Batch and Fixed-Bed Adsorption of Chloroquine Phosphate: Efficacy Validation Using Artificial Neural Networks.

The present study investigated the potency of biochar prepared from Blighia sapida seedpods (BSSPs) in the uptake of chloroquine phosphate (CQP) from single-component batch and multicomponent fixed-bed adsorption systems. BSSPs presented a highly porous structure with a BET surface area of 1122.05 m2/g, to which adsorption efficiency correlated. The Dubinin-Radushkevich isotherm energy was obtained as 129.09 kJ/mol, confirming the chemisorption nature of the BSSP-CQP adsorption system. The efficiency of the artificial neural network (ANN) was evaluated using the lowest mean square error (MSE = 7.27) and highest correlation coefficient (R2 = 0.9910). A good agreement between the experimental results and the ANN-predicted data indicated the efficiency of the model. The percentage removal of 95.78% obtained for the column adsorption studies indicated the effectiveness of BSSPs in a multicomponent system. The mechanism of the interaction proceeded via hydrogen bonding and electrostatic attraction. This was confirmed by the high desorption efficiency (69.11%) with a HCl eluent. The degree of reversibility was found to be 2.95, indicating the reusability potential of BSSPs. BSSPs are therefore considered multilayered adsorbents with potential applications in pharmaceutical wastewater treatment.

الايزوثيرمات والدوال الدينميكية الحرارية لامتزاز دواء الميتوبرولول على السليكا متوسطة المسام المحضرة

في هذه الدراسة ، تم تصنيع السيليكا متوسطة المسام ((MPS) باستخدام طريقة سول-جل من مصدر رخيص ((Na2SiO3 باستخدام هيدروكسي ستيل هيدروكسي إيثيل دايمونيوم كلوريد كقالب. وتتمثل المهمة في الإزالة القائمة على الامتزاز لعقار ميتوبرولول (MP) بتراكيز تتراوح بين 10 و50 جزء في المليون. تمت دراسة المتغيرات مثل: وقت التلامس، كمية المادة المازة، التراكيز الابتدائية للمادة الممتزة، ودرجة حرارة الامتزاز، ودلت النتائج ان زمن الاتزان وكمية المادة المازة هما 40 دقيقة و 0,05 غرام على التوالي. تم تطبيق ايزوثرمات Langmuir , Freundlich ,Temkin وDubinin-Radushkevich على البيانات التي تم الحصول عليها من التجارب و قد أظهرت مقارنة النتائج أنه ، من بين نماذج الايزوثرمات الأربعة التي تم فحصها ، يمكن لنموذج معادلة Freundlich التنبؤ بهذه البيانات بدقة. وبالاعتماد على تحليل ايزوثرم الامتزاز تبين انه مع ارتفاع درجة الحرارة أن كمية الامتزاز ارتفعت وأن الامتزاز كان مفيدًا ومن النوع الفيزيائي. بالإضافة إلى ذلك، تضمنت الدراسة تقدير ∆H°, ∆S°,∆G° , كعوامل ديناميكية حرارية. ووجد ان قيمة ∆G° كانت بين -20,24 و -26,22 كيلوجول لكل مول وتقل مع ارتفاع درجة الحرارة مما يدل على ان الامتزاز يصبح اكثر تلقائية بدرجات الحرارة العالية. كانت قيمة ∆H° هي 38.10 كيلوجول لكل مول والتي دلت بان عملية الامتزاز من نوع الامتزاز الفيزيائي. اما قيمة ∆S° فكانت 199.14 جول لكل مول والتي تدل عل زيادة درجات الحرية للمادة الممتزة MP. ودلت اشارة ∆G° و ∆H° بان العملية تلقائية وماصة للحرارة.