Freundlich Isotherm Research Articles

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.

Performance study of phenol sequestration from agricultural wastewater by chemical activated Montmorillonite

Agricultural by-products possess potential as cost-effective adsorbents for the remediation of phenolic contaminants in environmentally treated wastewater. This research focuses on the utilization of Algerian montmorillonite clay, specifically modified montmorillonite (Mo-5N), treated with 5N hydrochloric acid (HCl), compared to its untreated form (Mo-0N), for phenol sequestration from pesticide-laden waters. We employed various analytical techniques, such as chemical analysis, X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy, to characterize these adsorbents. The adsorption behavior was scrutinized under varying conditions, including pH, contact time, phenol concentration, and temperature. The maximum adsorption capacities achieved were 119.12 mg/g for Mo-5N and 100.89 mg/g for Mo-0N under optimal conditions of pH 5.72, a contact time of 120 minutes, and a temperature of 40°C. The kinetics of adsorption were best described by the pseudo-second-order and Elovich models, while the Freundlich isotherm model aptly described the equilibrium data. Thermodynamic analyses revealed that the phenol removal process using both forms of montmorillonite is spontaneous and endothermic. This study demonstrates the efficacy of Algerian montmorillonite clay in the removal of phenolic pesticides from agricultural wastewater.

Exploration of the role of Hibiscus esculentus (okra) mucilage for the removal of phenothiazinium dyes from water body: Spectroscopic, thermodynamic and molecular modeling study

Environmental pollution poses a major problem now a day. Several dyes, in the form of industrial waste, pollute water body and may cause adverse effects to human health. In this paper ADME and toxicity of fives Phenothiazinium group of dyes Methylene blue (MB), Azure A (AA), Azure B (AB), Azure C (AC) and Toluidine Blue O (TBO) were predicted using Swiss ADME and Protox II tools. Results showed these dyes may herm for living organism due to their carcinogenic, mutagenic and hepatotoxic properties. Removal efficiency of these dyes using okra plant product were determined using spectroscopic, thermodynamic and molecular modeling study. It was revealed that these dyes adsorb on the surface of okra leaf mostly at pH 7.0 and the adsorption isotherms were found to fit in Langmuir and Freundlich isotherm model, while Temkin model fails to do this. Mucilage present in different parts of okra plant plays a significant role on removal of these dyes and is able to remove near about 71–92 % of dyes from water body by itself. As this process did not fit in any of above said adsorption isotherm model, it may be suggested that some other mechanism may happen. Further studies explore that these dyes bound to the hydrophobic pocket of mucilage with binding affinity in the order of 105 M−1 and the bindings were exothermic in nature with enthalpy change in the range of − 2.94 to − 4.28 kcal/mole. Molecular docking study validate all the experimental results obtained from spectroscopic and thermodynamic study and enlighten the role of structure of dyes on their binding affinity to mucilage. This paper will help to systematically understand the role of okra plant products on removal efficiency of Phenothiazinium group of dyes with their structural variations.

Efficient ethidium bromide removal using sodium alginate/graphene oxide composite beads: Insights into adsorption mechanisms and performance

This study explores the efficacy of sodium alginate/graphene oxide (SA/GO) composite beads for ethidium bromide (EtBr) removal from aqueous solutions. GO was synthesized and crosslinked with SA to design composite beads, which were evaluated under various physicochemical conditions. Characterization techniques, including FESEM, TGA, XRD, and FTIR, were employed to analyze the beads before and after EtBr adsorption. Results demonstrated rapid EtBr adsorption onto SA/GO, following the Freundlich isotherm model with a maximum adsorption capacity of 2.97mmol g−1 (1171.05 mg g−1). The influence of solution pH and the negligible role of Br− ions suggested that electrostatic interaction was the primary mechanism for EtBr adsorption on SA/GO. XRD and FTIR analyses revealed that EtBr adsorption also occurred in the interlayer space of SA/GO beads, with the ethidium cations (Et+) entering this space in a horizontal or oblique (≥45°) orientation. The accumulation of Et+ within the interlayer space was estimated to form 1–6 basic inclined layers. SA/GO beads demonstrated promising characteristics for EtBr pollutant treatment, including low environmental impact, cost-effectiveness, rapid adsorption kinetics, and high removal efficiency. This study provides valuable insights into the adsorption mechanisms and performance of SA/GO beads, highlighting their potential for future field applications in the environmental remediation of EtBr contamination.

Microwave-assisted synthesis of γ-alooh nanoflowers as an adsorbent for cadmium removal from domestic wastewater.

In this study, cadmium ions were effectively removed from domestic wastewaters using an adsorptive treatment strategy based on γ-AlOOH nanoflowers. A novel, rapid, and simple procedure was developed for the synthesis of the nanoflowers. Characterization studies were performed using X-ray powder diffraction patterns and scanning electron microscope images. The synthesized nanoflowers were utilized as adsorbent in the batch adsorption experiments. The influential parameters of the adsorption process were optimized, and a flame atomic absorption spectrophotometry (FAAS) system was used to determine maximum percent removal of cadmium ions. Matrix-matched calibration strategy, in which the calibration plot was developed in wastewater medium, was utilized for the accurate and precise quantification of cadmium in the effluent samples. The percentage removal efficiency values were calculated between 84 and 98% for different concentrations of cadmium ions in the wastewater samples. Equilibrium data was fitted to the four different linearization methods of the Langmuir isotherm model, as well as the Freundlich isotherm model and Elovich isotherm model. The best fitting was achieved for the Langmuir model with a high R2 value of 0.9956 and maximum adsorption capacity was calculated as 6.23mg/g.

Synthesis and Characterization of Nano Iron Oxide Biochar Composite for Efficient Removal of Crystal Violet from Water

In the present study, Coconut Husk Biochar (CHB) was synthesise from widely available, locally sourced agro waste, coconut husk and characterized using different techniques like scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). CHB was tested for its ability to adsorb crystal violet (CV), a commonly used cationic dye, from water. It was capable of adsorbing more than 98% of CV from water and follows Freundlich isotherm model with pseudo second order kinetics though the overall process was unfavourable. Moreover, separation of CHB from water after adsorption is a cumbersome process. Thus, unmodified CHB is not suitable for use as an adsorbent for CV. Magnetic nano iron oxide Biochar Composite (MBC) was synthesized by deposition of nano iron oxide (Fe3O4) onto its surface by co-precipitation method and characterized using SEM, XRD and FTIR. SEM analysis provided visual evidence of this deposition which was further confirmed by XRD and FTIR analysis. MBC was also effective in adsorbing more than 90% of CV from aqueous solution though a decrease in adsorption capacity was observed. Adsorption data followed Langmuir isotherm model and pseudo second order kinetics. MBC is superparamagnetic and is strongly attracted to a small bar magnet, facilitating easy removal from water after CV adsorption.

Waste glass as a source for green synthesis of mesoporous adsorbent for efficient removal of heavy metals

Mesoporous analcime Adsorbent (MaA) was cogently synthesized in a hydrothermal reaction where a waste silica glass powder was mixed into NaOH solution. The satisfactory reaction properties were achieved by regulating the conditioning time (Ct), reaction temperature (Rt), and relative ratio of the reactants (Rr= SiO2:Na2O). XRF, XRD, SEM, BET, FTIR, AFM, TG and TEM analysis formed part of the selected samples. The prepared MaA adsorbent was then applied to treat Pb2+, Cd2+ and Cu2+ ions, thus effectively allowing the physicochemical properties (pH, temperature and contact duration), on the adsorption amount to be examined. Upon completion, the results indicated that the initial pH as well as the contact duration had notable effect on the adsorption amount. Conversely, the temperature change had an insignificant effect on the equilibrium adsorption amount. In addition, a dosage of 0.1 g of MaA, concentration of 1000 mg/L, pH ranging from 6−8, and temperature of about 25°C were found to be the optimum process conditions for the adsorption of the examined heavy metals, whereas difference in contact time was recorded as follows: 1 h for Pb2+ and Cu2+ ions with adsorption amounts of 75.081 mg/g and 74.054 mg/g, respectively; and 3 h for Cd2+ ion with adsorption equal to 75.530 mg/g. In the analysis of the trend, the coefficients of correlation (R2=0.99) of the Langmuir isotherm model were increasingly consistent compared to Freundlich isotherm model (R2 from 0.10 to 0.55), thus indicating that the process to be a homogeneous monomolecular layer adsorption. Moreover, the kinetic aspects were similarly consistent in relation to quasi-secondary kinetic equation, which then further established that the process was primarily controlled by ion exchange, extra-particle, intra-particle, and liquid film diffusion. In addition, research on the potential reusability of MaA adsorbent after being employed to treat heavy metals was also performed. The crystalline phase of the composite after subjected to high temperature indicated wollastonite (CaSiO₃) and gregoryite (Na₂CO₃) as the main mineralogical phases. These minerals are beneficial in the preparation of functional building materials by promoting a sustainable solution for the full recycling of waste glass and contributing to efficient solid waste management and environment protection.

Fundamentals of copper(II) adsorption on phyllosilicate minerals relevant to crud formation in solvent extraction from heap leach liquors

Because of the common presence of different silicate minerals, like kaolinite, montmorillonite and muscovite as gangue minerals in the beneficiation of copper oxide ores, the interaction between copper(II) ions in solution and each of these minerals is a field of strong interest, considering their implications on the aggregation of these minerals in the extreme pH conditions typical of hydrometallurgical unit operations for copper production. After copper adsorption isotherms determination at pH 2 and 4, specific adsorption data were fitted to both Langmuir and Freundlich models. It was found that adsorption is systematically larger at pH 4, and that montmorillonite is the mineral that displays a larger adsorption capacity, as in principle expected by its larger cation exchange capacity, CEC. A good fitting to the Langmuir model was obtained for the three samples, and montmorillonite also appears to conform to Freundlich isotherm predictions, as the tested concentrations of copper(II) do not allow to reach saturation. Furthermore, some desorption is measured for kaolinite and muscovite at the highest copper concentrations, probably because of significant interactions between the adsorbed ions. No such desorption was detected in montmorillonite samples. An XPS analysis of the surfaces of the three minerals suggests that copper adsorption in kaolinite is not associated to a cation exchange process but rather to electrostatic interactions between silica-like faces of the clay. In contrast, ionic exchange of structural calcium (for montmorillonite) or potassium (in the case of muscovite) seems to be the predominant mechanism of Cu(II) adsorption in the other two samples. Electrophoretic mobility determinations agree with this hypothesis: the mobility (always negative, with no traces of charge inversion) decreases in absolute value when kaolinite particles are in contact with solutions of increasing copper concentration at pH 2 or pH 4. On the other hand, the electrophoretic mobility values of muscovite and montmorillonite showed a weak pH and copper concentration dependence, a result that matches well with the ion exchange processes detected in the XPS measurements.

Enhanced sequestration of ciprofloxacin from aqueous solution using composite montmorillonite-kaolin clay adsorbent

Clay minerals are low-cost and environmentally benign natural adsorbents with huge potential for removing micropollutants from aqueous solutions owing to their intrinsic surface properties. In this study, montmorillonite and kaolin clay minerals were activated using NaNO3 and HNO3 to develop activated montmorillonite- kaolin clay composites (AMKCC) material for the sequestration of ciprofloxacin (CIP) from aqueous solution. The developed AMKCC was characterized using X-ray fluorescence (XRF), Brunauer-emmett-teller (BET), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The BET analysis reveals an improved BET surface area, pore volume and pore diameter of 139.13 m2/g, 0.17 cm3/g and 2.18 nm, respectively. At optimum conditions, pH (3.56), initial concentration (16.74 mg/L), time (77.9 mins) and adsorbent dosage (0.4 g), the percentage of ciprofloxacin removed from aqueous solution was 97 %. The adsorption of ciprofloxacin (CIP) using AMKCC was spontaneous, feasible, endothermic, and followed Freundlich isotherm with pseudo-second-order kinetics. The maximum monolayer adsorption capacity of AMKCC is 344.82 mg/g. The desorption studies revealed HCl as the best eluent for AMKCC regeneration. Therefore, AMKCC has considerable potential for the adsorption of pharmaceuticals from aqueous solution.

Estimated of Pomegranate Peel Waste for Biosorption of Cu (II) & Pb(II) Ions From Aqueous Solutions

This study intends to explore the waste natural materials’ adsorption capability. The use of pomegranate peels was investigated to see the chances of eradicating Pb(II) and Cu(II) ions from the aqueous solutions. Adsorption capability was evaluated using batch adsorption experiments, which also evaluated the impact of solution pH and initial metal concentration. The ideal biosorption conditions included a pH of 6.0, a dose of 0.1 g of biomass, and an equilibrium duration of 90 minutes. The adsorption data fit in a way that was comparable to the isotherm models by Freundlich and Langmuir. Pomegranate peel (PGP) was tested for its affinity and adsorption capability. Based on the values of the separation factor (RL) and Freundlich constant (n), it seems that the metal ions were taken up onto biosorbents in a preferred manner. According to this study's conclusions, the equilibrium data suit the Freundlich and Langmuir isotherms rather nicely. According to correlation coefficient data, the maximal sorption capacity of the produced pomegranate peel is 5000 mg/g. The Fourier Transform Infrared Spectrometer (FTIR), Energy Dispersive X-ray Spectrometer (EDX), and Scanning Electron Microscope (SEM) were utilised in the characterisation examinations. As a result, distinct aggregates formed on the surface of the biosorbent. In the characterisation experiments, an energy-dispersive X-ray spectrometer (EDX) and a scanning electron microscope (SEM) were employed. Different aggregates developed on the biosorbent surface as a result of contact with metal ions. On the surface of the biosorbent, distinct aggregates formed as a result of interaction with metal ions. Either via complexation or electrostatic attraction, the metal ions attached themselves to the biosorbents' active sites.

Synthesis of gamma aluminum oxide nano-powder for adsorptive removal of nitrate from aqueous solutions

Nitrate pollution of surface and groundwater could be a worldwide issue resulting in the threat to the environment and public health. The removal of nitrate from water was carried out using gamma aluminum oxide (γ-Al2O3) nano powder. The nano powder was synthesized from aluminum oxide powder using the aqueous-based reflux method and applied for nitrate removal. The surface properties of the activated γ-Al2O3 were characterized using FTIR, XRD, and BET surface area analysis. Analysis of variance (ANOVA) was used to analyze nitrate removal to determine the appropriate regression model, which was found to be the quadratic model with a coefficient of determination (R2 = 0.99). The adsorption process was observed to be dependent on initial nitrate concentration, adsorbent dose, and time. The optimized nitrate removal efficiencies were 97.01% using a dose of 2.26 gL−1, an initial nitrate concentration of 10 mgL−1, and a contact time of 45 min. Additionally, the kinetics of nitrate ion adsorption was discussed based on pseudo-first order and pseudo-second order kinetic models. The experimental data fitted well with the pseudo-second order kinetic model, indicating that the adsorption mechanism is chemisorption. The equilibrium adsorption of nitrate experimental data followed the both Freundlich and Langmuir isotherm (R2 = 0.95), implying a homogeneous nature of the γ-Al2O3 surface sites. These results suggest further consideration of the practical application of γ-Al2O3 for nitrate treatment for domestic purposes.

Methyl Orange Dye Removal by Dimethylamine Functionalized Graphene Oxide

Graphene oxide (GO) functionalized with dimethylamine (DMA) was successfully prepared using a facile technique. GO was first synthesized using the modified Hummers method, followed by chemical functionalization with DMA in the presence of an electrophilic linker, i.e., epichlorohydrin (ECH). FTIR analysis of the end product ascertains the successful synthesis of GO as well as its functionalization with DMA. Typical characteristic peaks attributed to GO and DMA are clearly discernible in the spectrum. The effect of pH, adsorbent dosage, dye concentration, and contact time towards methyl orange (MO) dye removal was studied and reported herein. In summary, enhanced adsorption of methyl orange was observed for DMA functionalized GO compared to GO alone. 90% removal was observed with 10 mg/L of MO concentration, pH = 2 at temperature 25 °C and 5 mg of adsorbent. Modelling study shows that the pseudo-second-order kinetic model and Freundlich isotherm model provide better fitness to the experimental data.

Ultrasonic-aided preparation of poly(vanillin-co-thiophene)/green Fe₃O₄ nanocomposites via solution mixing for methyl orange adsorption and antibacterial applications

This work describes the preparation of novel nanocomposite materials comprising a newly synthesized semiconducting copolymer, poly(vanillin-co-thiophene) (PVTH), blended with different weight proportions (3 %, 6 %, and 9 % by weight) of greenly synthesized magnetite nanoparticles (GFe3O4 MNPs) via solution mixing, assisted by ultrasonic irradiation. PVTH copolymer was synthesized through the polycondensation of vanillin, a bioderived aldehyde, and thiophene, catalyzed by sulfuric acid. GFe3O4 MNPs were prepared via the coprecipitation method with mint extract as an environmentally friendly stabilizer. The physicochemical properties of the prepared samples were investigated by 1H NMR, 13C NMR, FTIR, XRD, UV–vis, TGA, FE-SEM/Eds, AFM, VSM, tauc plot method and the four-points probe measurement. The samples were evaluated for two applications: methyl orange (MO) adsorption from aqueous solutions and antibacterial activities against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus) bacterial strains. The results showed that ultrasound irradiation facilitated the easy preparation of well-dispersed and homogeneous nanocomposites with combined semiconducting and magnetic properties and improved thermal stability compared to the parent PVTH. The most effective nanocomposite for MO removal was the sample containing 9 % GFe3O4 MNPs, whose adsorption behavior followed pseudo-second-order kinetics and Freundlich isotherm. Its maximum adsorption capacity was 103.79 mg g−1. In addition, all samples showed antibacterial action against the tested bacterial strains, with PVTH showing the highest efficacy, followed by PVTH/GFe3O4 nanocomposites.

Amine-modified SiO2 aerogel for efficient adsorption of low-pressure CO2: Response surface methodology optimization and adsorption mechanism

Amine-modified SiO2 aerogel (AMSA) has shown tremendous potential in CO2 capture due to its unique three-dimensional network structure and excellent stability. However, it still faces many challenges in the preparation optimization, adsorption enhancement at low CO2 partial pressure, and mechanism elucidation. Hence, in this paper, the response surface methodology is employed for the first time and the optimal preparation conditions for AMSA are determined. A regression model is successfully established to accurately predict the CO2 adsorption capacity of AMSA under different synthesis conditions (with a relative error of only 0.98 %). Additionally, the AMSA prepared at optimal conditions exhibits high CO2 adsorption capacity of 2.11 mmol/g and excellent stability (only decreased by 1.44 % after 8 cycles) at 10 % CO2 partial pressure, indicating enormous application potential. Notably, the CO2 adsorption mechanism by AMSA at different temperatures and partial pressures are revealed in detail through fitting with the Freundlich isotherm and the double-exponential model, as well as thermodynamic parameter calculations. Firstly, the CO2 adsorption behavior belongs to the multi-layer adsorption behavior with uneven energy of active sites. Secondly, the CO2 adsorption capacity and rate are jointly controlled by molecular motion and chemical reaction equilibrium, diffusion and chemical reaction steps, respectively. Finally, the adsorption process is exothermic and spontaneous, and the level of disorder decreases at the gas-solid interface. This study not only achieves efficient adsorption of low-pressure CO2, but also deepens the understanding of gas-solid interface adsorption mechanisms, providing scientific basis and technological support for the development of novel efficient AMSA adsorbent materials.

N-doped carbon nanospheres synthesized from a newly designed eco-friendly sustainable polymer for highly selective CO2 capture.

N-doped carbon nanospheres and porous carbon were produced by a hydrothermal template and the activation of hexamethylenetetramine (HMTA as a nitrogen source and activator) and ZnCl2 (only as an activator) from a poly(Ri-S-ε-CL-PDMS) multiblock/graft copolymer produced using a renewable resource and eco-friendly autoxidation. N-doped carbon nanospheres (PPiSiHMTA) exhibited excellent CO2 adsorption (2.73mmol/g at 0°C and 0.15atm, 1.72mmol/g at 25°C and 0.15atm) and CO2/N2 selectivity (344-512). Despite the higher BET surface area and pore volume, porous carbon (PPiSi) showed low CO2 adsorption (1.21 and 0.71mmol/g, 0.15atm) and CO2/N2 selectivity (57 and 112). PPiSiHMTA and PPiSi have low isosteric heats of adsorption (Qst, 18-33kJ/mol) and stability in humid environments. In addition, PPiSiHMTA exhibited an excellent CO2 recycling performance. The experimental data on CO₂ adsorption was evaluated using various isotherm models, including Freundlich, Langmuir, Sips, and Temkin. The results demonstrated a nearly perfect fit between the Freundlich isotherm and the experimental data, indicating the heterogeneous nature of the adsorbent surfaces. Our study is promising for industrial applications, offering excellent CO2 adsorption, CO2/N2 selectivity, moisture stability, and porous material fabrication strategies.

Photocatalytic NOx degradation and [formula omitted] adsorption by mortar modified with S-g-C3N4/MgAl-CLDH: Influence factors and stability

NOx is a harmful gas that causes respiratory diseases and acid rain. Commonly used photocatalysts for degrading NOx such as UV responsive TiO2 show weak photocatalytic degradation efficiency under visible light. Furthermore, the great concern is that the degradation product, nitrates (NO3-), from NOx could be washed away and increase the nitrogen deposition and eutrophication in the surrounding soil and aquatic environments, resulting in serious secondary pollution. To address these issues, this study proposes a novel solution by incorporating S-g-C3N4/MgAl-CLDH nanocomposites into a cementitious system which features high NOx degradation efficiency under visible light condition and the efficient capture and adsorption of NO3- in situ. The NOx degradation was comprehensively studied, encompassing the influencing factors and stability. The mechanism for NO3- adsorption process was expounded using the isothermal model. The results show that the amount of exposed S-g-C3N4/MgAl-CLDH and the contact area between S-g-C3N4/MgAl-CLDH and NOx are the essential reasons affecting the NOx degradation. The NOx degradation ability of photocatalytic mortar exhibits excellent stability with the NOx removal ratio decreasing by only 4.8 % and 14.5 % after ten consecutive tests and 120 min of ultrasonic washing, respectively. Furthermore, S-g-C3N4/MgAl-CLDH increases the NO3- adsorption capacity of photocatalytic mortar by about 1.5 times, and the adsorption process of NO3- follows the Freundlich isotherm. The study offers an alternate method for designing innovative nanocomposites in cement-based materials to control environmental pollution.

Enhanced phosphorus adsorption using modified drinking water treatment residues: A comparative analysis of powder and alginate bead forms

This study provides an analysis of the phosphorus adsorption efficacy of three modified drinking water treatment residues (MDWTRs): MDWTR-P (powdered form), MDWTR-D2, and MDWTR-D5 (alginate bead-entrapped forms with bead diameters of 2 mm and 5 mm, respectively). The preparation process involved washing and drying the drinking water treatment residue, followed by grinding and sieving to achieve particle sizes below 90 μm. The residue was then incinerated at 600 °C in oxygen-limited conditions. Subsequently, the MDWTR was formulated into alginate beads by mixing with sodium alginate and FeCl3 solutions, resulting in spherical particles of specified diameters. The evaluation of surface area, pore volume, pore size, and CHN concentration revealed that MDWTR-D5 possesses the largest surface area (284.7 m2 g−1) and highest micropore volume (0.04 cm3 g−1), indicating a greater capacity for adsorption. SEM-EDS analysis demonstrated significant compositional changes post-treatment, particularly elevated phosphorus levels, confirming effective adsorption. Metal content analysis indicated high aluminum levels in MDWTR-P and increased iron content in MDWTR-D5. Toxicity Characteristic Leaching Procedure (TCLP) and in vitro bioaccessibility (IVBA) tests confirmed the non-hazardous nature of all MDWTRs, ensuring their safety for environmental applications. Kinetic analyses using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models highlighted the superior performance of MDWTR-D5, with the highest equilibrium adsorption capacity and initial adsorption rate across all tested concentrations, suggesting both high efficiency and rapid adsorption potential. Further validation using Langmuir and Freundlich isotherms revealed MDWTR-D5's highest monolayer adsorption capacity (22.88 mg g−1) and Freundlich adsorption capacity parameter (6.97 mg g−1). Statistical analysis via one-way ANOVA confirmed significant differences in phosphorus concentrations among the MDWTRs samples (p-value <0.001), consistently underscoring MDWTR-D5's superior adsorption performance. These findings highlight MDWTR-D5's potential as an effective adsorbent for phosphorus removal in wastewater treatment, emphasizing its applicability in environmental remediation strategies.

Composite biopolymer foams fabricated from natural aldehyde functionalized chitosan-whey protein amyloid fibrils: Application for removal of phthalate esters from water

In this work, composite biopolymer foams from chitosan and whey isolate protein amyloid fibrils were prepared for the removal of phthalate esters from water. Natural aldehyde functionalization enhanced the affinity for dibutyl phthalate (DBP), with citral being the most effective. The citral-grafted foams (WCGC) had tunable hydrophobicity, strong mechanical properties, and good water stability. WCGC1.5 foam exhibited a high removal efficiency (96.06 %) of DBP. The adsorption process reached adsorption equilibrium rapidly within 8 h and could be described by pseudo-second-order kinetic and Freundlich isotherm models, indicating a non-homogeneous and chemisorptive sorption process. The maximum adsorption capacity for DBP reached 332.42 mg/g. Moreover, DBP adsorption could be enhanced in alkaline environment and the removal efficiency increased to 98.27 % at pH 10. The removal efficiency of DBP by WCGC1.5 remained above 85 % after the five adsorption-desorption cycles. WCGC1.5 also showed broad-spectrum adsorption behavior, with strong affinity and removal efficiency for six common plasticizers, including DIBP (85.97 %), DPP (91.7 %), DHXP (99.1 %), DEHP (99.09 %), DNOP (91.6 %) and BBP (89.88 %).

Magnetic Nanocomposites Revolutionize Heavy Metal Adsorption for Environmental Cleanup

General background: Magnetic nanocomposites have garnered significant attention due to their multifunctional properties, particularly in environmental remediation, where they can be used for the removal of heavy metals from aqueous solutions. Specific background: Polypyrrole (PPy) and poly(p-hydroxyaniline) (P(p-OH An)) are conductive polymers known for their adsorption capabilities, while Fe3O4 nanoparticles exhibit magnetic properties, facilitating separation and recovery. Knowledge gap: Despite the potential of Fe3O4-based composites, few studies have systematically explored the synergistic adsorption properties of PPy and P(p-OH An) in Fe3O4-based nanocomposites under varying environmental conditions. Aims: This study aimed to synthesize and characterize Fe3O4/PPy/P(p-OH An) magnetic nanocomposites and evaluate their adsorption performance under different temperatures and isotherm models. Results: The nanocomposite was synthesized through chemical oxidation polymerization and characterized using FTIR, TEM, AFM, and TGA, confirming its successful formation and nanoscale structure. Adsorption studies indicated an exothermic process, with a decrease in adsorption capacity at higher temperatures. The adsorption data fit the Freundlich isotherm better than the Langmuir model, suggesting heterogeneous surface adsorption. Novelty: This study demonstrates a novel Fe3O4/PPy/P(p-OH An) nanocomposite with superior adsorption properties, showing its potential in heavy metal ion removal and offering an improved understanding of temperature effects on adsorption performance. Implications: The findings underscore the composite's promise for environmental remediation applications, particularly in water treatment, and suggest further optimization of the adsorption conditions and evaluation of the composite's reusability for industrial-scale applications. Highlights: Enhanced Adsorption: Fe3O4/PPy nanocomposites offer combined magnetic and polymer adsorption properties. Temperature Sensitivity: Adsorption decreases as temperature rises, indicating exothermic behavior. Surface Interaction: Freundlich isotherm shows adsorption occurs on heterogeneous surfaces. Keywords: Magnetic nanocomposite, Fe3O4, Polypyrrole, Adsorption, Environmental remediation.

Eco-Friendly Carbon Nanotubes Reinforced with Sodium Alginate/Polyacrylic Acid for Enhanced Adsorption of Copper Ions: Kinetics, Isotherm, and Mechanism Adsorption Studies.

This study investigates the removal efficiency of Cu2+ from wastewater using a composite hydrogel made of carbon nanotubes (CNTs), sodium alginate (SA), and polyacrylic acid (PAA) prepared by free radical polymerization. The CNTs@SA/PAA hydrogel's structure and properties were characterized using SEM, TEM, FTIR, XRD, rheology, DSC, EDS, elemental mapping analysis, and swelling. The adsorption performance for Cu2+ was tested in batch adsorption experiments, considering the pH, dosage, initial concentration, and contact time. The optimal conditions for Cu2+ removal were pH 5.0, an adsorbent dosage of 500 mg/L, and a contact time of 360 min. The adsorption followed pseudo-second order kinetics. Isotherm analyses (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Sips, Toth, and Khan) revealed that the Freundlich isotherm best described the adsorption, with a maximum capacity of 358.52 mg/g. A thermodynamic analysis indicated that physical adsorption was the main interaction, with the spontaneity of the process also demonstrated. This study highlights the high efficiency and environmental friendliness of CNT@SA/PAA composites for Cu2+ removal from wastewater, offering a promising approach for water treatment.