Isotherm Model Research Articles

Simple Use of Low-cost and Available Adsorbent for Cationic Dye Adsorption from Aqueous Solution

The aim of this work was to study the adsorption of methylene blue (MB) on local agricultural waste in the batch process. The adsorbent, washed rice husk (WRH) was subjected to some physical and chemical analyses such as EDX/SEM, FT-IR, XRD and XRF. The adsorbent showed an amorphous structure and dominated by silica in its composition. The influence of adsorption parameters such as contact time, adsorbent dose and initial concentration was studied. The mass of washed rice husk (WRH) varied at 1 to 6 g, the initial concentrations MB (50-250 mg/L) and the contact time (10-90 min). The MB removal percentage reached 86% with a WRH amount of 4.5 g and an optimal time of 30 min. Langmuir and Freundlich isotherm models were used to process the adsorption data. Q<sub>max</sub>, the maximum adsorption capacity of MB from Langmuir’ model was 13.23 mg.g<sup>-1</sup>. The values of the R<SUB>L</SUB> constant varying between 0-1 for the initial concentrations studied proved that the adsorption is favorable. The value of the parameter n being less than 1obeys the condition of heterogeneity. Pseudo-first order and pseudo-second order models were used to study the kinetic adsorption process. The kinetic parameters calculated from each model showed that the adsorption of MB on the WRH could be describe by the pseudo-second order.

CoFe2O4/graphene oxide/ostrich eggshell/chitosan/polypyrrole nanocomposite for removal 4-nitrophenol

A nanocomposite comprising CoFe2O4/graphene oxide/ostrich eggshell/chitosan/polypyrrole (CF/GO/ES/CS/PPY) was fabricated as both an adsorbent and photocatalyst to examine the adsorption and degradation efficiency of the organic pollutant 4-nitrophenol (4-NP), both in the absence of light and under visible light irradiation. The nanocomposite material outperformed adsorption in photocatalytic experiments conducted using the Box-Behnken Design (BBD) within response surface methodology, which investigated the correlation between responses and process variables and identified optimal combinations with Design Expert software. Under optimal conditions, the highest percentage of adsorption and degradation of 4-NP was achieved, with a pH of 5.04, concentration of 4-NP of 24.73 mg/L, nanocomposite mass of 0.04 g, and time of 27.64 min, resulting in reported efficiencies of 89.76, and 99.98% for adsorption and degradation, respectively. Upon statistical analysis, it is clear that the Langmuir isotherm model is the best fit for the studied phenomena, displaying a strong correlation (0.990) and minimal error. The data suggests that the intraparticle diffusion kinetic model has the highest correlation coefficient (0.9925) among the models examined. The value of ΔG° computed for the adsorption process exhibits an increase from 1.3704 to 3.9439 kJ/mol as the temperature rises, indicating the nonspontaneous nature of the adsorption process.

PLASTIC POLLUTION CONVERSION INTO ADSORBENTS FOR HEAVY METAL TREATMENT: OPTIMIZATION OF ISOTHERM METHODS AND ADSORPTION APPLICATIONS

Plastic waste in the ocean leaches chemicals, polluting marine environments. A recent study examined adsorption capacities of various media to address this concern. After a natural leaching process of three months, it was observed that activated carbon (AC) and a combination of activated carbon and zeolite (ZEO) demonstrated superior heavy metal removal efficiency. Specifically, 30g of activated carbon removed 91.72% of metals and a 10g mix of AC:ZEO achieved 90.38%. In contrast, 50g of zeolite removed 88.10%. Notably, the mixture of activated carbon and zeolite was especially efficient in removing copper. Additionally, the pH remained stable during these processes. The adsorption behavior was best described using the Langmuir isotherm model, outperforming the Freundlich model. This was evident from a higher correlation coefficient value for the Langmuir model across all tested media. The study emphasizes the potential of AC and AC:ZEO in addressing marine contamination from plastic waste.

Synthesis and Evaluation of an Innovative Biochar Nanocomposite Adsorbent Derived from Cycas Revoluta Seeds, with Potential Applications in the Removal of Cationic Dyes

In this study, novel and functional adsorbents were synthesized by using Cycas revoluta seed (CS) biomass. The biomass was subjected to a slow pyrolysis process at a final temperature of 500°C with a heating rate of 10°C/min to synthesize Cycas revoluta seed biochar (CSB). After the thermochemical conversion of biomass into biochar, the nanocomposite structure (ZrO2NP@CSB) was synthesized by adding 5% zirconium oxide (ZrO2) nanoparticles into biochar to increase the adsorption capacity. The synthesized adsorbents (CS, CSB, and ZrO2NP@CSB) were characterized by XRD, FTIR, SEM, and EDX. The adsorption efficiency of these three adsorbents was investigated to remove Malachite Green (MG) and Methylene Blue (MB) dye from an aqueous solution. According to the results obtained from the adsorption experiments of the nanocomposite structure, solution pH had a significant effect on the process and the highest adsorption efficiencies were achieved at pH 9. The optimum adsorbent dose was 0.5 g/L. The process reached an equilibrium after 45 minutes and 90 minutes for MG and MB, respectively. The relevant data were in good agreement with the pseudo-second-order kinetic model. The maximum adsorbent capacities were 129.87 and 117.93 mg/g for MG and MB, respectively. The adsorption mechanism follows a monolayer Langmuir isotherm model. Experiments were carried out at different temperatures (25, 35, 45°C) to determine the effect of temperature on adsorption, and dye removal efficiency slightly increased with temperature. When repeated batch adsorption experiments were compared for raw biomass, biochar, and biochar nanocomposite adsorbents, it was observed that the raw adsorbent had a lower adsorption capacity than the biochar adsorbent. It was found that the biochar nanocomposite had the highest adsorption capacity among these three adsorbents. The findings suggest that ZrO2NP@CSB composite is a promising, cost-effective, and functional material for water treatment and can be employed as an alternative adsorbent for removing dyes.

Superior Adsorption of Chlorinated VOC by Date Palm Seed Biochar: Two-Way ANOVA Comparative Analysis with Activated Carbon

This study explores biochar (BC) derived from date palm seeds as a high-performance adsorbent for the removal of trichloroethylene (TCE) and tetrachloroethylene (PCE) from aqueous solutions, with comparative analysis against commercial activated carbon (AC). The optimized BC, characterized by a high BET surface area of 654.79 m2/g and unique nanotube morphology, demonstrated superior adsorption capacities of 86.68 mg/g for TCE and 85.97 mg/g for PCE, significantly surpassing the AC under identical conditions. Kinetic studies identified the pseudo-second-order model as the best fit, indicating chemisorption as the dominant mechanism. Isotherm modeling revealed a combination of multilayer and monolayer adsorption processes, underscoring the complexity of the BC’s adsorption behavior. Statistical analysis via two-way ANOVA further validated the BC’s significant superiority over the AC (p < 0.0001) for both contaminants. These results highlight the potential of date-palm-seed-derived biochar as a sustainable and cost-effective adsorbent for eco-friendly water treatment, emphasizing its role in reducing environmental impact and operational costs in real-world applications.

Graphene oxide functionalized with L-asparagine applied to crystal violet dye removal from water and wastewater.

The efficiency of graphene oxide functionalized with L-asparagine (GO@L-Asn) as adsorbent for crystal violet (CV) dye removal from water and wastewater was investigated. The surface and textural properties of this new nanomaterial were characterized by pH at point of zero charge, Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmet-Teller technique. The main experimental variables involved in dye adsorption process were evaluated and optimized. Adsorption equilibrium was reached after 120min, using 25mL of 50mg L-1 CV, and 30mg of GO@L-Asn at pH 8 and 328K. The Freundlich isotherm model was the most appropriate to correlate the experimental data, showing a maximum adsorption capacity of 102.5mgg-1 (R2 = 0.992). The results of the kinetic study were fitted with the pseudo-first order model (R2 = 0.997). Thermodynamic calculations indicated that the CV removal was an endothermic, spontaneous, and favorable process. Characterization and modeling results showed that an adsorption mechanism involving physisorption was associated with CV removal. This novel adsorbent was applied to remove CV from samples of natural water and textile effluents, obtaining pollutant removal percentages up to 92.0%, which indicated the high efficiency of GO@L-Asn for the treatment of complex matrices.

Research on the adsorption of Pb2+ ions and methylene blue dyes by a kapok and polypropylene fibre web

Purpose This study aims to investigate into the adsorption mechanism of heavy metal ions Pb2+ and methylene blue (MB) dyes on an adsorbent-web formed from kapok fibres (KP) and polypropylene fibres (PP). Design/methodology/approach Initially, the KP underwent pre-treatment with NaClO2 solution, and their morphology and structure changes were examined through scanning electron microscope images. Subsequently, the KP fibres were blended with PP fibres at a ratio of 70 / 30 and processed through a laboratory carding machine to form a fibre web, which was then secured using a heat press to fabricate the adsorbent-web. The resultant adsorbent-web was subjected to evaluation for the adsorption process. Findings The findings revealed that the adsorbent-web produced via the dry-laid method exhibited promising attributes, and the adsorption process conformed to the pseudo-second-order model and the Langmuir isotherm model. Parameters such as adsorbent-web porosity, solution pH, and adsorption thermodynamics exerted notable influences on the adsorption capacity of the adsorbent-web. Notably, the adsorbent-web demonstrated remarkable reusability and desorption capacity. In the fifth cycle, the adsorption capacity of adsorbent-web for MB and Pb2+ ions only decreased by 9.13% and 11.48%, respectively, compared to the first cycle. The desorption efficiency of the adsorbent-web exceeded 90% for MB and over 73% for Pb2+ ions. Originality/value This study makes a significant contribution to the practical application of KP as an adsorbent-web for treating waste from the textile dyeing industry.

Research on the Adsorption Mechanism and Performance of Cotton Stalk-Based Biochar.

In this research, we produced two types of biochar (BC) using cotton stalks as raw material and KOH as an activator, and compared their performance and adsorption mechanisms in the removal of tetracycline (TC) and methylene blue (MB) from wastewater. The results showed that the biochar generated using both procedures formed pores that connected to the interior of the biochar and had extensive microporous and mesoporous structures. The molten salt approach produces biochar with a higher specific surface area, larger pore size, and higher pore volume than the impregnation method, with a maximum specific surface area of 3095 m2/g. KBCM-900 (the BC produced using the molten salt method at 900 °C) had a better adsorption effect on TC, with a clearance rate of more than 95% in 180 min and a maximum adsorption amount of 912.212 mg/g. The adsorption rates of the two BCs for MB did not differ significantly at low concentrations, but as the concentration increased, KBCI-900 (the BC generated by the impregnation method at 900 °C) exhibited better adsorption, with a maximum adsorption of 723.726 mg/g. The pseudo-second-order kinetic model and the Langmuir isotherm model may accurately describe the TC and MB adsorption processes of KBCI-900 and KBCM-900. The KBCI/KBCM-900 adsorption process combines physical and chemical adsorption, with the primary mechanisms being pore filling, π-π interactions, hydrogen bonding, and electrostatic interactions. As a result, biochar generated using the molten salt method is suitable for the removal of large-molecule pollutants such as TC, whereas biochar prepared using the impregnation method is suitable for the removal of small-molecule dyes such as MB.

Adsorption Optimization of VNi‐Layered Double Hydroxide Encapsulated With Chitosan and Carboxymethyl Cellulose for Rhodamine B Dye Removal From Aqueous Solutions: Adsorption Isotherm, Kinetics, and Thermodynamics

ABSTRACTIndustrial dye–contaminated wastewater needs creative techniques to effectively remove these contaminants. An easy co‐precipitation technique was used in this work to create the VNi‐layered double hydroxide (VNi‐LDH) adsorbent. VNi‐LDH was encapsulated with chitosan (CS) and carboxymethyl cellulose (CMC) that cross‐linked with itaconic acid as the cross linker via chemical crosslinking to form VNi‐LDH/CS‐CMC hydrogel beads. FT‐IR, SEM, XPS, BET, XRD, BET, and point of zero charge (pHzpc) were employed to characterize the prepared material. Examining VNi‐LDH/CS‐CMC's ability to remove rhodamine B (RB) from water waste as an adsorbent was the aim of the study. The highest adsorption capacity of RB on VNi‐LDH/CS‐CMC was found to be 653.8 mg/g. The research findings designated that the Langmuir isotherm models provided the most accurate representation of the RB adsorption procedure for VNi‐LDH/CS‐CMC. At a dosage of 0.8 g/L for the adsorbent and an equilibrium time of 100 min, it was established that the RB adsorption of VNi‐LDH/CS‐CMC hydrogel beads occurred at a pH of 8. The model of pseudo‐second order, demonstrating chemisorption with an adsorption energy of 30.34 kJ/mol along with a diffusion‐limited adsorption process, was most appropriate for the RB adsorption kinetics on VNi‐LDH/CS‐CMC hydrogel beads. The impact of temperature was also investigated, with an analysis of the thermodynamic variables (∆H°, ∆S°, and ∆G°) revealing a spontaneous increase in positive enthalpy and entropy charge, along with a decrease in ΔG°, as the temperature rose. The adsorption process outcomes were further optimized using response surface methodology (RSM) and the Box–Behnken design (BBD). It was proposed that the elimination of RB through VNi‐LDH/CS‐CMC may occur through different potential mechanisms, such as chemisorption, pore‐filling, π‐π bonding, electrostatic interactions, and hydrogen bonding. Given that the adsorbent was made of reusable materials and could be reused more than six times with high efficiency, the VNi‐LDH/CS‐CMC hydrogel beads offer a viable low‐cost option for removing RB dye from wastewater streams.

Precipitation Polymerization-Based Molecularly Imprinted Polymers: A Novel Approach for Transdermal Curcumin Delivery.

This research describes the synthesis and characterization of a molecularly imprinted polymer (MIP) as a candidate for the transdermal delivery of curcumin. The MIP was synthesized through precipitation polymerization using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking agent. MIP characterization studies were conducted using SEM-EDX and FTIR spectroscopy to determine the morphology and interaction between curcumin and polymers. The MIP obtained through precipitation polymerization was in the form of a fine powder with a surface morphology resembling a collection of small granules with a uniform shape. The adsorption capacity of the MIP follows the Langmuir adsorption isotherm model, with a maximum capacity of 4.239 mg/g, which is greater than that of the NIP (3.219 mg/g), resulting in an imprinting efficiency of 1.317. The percentage of curcumin released from the MIP after 8 h was 41.26%, which is lower than that from the NIP, at 51.50%. The drug release kinetics study follows the Higuchi model, indicating drug diffusion from the polymer matrix. Imprinting on the MIP can modify drug diffusion from the polymer matrix, resulting in a reduced release rate in the MIP. Therefore, the MIP can be considered a candidate for the controlled transdermal delivery of curcumin.

KOH-activated tire pyrolysis char as an adsorbent for chloroorganic water pollutants

Activated carbons (ACs) produced from end-of-life tires with different tire pyrolysis char (TPC)-to-activator (KOH) ratios of 1:2, 1:3, and 1:4 were prepared and characterized. These materials were used as adsorbents for the removal of two common chloroorganic water contaminants such as 2,4-dichlorophenol (DCP) and 2,4-dichlorophenoxyacetic acid (2,4-D). The adsorption kinetics, equilibrium adsorption, and effects of solution pH were investigated. The adsorption of both adsorbates was found to be pH-dependent and preferred in acidic environments. The adsorption kinetics was evaluated using pseudo-first-order and pseudo-second-order kinetic models and mechanism - using Weber-Morris and Boyd models. Results demonstrated that the adsorption of DCP and 2,4-D on all ACs followed the pseudo-second-order model and was controlled by film diffusion. The Langmuir isotherm described the equilibrium data better than the Freundlich isotherm model. The maximum adsorption capacity of DCP adsorbed on AC1:2, AC1:3, and AC1:4 at equilibrium was 0.582, 0.609, and 0.739 mmol/g, respectively, while the maximum adsorption capacities for 2,4-D were 0.733, 0.937, and 1.035 mmol/g, respectively. The adsorption rate and efficiency were closely correlated with the porous structure of the tested adsorbents. The results showed that the activated carbons obtained from the scrap of end-of-life tires as raw materials could be used as a low-cost and alternative adsorbent for the removal of chlorinated organic pollutants from water.

The application of artificial neural network (ANN) to validate biosorption of Zn+2 ions onto chemically modified Hevea brasiliensis sawdust

The study examined the biosorption of Zn+2 by chemically modified Hevea brasiliensis sawdust using a batch adsorption system. The influence of concentration, pH, contact time, and adsorbent dose in a batch biosorption process were analyzed and the maximum Zn+2 uptake capacity was found as 36.8 mg/g. The Langmuir and Temkin model was found to be the most accurate when the experimental data were analyzed using the different adsorption isotherms models. This study presents an experimental modeling approach for the biosorption process based on artificial neural networks (ANN). Data from biosorption experiments were utilized to train and validate the ANN model. The ANN model can effectively represent the biosorption process, as demonstrated by the significant correlation (R 2 = 0.998) established between the model and experimental data. A kinetic study revealed that the Zn+2 biosorption was favored by the pseudo-first-order and pseudo-second-order models. The process is feasible, spontaneous, and endothermic, according to thermodynamic study. The H. brasiliensis sawdust underwent chemical carbonization, and its characteristics were examined using energy EDX, BET surface area analyzer, SEM, XRD, and FTIR.

Selective recovery of Co(II), Mn(II), Cu(II), and Ni(II) by multiple step batch treatments with nanocellulose products.

The recovery of Co(II), Mn(II), Ni(II), and Cu(II) from black mass e-waste solutions through cellulose nanofibers (CNFs) and nanocrystals (CNCs) was investigated. These materials were synthetized by TEMPO-oxidation followed by high-pressure homogenization, and acid hydrolysis, respectively. The NC characterization included the measurement of consistency, cationic demand, carboxylic content, dissolved amorphous cellulose, and transmittance at λ = 600nm. These parameters revealed a high transmittance of the NC solutions and a large presence of anionic groups on the surface. The high surface area and charge of the NC justify their high interaction with the cationic metals. Results indicate that short contact times (even 1min) and low sorbent doses (10mg/L) at acidic pHs (2 to 4) implied remarkable sorption capacities in most cases with more than 1g/g of sorption capacity of Co(II), Mn(II), and Cu(II) in single-step sorption tests. Such levels of sorption capacities exceed by at least one order of magnitude most of the literature values of metal recovery applying cellulosic materials. Isotherm modeling through a combination of Langmuir and Freundlich models suggested that both sorption and surface precipitation occurred. A novel procedure following multiple-step batch operation was applied for Mn(II) sorption. This new method was applied as a five-step process, leading to a fourfold and 18-fold increase of sorption capacity onto CNCs and CNFs, respectively, compared to the single-step process. Therefore, this process shows an innovative way to implement the multiple-step batch sorption with NC as an efficient and environmentally friendly solution for critical metal recovery from e-waste leachates.

Removal of Pb(II) from aqueous solution using xanthate modified waste walnut shells

A vast number of biomass-based materials are getting increasing attention for heavy metal removal and recovery due to their good performance, low cost, large availability, and environmental friendliness. This study primarily aims to fabricate a cost-effective, potent adsorbent derived from walnut shells through chemical modification, targeting the removal of Pb(II) ions from water. The experimentation involves the preparation of adsorbents from charred walnut shell (CWS) and xanthated walnut shell (XWS), followed by batch trials to eradicate Pb(II) from water. Parameters for instance pH, concentration of Pb(II), adsorbent quantity, and contact duration were examined using both CWS and XWS adsorbents. For characterization purposes, FTIR, XRD, and FE-SEM analyses were employed. Optimal conditions were identified at pH 4 and duration of contact 150 minutes for both adsorbents. Equilibrium sorption data adhered best to the Langmuir isotherm model, with maximum adsorption capacities of 61 mg/g for CWS and 109.9 mg/g for XWS. Kinetic modeling showed the well-fitting of pseudo-second order kinetic. These findings suggest that XWS presents a promising, eco-friendly alternative bioadsorbent intended for the elimination of lead (II) from water.

Efficient One-Pot Hydrothermal Synthesis of TiO2 Nanostructures for Reactive Black 5 Dye Removal: Experimental and Theoretical Insights

Water scarcity continues to be a major worldwide issue. Therefore, from a scientific perspective, it is crucial to develop a highly effective, affordable, environmentally friendly, and readily available metal-based adsorbent for wastewater treatment. This study focuses on synthesizing a mesoporous/nanosphere TiO2 using a free-template and eco-friendly method to effectively remove Reactive Black 5 (RB5) dye. The synthesis of TiO2 nanospheres was achieved through the use of titanium isopropoxide at 100 °C for 12 h in a one-pot hydrothermal process, successfully regulating their morphology and crystallite size. The TiO2 nanospheres were extensively characterized using multiple techniques, such as XRD, FE-SEM, zeta potential, FT-IR, HR-TEM, and BET surface area tools. Adsorption experiments revealed a notable capacity of 109 mg g−1 for RB5 dye, following pseudo-second-order kinetic behavior. The equilibrium data conformed well to the Langmuir isotherm model, indicating monolayer adsorption. Thermodynamic evaluations confirmed that the process was spontaneous, endothermic, and governed by physisorption. Calculations using density functional theory (DFT) provided additional support for the experimental findings, demonstrating strong binding interactions between the dye and the TiO2 (101) surface. The TiO2 nano-adsorbent showed excellent reusability and maintained high adsorption efficiency over multiple cycles, making it a promising candidate for wastewater treatment.

Kinetic adsorption and isotherm models of nickel

The study investigated the adsorption capacity of Pinus halepensis Mill biomass (PHM) that has been modified to remove nickel (II) from aqueous solutions. The underwent chemical modification using zinc chloride (0.1N) to produce activated carbon. The resultant products were analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. Several variables were taken into account to achieve optimal adsorption conditions. These factors include the duration of agitation, the starting concentration of copper, and the pH level. Consequently, the highest level of efficiency was obtained at 90 mg/g when equilibrium was established after 120 minutes. The pseudo-second-order kinetic model offers a more appropriate characterization of the adsorption kinetics. Nickel adsorption adheres to the principles of the Langmuir and Freundlich isotherms. The Langmuir isotherm model produces the most favorable parameters. The adsorption capacity increased with the elevation of the initial concentration (from 1000 to 400mg/l) employed in this work at a neutral pH and 25°C in temperature.

Adsorpsi Congo Red dan Remazol Red oleh Silika Pasir Pantai Panjang dengan Metode Spektroskopi

This study intended to 1) explain the process of synthesis silica from Bengkulu beach sand; 2) describe pH, weight, contact time, optimum temperature, thermodynamics, isotherms, kinetics of the Congo Red and Remazol Red adsorption process of silica from Bengkulu beach sand using spectroscopic UV-Vis analysis methods. Based on the experiments, the results were 1) The synthesis of silica from Bengkulu beach sand was carried out through the purification of the sample, the potassium silicate preparation (K2SiO3) by the alkali fussion method, gel making, and the silica gel preparation (SiO2). The optimum adsorption condition of Congo Red substance by silica occurs at pH 2 and the contact time is 40 minutes, while the Remazol Red substance occurs at pH 3 and the contact time is 60 minutes, each adsorbent weight 75 mg and 50 mg, and the optimum temperature 30°C. The thermodynamic parameters acquired are ∆G° and ∆H° are negative, while the ∆S° is positive, which means that the process of adsorption occurs exothermic and spontaneously irregularities towards the increased system. Isotherm adsorption is determined through the Freundlich isotherm model and follows pseudo-order kinetic model 2.

Effective adsorbents developed from magnetic iron oxides and thiamin for the removal of hazardous organic contaminants

Among the removal techniques for organic contaminants in water, adsorption is a highly selected method due to many advantages in cost, simple process, and good efficiency. A green and straightforward synthesis for generating an iron oxide-grafted thiamin based adsorbents is developed. Their physicochemical and adsorption properties varied depending on the mixing ratio of ferrous chloride salt and thiamin. Adsorbents exhibited different magnetic properties owing to the presence of Fe3O4, α-Fe2O3, and γ-Fe2O3 crystalline phases. Their surface charges of iron oxide and functionalized thiamin-adsorbents were 25 mV and 30–52.3 mV, respectively while the C and N contents of thiamin ranged from 3.87–14.5% and 3.95–8.15% at different mixing ratios. Besides, scanning electron microscope (SEM) and thermogravimetric analysis (TGA) were used to analyze the morphology and thermal stability of adsorbents, respectively. This work investigated the effect of thiamin content in the material composition-based iron oxide on the adsorption capacity of anionic dyes. At the optimal condition (pH 5, an adsorbent dosage of 2 g/L, and a 30 mg/L concentration), the MO adsorption efficiency reached 77.56% in 30 min. Meanwhile, a 93.83% EBT was removed at pH 7, an adsorbent dosage of 2 g/L, and a 90 mg/L concentration at the same time. The adsorption mechanism follows the Langmuir isotherm model and the pseudo second-order (PSO) kinetic model. The adsorption processes are spontaneous and exothermic. The characteristic vibrations of functional groups of adsorbents were identified via Fourier transform infrared spectroscopy (FTIR). After four cycles, adsorbents could be employed albeit with a lower efficiency.

The potential of Ti3C2Tx-KH2PO4 and Ti3C2Tx-chitosan in the efficient removal of cesium from nuclear wastewater

Ti3C2Tx is synthesized from Ti3AlC2 by two common methods, HF and HF in situ. The synthesis approach is very practical regarding the structure, morphology, space between layers, type and number of surface-active sites and its specific surface. XRD, SEM, EDS, FTIR and BET analyzes were used to investigate the structure, morphology, type and number of surface-active sites. Under the operating conditions of cesium initial concentration ~ 150 ppm, ambient temperature, pH ~ 7.00 and time of 60 min, the cesium adsorption intensity with Ti3C2Tx-HF and Ti3C2Tx-HF in situ was obtained as 194 and 219.5 mg.g− 1, respectively. The structural results of modification with KH2PO4 show that in this modification, in addition to the increase of hydroxyl functional groups, the distance between the layers has also increased and the cesium adsorption intensity has increased to 338.75 mg.g− 1 under the above operating conditions. Meanwhile, in modification with Chitosan by increasing the frequency of functional groups and specific surface up to 3 times the effective specific surface of Ti3C2Tx-HF in situ, no significant change in the cesium adsorption intensity has been observed (247.5 mg.g− 1). Experiments were conducted to evaluate the effect of parameters of initial concentration of Cs+ (250 − 50 ppm), time (30–60 min), ambient temperature (298.15–318.15 K), solution pH (3.0–11.0) with the help of RSM design. RSM results show that the pH parameter is one of the most important parameters affecting the cesium adsorption intensity with Ti3C2(OH)x and Ti3C2(OH)x-KH2PO4. Also, with the increase in temperature, the adsorption intensity should increase. It is shown in the isotherm modeling that R2 matches well with the Freundlich isotherm model, which is based on the layered structure of Ti3C2(OH)x and Ti3C2(OH)x-KH2PO4 and the presence of active sites with different energy levels, which leads to heterogeneous adsorption. The consistency will be of the adsorbent selectivity investigation shows that the Cs+ hydration radius plays a decisive role in its high adsorption potential. Reduction of MXene by 0.1 M HCl was carried out in 3 steps. The experimental results show that 15% absorption has been achieved in the third stage. The results of structural analysis show that its structure has not changed and the reduction of active sites as a result of washing with acid has led to a decrease in adsorption.

An extensive analysis of isoindigotin derivatives as effective corrosion inhibitors for mild steel in acidic corrosive environments: An electrochemical and theoretical investigation

Isoindigo and its derivatives are frequently employed as active ingredients in pharmaceuticals and in solar cells, largely due to their distinctive structural characteristics, which render them a green substance. The utilization of its polymers as efficacious corrosion inhibitors for the safeguarding of mild steel exhibits considerable promise. In order to achieve this, a green and highly efficient isoindigo polymer (E)-7-(9,9-bis(3-(dimethylamino) propyl)-9H-fluoren-2-yl)-1,1′-bis(3-(dimethylamino) propyl)-[3,3′-biindolinylidene]-2,2′-dione (PIIDN-FN) was synthesized using a simple one-step polymerization reaction and subsequently employed as a corrosion inhibitor for the first time. In this work, its ability to inhibit the corrosion of Q235 when added to 1 M HCl medium was the subject of corresponding electrochemical tests and surface analyses (including SEM, AFM and XPS etc.). The results implied that PIIDN-FN was able to achieve a maximum inhibition efficiency of 94.52 % at a concentration of 100 mg L−1, and the inhibition efficiency was still close to 90 % even at a high temperature of 328.15 K. Moreover, the PDP results indicated that PIIDN-FN is a hybrid corrosion inhibitor, and it was determined that the adsorption of the material onto the carbon steel surface conformed to the Langmuir isotherm model. Furthermore, quantum chemical calculations (QC) based on density functional theory (DFT) and molecular dynamics simulations (MD) facilitated the elucidation of the inhibition mechanism. The findings of the theoretical investigation suggest that PIIDN-FN adsorbs as a film on the surface of mild steel due to its conjugated structure, forming a complex with iron and thereby providing effective protection for carbon steel.