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Rice husk is an inexpensive and readily available adsorbent for heavy metal ions, though its natural form lacks sufficient adsorption capacity. This study focuses on improving its ability to adsorb Cr(VI) by treating it with NaOH. After treatment with 1N NaOH at 90 °C for 4 h, the adsorption efficiency of rice husk for Cr(VI) increased by almost 30%. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy revealed an increase in the cellulosic content of the treated rice husk, while X-ray diffraction indicated the formation of new polymorphs and enhanced crystallinity of the cellulose fraction. Among the applied isotherms, the Redlich-Peterson and Langmuir models best described the adsorption, suggesting both monolayer and multilayer adsorption. The maximum monolayer adsorption capacities were determined to be 18.9, 21.1, and 22.9 mg g−1 at 303 K, 313 K, and 323 K, respectively. The kinetic data fit well with pseudo-second-order and Elovich models, confirming the chemical nature of the adsorption process. Activation energy, along with other kinetic and thermodynamic parameters, showed that the process is endothermic, involving both physical and chemical interactions. FT-IR analysis identified various functional groups involved in the chemical interaction with chromium, while XPS confirmed that all adsorbed chromium was in the + 3 oxidation state. The presence of interfering anions reduced the adsorption efficiency of NaOH-treated rice husk for Cr(VI), regardless of the anion type, while regeneration studies showed that the adsorbent could be reused for up to five adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Copyright of Afyon Kocatepe University Journal of Science & Engineering / Afyon Kocatepe Üniversitesi Fen Ve Mühendislik Bilimleri Dergisi is the property of Afyon Kocatepe University, Faculty of Science & Literature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The most promising eco-friendly green synthesized iron nanoparticles (FeNPs) using jujube leaf extract to decolorize methylene blue (MB) dye was established. Synthesized nanoparticles were characterized through different techniques like TEM, SEM, and FTIR. Various parameters such as dye concentration (5 to 20 mg L−1), nanoparticles load (0.5 to 2.5 mg), temperature, pH, and contact time (30 to 150 min) were optimized. A maximum MB dye removal efficiency of 93.5% is achieved at a time interval of 150 min, temperature 30 °C and pH 9 with 2.5 mg FeNPs for a concentration of 20-mgL−1 methylene blue. The adsorption behavior was monitored using a wide range of isotherm models which includes Freundlich, Dubinin–Radushkevich, Langmuir, and Temkin. The Elovich and intraparticle diffusion models, as well as the dynamical models of pseudo-first- and pseudo-second order has been analyzed for the data obtained from dynamic adsorption. Experimental results were consistent along the paradigm of pseudo-second order. Langmuir adsorption isotherm well suited for adsorption data across exclusive concentration range in comparison to other models. The green synthesized FeNPs has high sorption capacity (1000 mg/g) and environmentally friendly in nature, makes it a potential candidate for wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Textile wastewater containing heavy metal ions has become a severe environmental problem worldwide. The combined uptake of heavy metals and dyes from wastewater discharged by different sectors is a challenging concept. This study explores the use of hybrid adsorbent based on magnetic chitosan (MC) and magnetic poly glycidyl methacrylate (Mp(GMA)) in adsorption technology, for simultaneous removal of Eriochrome Black T (EBT) dye and chromate anions from their binary aqueous solution. The adsorbent material was functionalized by loading diethylenetriamine (DETA) or dithizone to improve their adsorption capacity (R-DETA or R-Dithizone). The physicochemical characteristics of the materials have been characterized by a wide variety of analytical techniques. Pseudo-second order kinetic model and Langmuir adsorption isotherms were the best-fit models in the binary adsorption system. The co-presence of these anions in the binary solution increases the adsorption capacity of chromate and diminishes the EBT adsorption capacity of the investigated adsorbents (R-DETA and R-Dithizone). The adsorption capacity at monolayer saturation capacities (Langmuir) of R-DETA in binary system were 0.782 and 4.11 mmol g−1 towards EBT and chromate anions respectively, while R-Dithizone adsorbent recorded lower monolayer sorption capacity for EBT (0.490 mmol g−1) and higher sorption capacity for chromate 5.93 mmol Cr(VI) g−1 in the binary solution. The effects of competitive anions Cl−, NO3−, SO42−, and MnO4− on the adsorption of EBT and chromate anions in their binary mixture were examined. The good sorption ability of EBT and Cr(VI) anions against ionic interference supported their use in wastewater treatment applications. NaOH (0.5 M) proved the most effective for desorption from their binary mixture. [ABSTRACT FROM AUTHOR]

In this study, a novel naphthalene-based covalent organic polymer (N-COP) was synthesized and investigated as an advanced adsorbent for the efficient removal of Methylene Blue (MB) from aqueous solutions. The polymer was synthesized through a polycondensation reaction between cyanuric chloride and 1,5-dihydroxynaphthalene, followed by thorough purification. Comprehensive characterization was performed using Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Brunauer–Emmett–Teller (BET) surface area analysis, and Field Emission Scanning Electron Microscopy (FE-SEM), confirming the successful formation of the porous polymer with a high surface area and thermal stability. Key adsorption parameters including pH, contact time, and initial MB concentration were systematically optimized. The adsorption behavior followed the Langmuir isotherm model under conditions of pH 7 and a contact time of 30 min, indicating a maximum uptake capacity of 90.09 mg/g, while kinetic analysis revealed a strong fit with the pseudo-second-order model. These results demonstrate that N-COP is a promising candidate for environmental applications (in compression with other adsorbents), particularly in the removal of MB from wastewater, offering an eco-friendly, high-efficiency solution to mitigate water pollution. [ABSTRACT FROM AUTHOR]

The adsorption of As(V) and As(III) (0.01–1 mM) on a calcined oxidic lithologic material substrate with pH-dependent surface variable charges, chemically modifiable, was investigated. The substrate was prepared via thermal treatment using a natural lithologic material rich in amphoteric oxides of Fe, Al, Mn and Ti. The calcined substrate was treated with acid media (HCl 0.1) to homogenize the positive charge density on the oxide surface via oxide protonation so that anion adsorption would be favored. A batch experiment was performed on the acid-treated substrate (activated) and non-activated substrate. L-type isotherms were obtained, which fit the Freundlich model. Isotherm constants showed that there was a greater affinity between the activated substrate and As(V) (K = 10.58) compared to As(III) (K = 5.45). The adsorption capacity of the activated substrate was two times greater than that of the non-activated substrate, As(V) (Kact = 10.58 and Knoact = 5.45) vs. As(III) (Kact = 5.45 y Knoact = 2.44), which was due to the greater positive charge density on the activated surface, created by the protonation of the surface oxides. Protons were liberated during the adsorption reaction (As(V): 2.17 × 10−3 and As(III): 0.96 × 10−3 mmol/mL). The forms H2AsO4− and H3AsO3 deprotonated when adsorbed by the surface groups M - O H 2 + (M: Fe, Al). Kinetic data showed a second-order process for As(V) adsorption and a first-order process for As(III) adsorption. The adsorption rate on the activated substrate was two times greater compared with the non-activated substrate: As(V) (kact = 3.78 × 10−5 L/mg·min and knoact = 2.16 × 10−5 L/mg·min) vs. As(III) (kact = 0.055 h−1 and knoact = 0.027 h−1). The tested substrate is potentially useful as a low-cost natural material for arsenic removal from contaminated water. [ABSTRACT FROM AUTHOR]

The present research work revolves around the evaluation of the elimination of the cationic dye methylene blue (MB) from an aqueous solution by the exploitation of natural clay (TMG) from South-East Morocco. Several physicochemical techniques were used to characterize our TMG adsorbate, namely, X-ray diffraction, Fourier transform infrared absorption spectroscopy, differential thermal analysis, thermal gravimetric analysis, and zero charge point (pHpzc). The morphological properties and elemental composition of our material were identified using scanning electron microscopy coupled with an energy-dispersive X-ray spectrometer. The batch technique was used under different operating conditions to produce quantitative adsorption, namely, the amount of adsorbent, dye concentration, contact time, pH, and solution temperature. The maximum adsorption capacity of MB on TMG was 81.185 mg g−1 for a concentration of 100 mg L−1 MB at pHinitial = 6.43 (no initial adjustment of the pH-value was performed), temperature 293 K, and 1 g L−1 adsorbent. The adsorption data were examined by Langmuir, Freundlich, and Temkin isotherms. The Langmuir isotherm provides the best correlation with the experimental data, and the pseudo-second-order kinetic model is more appropriate for the adsorption of the MB dye. The thermodynamic study of MB adsorption indicates that the process is physical, endothermic, and spontaneous. The Box-Behnken method was applied to identify the optimal conditions for MB removal in the design of batch experiments. The parameters examined result in >99% removal. The TMG material's regeneration cycles and low cost ($0.393 per gram) show that it is both environmentally friendly and very effective for dye removal in the various textile sectors. [ABSTRACT FROM AUTHOR]

This study investigates the adsorption behavior of anionic (Congo red, Eosin yellow) and cationic (Malachite green) dyes on synthesized TD polymer particles, highlighting the material's potential as an effective adsorbent for industrial wastewater treatment. Key operational parameters, including initial solution's pH, contact time, initial dye concentration, and temperature, were systematically evaluated to determine their influence on adsorption efficiency. The experimental data demonstrated that the Langmuir isotherm provided the best fit for all three dyes, indicating monolayer adsorption with maximum adsorption capacities of 153.8 mg/g for Malachite green, 49.36 mg/g for Congo red, and 227.9 mg/g for Eosin yellow. Kinetic analysis revealed that the adsorption of Malachite green and Congo red followed pseudo‐second‐order kinetics, while Eosin yellow adsorption was better described by the intra‐particle diffusion model. Thermodynamic assessments, including Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), confirmed the spontaneous and endothermic nature of the adsorption processes for Malachite green and Eosin yellow, contrasting with the exothermic behavior observed for Congo red. These findings underscore the versatility and effectiveness of TD polymer particles in removing both anionic and cationic dyes from aqueous solutions. Further research could explore material optimization and real‐world applications to broaden their utility in sustainable water treatment strategies. [ABSTRACT FROM AUTHOR]

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

The present study investigated the capability of cassava peel (Manihot Esculenta Crantz) in Pb(II) and Cr(VI) removal. The comparative study was conducted using batch method observing some parameters. The results indicated that the optimum adsorption of Pb(II) occurred at pH 5, initial concentration of 1000 mg/L, and contact time of 50 min. On the other hand, the optimal adsorption of Cr(VI) was achieved at pH 2, initial concentration of 1200 mg/L, and contact time of 70 min. The adsorption isotherms of both metals tended to follow the Langmuir model, while the adsorption kinetics suited to pseudo-second-order model. Thermodynamic parameters indicated that the adsorption process was spontaneous (ΔG° negative), endothermic (ΔH° positive), and exhibited surface dispersion on the biosorbent (ΔS° positive). Characterization using Fourier Transform Infrared (FTIR), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Thermogravimetry (TGA) provided evidence of both physical and chemical adsorption. The adsorption capacity of cassava peel was also tested on samples collected approximately 30 m from the bay shoreline, resulting in a removal percentage of 94.67% for Pb(II) and 82.28% for Cr(VI) under optimal pH and contact time conditions. [ABSTRACT FROM AUTHOR]

The current research highlighted the usage of serpentine clay to remove Nile red dye from an aqueous solution. At first serpentine clay minerals were analyzed by various analytical techniques like Fourier transform infrared spectroscopy (FTIR), X ray diffraction (XRD), and thermal gravimetric analysis (TGA) analysis. From the characterization results it was found that the clay was determined to be a separate group. Sorption studies investigated the impacts of adsorbent dosage, initial pH, initial dye concentration, and temperature on Nile red color elimination. From the test results it was found that the capacity of adsorption was seen to increase from 32.4 mg/g to a high value of 43.8 mg/g by raising the pH value from 2 to 6. Adsorption on serpentine clay decreased from 234.7 to 33.2 mg/g due to an increase in the adsorbent dosage. The removal capacity of Nile red dye increased from 12.2% to 88.5% with the rise in the adsorbent dosage. This rise in the Nile red dye removal may be observed due to the increase in the area as well as the pore volume of the surface. Experimental study was carried out to study the effect of initial concentration of adsorbate on adsorption at a pH of 6, adsorbent dosage of 3 g/L, and at a temperature of 28°C. The removal efficiency of the Nile red dye was reduced from 96.7% to 42.6%. To determine the temperature effect on the removal of Nile red dye by the clay, the initial pH value was set to 6, and the temperature was set at 28, 38, 48, and 58°C. Without reaching the equilibrium conditions, at a time of 30 min, the removal efficiency of dye rises from 60% to 81% due to the temperature rise. The experimental findings indicated that the adsorption of the dye on the clay followed the "Langmuir adsorption" isotherm rather than the Freundlich adsorption isotherm. Adsorption on clay minerals follows the pseudo‐second‐order adsorption kinetics compared to pseudo‐first‐order adsorption kinetics. [ABSTRACT FROM AUTHOR]

The objective of this investigation is to look into the potential use of trash potato peels and processed potato peels as a solution for effectively removing Mn(II) ions extracted from aqueous solutions. The optimal working circumstances for removing Mn(II) ions from aqueous solution in PP are an initial concentration of 300 mg/L, an adsorbent dose of 0.3 g, a contact time (CT) of 100 min, and a solution pH of 6.08. The optimal working conditions for MPP were established to be an initial concentration of 300 mg/L, an adsorbent dosage of 0.15 g, a CT of 100 min, and a solution pH of 6.08. Studies were conducted at various temperatures to better understand the removal capabilities of adsorbent compounds. The removal abilities of Mn(II) ions for PP were determined to be 10.787, 13.698, and 16.556 mg/g at varied temperatures (25, 35, and 45°C), respectively. Under the same conditions, the removal capacity of MPP was determined to be 34.246, 45.045, and 51.813 mg/g. Further investigation of the adsorption kinetics revealed that the experimental results suited the pseudo‐second‐order model for both PP and MPP adsorbents. Thermodynamic analyses demonstrated that the endothermic process of Mn(II) metal ion adsorption onto the adsorbents occurred spontaneously. The study found that both PP and MPP were very efficient and ecologically friendly adsorbents for removing Mn(II) ions from aqueous solutions. Their demonstrated performance highlights their potential value in sustainable wastewater treatment applications, which accord with environmentally conscious behaviors. [ABSTRACT FROM AUTHOR]

The presence of pollutants in water sources, particularly dyes coming by way of the textile industry, represents a major challenge with far-reaching environmental consequences, including increased scarcity. This phenomenon endangers the health of living organisms and the natural system. Numerous biosorbents have been utilized for the removal of dyes from the textile industry. The aim of this study was to optimize discarded Zygophyllum gaetulum stems as constituting an untreated natural biosorbent for the efficient removal of C.I. Direct Black 80, an azo textile dye, from an aqueous solution, thus offering an ecological and low-cost alternative while recovering the waste for reuse. The biosorbent was subjected to a series of characterization analyses: scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), and infrared spectroscopy (IR) were employed to characterize the biosorbent. Additionally, the moisture and ash content of the plant stem were also examined. The absorption phenomenon was studied for several different parameters including the effect of the absorption time (0 to 360 min), the sorbent mass (3 to 40 g/L), the pH of the solution (3 to 11), the dye concentration (5 to 300 mg/L), and the pH of the zero-charge point (2–12). Thermodynamic studies and desorption studies were also carried out. The results showed that an increase in plant mass from 3 to 40 g/L resulted in a notable enhancement in dye adsorption rates, with an observed rise from 63.96% to 97.08%. The pH at the zero-charge point (pHpzc) was determined to be 7.12. The percentage of dye removal was found to be highest for pH values ≤ 7, with a subsequent decline in removal efficiency as the pH increased. Following an initial increase in the amount of adsorbed dye, equilibrium was reached within 2 h of contact. The kinetic parameters of adsorption were investigated using the pseudo-first-order, pseudo-second-order and Elovich models. The results indicated that the pseudo-first-order kinetic model was the most appropriate for the plant adsorbent. The isotherm parameters were determined using the Langmuir, Frendlich, Temkin, and Dubinin–Radushkevich models. The experimental data were more satisfactory and better fitted using the Langmuir model for the adsorption of dye on the plant. This study demonstrated that Zygophyllum gaetulum stems could be employed as an effective adsorbent for the removal of our organic dye from an aqueous solution. [ABSTRACT FROM AUTHOR]

The current study aims to develop a new adsorbent material using oak crown and explore its effectiveness in removing I2 ions through a series of batch experiments. ACOW was characterised by zero charge (pHpzc) and FTIR spectroscopy. The impact of the initial I2 concentration (20-100 mg/L), temperature (25-55 °C), pH (2-14), adsorbent dosage (2-10 g/L), Stirring speed (100-900 rpm), particle size (100-2000μm) and contact time (0-30 min) on I2 adsorption was examined. The adsorption kinetic obeys the pseudo-second order model with a determination coefficient (R2) equal to 0.999. Adsorption follows the Langmuir equation well, with the best fit to the experimental data at equilibrium. A qmax value (= 103.606 mg/g) at 25°C and 120.773 mg/g at 55°C were eliminated under the optimised conditions, indicating homogeneous adsorption on the surface of the adsorbent. The thermodynamic parameters gave a negative free energy ΔGo (-3.445 to -5.629 kJ/mol), a positive enthalpy ΔHo (18.406 kJ/mol) and an activation energy Ea (= 22.599 kJ/mol), thus confirming the spontaneous and endothermic nature of adsorption of iodine on ACOW. The positive entropy ΔSo (0.0733 kJ/mol K) show increased randomness of the solid-liquid interface during the adsorption. [ABSTRACT FROM AUTHOR]

The objective of this paper is to evaluate the adsorption isotherm analysis of black seed (Nigella Sativa L.) oil as an eco-friendly corrosion inhibitor for mild steel in acidic environment using appropriate standard techniques. Weight loss analyses showed that mild steel coupons immersed in the acidic solution without the inhibitor experienced much higher corrosion rates compared to those treated with the extract. Over time, corrosion rates increased initially but began to decline after 72 hours due to protective oxide film formation, consistent with observations from previous studies. Adsorption isotherm models were employed to understand the interaction between the inhibitor and the steel surface. The Langmuir isotherm was determined to be the best fit for the adsorption process, suggesting a monolayer coverage of the inhibitor on the mild steel surface. This model yielded a maximum adsorption capacity (Qmax) of 1.03 mg/g and a favorable Langmuir constant (KL) of 0.24 dm³/g. Scanning Electron Microscopy (SEM) analysis revealed changes in surface morphology, indicating the formation of a protective layer that mitigated corrosion. The mechanism of inhibition is attributed to a donor-acceptor interaction between the inhibitor molecules and iron, leading to a reduction in anodic and cathodic reactions. In conclusion, black seed oil extract demonstrates significant potential as an eco-friendly corrosion inhibitor for mild steel in acidic conditions, providing a sustainable alternative to conventional synthetic inhibitors. [ABSTRACT FROM AUTHOR]

Copyright of Afyon Kocatepe University Journal of Science & Engineering / Afyon Kocatepe Üniversitesi Fen Ve Mühendislik Bilimleri Dergisi is the property of Afyon Kocatepe University, Faculty of Science & Literature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Metal-organic frameworks (MOFs) have emerged as a class of highly promising materials for wastewater dye removal due to their unique properties. However, the existing body of research has primarily concentrated on the removal of organic dyes. To address this gap and contribute to advancements in water treatment technologies, this study investigates the efficacy of a zirconiumterephthalate-based MOF for the adsorptive removal of hematite, an inorganic dye, from aqueous environments. This investigation explored the influence of key parameters, including initial dye concentration, pH, adsorbent dosage, and adsorption temperature, on the adsorption capacity of NH2-UiO-66 for hematite. The findings revealed that elevated temperatures and initial dye concentrations promoted hematite adsorption onto NH2-UiO-66. Furthermore, the analysis of experimental data demonstrated concordance with the theoretical predictions of both the linearized Freundlich and Langmuir isotherm models. The study of kinetic models reveals that the pseudo-first-order model can adequately describe experimentally obtained data. The adsorption thermodynamic parameter ΔG0 was found to be approximately -3.70, -3.94, and -4.19 kJ.mol-1 at 298, 313, and 328 K, respectively. Furthermore, the ΔH0 and ΔS0 parameters were 5.15 kJ.mol-1 and 54.3 J.mol-1, respectively, indicating an endothermic adsorption mechanism. Further investigation found that the regeneration effectiveness is greater than 92% even after three adsorption cycles. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the effectiveness of Fe3O4-based clay as a cost-effective material for removing methylene blue (MB) dye from aqueous solutions was evaluated. The structural properties of the clay and Fe3O4-based clay were analyzed using SEM, XRF, BET, XRD, FTIR, and TGA techniques. In this research, the effects of various aspects, such as adsorbent amount, contact time, solution pH, adsorption temperature, and initial dye concentration, on the adsorption of Fe3O4-based clay are investigated. The experiments aimed at understanding the adsorption mechanism of Fe3O4-based clay have shown that the adsorption kinetics are accurately described by the pseudo-second order kinetic model, while the equilibrium data are well represented by the Langmuir isotherm model. The maximum adsorption capacity (qm) was calculated as 52.63 mg/g at 25 °C, 53.48 mg/g at 30 °C, and 54.64 mg/g at 35 °C. All variables affecting the MB adsorption process were systematically optimized in a controlled experimental framework. The effectiveness of the artificial neural network (ANN) model was refined by modifying variables such as the quantity of neurons in the latent layer, the number of inputs, and the learning rate. The model's accuracy was assessed using the mean absolute percentage error (MAPE) for the removal and adsorption percentage output parameters. The coefficient of determination (R2) values for the dyestuff training, validation, and test sets were found to be 99.40%, 92.25%, and 96.30%, respectively. The ANN model demonstrated a mean squared error (MSE) of 0.614565 for the training data. For the validation dataset, the model recorded MSE values of 0.99406 for the training data, 0.92255 for the validation set, and 0.96302 for the test data. In conclusion, the examined Fe3O4-based clays offer potential as effective and cost-efficient adsorbents for purifying water containing MB dye in various industrial settings. [ABSTRACT FROM AUTHOR]

In this research, we present a sustainable approach for the decontamination of methylene blue from water and wastewater, employing oxalic acid-modified Saccharum spontaneum (Kashful stalks) as an eco-friendly adsorbent. The material was strategically modified to improve its effectiveness and adsorption capabilities. The improved material was comprehensively characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and pH at isoelectric point (pHZPC). A detailed study was conducted to assess the material optimization under varying states, like contact time, concentration, pH, and temperature. The Freundlich isotherm model demonstrated the best fit for the interaction, with an R2 > 0.99. The kinetics of interaction is best given by pseudo-second-order kinetic indicating chemisorptions. The maximum adsorbability recorded was 54.55 mg/g, indicating the exceptional adsorption capability of the modified material. The material is also efficient in the presence of various ions and real water situations. The thermodynamic investigation demonstrates that the adsorption process is endothermic, viable, and spontaneous, enhancing the viability of the material for large-scale decontamination purposes. The dye-loaded material demonstrated successful regeneration in an alcoholic medium, making it suitable for multiple adsorption–desorption cycles without compromising its efficiency. [ABSTRACT FROM AUTHOR]

The use of construction and demolition waste (CDW) for the treatment of dye-contaminated water can be an effective way to minimize environmental impacts. This study evaluates its adoption as a potential adsorbent for methylene blue (MB) in aqueous solution. Cement mortar, roof tiles, and tiles were disintegrated and sieved for physicochemical characterization (pH, potential redox – Eh, electrical conductivity – CE, cationic exchange capacity—CEC, point of zero charge – PZC, specific surface area – SSA, pore distribution, functional groups, and elemental composition). The effect of initial concentration, pH, granulometric fraction and time were evaluated in adsorption and desorption studies. The results of adsorption studies were analyzed using nonlinear kinetic models and equilibrium data were analyzed by Langmuir, Freundlich, Sips, and Temkin isotherm models. The CDW evaluated has alkaline pH (pH 8.4 – 11.6) with high EC (680.5 – 1054.5 µS cm−1), reductive environment (-223 – -66 mV), low CEC (0.45 – 1.40 cmolc kg−1), SSA (1.83 – 11.06 m2 g−1), and basic PZC (8.3 – 10.0). Initial concentration, pH and adsorbent particle size affected the removal efficiency and desorption rate. Roof tiles showed higher MB removal efficiency (84.5%), followed by cement mortar (61.1%) and tiles (41.6%), and the materials displayed the following maximum adsorption capacities (qm): tiles (13.983 mg g−1) > roof tiles (8.389 mg g−1) > cement mortar (1.305 mg g−1). Pseudo-first order model best described the chemical kinetics. Freundlich isotherm best described the adsorption process of MB onto tiles and Sips model best described the process onto roof tiles and cement mortar. Therefore, the materials can be used for removing MB from aqueous solutions. [ABSTRACT FROM AUTHOR]

In the present study, nano-ligninwas synthesized from rice straw using Lactobacillus rhamnosus for the cost-effective removal of harmful dye from wastewater. The UV absorption maxima of the synthesized nano-lignin were around 280–290 nm. Several FTIR bands between 1075 cm−1 to 3500 cm−1 confirmed the successful confirmation of nano-lignin synthesis from rice straw. STEM and DLS studies confirmed the spherical morphology of nano-lignin with an average particle size of 286.3 nm. The nano-lignin showed a negative zeta potential value of −16.9 ± 5.94 mv. Afterward, nano-lignin was used to remove basic methylene blue (MB), phenol red (PR),and brilliant green (BG) dye from aqueous solutions. The adsorption of these dyes increased with increased incubation time. The adsorption concentration of the MB, PR, and BG dyes ranged from 3.5 mg/g to a final of 24 mg/g, 2.5 mg/g to 42.5 mg/g, and 1.5 gm/g to 5.5 mg/g, respectively.

Abstract In this study, a novel naphthalene-based covalent organic polymer (N-COP) was synthesized and investigated as an advanced adsorbent for the efficient removal of Methylene Blue (MB) from aqueous solutions. The polymer was synthesized through a polycondensation reaction between cyanuric chloride and 1,5-dihydroxynaphthalene, followed by thorough purification. Comprehensive characterization was performed using Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Brunauer–Emmett–Teller (BET) surface area analysis, and Field Emission Scanning Electron Microscopy (FE-SEM), confirming the successful formation of the porous polymer with a high surface area and thermal stability. Key adsorption parameters including pH, contact time, and initial MB concentration were systematically optimized. The adsorption behavior followed the Langmuir isotherm model under conditions of pH 7 and a contact time of 30 min, indicating a maximum uptake capacity of 90.09 mg/g, while kinetic analysis revealed a strong fit with the pseudo-second-order model. These results demonstrate that N-COP is a promising candidate for environmental applications (in compression with other adsorbents), particularly in the removal of MB from wastewater, offering an eco-friendly, high-efficiency solution to mitigate water pollution.

Levulinic acid (LA) is a significant building block in industry. It can be produced by the hydrolysis of lignocellulosic feedstocks and needs to be separated from the aqueous production medium. This study focuses on evaluating fly ash, a waste byproduct from a sugar factory, for use in the adsorption of LA from aqueous media. The sugar beet processing fly ash (SBFA) was characterized using XRD, FTIR, SEM, and N2 adsorption-desorption analysis. The data fit the pseudo-second-order kinetic model, with good agreement between the experimentally measured (454.55 mg g–1) and calculated (452.40 mg g–1) adsorption capacities. It was observed that the efficiency slightly decreased with increasing temperature, with the effect more pronounced at lower concentrations. Calculated thermodynamic parameters demonstrated that the process was exergonic and exothermic. The capacity of LA adsorption reduced with SBFA dose while enhanced with acid concentration, achieving a maximum of 464 mg LA/g SBFA, higher than values previously achieved with other adsorbents. The Langmuir isotherm model fit well with equilibrium data. Complete recovery of LA was achieved using 0.2 M NaOH, and SBFA could be reused with high efficiency for five consecutive cycles.

The herbicide oxyfluorfen [OXY; 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] has recently surged in interest among rice farmers with the development of OXY-tolerant rice and its demonstrated effectiveness against problematic rice weeds in California. Not currently registered for use with rice, its fate in rice fields is poorly understood. Using a batch equilibrium method, we characterize the soil-water partitioning behavior of OXY under simulated California rice field conditions. Sorption data imply strong, primarily concentration-independent binding correlated with soil organic carbon (log[Koc] 4.79−5.19; N 0.87−1.08) across all soil, temperature, and salinity treatments. Temperature significantly enhanced binding affinity for sorption and desorption processes (P < 0.01). Bound OXY was poorly desorbed (9.3 to 27.0% desorption) from rice soils and exhibited significant sorption hysteresis (HI > 0) in all treatments. These results indicate that OXY will predominantly remain in soil and will be resistant to release into water in California rice fields.

The presence of heavy metals in wastewater used for irrigation constitutes significant environmental problem and health risk with an economic burden of ~ 271 billion dollars. This study aimed at developing a low-cost bacterial biofilm-based heavy metal removal system for use in low economic setting. After an extensive screening a total of 7 strains exhibiting resistances to even a combination of five metals (Cu2+, Zn2+, Ni2+, Pb2+, and Cr6+, 200 mg/L each) were isolated. This is the first report of strains showing resistance to a combination of five metal. Among these strain ZW-28, identified as Bacillus sp. based on partial 16S rRNA gene sequence formed strong biofilms on polyurethane sponge (MTBPS). The kinetics of metal biosorption by the MTBPS was studied and validated using SEM–EDX and FT-IR analysis. The MTBPS under optimal conditions was able to remove 85.46 ± 3.41, 100 ± 0, 68.8 ± 9.16, 100 ± 0, and 79.2 ± 7.21% of Cu2+, Ni2+, Zn2+, Pb2+, and Cr6+, respectively from a mixture of metals with an initial concentration of 50 mg/L. Kinetic experiments show that pseudo-second order model can be used to predict rate constants. The R2 values and isotherm data best fits in both Langmuir and Freundlich-isotherm models. FT-IR spectra of biofilms indicated the involvement of various functional groups in metal adsorption. Results presented in this study strongly suggest that the MTBPS offers a very low-cost (0.29 US dollar/L) option for metal removal from wastewater. This study for the first time demonstrates a low-cost simultaneous removal of 5 metals by a bacterial biofilm.Article Highlights: A multi-metal tolerant bacteria with strong biofilm formation ability on Polyurethane was isolated. The isolate was identified as Bacillus sp. using polyphasic approch including 16S rRNA sequencing The strains biofilm on polyurethane (MTBPS) removed Cu, Ni, Zn, Pb, and Cr by 68-100% in a mixture. The Biofilm is useful for concurrent removal of multi metals from small-scale industry wastewater [ABSTRACT FROM AUTHOR]

Environmental pollution with heavy metals is a problem of worldwide importance due to their toxicity and potential health risks. Among the heavy metals found in industrial waters are such toxic metals as Cd(II), Zn(II), and Cr(VI). In this study, the potential of Georgian natural and modified mordenite as a low-cost, eco-friendly adsorbent for the removal of cadmium (II), zinc (II), and chromium (IV) from aqueous solutions is studied. Langmuir and Freundlich isotherms are used to model adsorption data. Studies have shown that the correlation coefficient values (R²) were best fitted by the Langmuir isotherm. The maximum adsorption capacities are 0.84mg/g, 118.92mg/g and 2.25mg/g for cadmium(II), zinc(II) and chromium(IV) respectively as described by Langmuir isotherm. [ABSTRACT FROM AUTHOR]

In the current report, both response surface methodology (RSM) and artificial neural network (ANN) were employed to develop an innovative way for removing crystal violet (CV) from aqueous media using Haloxylon salicornicum (HS) as a cost‐effective, eco‐friendly adsorbent. HS was characterized using scanning electron microscopy (SEM) and Fourier‐transform infrared (FTIR) spectroscopy. The effects of operational parameters such as adsorbent dosage, initial dye concentration, and pH on HS were studied using a central composite design (CCD). A comparative analysis of the model findings and experimental measurements revealed high correlation coefficients (R2ANN = 0.994, R2RSM = 0.971), indicating both models accurately predicted HS. The predictive performance of the ANN and RSM models was evaluated using metrics such as mean absolute deviation (MAD), mean absolute percentage error (MAPE), root mean square error (RMSE), mean square error (MSE), and the correlation coefficient (R2). The results indicate that the ANN model provides greater accuracy compared to the RSM model. The experimental data were analyzed using both linear and nonlinear forms of pseudo‐first and pseudo‐second order kinetic models (LPFO, NLPFO, LPSO, and NLPSO). Statistical error analysis was conducted to identify the best‐fitting kinetic or isotherm models for the adsorption data. The adsorption process of CV/HS was best described by NLPSO and LPSO. Additionally, the adsorption isotherms were analyzed using linear and nonlinear regression methods. The findings indicated that the linear Langmuir and Freundlich isotherms provided a more accurate fit compared to the nonlinear models, demonstrating greater effectiveness in accounting for the adsorption parameters. Thermodynamic investigations clearly demonstrate that the biosorption of CV is spontaneous and exothermic. This cost‐effective adsorbent is highly promising for treating textile wastewater. [ABSTRACT FROM AUTHOR]

The industry has suffered major chromium wastewater issues. Chromium is a heavy metal that can threaten both nature and people's health. Adsorption is a simple, environmentally friendly, and effective process for removing chromium from wastewater. Iron sand is an alternate adsorbent that can adsorb chromium. The iron sand in this research originated from Sukabumi, Indonesia, with a hematite content of 63.335%. The goal of this study is to evaluate the adsorption mechanism of hematite based on adsorbent weight, Cr(VI) initial concentration, pH of the solution, and contact time. This study was conducted experimentally throughout multiple phases. First, hematite was characterized using XRD, BET, FTIR and XRF to assess crystal structure, mineral composition, surface area, functional groups and the percentage of hematite in iron sand. Subsequently, the pH and contact time were optimized. The highest adsorption capacity is then determined using the Langmuir and Freundlich isotherms. The study found that hematite has a surface area before and after adsorption of 619.486 m²/g and 334.783 m²/g, with XRD peaks at 2θ = 33.037° and 35.357°, Fe-O bonds with a wavelength of 647.17 cm-1 and hematite content of 63.335%. Optimal Cr(VI) adsorption occurs at pH 1, with a contact time of 120 minutes, Cr(VI) concentration of 50 mg/L, 5.0 g mass of hematite, with an adsorption capacity (Qe), and adsorption efficiency (%) of 3.83 mg/g and 75.95%. The Freundlich isotherm model accurately represents adsorption, revealing a heterogeneous surface. The linear equation of the Freundlich curve is Log Qe = 0.1152 Log Ce + 0.6376, R² = 0.9999, with the value of adsorption capacity (kf) = 4.3411 mg/g and adsorption intensity (n) = 8.681. The enthalpy of adsorption (ΔHads) at a concentration of 20 mg/L, 2.5 g, pH 3, and 30 minutes is -95.852 kJ/mol, indicating chemisorption. [ABSTRACT FROM AUTHOR]

This study investigates the potential of 5-amino-1,3-diphenylpyrazole and nitrogen-enriched 5-hydroxy-1,3-diphenylpyrazole to inhibit corrosion of mild steel in acidic environments. A comprehensive approach combining weight loss measurements and Density Functional Theory (DFT) calculations was employed to analyze the inhibitory effect under various concentrations, immersion times, and temperatures. At an optimal concentration of 0.5 mM, 5-amino-1,3-diphenylpyrazole displayed an impressive 94.7% inhibition efficiency, while 5-hydroxy-1,3-diphenylpyrazole achieved 86.4% efficiency at 303 K after 10 hours of exposure. Both compounds exhibited a mixed-type inhibition behavior, with increasing efficiency observed at higher concentrations. DFT calculations provided insights into the interaction between the molecules and the metal surface, along with their electronic properties, aiding in understanding the corrosion inhibition process. The investigation revealed that Langmuir isotherms govern the adsorption mechanism, and the calculated thermodynamic parameters suggest a complex interplay at the metal/solution interface, involving both chemisorption and physisorption. These findings provide valuable knowledge about the mechanisms of corrosion inhibition by these molecules, paving the way for the development of effective strategies to protect mild steel in corrosive environments. [ABSTRACT FROM AUTHOR]

Abstract The non-biodegradable Congo red (CR) dye which is widely used in textile industries has poses carcinogenic risks due to its complex reactions that may generate benzidine. Effective treatment of industrial effluent containing CR dye is imperative. This study assessed chitosan (Cs) and chitosan/fly ash (Cs/Fa) composites for biosorbing CR dye from synthetic textile wastewater. Fly ash varied in the range of (1:0.25–1:1) with chitosan to assess adsorption performance. Characterization techniques included FTIR, SEM, EDX, BET, and zeta potential analyses. Response surface methodology guided the determination of optimal variables. The study examined Cs and Cs/Fa dosage (A), time (B), and initial dye concentration (C) effects on CR removal. Incorporating fly ash substantially cut adsorption costs by 50% while enhancing dye removal up to 85% at pH 6. Improved acidic stability of chitosan (Cs/Fa 1:0.75) was notable. Chitosan (Cs) exhibited a high Congo red removal efficiency of 98% while the chitosan/fly ash (Cs/Fa) composites showed a substantial removal efficiency of 94%. Optimal conditions were 2 g L−1 of adsorbents, initial CR concentration of 40 mg L−1 for 120 min. Freundlich isotherm model best described adsorption behavior. Pseudo-second-order kinetics correlated significantly (R2 = 0.999). This study showed the potential of Cs and Cs/Fa bio-composites for effective textile wastewater treatment.

Objectives This study is to compare the removal efficiency of cesium ions in aqueous solutions by natural and acid-activated kaolinite clay. Methods Natural kaolinite clay was acid-treated with H2SO4 (2M) at 80oC for 6 h under mechanical stirring. While activating natural kaolinite clay with acid, cations such as Al3+, Ca2+, Mg2+ and Fe3+ were partially eluted from the crystal lattice of natural kaolinite clay, and resulted in the increase in the surface area and the pore volume through the opening of crystal lattice. The surface area and the pore volume of acid-activated kaolinite clay were found to be roughly three times higher than natural kaolinite clay. The characteristics of natural and acid-activated kaolinite clay were observed by X-ray Fluorescence Spectroscopy, Energy Dispersive X-ray Spectroscopy, and BET Surface Area Analyzer. Results and Discussion Generally, adsorption efficiency of Cs+ ion by acid-activated kaolinite clay showed much higher compared with natural kaolinite clay. At 50 mg L-1 of Cs+ ion concentration and the unit of dose in g L-1 , the adsorption efficiencies of Cs+ ion by natural and acid-activated kaolinite clay were 57.5% and 96.9%, respectively. The data obtained from this study were fitted to the adsorption isotherm and the kinetic models, respectively. It revealed that the Langmuir isotherm and the pseudo-second-order kinetic models described well the adsorption behavior of Cs+ ions on both natural and acid-activated kaolinite clay owing to their higher correlation coefficient R2. Based on the Langmuir isotherm coefficient Q, adsorption capacity of Cs+ ion by natural kaolinite clay and acid-activated kaolinite clay were 5.65 mg g-1 and 10.6 mg g-1, respectively. Conclusion The results demonstrated that acid-activated kaolinite clay with acid treatment can be used as more effective adsorbent for the adsorption of Cs+ ions from aqueous solution than natural kaolinite clay.

Abstract Sorption of Sr(II) and Eu(III) from aqueous solutions was studied using tin molybdate talc sorbent synthesized by the precipitation technique. The synthesized sorbent was characterized using different analytical tools, such as; FT-IR, SEM, XRD, XRF, TGA, and DTA. The sorption studies applied to Sr(II) and Eu(III) include the effects of shaking time, pH, concentrations, and saturation capacity. The sorption of Sr(II) and Eu(III) depends on pH, reaction kinetics obey the pseudo-2nd-order model, and the Langmuir model is better suited for the sorption isotherm. The thermodynamic parameters reflect an endothermic and spontaneous sorption process. Desorption studies showed that 0.1 M HCl was the best desorbing agent for the complete recovery of Sr(II) (96.8%) and Eu(III) (92.9%). Finally, the obtained data illustrates that the synthesized sorbent can be applied and used as an efficient sorbent for the sorption of Sr(II) and Eu(III) from aqueous solutions and can be used as a promising sorbent to remove Sr(II) and Eu(III).

This work prepared new eco-friendly biocomposite hydrogels by graft co-polymerization from starch (ST), sodium alginate (SA), acrylamide (AM), and acrylic acid (AC). The performance of starch graft-poly(acrylamide-co-acrylic acid) (ST-g-P(AM-co-AC)) and sodium alginate graft-poly(acrylamide-co-acrylic acid) (SA-g-P(AM-co-AC)) absorbent hydrogels was evaluated for efficient dye removal from aqueous solution due to their unequal network structure and a restricted number of the hydrophilic groups. Adsorption characteristics of the as-prepared hydrogels were tested for methylene blue (MB) as an adsorbate. The removal percentage increases when increased the adsorbent doses of both hydrogels due to the increase of active sites of the hydrogel. The isotherm models and thermodynamic studies of MB dye on hydrogels have been assessed at several conditions like adsorbent dosage, solution temperature, and equilibrium time. The equilibrium results followed the Freundlich model. The thermodynamic parameter indicated that MB dye adsorption on hydrogels was endothermic and spontaneous. On the basis of the obtained result, the hydrogels are environmental and expansive adsorbent that might be a reliable alternative to elimination dyes from aqueous solution.

Metal-organic frameworks (MOFs) have emerged as a class of highly promising materials for wastewater dye removal due to their unique properties. However, the existing body of research has primarily concentrated on the removal of organic dyes. To address this gap and contribute to advancements in water treatment technologies, this study investigates the efficacy of a zirconium- terephthalate-based MOF for the adsorptive removal of hematite, an inorganic dye, from aqueous environments. This investigation explored the influence of key parameters, including initial dye concentration, pH, adsorbent dosage, and adsorption temperature, on the adsorption capacity of NH2-UiO-66 for hematite. The findings revealed that elevated temperatures and initial dye concentrations promoted hematite adsorption onto NH2-UiO-66. Furthermore, the analysis of experimental data demonstrated concordance with the theoretical predictions of both the linearized Freundlich and Langmuir isotherm models. The study of kinetic models reveals that the pseudo-first-order model can adequately describe experimentally obtained data. The adsorption thermodynamic parameter ΔG0 was found to be approximately -3.70, -3.94, and -4.19 kJ.mol−1 at 298, 313, and 328 K, respectively. Furthermore, the ΔH0 and ΔS0 parameters were 5.15 kJ.mol-1 and 54.3 J.mol-1, respectively, indicating an endothermic adsorption mechanism. Further investigation found that the regeneration effectiveness is greater than 92% even after three adsorption cycles.

This study focuses on the biosorption of harmful metals from aqueous solutions using Enteromorpha compressa macroalgal biomass nanoparticles as the biosorbent. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) were employed to characterize the biosorbent. The effects of pH, initial metal ion concentration, biosorbent dosage, and contact time on the biosorption process were investigated. The maximum biosorption capacity for metals was observed at a pH of 5.0. The experimental equilibrium data were analyzed using three-parameter isotherm models, namely Freundlich, Temkin, and Langmuir equations, which provided better fits for the equilibrium data. A contact time of approximately 120 min was required to achieve biosorption equilibrium for various initial metal concentrations. Cr(III), Co(II), Ni(II), Cu(II), and Cd(II) demonstrated distinct maximum biosorption capacities of 24.99375 mg/g, 25.06894 mg/g, 24.55796 mg/g, 24.97502 mg/g, and 25.3936 mg/g, respectively. Different kinetic models were applied to fit the kinetic data, including intraparticle diffusion, pseudo-second-order, and pseudo-first-order versions. The pseudo-second-order model showed good agreement with the experimental results, indicating its suitability for describing the kinetics of the biosorption process. Based on these findings, it can be stated that E. compressa nanoparticle demonstrates potential as an effective biosorbent for removing targeted metals from water.

Rapid industrial development causes environmental contamination of land, water, and air with heavy metals which pose a significant threat to human survival. This study aims to remove antimony from wastewater using tea leaves and tea fiber (Camellia sinensis) as an adsorbent to curb the environmental decay posed by industrialization. The FTIR study presents significant vibration frequencies that correspond to –OH, C-H, and C=O in both the leaves and fibers which impact the adsorption. The adsorption study was performed by the batch adsorption method, varying different parameters including pH, adsorbent dosage, temperature, initial concentration, and contact time to find best-suited conditions for the removal of antimony from aqueous media. The results show an equilibrium condition at pH 5 and 30 minutes for both tea leaves and fibers whereas for tea leaves the equilibrium concentration was obtained at a dosage of 2g, and 3g for the fiber. From the adsorption model, the sorption of antimony by tea leaves follows the Langmuir model (R2 = 0.783), whereas that of tea fiber follows Freundlich (R2 = 0.827). From Kinetic studies, the sorption of antimony by both plant parts follows second-order kinetics with approximate R2 values of 1. From the adsorption capacity, it is no exaggeration to consider tea leaves and fibers as an excellent biosorbent for the sorption of antimony.

The non-biodegradable Congo red (CR) dye which is widely used in textile industries has poses carcinogenic risks due to its complex reactions that may generate benzidine. Effective treatment of industrial effluent containing CR dye is imperative. This study assessed chitosan (Cs) and chitosan/fly ash (Cs/Fa) composites for biosorbing CR dye from synthetic textile wastewater. Fly ash varied in the range of (1:0.25–1:1) with chitosan to assess adsorption performance. Characterization techniques included FTIR, SEM, EDX, BET, and zeta potential analyses. Response surface methodology guided the determination of optimal variables. The study examined Cs and Cs/Fa dosage (A), time (B), and initial dye concentration (C) effects on CR removal. Incorporating fly ash substantially cut adsorption costs by 50% while enhancing dye removal up to 85% at pH 6. Improved acidic stability of chitosan (Cs/Fa 1:0.75) was notable. Chitosan (Cs) exhibited a high Congo red removal efficiency of 98% while the chitosan/fly ash (Cs/Fa) composites showed a substantial removal efficiency of 94%. Optimal conditions were 2 g L−1 of adsorbents, initial CR concentration of 40 mg L−1 for 120 min. Freundlich isotherm model best described adsorption behavior. Pseudo-second-order kinetics correlated significantly (R2 = 0.999). This study showed the potential of Cs and Cs/Fa bio-composites for effective textile wastewater treatment. [ABSTRACT FROM AUTHOR]

The search for adsorbents that are non-toxic and low cost with a high adsorption capacity and excellent recyclability is a priority to determine the way to reduce the serious environmental impacts caused by the discharge of effluents loaded with heavy metals. Bacterial cellulose (BC) biomass has functional groups such as hydroxyl and carbonyl groups that play a crucial role in making this cellulose so efficient at removing contaminants present in water through cation exchange. This research aims to develop an experimental process for the adsorption, elution, and reuse of bacterial cellulose biomass in treating water contaminated with Cr (VI). SEM images and the kinetics behavior were analyzed with pseudo-first- and pseudo-second-order models together with isothermal analysis after each elution and reuse process. The adsorption behavior was in excellent agreement with the Langmuir model along with its elution and reuse; the adsorption capacity was up to 225 mg/g, adding all the elution processes. This study presents a novel approach to the preparation of biomass capable of retaining Cr (VI) with an excellent adsorption capacity and high stability. This method eliminates the need for chemical agents, which would otherwise be difficult to implement due to their costs. The viability of this approach for the field of industrial wastewater treatment is demonstrated. [ABSTRACT FROM AUTHOR]

This study focuses on the biosorption of harmful metals from aqueous solutions using Enteromorpha compressa macroalgal biomass nanoparticles as the biosorbent. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) were employed to characterize the biosorbent. The effects of pH, initial metal ion concentration, biosorbent dosage, and contact time on the biosorption process were investigated. The maximum biosorption capacity for metals was observed at a pH of 5.0. The experimental equilibrium data were analyzed using three-parameter isotherm models, namely Freundlich, Temkin, and Langmuir equations, which provided better fits for the equilibrium data. A contact time of approximately 120 min was required to achieve biosorption equilibrium for various initial metal concentrations. Cr(III), Co(II), Ni(II), Cu(II), and Cd(II) demonstrated distinct maximum biosorption capacities of 24.99375 mg/g, 25.06894 mg/g, 24.55796 mg/g, 24.97502 mg/g, and 25.3936 mg/g, respectively. Different kinetic models were applied to fit the kinetic data, including intraparticle diffusion, pseudo-second-order, and pseudo-first-order versions. The pseudo-second-order model showed good agreement with the experimental results, indicating its suitability for describing the kinetics of the biosorption process. Based on these findings, it can be stated that E. compressa nanoparticle demonstrates potential as an effective biosorbent for removing targeted metals from water. [ABSTRACT FROM AUTHOR]

A nanostructured material, ordered mesoporous carbon (OMC), was synthesised in metal- and halide-free form and its use for the sequestration of crystal violet, a hazardous triphenylmethane dye, is reported for the first time. The OMC material is characterised using scanning transmission electron microscopy with energy-dispersive spectroscopy for chemical analysis, by Fourier-transform infrared spectroscopy, and by nitrogen gas physisorption. The ideal conditions for the uptake of crystal violet dye were determined in batch experiments covering the standard parameters: pH, concentration, contact time, and adsorbent dosage. Experimental data are validated by applying Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherms. The thermodynamic parameters, ΔH°, ΔG°, and ΔS°, are calculated and it has been found that the adsorption process is spontaneous and endothermic with increasing disorder. An in-depth analysis of the kinetics of the adsorption process, order of the reaction and corresponding values of the rate constants was performed. The adsorption of crystal violet over OMC has been found to follow pseudo-second-order kinetics through a film diffusion process at all temperatures studied. Continuous flow column operations were performed using fixed bed adsorption. Parameters including percentage saturation of the OMC bed are evaluated. The exhausted column was regenerated through a desorption process and column efficiency was determined. [ABSTRACT FROM AUTHOR]

This work includes the preparation of Fe3O4 NPs coated with mesoporous silica nanoparticles (MSNs). The combination between two different materials could improve the removal efficiency of pollutants from wastewater. The surface modification of magnetic nanoparticles could reduce the agglomeration. The Fe3O4-MSNs surface was modified with aspartic acid liked with the adsorbent surface via hydrophobic linker (1,4-phenylene diisothiocyanate, PDITC) to effectively remove the methylene blue (MB) dye from the contaminated water. The particles size was ranged between 110 and 160 nm, as estimated by SEM and TEM. The surface zeta potential of the surface was found to be negatively at pH above 2.5. The nanosorbent efficiency was evaluated at different conditions such as pH, contact time and initial MB concentration. The maximum adsorbed amount of the MB was estimated to be 135 mg/g at 200 mg/L MB concentration and 80 min contact time. The adsorption isotherm fits with the Langmuir model and pseudo-second-order kinetics. [ABSTRACT FROM AUTHOR]

A new composite material, named TSC/AXAD-2, was developed by incorporating a bis-thiosemicarbazone derivative (TSC) into Amberlite XAD-2 to extract Pb2+ ions from wastewater. The new composite was characterized using XPS, TGA, FTIR, BET, EDX, 1H-NMR, 13C-NMR, and GC-MS analyses. The sorption parameters, such as pH value of media, equilibrium time, initial Pb2+ ion concentration, composite dose, temperature, and eluting agents, were methodically optimized. The utmost adsorption capacity is 45.3 mg.g−1; it was achieved at pH value of of 5.5, 15 min of agitation, room temperature, and initial concentration of 200 mg.L−1 Pb2+ ions. The isotherm studies revealed that the adsorption process closely matches the Langmuir model, with a theoretical retention capacity of 46.12 mg.g−1. Furthermore, kinetic modeling using the pseudo-first-order accurately depicted the adsorption of Pb2+ ions. The thermodynamic study suggested that the adsorption process is exothermic, spontaneous, and more favorable at lower temperatures. The desorption of Pb2+ ions from the loaded composite was conducted with 1.0 M of either HCl or HNO3. The TSC/AXAD-2 composite successfully met WHO and FAO guidelines for removal of Pb2+ ions from wastewater before its discharge into the marine environment. [ABSTRACT FROM AUTHOR]

In response to the pressing environmental issue of efficiently removing methylene blue (MB) from aqueous solutions, this study introduces a novel approach utilizing activated carbon (AC) synthesized via a two-stage activation process involving zinc chloride (ZnCl 2) and ammonium sulfate ((NH 4) 2 SO 4). SEM analysis confirms the development of a porous structure at distinct activation temperatures (700 °C and 260 °C), while comprehensive characterizations, including FTIR, BET, TGA, CHNOS, and XRD, provide valuable insights into the structural and chemical properties of the synthesized AC. Optimization of the activation process at the second stage using (NH 4) 2 SO 4 yields a remarkable surface area of 939.63 m2/g, crucially enhancing functional groups such as Hydroxyl (O-H) and Carbonyl (C O). The experimental design involved optimizing various parameters, including contact time (0–180 mins), initial concentration (200–500 ppm), temperature (25–55 °C), pH (4−10), and adsorbent dosage (0.4–0.65 g). Batch adsorption optimization experiments demonstrate exceptional efficiency, achieving 99.91 % MB removal and a 90.827 mg/g capacity. Furthermore, Langmuir and second-order kinetic model fitting indicate favorable adsorption behavior, supported by thermodynamic analysis revealing an endothermic process. Notably, AC exhibits excellent regenerative potential over four cycles, emerging as a promising candidate for advancing water purification practices; the modified AC achieves WHO standards for MB removal in drinking water. [Display omitted] • Unique 2-stage ZnCl 2 & (NH 4) 2 SO 4 activation enhances activated carbon AC for methylene blue MB removal. • (NH 4) 2 SO 4 treatment enhances crucial functional groups, porosity, and surface area. • AC achieves 99.91 % MB removal, 90.827 mg/g adsorption from 500 ppm. • Analytical techniques reveal crucial insights into adsorbents' structure and properties. • Achieving WHO-standard drinking water quality by removing 500 ppm of MB. [ABSTRACT FROM AUTHOR]

In this study, the removal of Malachite green (MG) dye, which has a toxic effect on the aquatic ecosystem, was carried out with kaolin clay, a natural and inexpensive material. In batch adsorption tests, the effects of pH, adsorbent dose, initial dye concentration and contact time were determined. Also, Pseudo first order and Pseudo second order kinetic models and Freundlich, Langmuir and Temkin isotherm models were tested. On the other hand, Scanning Electron Microscope (SEM) and Fourier Transform Infrared spectroscopy (FTIR) analyzes of raw and MG-loaded kaolin clay were performed. According to the results obtained, the removal efficiency was over 99% at 23±2 0C, pH 7.0 (±0.5), initial MG concentration of 4 mg/L and kaolin dosage of 1.75 g/L. Also, the most suitable kinetic and isotherm models were determined as Pseudo second order (R2: 0.999) and Freundlich (R2: 0.960), respectively. Additionally, the amount of MG dye removed per unit kaolin (qmax) was calculated as 16.36 mgMG/gkaolin. This study reveals the suitability of using kaolin clay in the adsorption of MG dye. [ABSTRACT FROM AUTHOR]

The sorption of some essential ions by economical and effective methods is crucial in development and technology. The sorption of Cs(I), Co(II), and Ni(II) from aqueous solutions using carboxymethyl cellulose/clay (CMC/clay) sorbent synthesized by precipitation method was studied by batch technique. Different analytical tools like SEM, XRD, FTIR, DTA, and TGA analysis were utilized to find morphology, structure, functional groups, and thermal analysis for CMC/clay. The adsorption process was performed by changing different adsorption factors such as pH, shaking time, initial Cs(I), Co(II), and Ni(II) concentrations, and temperature to get maximum removal of the studied cations. The elements removal process followed pseudo-second-order with the values of regression factor (R2) found as 0.988, 0.995, and 0.996 for Cs(I), Co(II), and Ni(II), respectively. The equilibrium data fitted well to the Langmuir isotherm. The monolayer capacity values were found to be 25.9, 23.7, and 18.5 mg/g for Cs(I), Co(II), and Ni(II), respectively. The thermodynamic functions reflect an endothermic and spontaneous sorption process. Desorption of Cs(I), Co(II), and Ni(II) from the loaded CMC/clay was done using different eluents, and the best eluant was 0.5M of HCl. The data revealed that CMC/clay sorbent is suitable for recovering Cs(I), Co(II), and Ni(II) from aqueous solutions. The real sample application proved that CMC/clay is an excellent sorbent for the capture of Ni(II) from industrial wastewater. [ABSTRACT FROM AUTHOR]

The potential of Zingiber officinale powder was explored as a biosorbent for the uptake of Acid Violet 90 dye from the aqueous solutions. The biosorbent was characterized using FTIR, XRD, SEM, and Zeta potential techniques. The impact of various experimental parameters such as pH, dye concentration, adsorbent dose, contact time, and temperature on the adsorption capacity of biosorbent was investigated using batch adsorption. The Zingiber officinale powder showed a dye adsorption efficiency of 342.68 mg/g. The optimum adsorption was achieved at pH 2, adsorbent dose of 0.2 g/L, contact time of 10 min, and 40 mg/L dye concentration at a temperature of 30 °C. The experimental isotherm data was analyzed by two-parameter and three-parameter models and best explained by the Freundlich model. The pseudo-second-order model elucidated the kinetic behavior of the uptake with pore-diffusion as the rate-determining step. The thermodynamic study suggested the uptake of dye was feasible, spontaneous, and exothermic in nature. The results revealed that the Zingiber officinale powder has the potential to be used as an adsorbent for the treatment of water. [ABSTRACT FROM AUTHOR]

Hazardous pollution of water sources is a major impediment to the supply of usable and potable water around the world. Economical, innovative, renewable and environmentally friendly technologies are needed for the treatment of wastewater. Untreated waste materials, like date palm flower stalks (PFS) collected directly from trees, can serve as adsorbents for removing textile dyes. Batch kinetic and equilibrium experiments performed to investigate the effects of various factors, including contact time (0 – 180 min), adsorbent dose (10–50 mg / 25 mL), initial pH (2 – 12), initial concentration of dye (0 – 200 mg/L) and temperature (15 – 60 °C). The equilibrium capability achieved after 90 min of biosorption was 38.522 mg/g. The Freundlich and Langmuir isotherm models were fitted to the experimental data and their goodness of fit for adsorption was compared. Langmuir isotherm (R2 ~ 0.998) best described the equilibrium of SRL sorption on PSF. Adsorption was found to be greater under highly basic conditions (pHpzc = 6.3). The thermodynamic parameters such as Gibbs free energy ΔG°, enthalpy change ΔH°, and entropy ΔS° were calculated. Adsorption Gibbs free energy (ΔG°) was calculated to be in the range -8.49 to -8.62 kJ / mol. The values of activation parameters such as enthalpy (ΔH°) and entropy (ΔS°) were also determined as -7.76 kJ / mol and 2.49 J / mol.K, respectively. These findings indicate that palm flower stalk would be suitable adsorbents for textile dyes in wastewater. [ABSTRACT FROM AUTHOR]