Maximum Adsorption Efficiency Research Articles

Investigation of the kinetics of imidacloprid adsorption onto bimetallic Cu-BTC MOF

Imidacloprid, which is harmful for humans as well as many other aquatic invertebrate species, is extensively present in water worldwide. Hydrophobic Cu-BTCIPA and a novel composite, Ag@Cu-BTCIPA, was synthesized for adsorption of imidacloprid from water. The synthesis of the composite and the increase in surface area and pore volume were confirmed by FTIR, XRD, SEM, and BET analysis. A comparative study of the adsorption efficiencies of the synthesized composites was performed. The maximum adsorption efficiency achieved was 83.6 % at pH 7 by the Ag@Cu-BTCIPA composite. Kinetic and isotherm analyses suggested multilayer chemisorption involving p-p conjugation and pore-filling mechanisms. Intra-particle diffusion was the rate limiting step. Release studies of imidacloprid from water showed that the percentage release amount was 90.2 % at 70 min. Kinetic analysis of the release process suggested release through chemisorption, with swelling-controlled release from the dosage form, corresponding to the super case II transport mechanism.

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.

Removal of Pyrocatechol from Aqueous Solution Using Activated Carbon Coated with Aluminum Nanoparticles by a Green Method

Background: Pyrocatechol, a phenol derivative, is commonly found in industrial effluents at various concentrations due to its extensive use in multiple industries. These toxic compounds are resistant to biological degradation and pose significant threats to environmental and human health when they enter aquatic environments. Objectives: This study explores the removal of pyrocatechol from aqueous solutions using activated carbon coated with aluminum nanoparticles. Methods: Laboratory materials included oak wood (collected from the mountains around Lorestan province, Iran), pyrocatechol, H3PO4, HCl, Al2O3, NaCl, NaOH, graphite oxide, and NH3. This experimental study was conducted on a laboratory scale. Oak wood was used to synthesize activated carbon, while aluminum oxide and oak moss were employed to produce aluminum nanoparticles using a green method. The characteristics of the adsorbents were examined using XRD, FESEM, FTIR, and BET analyses. Parameters such as contact time (5 - 40 min), pH (3 - 11), initial concentration of pyrocatechol (20 - 200 mg/L), adsorbent dose (50 - 250 mg), and ionic strength were investigated. The residual concentration of pyrocatechol was measured using a spectrophotometer at a wavelength of 275 nm. Results: The results indicated that maximum adsorption efficiency was achieved with a pyrocatechol concentration of 100 mg/L, a pH of 7, a contact time of 20 minutes, and an adsorbent dose of 250 mg. Isotherm and kinetic analyses showed that the adsorption data correlated well with the Langmuir model and the pseudo-second-order kinetic model, respectively. Conclusions: Activated carbon derived from oak wood and coated with aluminum nanoparticles using a green method is highly efficient in removing pyrocatechol from aqueous solutions. This method is recommended as an effective, rapid, cost-effective, and environmentally friendly approach for the removal of pyrocatechol from aqueous environments.

Studying removal of anionic dye by prepared highly adsorbent surface hydrogel nanocomposite as an applicable for aqueous solution

In this study, a Sodium alginate-g-poly (acrylamide-clay)/TiO2 hydrogel nanocomposite [SA-g-p(AM-Bn)/TiO2] was synthesized using the biopolymer sodium alginate (SA), acrylamide (AM), and bentonite clay (Bn) as hybrid materials embedded with titanium dioxide nanoparticles (TiO2NPs) for the removal of toxic Congo Red (CR) dye from an aqueous solution. The [SA-g-p(AM-Bn)/TiO2] nanocomposite has been described on the basis of thermal stability, morphological analysis, estimation of functional group, and crystalline/amorphous character by TGA, EFSEM/EDX, TEM, FT-IR, and XRD analysis, respectively. The effects of operational parameters toward the CR dye adsorption on [SA-g-p(AM-Bn)/TiO2], including contact time, adsorbent dosage, initial concentration, initial pH, and temperature were investigated. The maximum adsorption efficiency was found to be 185.12 mg/g for [SA-g-p(AM-Bn)/TiO2] in 100 mg/L of solution CR at pH 6.0 within 1 h. The equilibrium isotherms, kinetics, and thermodynamics parameters of adsorption were examined, and results showed that the isotherm fitted the Freundlich model and the kinetics adsorption model of CR followed pseudo-first-order, thus indicating physisorption of anionic-CR onto the sorbent due to the development of an electrostatic attraction bond. Thermodynamic parameters for [SA-g-p(AM-Bn)/TiO2] have values (ΔG and ΔH) reflecting the spontaneous and endothermic nature of the adsorption processes. Moreover, [SA-g-p(AM-Bn)/TiO2] presented outstanding excellent reusability and recyclability with a relatively best removal percentage as compared to [SA-g-p(AM-Bn)] and suggested their applicability towards the textile industry and water purification purposes.

Adsorption of Coomassie Brilliant Blue on a Novel Eco‐Friendly Nanogel from Simulated Water: Equilibrium, Kinetic, and Thermodynamic Studies

AbstractHerein a novel gum acacia‐alginate nanogel (GAA) was synthesized via ultrasound‐assisted crosslinking by DPPH and applied for the removal of coomassie brilliant blue (CBB) dye. The fabrication of GAA and its interaction with CBB was specified via FTIR, XRD, SEM, and TEM techniques. The process parameters at which maximum adsorption efficiency, qe (80.12 mg/g), and % efficiency >94 % were achieved include dosage (0.8 g/L), time (80 min), initial dye concentration (20 mg/L), and pH (6). Ultrasound‐assisted uptake was greater than stirring‐assisted due to acoustic cavitation′s hydrodynamic and thermal processes. Pseudo‐second‐order model described the adsorption kinetics and the diffusion mechanism suggested that the rate‐determining step was controlled by both the intraparticle diffusion and the liquid film models. Isotherms showed an excellent fit to the Freundlich model based on higher R2 (0.998) and lower standard error of estimate values (SEE=0.367). The −ΔG° values (−8.152, −8.292, −8.433, −8.586 kJ/mol) indicated that the adsorption process was feasible and spontaneous. The removal of CBB ensued via hydrogen bonding, electrostatic, π‐π, and n‐π interactions. The maximum adsorption capacity of 182.096 mg/g, eco‐friendly characteristics along with regeneration competence depicted that GAA could be effective for scavenging CBB from wastewater.

Ethidium bromide adsorption on pyrophyllite nanoclay: Insights from batch, thermodynamic, kinetic, and recyclability studies and optimization through response surface methodology

The efficient removal of Ethidium Bromide (EB), a toxic yet widely used chemical in biochemical industries and laboratories, is crucial to avoid its detrimental effect on human health, aquatic life, and the environment. One effective method is adsorption onto inert surfaces, but the choice of adsorbents is critical for the success of the removal protocols, primarily because of the limitations such as low adsorption capacity, high cost, limited availability, and a lack of understanding of the adsorption mechanism. In this work, Pyrophyllite Nanoclay (PNC), a naturally abundant aluminosilicate is explored as a promising adsorbent for EB. The adsorption process follows the Freundlich isotherm and displays pseudo-second-order kinetics. Under the optimized condition, PNC demonstrates nearly quantitative adsorption of EB and the maximum adsorption efficiency obtained from experiment was 6.53 mg/g (0.017 mmol/g) at room temperature under optimized condition. Through thermodynamic, kinetic analysis coupled with characterization techniques, the mechanism of adsorption is proposed. The adsorbent proves to be reusable, maintaining its performance over three cycles. The utility of the process is further validated and optimized using Response Surface Methodology (RSM). The present work focuses on the performance of PNC as adsorbent and elucidates distinctive surface adsorption mechanism (in comparison to other nanoclays), thus emphasizing the significance of structural, experimental, mechanistic and validation studies in choosing the right adsorbent for the removal toxic chemicals.

Removal of Cephalexin-Antibiotic from Drinking Water by Designing CaCl2 Incorporated Chitosan Co- Tragacanth Gum Composite Hydrogel

Background: The prevalence of antibiotic contaminants in aquatic environments presents a critical challenge to public health, necessitating the development of efficient removal methods. Emerging pollutants, especially antibiotics, have been implicated in the rise of antibiotic-resistant bacteria, threatening ecological balance and human well-being. Objective: This study aims to synthesize and evaluate the efficacy of a CaCl2-based composite hydrogel using chitosan as a biopolymer for the adsorption of antibiotic pollutants from water, targeting the improvement of water purification technologies in healthcare settings. Methods: Chitosan-based composite hydrogels were synthesized via free radical polymerization, incorporating CaCl2 and utilizing techniques such as Field Emission Scanning Electron Microscopy (FESEM) for morphology analysis, Energy-dispersive X-ray (EDX) analysis for elemental verification, Fourier-transform infrared spectroscopy (FTIR) for functional group identification, and X-ray diffraction (XRD) to determine crystallinity. Physicochemical parameters, including contact time, pH, temperature, reusability, and swelling behavior in various media, were systematically assessed to ascertain the hydrogel's adsorptive performance. Results: The synthesized hydrogels demonstrated a porous and rough surface ideal for adsorption, with an initial antibiotic removal rate of 80% within 30 minutes of contact time. FTIR analysis confirmed the presence of functional groups corresponding to absorption bands at 1053, 1415, 1601, 2600, 2900, 3300, and 3500 cm-1. EDX and XRD analyses affirmed the incorporation of CaCl2, with a crystalline phase characterized by sharp peaks. The hydrogel's maximum adsorption efficiency reached 95% at an optimized adsorbent dose of 0.05 g. Conclusion: The CaCl2-based composite hydrogel exhibits significant potential for the removal of antibiotic pollutants from water, suggesting a viable approach to mitigate the environmental impact of pharmaceutical contaminants and enhance human health by reducing the spread of antibiotic resistance.

Adsorptive capacity of PANI/Bi2O3 composite through isotherm and kinetics studies on alizarin red

Adsorption offers numerous advantages for eliminating organic pollutants such as dyes, making it a valuable method for water treatment. Polyaniline/Bi2O3 (PANI/Bi2O3) nanocomposite is synthesized from aniline by the chemical oxidative polymerization method. The sample shows a high positive surface charge density as seen from zeta potential analysis. X-ray Diffraction analysis, FTIR analysis, UV–vis spectroscopy technique, thermogravimetric analysis, BET N2 Adsorption-desorption analysis, DLS, and zeta potential analysis are the tools employed to characterize the PANI/Bi2O3 nanocomposite. The impact of PANI/Bi2O3 on the outcome of adsorption is confirmed by comparing the composite with pristine Bi2O3 and PANI. The effect of various factors like time, temperature, initial dye concentration, and varying pH on the adsorption efficiency is studied. A maximum adsorption efficiency of 95 % is observed when 100 mg of PANI/Bi2O3 nanocomposite is utilized for a duration of 100 min. The adsorption efficiency increases at higher temperatures, and a maximum adsorption efficiency is observed at a pH of 11.4. The adsorption isotherms proposed by Freundlich and Langmuir are examined to confirm the adsorption mechanism, which entails the creation of a single layer of dye molecules on the adsorbent's surface. Analysis of kinetic parameters indicates that the reaction follows pseudo-second-order adsorption kinetics. The composite produced demonstrates effectiveness as an adsorbent for removing harmful organic pollutants from water sources.

Molecularly imprinted polymers as solid-phase and dispersive solid-phase extraction sorbents in the extraction of antiretroviral drugs in water: adsorption, selectivity and reusability studies

AbstractThe antiretroviral drugs (ARVDs) have been reported to be among the emerging water pollutants as a results attention is being paid on their analysis. This work therefore explored for the first time the multi-template MIP for the selective removal of selected ARVDs (abacavir, efavirenz and nevirapine) in wastewater, river water and tap water. The adsorption studies of a multi-template MIP were conducted by determining the effect of an increase in ARVDs concentration in solution and the effect of an increase in contact time between the sorbent and the ARVDs. High adsorption efficiencies were observed for abacavir, efavirenz and nevirapine analytes within 5 min and the maximum adsorption efficiency was observed at 60 min ranging from 94.76 to 96.93%. Adsorption kinetics showed that pseudo-second rate order was the best fitting model, while adsorption isotherms indicated that the Freundlich isotherm (R2 = 0.94–0.98) best described the adsorption mechanism of ARVDs onto the MIPs. These results indicated that the electrostatic attractions influenced the multilayer coverage and chemisorption process. Selectivity studies conducted in the presence of competitors gave the recoveries between 92 and 98% for the target analytes, while they were 63–79% for competitors indicating good selectivity and strong affinity of the polymer towards the target analytes. Reusability studies showed that the MIP can be reused for up to 8 cycles with recoveries above 92% for all target ARVDs. The application of the MIP-DSPE method to wastewater, river and tap water samples gave concentrations of 28.75–178.02, 1.95–13.15 and 2.17–6.27 µg L−1, respectively. These results indicate the potential unplanned consumption of ARVDs upon drinking contaminated water which could result to their resistance by the human body. Therefore, their continuous monitoring as well as investigation of their removal strategies is of paramount importance.

Amendment of Sargassum oligocystum bio-char with MnFe2O4 and lanthanum MOF obtained from PET waste for fluoride removal: A comparative study

The use of biomass and waste to produce adsorbent reduces the cost of water treatment. The bio-char of Sargassum oligocystum (BCSO) was modified with MnFe2O4 magnetic particles and La-metal organic framework (MOF) to generate an efficient adsorbent (BCSO/MnFe2O4@La-MOF) for fluoride ions (F−) removal from aqueous solutions. The performance of BCSO/MnFe2O4@La-MOF was compared with BCSO/MnFe2O4 and BCSO. The characteristics of the adsorbents were investigated using various techniques, which revealed that the magnetic composites were well-synthesized and exhibited superparamagnetic properties. The maximum adsorption efficiencies (BCSO: 97.84%, BCSO/MnFe2O4: 97.85%, and BCSO/MnFe2O4@La-MOF: 99.36%) were achieved under specific conditions of pH 4, F− concentration of 10 mg/L, and adsorbent dosage of 3, 1.5, and 1 g/L for BCSO, BCSO/MnFe2O4, and BCSO/MnFe2O4@La-MOF, respectively. The results demonstrated that the experimental data adheres to a pseudo-second-order kinetic model. The enthalpy, entropy, and Gibbs free energy were determined to be negative; thus, the F− adsorption was exothermic and spontaneous in the range of 25–50 °C. The equilibrium data of the process exhibited conformity with the Langmuir model. The maximum adsorption capacities of F− ions were determined as 10.267 mg/g for BCSO, 14.903 mg/g for the BCSO/MnFe2O4, and 31.948 mg/g for BCSO/MnFe2O4@La-MOF. The KF and AT values for the F− adsorption were obtained at 21.03 mg/g (L/mg)1/n and 100 × 10+9 L/g, indicating the pronounced affinity of the BCSO/MnFe2O4@La-MOF towards F− than other samples. The significant potential of the BCSO/MnFe2O4@La-MOF magnetic composite for F− removal from industrial wastewater, makes it suitable for repeated utilization in the adsorption process.

Removal of lead from aqueous solution by magnetic modified dendrimer (Fe3O4@SiO2/(3-aminopropyl) triethoxysilane@dendrimer/benzaldehyde)

Synthesis of a magnetite nanoadsorbent was reported in the study. In this regard, poly(amidoamine) (PAMAM) dendrimer (with generation 10)-functionalized Fe3O4@SiO2/APTES ((3-aminopropyl) triethoxysilane) was prepared, modified by benzaldehyde (BZ), and characterized by fourier-transfer-infrared (FTIR), vibrating-sample-magnetometer (VSM), field-emission-scanning-electron-microscope (FE-SEM), X-Ray-diffraction (XRD), thermal-gravimetric-analysis (TGA), and elemental analysis. The nanoadsorbent with VSM value of 35.3 emu/g was used to investigate adsorption of Pb(II) ions from aqueous solutions and this process relied on the solution pH, lead concentration, nanoadsorbent dose, contact time, and temperature. The results revealed the maximum adsorption efficiency of 97.56% in pH = 6, initial lead concentration = 160 mg L−1, adsorbent dose of 15 mg, contact time = 60 min, and temperature = 45 °C. The adsorption isotherm and kinetic models of Pb(II) removal followed the Freundlich model and pseudo-second-order, respectively. The adsorption was endothermic and spontaneous, which was exhibited by the thermodynamic parameters. This research suggests that the nanoadsorbent can be considered for the other metal ions removal from wastewater treatment.

Bone Char Adsorption of COD and Colour from Tannery Wastewater: Breakthrough Curve Analysis and Fixed Bed Dynamic Modelling

This study delves into the simultaneous adsorption of chemical oxygen demand (COD) and colour from tannery wastewater using bone char through a fixed bed column. The bone char, which was derived from cattle skulls, was characterised using the Fourier transform infrared spectroscopy, Braeuer–Emmett–Teller surface area analysis, and the scanning electron microscope/energy-dispersive X-ray spectroscopy. The effects of different process conditions, specifically, packed bed height (5, 10, and 15 cm) and flow rate (2, 5, and 8 mL/min), on the adsorption efficiency of the fixed bed column were assessed through breakthrough curve analysis. The results revealed that the efficiency of the column bed enhanced with increasing bed height and declined with increasing wastewater flow rate. The optimal operating conditions for COD and colour removal onto the bone char occurred at 15 cm bed height and 2 mL/min flow rate. The adsorption capacities at these conditions were 227.4 mg/g and 53.03 Pt-Co/g for COD and colour, respectively. The kinetics associated with the fixed bed adsorption of COD and colour onto bone char were elucidated through the fitting of the Thomas, Adams–Bohart, and Yoon–Nelson models to the experimental data. Among the three models, the Yoon–Nelson model gave the best prediction of the experimental data. Maximum adsorption efficiencies of 80.65% and 84% were attained for COD and colour removal, respectively, proving that bone char is a promising and ecologically friendly alternative adsorbent for the treatment of tannery wastewater.

Copper Oxide Nano Biochar from Spent Coffee Grounds for Phosphate Removal and its Application as an Antibacterially Active Entity

From the viewpoint of both eutrophication and sustainable use of phosphate, the removal and recovery of phosphate from wastewater are important. Adsorption is seen as a viable alternative for effective phosphate removal, even at low concentrations. It is very simple to operate and cheaper. Among the various adsorbents tested, biomass-derived nanomaterials, such as nanobiochar, have shown promising efficiency. However, the use of pristine biochar is often less effective and difficult to recycle. In the present study, copper oxide-modified nanobiochar from spent coffee grounds is presented as an effective phosphate adsorbent. The adsorbent was prepared by the acid digestion of spent coffee grounds, followed by the co-precipitation of copper metal. The developed adsorbent was characterized by BET, FTIR, and XRD. Batch mode adsorption studies were conducted to assess the adsorption efficiency of the developed adsorbent and to investigate the effect of pH, initial concentration, contact time, and adsorbent dose. It was observed that acidic conditions favored the adsorption of phosphate, with maximum adsorption efficiency (93%) at pH 3. The maximum equilibrium phosphate adsorption capacity in this study was 50.2 mg/g at 25 oC, pH 3, a phosphate concentration of 20 mg/L, and an adsorbent dose of 35 mg/mL. The batch experimental data fit the Freundlich isotherm with regression (R2 = 0.991), which signifies that the surface of the adsorbent is heterogeneous. Adsorption kinetic data were best fitted with the pseudo-second-order kinetic model (R2 = 0.996), indicating that the adsorption process was dominated by chemisorption. The copper oxide nanoparticles and Cu/NBC showed relatively higher zone inhibition in gram-positive bacteria than in gram-negative bacteria at similar concentrations. This might be due to the higher activity of the nanoparticle extract on gram-positive bacteria, as most nanoparticle extracts were more active in gram-positive bacteria. This difference may be explained by the difference in the structure of the cell wall in gram-positive bacteria, which consists of a single layer, and in gram-negative bacteria, which has a multi-layered structure and is quite complex. In the majority of test bacteria, Cu/NBC showed better activity. The higher activity of this nanomaterial might be associated with the number of bioactive metabolites and their synergetic activities.

Reduced Graphene Oxide/Cellulose Sodium Aerogel-Supported Eutectic Phase Change Material Gel Demonstrating Superior Energy Conversion and Storage Capacity toward High-Performance Personal Thermal Management.

By virtue of their capacity to absorb and release energy during the phase change process, phase change materials (PCMs) are ideal for personal thermal management (PTM). The combination of reduced graphene oxide/cellulose sodium aerogel (rGCA) and lauric acid/myristic acid binary eutectic phase change gel (LMG) creates a composite phase change material that possesses outstanding photothermal conversion capabilities, electro-thermal conversion capabilities, energy storage capabilities, and shape-stable performance. The results showed that rGCA had a maximum adsorption efficiency of 99.7% with a melting latent heat of 124.6 J g-1. The high absorption rate of rGCA to LMG is a result of the capillary force, pore characteristics, hydrogen bonding, and the π-π interaction. Notably, rGCA and LMG composite material (rGCG) exhibited an excellent photothermal conversion efficiency of 96.5% and electro-thermal conversion of 82.3%. Results indicate that binary eutectic phase change materials are more suitable for temperature regulation than single phase change materials, making them more suitable for PTM. It is anticipated that the innovative thermal comfort solution, which provides thermal shielding, thermal energy storage, self-supporting characteristics, and wearability, will offer new possibilities for the next generation of wearable PTMs.

Synthesis and Characterizations of Molecularly Imprinted Polymer of Atrazine: Removal of Atrazine from Aqueous Samples

AbstractAtrazine (ATZ) is a widely used triazine herbicide in agriculture, however, it negatively affects the environment and human health. Therefore, a molecularly imprinted polymer (MIP) was employed for the selective removal of ATZ. In this study, MIPs were produced by precipitation polymerization using ATZ as the target molecule, methacrylic acid (MAA), acrylamide (AAm), and 2‐vinylpyridine (2VP) as functional monomers and ethylene glycol dimethacrylate (EGDMA) as cross‐linker, respectively. MIP characterizations were performed using Fourier Infrared spectroscopy (FTIR) and Field Emission Electron Microscopy (FESEM). The batch binding study revealed that MIP (2VP) exhibited the highest rebinding efficiency (88.44 %) among the MIPs. Furthermore, MIP (2VP) was analyzed by Energy‐Dispersive X‐ray spectroscopy (EDX), Brunauer‐Emmett‐Teller (BET) analysis, and thermogravimetric analysis (TGA). Adsorption studies revealed that the optimum conditions for maximum adsorption efficiency were 8 ppm ATZ solution at pH 7, using 0.3 g of MIP (2VP). MIP (2VP) demonstrated higher selectivity towards ATZ than the Ametryn (AME) a competitive interferent, with a relative selectivity coefficient of 2.77. MIP (2VP) successfully removed ATZ from distilled water (95.39 %), tap water (88.16 %) and river water (86.75 %). These findings contributed for the development of MIP for the removal of ATZ, which would be helpful in the protection of ecosystem and human health in future.

ADSORPTIVE REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS PHASE USING VEGETABLE-TANNED BUFFING DUST

Removal of hexavalent chromium from synthetic wastewater was performed by employing vegetable-tanned buffing dust, a byproduct of tanneries. Different analysis techniques such as SEM, BET, and FTIR were used to characterize the vegetable-tanned buffing dust. The experiment on adsorption was carried out in a batch manner. Investigations were conducted into the various operating parameters, such as the dose of adsorbent, contact period, and initial Cr (VI) concentration. At a dose of 1g/100 mL and a contact period of 280 minutes, the maximum adsorption capacity was noted. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherms were examined at various concentrations. With a maximum adsorption efficiency of 14.14 mg/g, the Langmuir isotherm model was found to be the most well-fitting for the current investigation. Kinetic analysis was performed for pseudo first and second order; the pseudo-second-order model demonstrated the most optimal fit with a regression coefficient (R2 ) of 0.9936.

Advancements in sustainable platinum and palladium recovery: unveiling superior adsorption efficiency and selectivity with a novel silica-anchored acylthiourea adsorbent.

This study addresses the pressing issue of depleting natural resources of platinum group metals (PGMs), driven by their widespread use in modern applications and increasing demand for renewable energy technologies. With conventional sources dwindling, the search for economically viable recovery methods from alternative sources has become crucial. Our focus was on innovating efficient recovery strategies, leading to the development of two novel silica-anchored adsorbents: DTMSP-BT-SG, a highly efficient acylthiourea adsorbent, and BTMSPA-SG, a silica-anchored amine adsorbent. We conducted comprehensive experiments under PGM mining wastewater conditions, varying parameters such as adsorbent mass, pH, concentration, contact time, competing ions, and volume. DTMSP-BT-SG demonstrated exceptional performance, achieving maximum adsorption efficiencies of >98% for Pt and >99% for Pd at pH 2, 0.5 g L-1 dosage, and 5 mg L-1 concentration. In contrast, under the same conditions, BTMSPA-SG recovered <56% and <89% of Pt and Pd, respectively. The experimental data for both adsorbents were analysed using Langmuir and Freundlich isotherm models for concentration and pseudo-first and second-order models for contact time. The Langmuir model best described the adsorption data, indicating homogenous monolayer adsorption of Pt and Pd. The kinetic models suggested a pseudo-second-order process, implying chemisorption. Furthermore, in the presence of competing ions and other PGMs, DTMSP-BT-SG exhibited significantly higher recovery rates for Pt and Pd compared to BTMSPA-SG. Overall, DTMSP-BT-SG emerged as a more selective and efficient adsorbent across varied parameters. Its exceptional adsorption efficiency, coupled with cost-effectiveness, positions it as a promising and competitive recovery agent for extracting PGMs from mining wastewaters.

Removal of dyes using chemically modified elephant grass in single and binary-component system

The present study investigated the potential use of citric acid-treated Elephant grass (Pennisetum purpureum), as an adsorbent for the removal of various dyes (Congo red, Erichrome black T, methyl red, and thymol blue) from aqueous solutions. The effects of initial concentration, adsorbent dosage, and temperature on the adsorption capacity of the dyes were evaluated. The results showed that Pennisetum purpureum had a high adsorption capacity for all dyes, with maximum adsorption efficiencies ranging from 74% to 98.92%, depending on the dye type and experimental conditions. The highest adsorption efficiency was recorded at 10 mg/L initial concentration for most of the dyes. The optimum adsorbent dosage was found to be 0.3 g for all dyes, except for Erichrome black T, which showed maximum adsorption capacity at 0.2 g. The maximum adsorption capacity for all dyes was observed at a temperature of 60°C, except for methyl red and thymol blue, which showed maximum adsorption at temperatures lower than 60°C. Overall, the results indicate that citric acid-treated Pennisetum purpureum has great potential as an effective and sustainable adsorbent for the removal of various dyes from wastewater.

On the adsorption characteristics and mechanism of methylene blue by ball mill modified biochar

In this study, modified biochar (BRB) was prepared from rice straw by ball milling technique and used for the adsorption of methylene blue (MB) in wastewater. The BRB was characterized by SEM, FTIR and XPS, and the adsorption model and Box–Behnken design were used to optimize the five influencing factors. The results showed that the ball milling technique could increase the content of functional groups (–OH, C=C and C–O, etc.) and aromatic structures on the surface of biochar, thus facilitating the removal of MB. The isotherm model was consistent with the Langmuir adsorption model (R2 = 0.947) and the maximum adsorption capacity was 50.27 mg/g. The adsorption kinetics was consistent with the pseudo-second-order kinetic model (R2 = 1) and the adsorption rate was mainly controlled by chemisorption. The thermodynamic model confirmed that the adsorption process was a spontaneous heat absorption reaction. The maximum adsorption efficiency was 99.78% under the optimal conditions (40℃, pH 8, reaction time = 90 min, dosing amount = 0.1 mg), and the adsorption efficiency could be improved by increasing the pH and BRB dosing amount. The surface functional groups and crystal structure properties of BRB were the main determinants of adsorption, and it was clarified that physical adsorption, electrostatic attraction and π-π interaction were the main mechanisms for the adsorption of MB by BRB. The main mechanisms were clarified. Therefore, BRB is an economic, efficient and green adsorption material with good potential for the removal of dye pollutants in the aqueous environment.

Detection and sorption of heavy metal ions in aqueous media using Zn-based luminescent metal-organic framework

In this study, we present the synthesis and comprehensive characterisation of a novel, luminescent Metal-Organic Framework (MOF) denoted as PUC7, derived from Zn(NO3)2·6H2O, 1,2-di(4-pyridyl)ethylene, and 2-amino-terephthalic acid through solvothermal method. The PUC7 was successfully characterised using many techniques, including single crystal X-ray diffraction, powder X-ray diffraction, FTIR spectroscopy, BET surface area analysis, FESEM imaging, XPS, UV–visible spectroscopy, and zeta potential measurements. Remarkably, PUC7 exhibited high luminescence properties and water stability. The luminescence properties were utilised for the detection of heavy metal ions. Consequently, PUC7 displayed exceptional selectivity and sensitivity towards W6+ and V5+, with impressively low detection limits of 0.17 μM and 0.22 μM, along with high quenching constant values of 2.5 × 105 M−1 and 1.1 × 105 M−1, respectively. Additionally, we explored PUC7′s proficiency in removing W6+ and V5+ ions from aqueous solution, revealing maximum adsorption efficiencies of 476.2 mg/g and 460.8 mg/g, respectively, fitting well with the Langmuir adsorption model and exhibiting second-order kinetics. Encouragingly, PUC7 demonstrated reusability for up to five cycles in removing W6+ and V5+ ions. Altogether, this research underscores the potential of PUC7 as a versatile and promising tool for efficiently detecting and removing W6+ and V5+ ions from water, with implications for environmental remediation and water purification applications.