Optimum Adsorption Conditions Research Articles

Adsorption of Heavy Metal from Wastewater by Bioabsorbent Modified Azolla microphylla and Lemna minor

Environmental toxicity from rapid industrialization raises concerns about water pollution caused by industrial waste and urban sewage. Aquatic macrophytes, such as the Azolla species, have shown promise in absorbing heavy metals and nutrients from water. This study introduces a novel approach by evaluating Azolla Microphylla and lemna minor as an economical adsorbent for copper removal from rivers. Moreover, this study stands out by conducting thorough characterization analyses. The adsorbent material underwent XRD, SEM, BET, and FTIR analyses after being crushed and sieved to 1-2 mm. Copper was extracted from river water using UV-Vis detection at 285 nm. Optimal conditions for adsorption were determined at pH 4, 30 minutes of contact time, and 0.4 g of adsorbent. Copper concentrations in the Sungai Petani, Sungai Selangor, and Sungai Langat ranged from 2 mgL-1 to 5 mgL-1. Azolla proves effective as a copper adsorbent due to its simplicity in sample preparation, time-saving benefits, cost-effectiveness compared to conventional systems, and high copper recovery rate. By successfully removing copper, a prevalent heavy metal contaminant in industrial waste and urban sewage, this research contributes to achieving Sustainable Development Goal 6 for clean and safe water supplies.

Preparation and Application of Responsive Nanocellulose Composites

Cellulose nanofibrils/poly(N-Isopropylacrylamide) semi-interpenetrating networks (MMCNF-PNAs) were synthesized using an in situ fabrication (semi-IPN). The polymerization of N-isopropylacrylamide (NIPAM) (free radical) was conducted in the presence of magnetic modified cellulose nanofibrils (MMCNFs). The adsorption behaviors and surface morphology of the synthesized adsorbents were investigated systematically. The adsorption behaviors of the as-prepared MMCNF-PNA towards methylene blue (MB, as the model contaminant) dye was studied, and the optimal adsorption conditions were also studied. The adsorption processes could be well fitted using pseudo-second-order and Elovich kinetic models. Meanwhile, Langmuir and Freundlich isotherm models were used to fit the adsorption which occurred at 25, 37 and 65 °C. The corresponding results showed that the Freundlich isotherm model fitted the adsorption process better, indicating that the dye’s adsorption happened via heterogeneous adsorptive energies on the prepared MMCNF-PNAs. Their desorption and reusability were also studied to verify magnetic responsivity. To sum up, MMCNF-PNAs are promising magnetic and thermal stimuli-responsive adsorbents, showing a controlled adsorption/desorption process.

Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions.

In this work, iron-phosphorus based composite biochar (FPBC) was prepared by modification with potassium phosphate and iron oxides for the removal of heavy metal ions from single and mixed heavy metal (Pb and Cd) solutions. FTIR and XPS characterization experiments showed that the novel modified biochar had a greater number of surface functional groups compared to the pristine biochar. The maximum adsorption capacities of FPBC for Pb(II) and Cd(II) were 211.66mg·g-1 and 94.08mg·g-1 at 293K. The adsorption of Pb(II) and Cd(II) by FPBC followed the proposed two-step adsorption kinetic model and the Freundlich isothermal adsorption model, suggesting that the mechanism of adsorption of Pb(II) and Cd(II) by FPBC involved chemical adsorption of multiple layers. Mechanistic studies showed that the introduction of -PO4 and -PO3 chemisorbed with Pb(II) and Cd(II), and the introduction of -Fe-O increased the ion exchange with Pb(II) and Cd(II) during the adsorption process and produced precipitates such as Pb3Fe(PO4)3 and Cd5Fe2(P2O7)4. Additionally, the abundant -OH and -COOH groups also participated in the removal of Pb(II) and Cd(II). In addition, FPBC demonstrated strong selective adsorption of Pb(II) in mixed heavy metal solutions. The Response Surface Methodology(RSM) analysis determined the optimal adsorption conditions for FPBC as pH 5.31, temperature 26.01°C, and Pb(II) concentration 306.30mg·L-1 for Pb(II). Similarly, the optimal adsorption conditions for Cd(II) were found to be pH 5.66, temperature 39.34°C, and Cd(II) concentration 267.68mg·L-1. Therefore, FPBC has the potential for application as a composite-modified adsorbent for the adsorption of multiple heavy metal ions.

Adsorption of fast green dye onto Fe3O4 MNPs and GO/Fe3O4 MNPs synthesized by photo-irradiation method: Isotherms, thermodynamics, kinetics, and reuse studies

In this study, the adsorption of Fast Green dye (FGD) on the surface of ferrous ferric oxide Fe3O4 MNPs and Graphene oxide Nano-Sheets/ferrous ferric oxide GO/Fe3O4 MNPs as adsorbents was examined. The photo-irradiation method was successfully used to synthesize Fe3O4 MNPs and GO/Fe3O4 MNPs using UV lamp. Raman spectroscopy was used to characterize the GO and GO/ Fe3O4 MNPs. XRD, FESEM, and EDX were used to characterize the Fe3O4 MNPs and GO/ Fe3O4 MNPs. Optimal adsorption conditions were studied, including a contact time of 60 min, MNPs amount of 0.05 g, pH 2, FGD concentration of 10 mg/L, and temperature of 308 K. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherm models were used to fit the experimental equilibrium data at five different temperatures (288, 298, 308, 318, and 328 K). It was noticed that FGD adsorption on Fe3O4 MNPs and GO/ Fe3O4 MNPs is consistent with the Freundlich model at 308 K. The PSO rate kinetics suggests that both MNPs are promising materials for the removal of FGD from aqueous solutions. Thermodynamic studies showed that the adsorption processes are non-spontaneous on both MNPs surfaces, endothermic for Fe3O4 MNPs, and exothermic for GO/ Fe3O4 MNPs. All the results confirm that Fe3O4 MNPs and GO/ Fe3O4 MNPs have the potential to be efficient, low-cost, reusable, and stable adsorbents for the removal of FGD from aqueous solutions.

Factorial experimental design optimisation of adsorption process for removing chrome ion using crude biomass

ABSTRACT The pollution of water and the environment by heavy metals has recently increased dramatically, creating a severe environmental problem due to their non-biodegradability and high toxicity. Among these metals, we are interested in chromium (Cr), essential for human life but can be toxic in large quantities. It is vital to develop a simple, effective, and inexpensive method for its removal from aqueous media. This work aims to combine two aspects: environmental protection and waste recovery. We studied the adsorption capacity of Cr(VI) by biomass consisting of a mixture of walnut shells, pecan nuts, and peanuts. The ion was quantified using high-resolution magnetic sector inductively coupled plasma mass spectrometry, and several techniques characterised the raw adsorbent. To optimise the removal of Cr(VI), four factors were optimised using a 24-full factorial design, enabling us to determine the optimum adsorption conditions: a contact time of 360 min, an adsorbent mass of 30 mg, an initial ion concentration of 50 mg/L, and a pH of 6. The response efficiency Y (Qe) achieved its optimum at 58.47976 ± 4.168804 (mg/g), resulting in a maximum desirability of 0.957419. The adsorption phenomenon was studied kinetically, and it was found to follow the pseudo-first-order reaction (R 2 = 0.9894); concerning adsorption isotherms, the Freundlich isotherm proved to be the best (R 2 = 1). Overall, the present biosorbent demonstrates excellent capacity to remove Cr (VI) from water and can be used on a large scale.

Salsola Tetragona as a new low-cost adsorbent for water treatment: highly effective adsorption of crystal violet

Synthetic dyes are prevalent in aquatic environments, they have high toxicities, are non-degradable, and accumulate in the water. The removal of Crystal violet (CV) is carried out using batch experiments on the Salsola Tetragona (ST) plant as a novel adsorbent. The prepared adsorbent was analyzed by various methods (MEB, EDX, IRTF and PZC), to support its applicability as adsorbent. The adsorption study of CV is performed by optimizing the parameters affecting the adsorption process. The adsorption kinetics study is represented by pseudo-second-order (R2 = 0.999) and the adsorption process is limited by external mass transport. In addition, the isotherm results demonstrate that the Langmuir model interprets better the adsorption isotherm. The thermodynamic parameters suggest that the adsorption phenomena are spontaneous and exothermic. Furthermore, the adsorption reactions involved are of physisorption type, which facilitates the desorption of pollutants from the surface of the adsorbent. The results show that ST adsorbent effectively removes CV in an aqueous solution, which is demonstrated by the maximum amount adsorption of 246.7 mg.g−1 at optimum adsorption conditions: pH = 6, adsorbent dose of 0.5 g.L−1, initial CV concentration of 10 mg.L−1, and adsorption time of 30 min at 298 K. Finally, these results can be considered as a useful reference for wastewater treatment using ST.

Predictive capability of rough set machine learning in tetracycline adsorption using biochar

Machine learning algorithms investigate relationships in data to deliver useful outputs. However, past models required complete datasets as a prerequisite. In this study, rough set-based machine learning was applied using real-world incomplete datasets to generate a prediction model of biochar’s adsorption capacity based on key attributes. The predictive model consists of if–then rules classifying properties by fulfilling certain conditions. The rules generated from both complete and incomplete datasets exhibit high certainty and coverage, along with scientific coherence. Based on the complete dataset model, optimal pyrolysis conditions, biomass characteristics and adsorption conditions were identified to maximize tetracycline adsorption capacity (> 200 mg/g) by biochar. This study demonstrates the capabilities of rough set-based machine learning using incomplete practical real-world data without compromising key features. The approach can generate valid predictive models even with missing values in datasets. Overall, the preliminary results show promise for applying rough set machine learning to real-world, incomplete data for generating biomass and biochar predictive models. However, further refinement and testing are warranted before practical implementation.

ACTIVATED CARBON DERIVED FROM GROUNDNUT SHELL AND RICE HUSK FOR THE ADSORPTION OF HEAVY METALS IN TANNERY WASTEWATER

The Effluents from tanneries are considered to be one of the major environmental pollutants from industries. The challenge from leather processing arises from the nature and quality of the chemicals used along with the amount of wastes generated and discharged. Heavy metals present in tannery wastewater pose a significant risk to both the environment and public health. This study investigates the use of activated Carbon produced from Composite of Groundnut shell and Rice husk (GR-AC) to remove heavy metals (Pb, Cr and Cd) from tannery wastewater. The raw material was carbonized at temperature of 400 ͦ C for 1 hour to obtain bio char. The obtained char was impregnated with NaOH and H 3PO 4 for 24 hours thereafter, filtered and washed several times until a neutral pH was obtained. A measured amount of the adsorbent, 0.5g was introduced into 250mL vessel with 50mL wastewater, it was stirred at 250rpm for 60minutes and later subjected to centrifugation and the concentrations of residual Lead, Chromium and Cadmium was determined using Flame Atomic Absorption Spectrometry. The produced adsorbent was characterized using Fourier transform infrared (FTIR) spectroscopy, Energy-dispersive X-ray fluorescence (EDXRF) and scanning electron microscopy (SEM), elemental composition analysis. The effects of adsorbent dosage and contact time on the adsorption process were studied in a batch system. From the research conducted, it shows that pH, adsorbent dosage, contact time, initial Concentration and temperature plays a vital role in the uptake of heavy metals. Optimal conditions for effective adsorption were determined at a pH range of 7 to 8, an adsorbent dosage of 0.5g, contact time of 60 min and a temperature of 40 0C. The maximum adsorption capacities of Pb, Cr and Cd adsorbed onto GR-AC were found to be 98.2, 82.4 and 75.2 mg/g respectively. Therefore, the GR-AC can be effectively utilized as agricultural waste to remove heavy metals in tannery effluents.

Assessing the Lead Removal Potential of Pineapple Waste Hydrochar in Simulated Wastewater Treatment

This study explores the viability of utilizing biochar and hydrochar derived from pineapple waste as adsorbents for removing lead (Pb) from water. Pineapple residues, including stems, leaves, and fruit, were subjected to pyrolysis and Hydrothermal Treatment to produce biochar (PWB) and hydrochar (PWH) respectively. Fourier Transform Infrared (FT-IR) analysis was employed to characterize the surface properties of PWB and PWH, validating their potential as adsorbents. A series of adsorption experiments assessed the impact of pH (ranging from 2 to 6), contact time (ranging from 15 to 90 minutes), and temperature (ranging from 30 to 90°C) on the adsorption efficiency of both materials. Results indicate PWH to be markedly more effective, with an average Pb removal efficiency of 84.07% compared to PWB's 55.68%. The optimal contact time was determined to be 60 minutes for both materials. Moreover, pH 4.0 was identified as the optimal condition for Pb adsorption, showcasing a significant increase in biosorption capacity within this pH range. Additionally, higher temperatures corresponded to enhanced Pb2+ removal efficiency, rising from 75.02% to 87.58% as temperature increased from 30°C to 90°C. Overall, these findings underscore the potential of pineapple waste-derived biochar and hydrochar as promising, environmentally friendly adsorbents for addressing heavy metal contamination in water, particularly in wastewater treatment applications.

Stepwise extraction of Fe, Si from copper slag and self-assembly synthesis of microspheres for As(V) removal: Resource transformation and environmental governance

Heavy metal pollution control and industrial solid waste management have always been urgent environmental issues. The management of heavy metal pollution through industrial solid waste may be a solution to both problems. In this paper, copper slag (CS) is used as a base material to separate the iron and silicon with a relatively high percentage of content. The Fe-mSiO2/SA (FSA), a microsphere (Φ = 2–3 mm) adsorbent with specific adsorption capacity for As(Ⅴ), was finally synthesized by “Acid leaching & Alkaline extraction & Template synthesis & Gelatinization”. The optimal adsorption conditions were explored using response surface methodology. FSA has a wide range of pH applicability (3–9) and the maximum adsorption capacity is 140.45 mg/g by theoretical calculation. The adsorption process follows pseudo-second-order kinetic model, which indicates that the adsorption process is a surface homogeneous monolayer adsorption controlled by chemisorption mechanism. The synthesis mechanism of FSA was explored by systematic characterization of FSA, and the mechanism of As(Ⅴ) adsorption was elucidated. The −OH and FeOOH formed stable single-tooth or double-tooth complexes with As(Ⅴ) on the surface of FSA. Moreover, the unique spherical structure of FSA facilitates subsequent solid–liquid separation. This study is in line with the concept of economic applicability and “waste for waste”.

Green synthesis of iron nanoparticles using Pistacia-atlantica leaf extract for enhanced removal of Cr(VI) from aqueous solution

The discharge of chromium-containing wastewater from various industries into aqueous environments is regarded as an important and challengeable matter due to its high toxicity. The application of conventional methods for eliminating this pollutant are often very expensive and difficult. Therefore, the adsorption process has been introduced as a desirable and effective method for removing chromium ions from aqueous media. In this research, iron nanoparticles (Fe-NPs) were synthesized using Pistacia-atlantica leaf extract as a reducing agent, then they were characterized by DLS, XRD, FT-IR, FESEM/EDS, and TEM techniques and its effectiveness to eliminate hexavalent chromium (Cr (VI)) from aqueous solutions was carried out. The capability of the batch adsorption procedure was assessed under different operational factors, such as initial pH, adsorbent dose and initial Cr (VI) concentration. Optimum adsorption conditions were determined at initial pH of 2, Cr (VI) concentration of 25 mg L−1 and adsorbent dose of 0.24 g L−1. Based on the obtained results, the highest removal efficiency (99.9%) by the adsorption process was occurred at pH of 2, concentration of 5 mg L−1 and 30 min of operational time. On the other hand, the results showed that the percentage of the pollutant elevated by increasing the contact time and amount of adsorbent dose, whereas that of was declined by increasing the initial concentration of Cr (VI). Besides, the experimental equilibrium data was evaluated by Langmuir, Freundlich, and Temkin isotherm models, and the outcomes revealed conformity with the Langmuir isotherm model. The Cr (VI) adsorption utilizing Fe-NPs adhered to a pseudo-first-order kinetic model. Eventually, thermodynamic studies demonstrated that the adsorption of Cr (VI) onto the surface of the Fe-NPs is endothermic and spontaneous.

Novel magnetic N-doped biochar derived from sugarcane bagasse and red mud for effective adsorption of tetracycline hydrochloride

In this work, with sugarcane bagasse (SB) and red mud (RM) as raw materials, magnetic nitrogen (N)-doped biochar (MNSB) was synthesized by a facile one-pot pyrolysis method and then applied as an efficient adsorbent to remove tetracycline hydrochloride (TC-HCl) from wastewater. The results of SEM, EDS, VSM, BET, FT-IR, and XPS demonstrated that the synthesized MNSB adsorbent had a large specific surface area, excellent superparamagnetic properties, and rich mesopore pore structures. The batch adsorption experiments revealed that the TC-HCl could be removed 96.3% with the optimal adsorption conditions: MNSB dosage of 0.25g/L, initial pH of 6.58, TC-HCl initial concentration of 20mg/L, and adsorption temperature of 30oC. The analysis of adsorption kinetics and isotherms showed that the adsorption process was mainly controlled by chemisorption, and the theoretical maximum adsorption capacity of TC-HCl on MNSB was 143.9mg/g. Mechanistic analysis revealed that the excellent adsorption process of MNSB for TC-HCl was mainly contributed by pore filling, π–π interaction, hydrogen bonding, and electrostatic attraction. The recycling and settlement experiments demonstrated that MNSB had good stability and settleability. This study successfully opened new prospects that utilizing RM and SB to prepare a low-cost adsorbent to remove TC-HCl from water.

Preparation and optimization of dummy molecularly imprinted polymer-based solid-phase extraction system for selective enrichment of p-toluene sulfonate esters genotoxic impurities

Sulfonate esters, one class of genotoxic impurities (GTIs), have gained significant attention in recent years due to their potential to cause genetic mutations and cancer. In the current study, we employed the dummy template molecular imprinting technology with a dummy template molecule replacing the target molecule to establish a pretreatment method for samples containing p-toluene sulfonate esters. Through computer simulation and ultraviolet–visible spectroscopy analysis, the optimal functional monomer acrylamide and polymerization solvent chloroform were selected. Subsequently, a dummy template molecularly imprinted polymer (DMIP) was prepared by the precipitation polymerization method, and the polymer was characterized in morphology, particle size, and composition. The results of the adsorption and enrichment study demonstrated that the DMIP has high adsorption capability (Q = 7.88 mg/g) and favorable imprinting effects (IF = 1.37); Further, it could simultaneously adsorb three p-toluene sulfonate esters. The optimal adsorption conditions were obtained by conditional optimization of solid-phase extraction (SPE). A pH 7 solution was selected as the loading condition, the methanol/1% phosphoric acid solution (20:80, v/v) was selected as the washing solution, and acetonitrile containing 10% acetic acid in 6 mL was selected as the elution solvent. Finally, we determined methyl p-toluene sulfonate alkyl esters, ethyl p-toluene sulfonate alkyl esters, and isopropyl p-toluene sulfonate alkyl esters in tosufloxacin toluene sulfonate and capecitabine at the 10ppm level (relative to 1 mg/mL active pharmaceutical ingredient (API) samples) by using DMIP-based SPE coupled with HPLC. This approach facilitated the selective enrichment of p-toluene sulfonate esters GTIs from complex API samples.

Microwave-Assisted Hydrothermal Synthesis of Zinc-tin Based Nanoflower for the Adsorptive Removal of Cadmium from Synthetic Wastewater

The present study utilized zinc-tin nanoflowers (ZT-NFs) in a batch adsorption treatment process to effectively remove cadmium from synthetic wastewater. The batch adsorption strategy was optimized using the univariate approach to enhance the efficiency of the adsorption process. The dominant parameters examined in the optimization experiments were pH/volume of buffer solution, nanoflower amount, and sample agitation type/period. After determining the optimal batch adsorption conditions, equilibrium studies were performed by adding cadmium to synthetic wastewater at concentrations in the range of 1.0 – 40 mg/L. The quantification accuracy for cadmium was improved by developing the calibration plot with spiked sample matrix. The equilibrium data were subjected to mathematical modelling utilizing the Langmuir adsorption isotherm model. The calculated isotherm constants indicated a well-fitted isotherm model to the experimental data. The reported ZT-NFs-based adsorptive removal strategy was effectively employed to remove cadmium from synthetic wastewater.

Application of Noug (Guizotia abyssinica cass.) stalk activated carbon for the removal of lead (II) ions from aqueous solutions

Due to the rise of industries worldwide, huge amounts of pollutants including heavy metals are released into the surroundings. Disposal of effluents containing heavy metals in higher concentrations without proper treatment is common in industries; lead is one of them. This study aims to determine and optimize the efficiency of Noug (Guizotia abyssinica Cass.) stalk porous carbon (NSAC) for the elimination of lead (II) from aqueous solutions. For studying the adsorption characteristics of Noug stalk activated carbon (NSAC) an adsorbate of lead (II) ions was used. The interaction and effect of the following parameters on Pb(II) adsorption were investigated using Design Expert version 7.0 software (central composite design) to determine the optimum adsorption condition: pH, initial concentration of Pb(II) ion, adsorbent dose, and contact time. The optimized condition for the elimination of lead (II) using Noug stalk porous carbon (98.77 %) was achieved at pH [4.87], initial concentration of Pb(II) [84.66 mg/L], adsorbent dose [18.43 g/L], and contact time [2.04 h]. The pseudo-second-order kinetics and the Langmuir isotherm model which had a maximum adsorption capacity of 89.25 mg/g, provided the best-fit models for Pb(II) adsorption, with R2 values of 0.99 and 0.98, respectively. Efficient elimination of Pb(II) from wastewater can be performed through the use of NSAC. Future research should delve more into column adsorption under continuous wastewater flow.

Optimizing 2-Nitrophenol and Chromium Adsorption from Water with Aluminium Oxide via Response Surface Methodology

Optimizing 2-Nitrophenol and Chromium Adsorption from Water with Aluminium Oxide via Response Surface Methodology

Comprehensive Studies of Adsorption Equilibrium and Kinetics for Selected Aromatic Organic Compounds on Activated Carbon.

This work presents a comprehensive analysis of the adsorption of selected aromatic organic compounds on activated carbons. Both the equilibrium and kinetics of adsorption were studied using UV-Vis spectrophotometry. The influence of a number of factors: pH, contact time, presence of an accompanying substance, adsorbate concentration, as well as the mass and size of adsorbent grains, on the adsorption process from aqueous solutions was investigated. Phenol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol and methylene blue (as an accompanying substance) were selected as adsorbates. GAC 1240W and RIAA activated carbons were used as adsorbents. The equilibrium data were analyzed using the generalized Langmuir isotherm equation (R2 = 0.912-0.996). Adsorption rate data were fitted using a multi-exponential kinetic equation (1 - R2 = (1.0 × 10-6)-(8.2 × 10-4)). As an additional parameter, the half-time was also used to present the influence of selected factors on the adsorption kinetics. An increase in the amount of adsorption was demonstrated with increasing contact time as well as with decreasing solution pH and adsorbent grain size. For selected systems, an increase in the adsorption rate was observed with increasing adsorbate concentration, adsorbent mass and at lower pH values. In some cases, the presence of an accompanying substance also resulted in an increase in adsorption kinetics. In the tested experimental systems, optimal conditions for adsorption were established (T = 298 K, pH = 2, contact time: 7 days, grain diameter: >0.5 mm and the ratio of the mass of the adsorbent to the volume of the adsorbate solution: 1 g/L). Additionally, the acid-base properties (potentiometric titration), morphology (SEM) and structure (TEM) of the used adsorbents were also examined.

Assessment of chromite ore wastes for methylene blue adsorption: Isotherm, kinetic, thermodynamic studies, ANN, and statistical physics modeling

This research investigates the adsorption potential of chrysotile and lizardite, two minerals derived from chromite ore wastes, for the uptake of Methylene Blue (MB) dye from waste streams. The characterization of these minerals involves XRD, XRF, FTIR, and SEM. Results confirm the dominance of polymorphic magnesium silicate minerals, specifically chrysotile and lizardite, in the samples. The FTIR spectra reveal characteristic vibration bands confirming the presence of these minerals. The SEM analysis depicts irregular surfaces with broken and bent edges, suggesting favorable morphologies for adsorption. N2 adsorption-desorption isotherms indicate mesoporous structures with Type IV pores in both adsorbents. The Central Composite Design approach is employed to optimize MB adsorption conditions, revealing the significance of contact time, adsorbent mass, and initial MB concentration. The proposed models exhibit high significance, with F-values and low p-values indicating the importance of the studied factors. Experimental validation confirms the accuracy of the models, and the optimum conditions for MB adsorption are determined. The influence of solution acidity on MB uptake is investigated, showing a significant enhancement at higher pH values. Isothermal studies indicate Langmuir and Freundlich models as suitable descriptions for MB adsorption onto chrysotile and lizardite. The maximum adsorption capacities of MB for chrysotile and lizardite were found to be 352.97 and 254.85, respectively. Kinetic studies reveal that the pseudo-first-order model best describes the adsorption process. Thermodynamic analysis suggests an exothermic and spontaneous process. Statistical physics models further elucidate the monolayer nature of adsorption. Additionally, an artificial neural network is developed, exhibiting high predictive capability during training and testing stages. The reusability of chrysotile and lizardite is demonstrated through multiple regeneration cycles, maintaining substantial adsorption potential. Therefore, this research provides comprehensive insights into the adsorption characteristics of chrysotile and lizardite, emphasizing their potential as effiective and reusable sorbents for MB uptake from wastewater.

Removal of ciprofloxacin and heavy metals from water by bentonite/activated carbon composite: Kinetic, isotherm, thermodynamic and breakthrough curve modeling studies

This study explores the potential of a new, cost-effective adsorbent for removing ciprofloxacin (CIP) and heavy metals (HMs) from wastewater. This adsorbent is a mesoporous activated carbon (AC) crafted from sugarcane bagasse modified with bentonite (SCBB). The prepared composite was characterized using FTIR, XRD, SEM, and BET techniques. Optimal adsorption conditions were determined, with initial concentrations set at 15 and 300 mg/L, adsorbent doses at 100 and 50 mg, temperatures at 25 and 45 °C, and pH levels at 6 for CIP and HMs, respectively, in batch experiments. Kinetics data confirmed that adsorption follows pseudo-first-order model, with intraparticle diffusion identified as the rate-determining step. Three-parameter models were superior in describing experimental data compared to two-parameter models, with the Sips isotherm model indicating multilayer adsorption beyond monolayer saturation. Hydrophobicity likely plays a key role in CIP adsorption, potentially complemented by hydrogen bonding, while HMs are adsorbed through ion exchange, complexation, and pore diffusion processes. Furthermore, SCBB exhibited excellent adsorption performance (≥90 %) even after ten regeneration cycles. The impact of various operating parameters, including bed depth, feed concentration, and flow rate, were optimized in fixed bed column. Breakthrough data fitting the Dose Response, Thomas, and Yoon-Nelson models yielded high coefficients of determination (R2 ≥ 0.98). The techno-economic analysis identified SCBB preparation ($0.31/kg) as the main cost factor, but still predicts profitability with a payback period of 0.88 years and a break-even point of 58.6 %. Overall, the developed SCBB composite demonstrates significant potential as an efficient, cost-effective, and sustainable adsorbent, with applicability for the treatment of industrial wastewater contaminated with CIP and HMs.

Zeolite prepared from high-calcium ladle furnace slag and fly ash for Pb2+ removal

The stockpiling of industrial solid waste and lead (Pb) pollution have become a worldwide problem, which can be potentially solved by using solid waste such as ladle furnace slag (LFS) and fly ash (FA) to prepare Pb adsorbents. In this paper, zeolites prepared from untreated high-calcium LFS and FA were used to remove Pb2+ by adsorption. The optimal adsorption conditions were an adsorbent dose of 1 g/L, pH 5, a contact time of 180 min, and an initial Pb2+ concentration of 300 mg/L. The zeolites prepared from high-calcium solid waste had a Pb2+ adsorption capacity of 292.8 mg/g and an adsorption efficiency of 97.6 %. Adsorption mainly occurred via the ion exchange of Pb2+ with Ca2+ and Na+, as well as the complexation of Pb2+. The pseudo-second-order kinetic model and the Langmuir model were used to analyze adsorption kinetics and isotherm data, supporting the occurrence of chemisorption and monolayer adsorption. Regeneration experiments demonstrated that the zeolite synthesized in this study exhibited good repeatability and cost-effectiveness. The zeolites derived from LFS and FA-based geopolymers removed Pb2+ from wastewater, offering new perspectives on utilizing high-calcium industrial waste and advancing geopolymer-based adsorbents for sustainable industrial solid waste management and water pollution treatment strategies.