Initial Solution Temperature Research Articles

Mesoporous Fe3O4@SiO2@La nanocomposite for efficient methylene blue removal from wastewater

This study investigates the synthesis and application of Fe3O4@SiO2@La mesoporous nanocomposites for methylene blue (MB) removal from wastewater. The successful synthesis of the nanocomposite was confirmed by various characterization techniques including FE-SEM, XRD, BET/BJH, and FT-IR. The adsorption efficiency of the nanocomposite for MB removal was evaluated under different operating conditions, including initial solution pH, adsorbent dosage, contact time, and temperature. The results revealed that the nanocomposite demonstrated optimal performance at neutral pH (pH=7), with an adsorbent dosage of 0.01 g, a contact time of 5 min, and 25 °C. Kinetic studies revealed pseudo-second-order kinetics, indicating chemisorption as the rate-limiting step. Langmuir and Freundlich isotherms were applied to describe the adsorption process. The nanocomposites demonstrated excellent reusability and high removal efficiency in real wastewater samples. The enhanced MB removal efficiency of the Fe₃O₄@SiO₂@La nanocomposites is attributed to electrostatic interactions, π-π stacking, and hydrogen bonding between MB and the adsorbent surface. Overall, the synthesized nanocomposites offer a promising and efficient solution for MB removal from wastewater, demonstrating potential for practical applications in environmental remediation.

ADSORPTION OF TEXTILE DYE ACID GREEN 42 (AG42) ON ACTIVATED CARBON FROM CHICKEN EGGSHELLS (CAC30)

The present work is a contribution to the valorization of chicken eggshells, an abundant waste product in Cote dIvoire, as a credible alternative to commercial activated carbon.Chemicalactivation of the precursorwascarriedoutwith30%phosphoricacidfor24h of contactin a ratio of 200 g of material to 100 mL of acid, and calcined at 600°C for 1h. The surface of the activated carbon obtained was studied using the BET (Brunauer-Emmett and Teller) method, which consists in establishing the adsorption isotherm for nitrogen N2. The results reveal a specific surface area of 5.42 m2.g-1, 65.68% of micropores and a pHzc of 7.40. Chemical characteristics determined by Boehms method indicate the basic nature of the surface. The elemental composition is dominated by oxygen(50.53%),calcium(30.78%)andcarbon(11.33%).The experiments demonstrated that the removalof AG42by adsorption on CAC30 is influenced by contact time, activated carbon mass, solution pH, and initial concentration and temperature of the dye aqueous solution. Adsorption kinetics followed the pseudo-second-order model and the isotherm is described by the Langmuir model. The thermodynamic study revealed the spontaneous (ΔG < 0) and exothermic (ΔH < 0) nature of dye adsorption, with a well-organized distribution of dye molecules at the adsorption sites (∆S°< 0).

Turning waste into wonder: Arsenic removal using rice husk based activated carbon

In this study, rice husk activated carbon (RHAC) was synthesized by physicochemical activation, which consists of heat treatment with CO2 gasification and KOH chemical treatment to eliminate arsenic (As) from the polluted water. Initial arsenic concentrations, solution pH, solution temperature and contact time are the parameters that have been tested in this study. The characterization study showed that RHAC has a high BET surface area (815.52 m2/g) and its pore structure was found to be mesoporous with an average pore diameter of 2.96 nm. Characterization studies, including X-ray diffraction analysis (XRD), Raman spectroscopy and scanning electron microscopy (SEM) were employed to determine the RHAC’s performance. The adsorption of As towards RHAC followed the Freundlich isotherm model and pseudo-first order with adsorption process was favorable at higher arsenic concentrations. The mechanism study also signified that the adsorption of As-RHAC was limited by film-diffusion. Thermodynamic studies indicated that the As-RHAC adsorption system was endothermic, random, spontaneous, feasible in nature and governed by the chemisorption process. Desorption and regeneration studies of RHAC showed that it can be utilized up to 5 cycles and is stable for the water treatment facilities.

Adsorption Studies of Pb<sup>2+</sup>, Cu<sup>2+</sup> and Cr<sup>3+</sup> from Aqueous Solution Using <i>Azadirachta Indica </i>(Neem) Seed Husk and <i>Adansonia Digitata </i>(Baobab) Seeds

The adsorption of Pb<sup>2+</sup>, Cu<sup>2+</sup> and Cr<sup>3+</sup> from aqueous solution using Neem seed husk (NSH) and baobab seed (BS) were studied through the use of batch adsorption system. The adsorbents were prepared by drying at 120°C for 24hours and were characterized using FT-IR, XRD, and SEM analysis. The FTIR spectroscopy revealed the presence of O-H, N-H, C-H, C=C, C=O, and C-O stretching; XRD revealed the particle sizes as 44.51nm for NSH and 42.61nm while the morphology of the NSH and BS were revealed by SEM to be porous for NSH and BS. Various parameters such as, initial metal ion concentration, adsorbent dosage, contact time, Temperature and pH of metal ion solution were investigated in a batch-adsorption System. The adsorption uptake was found to increase with increase in adsorbent dose, contact time and temperature but decreases with the initial concentration. The uptake of the metal ions increases and reaches optimum at pH of 4-6. The maximum adsorption capacity was found to be Pb-NSH (15.267mg/g) and Cu-NSH (19.46mg/g). Adsorption of Cu<sup>2+</sup>onto NSH fitted Langmuir isotherm model with (R<sup>2</sup> > 0.93) while Adsorption of Pb-NSH Fitted Freundlich isotherm Model with (R<sup>2</sup>> 0.99). Kinetic data fitted pseudo-second-order model (R<sup>2</sup> > 0.98) which was more suitable in explaining the adsorption rate. Thermodynamic data showed that Gibb’s free energy (ΔG°) values for all metal ions were negative indicating feasibility and favorability of adsorption. Positive enthalpy change (ΔH°) and Entropy change (ΔS°) values indicate endothermic processes and increase in randomness.

Removal of Copper and Zinc Metal Ions from Industrial Effluents in Continuous Mode using Modified Date Pits

Adsorbents based on agricultural biomass have been subjected to several investigations in recent years owing to their low cost and promising adsorption capabilities. This paper aimed to demonstrate the efficiency of utilizing date pits modified with hydrogen peroxide as agricultural biomass in extracting heavy metals from polluted water in a column continuous flow system. The resulting modified adsorbent (MDP) has a surface area of 278.18 m2/g. The derived adsorbent was investigated under changed operating parameters including the flow rate (4-12) ml/min, pH (4-10), initial metal ion concentration (30-60) mg/L, and temperature (20-50) °C to determine their effect on heavy metals adsorption efficiency. The response surface methodology (RSM) experimental design was utilized to study the primary and combined influence of four key parameters, including (A) initial metal ion concentration, (B) pH solution, (C) solution temperature, and (D) flow rates of the influent, on the metal removing efficiency (Re%). optimization in fact, an analysis of variance (ANOVA) revealed a high coefficient of regression, or R2 > 0.90. Furthermore, the removal efficiency was positively influenced by reducing the initial ion concentration, flow rate, and temperature. in addition, the pH shows maximum effectiveness at a neutral state. In general, Cu (II) adsorption shows a higher affinity to adsorb over the MDP surface compared to Zn (II). The MDP adsorbents exhibited a promising removal efficiency for metal ions and further investigations are needed.

Trichoderma aureoviride hyphal pellets embedded in corncob-sodium alginate matrix for efficient uranium(VI) biosorption from aqueous solutions

The discharge of effluents containing uranium (U) ions into aquatic ecosystems poses significant risks to both human health and marine organisms. This study investigated the biosorption of U(VI) ions from aqueous solutions using corncob-sodium alginate (SA)-immobilized Trichoderma aureoviride hyphal pellets. Experimental parameters, including initial solution pH, initial concentration, temperature, and contact time, were systematically examined to understand their influence on the bioadsorption process. Results showed that the corncob-SA-immobilized T. aureoviride hyphal pellets exhibited maximum uranium biosorption capacity at an initial pH of 6.23 and a contact time of 12 h. The equilibrium data aligned with the Langmuir isotherm model, with a maximum biosorption capacity of 105.60 mg/g at 301 K. Moreover, biosorption kinetics followed the pseudo-second-order kinetic model. In terms of thermodynamic parameters, the changes in Gibbs-free energy (ΔG°) were determined to be −4.29 kJ/mol at 301 K, the changes in enthalpy (ΔH°) were 46.88 kJ/mol, and the changes in entropy (ΔS°) was 164.98 J/(mol·K). Notably, the adsorbed U(VI) could be efficiently desorbed using Na2CO3, with a maximum readsorption efficiency of 53.6%. Scanning electron microscopic (SEM) analysis revealed U(VI) ion binding onto the hyphal pellet surface. This study underscores the efficacy of corncob-SA-immobilized T. aureoviride hyphal pellets as a cost-effective and environmentally favorable biosorbent material for removing U(VI) from aquatic ecosystems.

Enhancing Cr (VI) Adsorption of Chestnut Shell Biochar through H3PO4 Activation and Nickel Doping.

A high-efficiency nickel-doped porous biochar (PCNi3) has been successfully synthesized from chestnut shell waste via a two-step chemical activation treatment with H3PO4. The influences of microstructure, surface morphology, elemental composition, surface functional groups, specific surface area, porosity, pore-size distribution, and chemical properties of the surface state on the removal of Cr (VI) from water were thoroughly investigated by using XRD, FESEM, FTIR, Raman, BET, and XPS testing methods, N2 adsorption, and XPS testing techniques respectively. The results indicate that the treatment of H3PO4 activation and nickel doping can effectively improve microstructure characteristics, thus promoting Cr (VI) adsorption capacity. The effects of initial solution pH, solution concentration, time, and temperature on remediation are revealed. The Cr (VI) uptake experiments imply that the adsorption curves of PCNi3 fit well with the Freundlich model, the pseudo-second-order kinetic model, and the Elovich model. The adsorption process of PCNi3 can be regarded as a spontaneous endothermic reaction limited by diffusion among particles and porosity. The adsorption mechanisms of PCNi3 are ion exchange, complexation, electrostatic adsorption, and coprecipitation with the assistance of surface active sites, porosity, Ni0 particles, and Ni7P3. With these advantages, PCNi3 reveals an extraordinary Cr (VI) removal capacity and a strong ability to reduce Cr (VI) to Cr (III).

Numerical Modeling and Simulation of the Nonisothermal Double Quench Phase Separation Process for the Production of Polymeric Membranes Using Polystyrene‐Cyclohexanol Polymer Solution

AbstractThe double quench phase separation is a simplified type of continuous cooling process that is widely seen in industrial processes for polymeric membrane formation. Uncommon quenching conditions can lead to the creation of novel membrane microstructures. This study aims to theoretically investigate the impact of nonisothermality on the morphology formation during the double‐quench thermally‐induced phase separation process. First, quench is employed during different stages of phase separation to observe the possibility of secondary morphology formation. Next, two initial quench temperatures are selected, one shallow and the other deep. The initial solution temperature and the secondary quench temperature are kept constant to inspect the impact of the initial quench temperature on the structure formation. Lastly, the results of the secondary quench are compared with and without employing the enthalpy of demixing. Results verified that the stage of phase separation, the initial and secondary quench temperatures, cooling rate, and the secondary quench composition are the most important parameters in the the nonisothermal double quench phase separation process. The morphology should be well‐developed in order for the secondary structure formation. In addition, it is shown that heat generation during demixing in the primary and secondary quenches significantly influences the secondary morphology formation.

Influential lead uptake using dried and inactivated-fungal biomass obtained from Panaeolus papilionaceus: biological activity, equilibrium, and mechanism

AbstractIn this study, the use of fungal (Panaeolus papilionaceus) biomass as a biosorbent was investigated to effectively remove Pb2+ ions from aquatic medium. The removal of Pb2+ ions using a fungal biosorbent was examined in a batch system in terms of initial solution pH, temperature, time, and initial Pb2+ concentration. Optimal operating conditions for biosorption of Pb2+ ions; pH: 4.5, T: 25 °C, and t: 24 h. The max biosorption capacity for Pb2+ ions was found to be 31.2 mg g−1 from the Langmuir model. Thermodynamic studies showed that Pb2+ ions biosorption into fungal biomass was possible, spontaneous, and endothermic. Additionally, the antimicrobial activity and antibiofilm activity of the extract of fungus were also investigated. It was determined that the fungal extract did not have antimicrobial properties. On the other hand, the extract has been shown to have the potential to prevent biofilm formation. 1 mg of the extract prevented the biofilm formation of Staphylococcus aureus by 87.85%. It has been observed that the biosorption mechanism of Pb2+ ions into fungal biomass includes the steps of surface biosorption, film diffusion, and intra-particle diffusion.

Adsorptive removal of methylene blue dye using durian peel waste reinforced polyvinyl alcohol‐based composite membrane

AbstractA large amount of dye effluents with biodegradable and highly toxic nature from the dyeing and finishing processes has discharged into natural water bodies without adequate treatment, which adversely impacted on aquatic life and human health. Herein, polyvinyl alcohol/agarose/maltodextrin composite membrane (PAM)‐reinforced durian skin fiber is fabricated for methylene blue (MB) uptake from aqueous medium. Structural analyses of the as‐prepared composite membrane are conducted using scanning electron microscopy, Fourier‐transform infrared spectroscopy, water contact angle, and nitrogen adsorption/desorption isotherm measurement. The important influence of experimental conditions including exposure time between adsorbates and adsorbents, initial MB concentration, solution temperature, and pH are also explored. Furthermore, thermodynamic behavior, nonlinear isotherms, and kinetics along with possible adsorption mechanism are provided to attain the insight into the adsorption nature. The results show that PAM‐reinforced durian peel waste possesses high MB adsorption capacity (105.54 mg g−1), which was controlled by diffusion and chemisorption mechanism. The thermodynamics of methyl blue removal on the composite membrane suggest that the adsorption is spontaneous, favorable, and endothermic in nature. This contribution is expected to inspire the efficient utilization of agriculture by‐products into eco‐friendly and biodegradable adsorbents to purify the dye‐contaminated water.

In situ chemical oxidation of tinidazole in aqueous media by heat-activated persulfate: kinetics, thermodynamic, and mineralization studies

This study investigated the use of heat-activated persulfate (HAP) as a chemical oxidation technique for removing tinidazole (TNZ) antibiotic from aqueous solutions. The impact of various operating parameters, including TNZ initial concentration (20 μM), persulfate (PS) initial dose (0.2–2 mM), solution pH (3–11), solution temperature (20–60 °C), and reaction time (10–120 min), was examined. The results indicated that sulfate radicals were the primary species responsible for TNZ degradation. Higher temperatures and PS concentrations improved the process, while higher pH values and TNZ initial concentrations slowed it down. Additionally, chloride and bicarbonate ions reduced reaction rates, with chloride ions having a more significant effect. Under optimal conditions (including [TNZ]0 = 20 μM, pH = 7, [PS]0 = 1 mM, temperature = 60 °C, and reaction time = 120 min), the removal efficiency achieved was 91.15%, with a mineralization rate of 85.8%. These results suggest that the process is relatively safe. The degradation of TNZ was best described by the pseudo-first-order model compared to other models. Additionally, the process was found to be exothermic and spontaneous, with a negative Gibbs free energy change indicating that it is thermodynamically feasible. The study found HAP to be an effective and cost-efficient technique for removing TNZ antibiotic due to its ease of operation and the absence of the need for additional chemicals or waste handling. Based on these findings, HAP can be considered an advanced oxidation technique for treating antibiotic-contaminated water.

Efficient removal of Rhodamine B dye using biochar as an adsorbent: Study the performance, kinetics, thermodynamics, adsorption isotherms and its reusability

Removal of toxic dyes such as Rhodamine B is essential as it pollutes aqueous and soil streams as well. This comprehensive study explores the potential of Calophyllum inophyllum seed char as an efficient bio-adsorbent based on their characteristic properties and a comparative study between various carbon-based adsorbents on the adsorption capacity of Rhodamine B dye. In this study, the char was prepared from Calophyllum inophyllum seed using a slow pyrolysis process (298 K/min) at an optimum temperature of 823 K and used as an adsorbent for the removal of Rhodamine B from water. The resulting char was mesoporous and had 155.389 m2/g surface areas (BET) and 0.628 cc/g pore volume. The formation of pores was observed from the SEM analysis. The adsorption studies were tested and optimized through various parameters such as solution pH, adsorbent dosage, initial dye concentration, stirring speed, contact time, and solution temperature. Maximum 95.5 % removal of Rhodamine B was possible at the pH: 2, stirring speed: 100 rpm, time: 25 min, temperature 308 K, and dose: 1.2 g/L. The highest adsorption capacity at equilibrium was determined to be 169.5 (mg/g) through Langmuir adsorption isotherm studies and followed pseudo 2nd order kinetics. The thermodynamics study confirmed the adsorption processes were spontaneous (ΔG°=−0.735 kJ/mol) and endothermic (ΔH° = 4.1 kJ/mol) processes. The reusability study confirmed that the mesoporous char can be reused as an efficient adsorbent for up to 3 cycles for environmental remediation.

CS/CoFe2O4 nanocomposite as a high-effective and steady chainmail catalyst for tetracycline degradation with peroxymonosulfate activation: performance and mechanism.

Tetracycline becomes a crucial measure for managing and treating communicable diseases in both human and animal sectors due to its beneficial antibacterial properties and cost-effectiveness. However, it is important not to trivialize the associated concerns of environmental contamination following the antibiotic's application. In this study, cobalt ferrate (CoFe2O4) nanoparticles were loaded into chitosan (CS), which can avoid the agglomeration problem caused by high surface energy and thus improve the catalytic performance of cobalt ferrate. And it can avoid the problem of secondary contamination caused by the massive leaching of metal ions. The resulting product was used as a catalyst to activate peroxymonosulfate (PMS) for the degradation of tetracycline (TC). To determine the potential effects on TC degradation, various factors such as PMS dosing, catalyst dosing, TC concentration, initial solution pH, temperature, and inorganic anions (Cl-, H2PO4- and HCO3-) were investigated. The CS/CoFe2O4/PMS system exhibited superior performance compared to the CoFe2O4-catalyzed PMS system alone, achieving a 92.75% TC removal within 120 min. The catalyst displayed high stability during the recycling process, with the efficiency observed after five uses remaining at a stable 73.1%, and only minor leaching of dissolved metal ions from the catalyst. This confirms the high stability of the catalyst. The activation mechanism study showed that there are free radical and non-free radical pathways in the reaction system to degrade TC together, and SO4•- and 1O2 are the primary reactive oxygen radicals involved in the reaction, allowing for effective treatment of contaminated water by TC.

Valorization of Silybum marianum seed shells waste as biosorbent for basic fuchsin dye removal from water: kinetics, isotherms, and thermodynamic studies

Over the last decades, the valorization of agro-industrial wastes into adsorbents has received a lot of attention due to the low-cost, high performance and sustainability factors. This work aims to valorize Silybum marianum seed shells (SMSS) as biosorbent for the removal of basic fuchsin dye (BF) from water. The prepared biosorbent from SMSS was characterized to check the morphological and structural proprieties using several techniques including FTIR, XRD, SEM, TGA-DTA, and BET. It was found that SMSS has a fibrous semi-amorphous structure typical of lignocellulosic materials. The study also investigated the impact of numerous operational parameters on basic fuchsin biosorption efficiency, including particle size, biosorbent mass, stirring speed, initial dye concentration, temperature, and pH of solution. Additionally, the research explored the influence of natural water matrices on dye removal. The adsorption performance was found to be higher at basic pH values, reaching 97.50%. The adsorption process was analyzed using different kinetic models, and it was found that the process follows a pseudo-second-order model. The experimental data was thoroughly scrutinized using the Freundlich and Langmuir isotherm models. The results confirm that Langmuir model fits well the BF dye adsorption on SMSS surface. The thermodynamic study revealed that the adsorption process of BF dye onto SMSS was endothermic. Overall, SMSS shows great adsorption ability which might be a good candidate for real wastewater treatment, by considering low-cost and availability of the original waste.

In situ polyaniline polymerization on electrospun cellulose acetate nanofibers derived from recycled waste filter butts of cigarettes for the enhanced removal of methyl orange and rhodamine

In this study, waste cigarette butts (CBs) were processed to produce electrospun cellulose acetate (CA) nanofibrous membranes modified with polyaniline (PANI) via chemical oxidation polymerization. This cost-effective method of preparing CA coated with PANI was initially investigated by comparing CA, CA-PANI, and CA-dPANI (as deprotonated PANI) for the rapid adsorption of cationic and anionic dyes. The results depicted CA-PANI with the highest dye removal capacity. As the optimum material, CA-PANI was applied to remove methyl orange (MO) and rhodamine chloride (RC) dye from an aqueous phase. Essential factors: contact time, solution pH, initial dye concentration, nanofiber dosage, and temperature of solution were evaluated with maximum equilibrium adsorption capacity and removal percentage achieved for MO as 24.87 mg/g and 99 %, for RC as 6.93 mg/g and 55 %, respectively. The adsorptive experimental data for both dyes best fitted the pseudo-second-order kinetic, intraparticle diffusion, and Freundlich models. Moreover, the thermodynamics result indicated the adsorption processes were exothermic and spontaneous in nature. Reusability studies also showed the stable performance of CA-PANI material for up to 7 adsorption-desorption cycles. The high dye removal efficiency suggests that the adsorbent material in the water filtration of azo dyes.

Fabrication of sodium alginate-doped carbon dot composite hydrogel and its application for La (III) adsorption and enhanced the removal of phosphorus.

Adsorption is an effective method for the removal of hazardous substances from wastewater. In this work, a low-cost and environmental-friendly composite hydrogel material of sodium alginate doped with nitrogen doped carbon dots (SA@NCDs) was fabricated by impregnation for lanthanide and enhanced phosphorus adsorption in wastewater. The effects of NCDs doping amount, dosage, pH, initial solution concentration, adsorption time and temperature on the process of La (III) adsorption by SA@NCDs were investigated. The adsorption isotherms fitted to Langmuir isotherm model (R2 = 0.9970-0.9989) and the adsorption kinetics followed pseudo-second-order kinetic model (R2 = 0.9992). The maximum adsorption capacity of the adsorbent for La (III) was 217.39mg/g according to the Langmuir model at 298.15K. After five cycles, the removal efficiency of La (III) adsorbed by SA@NCDs was still 85.1%. Moreover, the loaded La (III) enhanced the adsorption of phosphorus. The La (III)-SA@NCDs-5 hydrogel adsorbent greatly improved the adsorption capacity for phosphorus compared with the La (III)-free adsorbent, and the adsorption amount can reach 9.64mg-P/g. The SA@NCDs complex hydrogels for rare earth adsorption were prepared by introducing NCDs rich in amino group into SA hydrogels. The introduction of NCDs increases the adsorption sites of hydrogels, and also overcomes the problem that NCDs itself is difficult to recover in wastewater treatment applications. The lanthanide adsorbed material has a stable structure and can be used to remove phosphorus to deal with waste using the waste. It indicates the SA@NCDs hydrogel composite adsorbent have good potential for wastewater treatment.

MOF-derived Co-Ni layered double hydroxides/polyethyleneimine modified chitosan micro-nanoreactor for high-efficiency capture of uranium from seawater

The preparation of powder adsorbent into microsphere adsorbent is one of the effective methods for the industrialization of uranium extraction from seawater. Herein, a MOF-derived Co-Ni layered double hydroxides/polyethyleneimine modified chitosan micro-nanoreactor (DNPM) was prepared by a simple method in this work. The microstructure and chemical structure of DNPM were comprehensively characterized. The pH value, adsorption time, initial solution concentration, temperature, competitive ions, regeneration performance, and bed column heights were investigated for the adsorption performance of DNPM by batch adsorption and fixed-bed column continuous adsorption experiments. When the contact time was 8 h, the initial concentration was 150 mg/L, and the pH value was 6, the adsorption capacity of DNPM was 334.67 mg/g. The uranium adsorption by DNPM fits with the pseudo-second-order kinetic and Langmuir models, which was a spontaneous and endothermic process. In addition, DNPM has good adsorption selectivity and reusability. The fixed-bed column continuous adsorption experiment shows that the adsorption capacity increased with the increase of bed column height. The adsorption mechanism can be attributed to coordination chelation and electrostatic interaction. In general, this work provides an effective strategy for developing environmentally friendly uranium adsorbent that can be industrially used.

Adsorption of Basic Yellow 28 and Basic Blue 3 Dyes from Aqueous Solution Using Silybum Marianum Stem as a Low-Cost Adsorbent.

In the present study, the ability of an adsorbent (SLM Stem) obtained from the stem of the Silybum Marianum plant to treat wastewater containing the cationic dyes basic blue 3 (BB3) and basic yellow 28 (BY28) from aqueous solutions was investigated using a batch method. Then, the SLM Stem (SLM Stem-Natural) adsorbent was carbonized at different temperatures (200-900 °C) and the removal capacity of the products obtained for both dyes was examined again. The investigation continued with the product carbonized at 800 °C (SLM Stem-800 °C), the adsorbent with the highest removal capacity. The dyestuff removal studies were continued with the SLM Stem-Natural and SLM Stem-800 °C adsorbents because they had the highest removal values. The surface properties of these two adsorbents were investigated using IR, SEM, and XRD measurements. It was determined that the SLM Stem-Natural has mainly non-porous material, and the SLM Stem-800 °C has a microporous structure. The optimal values for various parameters, including adsorbent amount, initial dye solution concentration, contact time, temperature, pH, and agitation speed, were investigated for BY28 dye and were 0.05 g, 15 mg/L, 30 min, 40 °C, pH 6 and 100 rpm when SLM Stem-Natural adsorbent was used and, 0.15 g, 30 mg/L, 30 min, 40 °C, pH 10, and 150 rpm when SLM Stem-800 °C adsorbent was used. For BB3 dye, optimal parameter values of 0.20 g, 10 mg/L, 30 min, 25 °C, pH 7, and 100 rpm were obtained when SLM Stem-Natural adsorbent was used and 0.15 g, 15 mg/L, 40 min, 40 °C, pH 10, and 100 rpm when SLM Stem-800 °C adsorbent was used. The Langmuir isotherm described the adsorption process best, with a value of r2 = 0.9987. When SLM Stem-800 °C adsorbent was used for BY28 dye at 25 °C, the highest qm value in the Langmuir isotherm was 271.73 mg/g. When the study was repeated with actual water samples under optimum conditions, the highest removal for the BY28 dye was 99.9% in tap water with the SLM Stem-800 °C adsorbent. Furthermore, the reuse study showed the adsorbent's efficiency even after three repetitions.

Efficient adsorption of azo anionic dye Congo Red by micro-nano metal-organic framework MIL-68(Fe) and MIL-68(Fe)/chitosan composite sponge: Preparation, characterization and adsorption performance

Micro-nano metal-organic framework (MIL-68(Fe)) for efficient adsorption of azo anionic dye Congo red (CR) was successfully prepared by one-step hydrothermal method under acidic environment. And a MIL-68(Fe)/chitosan composite sponge (MIL-68(Fe)/CS) was prepared under the coating of chitosan (CS). After comparing the performance of MIL-68(Fe) and MIL-68(Fe)/CS, we focus on exploring MIL-68(Fe)/CS. It ensured the CR removal efficiency while reaching the adsorption equilibrium faster than MIL-68(Fe), and solved the defect that the powder was difficult to be stripped by water after adsorption. The physicochemical properties and surface morphology of the adsorbent were characterized by SEM, FTIR, XRD, TGA, BET, and Zeta potential. The effects of pH, contact time, adsorbent dosage, initial solution concentration and temperature on the adsorption performance of the adsorbent were systematically analyzed. The pseudo-second-order model and the Sips model were most consistent for the adsorption process, indicating that the adsorption process of MIL-68(Fe)/chitosan composite sponge on CR is a complex physicochemical process. The removal rates of CR by MIL-68(Fe) and MIL-68(Fe)/chitosan composite sponge reached the maximum values of 99.55 % and 99.51 % at 318 K, respectively. And the maximum adsorption capacity of CR by MIL-68(Fe)/chitosan composite sponge at 318 K was 1184.16 mg·g−1. After six cycles of adsorption and desorption, the removal rate of CR was still higher than 80 %. The synergistic effects of π-π stacking, electrostatic interactions, hydrogen bonding and pore filling have important effects on CR removal.

Removal of Malachite Green Dye from Aqueous Solution Using Lemon Leaf Powder as an Adsorbent

The majority of developing nations experience significant water contamination from textile sector wastewater. The use of low-cost, environmentally friendly adsorbents has been researched as a means of addressing problems of water contamination and high costs for waste - water treatment processes. Malachite green is an incredibly dangerous colour that not only damages mammalian cells but also has a key influence in the growth of liver cancers. The life cycle of aquatic creatures, plants, and people is hampered by dye released into bodies of water without sufficient treatment. In this study, the powdered lemon leaves are utilized for removal of the aniline green dye. By using batch-style setting and design of the experiment (the Box– Behnken technique) adsorbent has been investigated & have been developed to evaluate the process's critical factors, including agitation time, size of adsorbent, dosage of adsorbent, pH, initial concentration and temperature. The acquired values were fitted with adsorption isotherms. Malachite green dye sequestration onto Lemon Leaf Powder was chosen using kinetic models. The results of the trials showed that employing powdered lemon leaves, malachite green could be removed to a maximum of 82.21%. Malachite green dye concentration of 50 mg/L, temp of solution 303 K, and dosage of adsorbent 20 g/L are the ideal parameters. Lemon leaf powders have a maximum sorption capacity (qmax) of 8.08 mg/g. The equilibrium was more accurately modelled using the Freundlich isotherm. When compared to other models, the data which fits the pseudo 2nd order kinetics model is better. Previously researchers had proved several low– cost materials such as wheat bran, marina alga, wood apple shell etc In the current work, to remove malachite green dyes the efficacy of citrus lemon leaves is thoroughly done. The operating parameters that are optimized include dye solution concentration, initial solution pH, sorbent dose, and temperature. Studies on thermodynamics have demonstrated that the adsorption process was endothermic & spontaneous.