Freundlich Isotherm Model Research Articles

Methyl Orange Dye Removal by Dimethylamine Functionalized Graphene Oxide

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

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

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

Green integrative large scale treatment of tannery effluent, CO2 sequestration, and biofuel production using oleaginous green microalga Nannochloropsis oculata TSD05: An ecotechnological approach

In this present investigation, the freshwater microalga Nannochloropsis oculata TSD05 was used to demonstrate multiforius environmental applications viz., bioremediation of tannery effluent, carbon sequestration, and green renewable biodiesel production from treated microalgal biomass. The microalga Nannochloropsis oculata TSD05 was exhibited unique heavy metal reduction capabilities and reduced significant amount of heavy metals viz., 96.62% of copper (Cu2+), 99.9% of chromium (Cr3+), 98.36% of zinc (Zn2+), 98.71% of cadmium (Cd2+), 97.96% of lead (Pb2+), 98.88% of Cobalt (Co2+), and 98.76% of nickel (Ni2+). The biosorption capacity rate (qmax) of heavy metals reduction and highest R2 of 97.84% exhibited at 12 days of effluent treatment by Langmuir and Freundlich isotherm models. The phytotoxicity analysis was tested againt treated tannery effluent using Vigna radiate, Sapindus muukorossi seeds and 98.45%, 99.05% seeds were germinated. The Nannochloropsis oculata TSD05 microalga was utilized 98.45% of CO2 by biofixation kinetics, 372 mg g−1 of lipid, 3.65 mg mL−1 of biomass and 4.64 mLg−1 of biodiesel were produced. The produced biodiesel was confirmed and identification of 18 fatty acid methyl ester (biodiesel) compounds using GCMS. The recognition of 17 functional groups was identified using FTIR analysis and the microalga Nannochloropsis oculata TSD05 potential for sustainable and renewable green energy production. The potential future application of Nannochloropsis oculata TSD05 is to increase lipid production and biodiesel yield. Scaling up the bioremediation process can also validate these microalga's feasibility for use in wastewater treament. Enhancing heavy metal biosorption and carbon sequestration efficiency through genetic engineering could also maximize environmental benefits.

Synthesis and characterizations of a novel hydrogel for adsorptive removal of crystal violet dye from wastewater

Herein, a novel hydrogel (HG-cl-poly(AA)) was synthesized by grafting acrylic acid (AA) onto Hing gum (HG) using methylene-bis-acrylamide (MBA) as a cross-linker and ammonium persulfate (APS) as an initiator in a hot air oven. The percentage swelling of the hydrogel was examined by optimizing various reaction parameters to ensure its maximum swelling percentage. The formation of crosslinked networks was confirmed using Fourier-Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) techniques. The surface area and hydrophilicity of the prepared hydrogel were determined using Brunauer–Emmett–Teller analyzer and wettability studies, demonstrating a clear correlation with adsorption. The adsorption of crystal violet (CV) dye on the prepared hydrogel was studied via a batch adsorption system based on the amount of adsorbent, immersion time, pH level, and initial dye concentration. The prepared hydrogel showed a 99% removal rate and an excellent adsorption capacity of 492.61[Formula: see text]mg/g due to the electrostatic, H-bonding, and dipole–dipole interactions between the adsorbent surface and dye molecules. The results were further analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The study suggests consistency with the pseudo-second-order kinetic model ([Formula: see text]), further supported by the best data fit with the Langmuir isotherm model ([Formula: see text]). The thermodynamic study results indicated that the adsorption process is endothermic and spontaneous. Regeneration (desorption) studies showed that the prepared hydrogel could remove CV dye from an aqueous solution and maintain the highest adsorption capacity even after multiple adsorption and desorption cycles. Therefore, the prepared HG-cl-poly(AA) hydrogel could be a potential adsorbent for dye removal and have an admirable capacity for cleaning the aquatic environment.

Facile synthesis of zeolitic‐imidazole framework‐67 (ZIF‐67) for the adsorption of indigo carmine dye

AbstractThis study aims to synthesize ZIF‐67 for the adsorption of indigo carmine (I.C.) dye. ZIF‐67 materials were synthesized under different conditions and the synthesis condition of ZIF‐67 giving the best adsorption efficiency was obtained. In batch adsorption studies, pH, adsorbent amount, contact time, initial dye concentration, and temperature effects were investigated. Adsorption data were applied to Langmuir, Freundlich, and Temkin isotherm models. The best correlation value was obtained in Langmuir isotherm (R2 = 0.999). The adsorption of I.C. dye with ZIF‐67 occurred in a monolayer with a homogeneous surface according to Langmuir isotherm. The highest adsorption capacity value of ZIF‐67 metal–organic framework for I.C. dye was found as 370 mg/g. Kinetic model studies were also performed and pseudo first‐order, pseudo second‐order, and intraparticle diffusion models were used. Pseudo second‐order was the best fitting kinetic model to the data (R2 = 0.997). Adsorption mechanisms of ZIF‐67 for I.C. dye include electrostatic interaction, π–π interaction, and hydrogen bonding. Thermodynamic studies showed that I.C. removal by ZIF‐67 is an exothermic and spontaneous process. ZIF‐67 was characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), field emission scanning electron microscope (FE‐SEM), and N2 adsorption–desorption. The surface area of synthesized ZIF‐67 was found 1493 m2 g−1. The salt concentration effect on I.C. adsorption by ZIF‐67 was also investigated, showing an increase in adsorption capacities with increasing salt concentration. The regeneration study was carried out and after 5 cycles, the reduction in efficiency was 21%.

Preparation and characterization of biochar from four different solid wastes and its ampicillin adsorption performance.

The integration of biochar (BC) production from organic waste with ampicillin (AMP), an emerging pollutant, adsorption is a novel and promising treatment approach. In this study, peanut shells, coffee grounds, digestates, and oyster shells were used for BC production. Among these, the use of anaerobic digestate from food waste fermentation to produce extracts for antibiotic adsorption is relatively unexplored. The pyrolysis temperature was determined using thermogravimetric analysis (TGA) and the materials were characterized with BET, SEM, FTIR, and XRD. The TGA results indicate that PSB, CRB, and DSB underwent pyrolysis involving cellulose, hemicellulose, and lignin, whereas OSB underwent crystal formation. Characterization revealed that DSB has more functional groups, a superior mesoporous structure, appropriate O/C ratio, and trace amounts of calcite crystals, which are favorable for AMP adsorption. Adsorption experiments demonstrate that all four materials adhere to the Freundlich and Langmuir isotherm and Elovich kinetic models, indicating predominant physical adsorption, with some chemical adsorption also present. Thermodynamic studies demonstrate that BC is spontaneous during adsorption and is a heat-absorbing reaction. DSB exhibits the strongest AMP adsorption. A 53.81mgg-1 adsorbance was obtained at a dosage of 150mg, pH = 2, and 60°C. This study introduces innovative approaches for managing waste types and provides data to support the selection of suitable solid wastes for the preparation of BC with excellent adsorption properties. Furthermore, it lays the groundwork for future studies aimed at enhancing the AMP treatment efficacy.

Removal process of an industrial dye using a biosorbent: characterization, kinetic, equilibrium, and thermodynamic studies

Adsorption-based removal is a highly efficient environmental phenomenon employed to eliminate various dyes, such as crystal violet (CV), which is prevalently used in the textile industry and subsequently discharged into natural ecosystems. This study aims to utilize natural bentonite clay sourced from Algeria for the extraction of cationic dye (CV) from wastewater. The characterization of the bentonite was conducted using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). Evaluations assessed the impact of various parameters including pH, stirring time, temperature, and initial dye concentration on the adsorption efficiency. Optimal conditions for the maximal adsorption of CV were determined to be 430.18 mg g-1 at an adsorbent-to-dye solution ratio of 1 g L-1, pH 11.06, an equilibrium time of 40 minutes, and a temperature of 40°C. The adsorption kinetics were best described by the pseudo-second-order model, while the Freundlich isotherm model aptly described the adsorption isotherms. Thermodynamic parameters underscored the spontaneous and exothermic nature of the crystal violet removal process using raw bentonite. This research provides novel insights into the effective removal of a cationic dye from water and wastewater using Algerian bentonite clay.

An Investigation of Lanthanum Recovery from an Aqueous Solution by Adsorption (Ion Exchange)

Lanthanum (La(III)) is one of the high-demand rare earth elements with applications in various products. However, La(III) in mining waste streams and electronic waste also poses environmental and health concerns. Therefore, the recovery of La(III) in the waste is needed. In the present study, the adsorption of La(III) with Dowex 50W-X8, Amberchrom50WX4, Amberlyst 15, and Amberchrom 50WX2 was evaluated using a shaker water bath. Dowex 50W-X8 was found to be the best adsorbent and was used to investigate the effect of the shaker speed (RPM = 50–150), adsorbent dosage (1.0–4.0 g), pH (2.0–7.0), and temperature (20–40 °C) on adsorption. La(III) adsorption was found to increase with the shaker speed, as expected. On the other hand, the adsorption capacity decreased with the adsorbent amount. Also, the highest La(III) adsorption was observed at pH = 6.0. La(III) percentage removal did not vary significantly with a temperature from 20 °C to 40 °C. However, the first-order kinetic rate constant decreased moderately with increases in temperature. The adsorption of La(III) by Dowex 50-X8 followed the Freundlich isotherm model better than the Langmuir model. In addition, the adsorption kinetics were represented well by the pseudo-first-order kinetic model. Moreover, enthalpy and Gibbs free energy changes were found to be negative, indicating an exothermic and thermodynamically favorable adsorption process.

A systematical comparation of Cu (II) adsorption behavior and mechanism between biomass fly ash and biogas residue pyrolysis char

Biomass fly ash (BFA) and biogas residues are the main by-products of biomass direct-fired power generation and biogas production. This study compares the Cu(II) adsorption mechanisms of BFA and biogas residue pyrolysis char (BRPC) through systematic tests. BFA exhibited a significantly higher adsorption capacity (75.34 mg/g) than BRPC (42.80 mg/g). The pseudo-first-order kinetic model best described BFA, while the Elovich model was optimal for BRPC. Both materials fit the Freundlich isotherm model. BFA's superior mineral co-precipitation and ion-exchange capacity are due to its rich mineral content, particularly calcium. BRPC benefits from an additional functional group complex adsorption due to its pyrolytic charcoal content. Variations in pore structure of BFA and BRPC did not demonstrate a significant effect on the adsorption. The results of this study provide essential data support for the potential of high-value utilization of BFA and BRPC and the innovative modification of high-performance biomass-based heavy metal adsorbent materials.

Hydrothermal fabrication of composite chitosan grafted salicylaldehyde/coal fly ash/algae for malachite green dye removal: A statistical optimization

In this study, chitosan grafted salicylaldehyde/coal fly ash/algae (Chi-SL/CFA/Alg) was synthesized by assistance of hydrothermal process to be an effective adsorbent to remove cationic dye (malachite green: MG) from water. The physicochemical properties of the Chi-SL/CFA/Alg biomaterial were examined using SEM-EDX, pHpzc, specific surface area (BET), and FTIR analyses. The optimization process of the adsorption operation parameters for MG removal by Chi-SL/CFA/Alg were optimized using a Box-Behnken design (BBD). The selected adsorption operation parameters Chi-SL/CFA/Alg dosage (A: 0.02–0.1 g/100 mL), solution pH (B: 4–8), and contact time (C: 20–360 min). Analysis of variance (ANOVA) test was applied to determine the significant interaction between the adsorption operation parameters and to validate BBD output. The adsorption kinetics and isotherms of MG dye by Chi-SL/CFA/Alg were well described by pseudo-second order (PSO) kinetic and Freundlich isotherm model respectively. Thus, the maximum adsorption capacity (qmax) of MG dye by Chi-SL/CFA/Alg was found to be 493.7 mg/g at basic pH environment (pH = 8) and working temperature 25 °C. The adsorption mechanism can be ascribed to various interactions, including hydrogen bonding, π-π interactions, electrostatic attraction, and n-π interactions. Thus, Chi-SL/CFA/Alg can be considered as preferable and potential adsorbent for removing cationic dye from aqueous environment.

Highly efficient adsorption of eosin yellow dye from aqueous solutions using polymer-based nanocomposite developed from cross-linked chitosan-citrate and Co2O3 nanoparticles

The utilization of polymer-based nanocomposites offers a particularly interesting method for removing organic dyes from waterways. This study aimed to efficient removal of eosin yellow (EOY) dye from aqueous solutions using polymer-based nanocomposite (hereinafter, CHA-CIT/Co2O3 NPs) prepared from crosslinked chitosan-citrate (CHA-CIT) and Co2O3 nanoparticles (Co2O3 NPs). The CHA-CIT/Co2O3 NPs adsorbent was investigated by several approaches like XRD, BET analysis, FTIR spectroscopy, FESEM-EDX, and pHpzc analysis, to get a thorough understanding of its structural and chemical characteristics. Box-Behnken design (BBD) was adopted to systematically optimize crucial adsorption parameters, including CHA-CIT/Co2O3 NPs dose (0.01–0.07 g), starting solution pH (4–10), and contact duration (10–40 min). The CHA-CIT/Co2O3 NPs nanocomposite's BET surface area was found to be 19.85 m2/g. The mean pore diameter was determined to be 4.3 nm, and the total pore volume was measured to be 0.0213 cm3/g. The average crystallite size of 23.22 nm is indicative of the CHA-CIT/Co2O3 NPs nanocomposite's mainly polycrystalline characteristics. The kinetic investigations showed an agreement with the pseudo-first-order model, while the equilibrium results agreed well with the Freundlich isotherm model, suggesting the presence of multilayer adsorption behavior. The adsorption capacity of CHA-CIT/Co2O3 NPs for EOY was found to be 650.03 mg/g at a temperature of 25 °C, highlighting its exceptional adsorption ability. The work introduces a novel and efficient chitosan nanocomposite as a potential adsorbent for the high-performance removal of organic dyes from water-based solutions.

Interaction between modified magnetic nanoparticles and human albumin: Kinetics and isotherm studies and application in protein depletion

Magnetic nanoparticles modified with tetraethyl orthosilicate (Fe3O4@TEOS) and bovine serum albumin (Fe3O4@TEOS@BSA) were evaluated as sorbent in albumin depletion from human serum samples by magnetic dispersive solid phase extraction. Characterization studies were carried out by X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, zeta potential, and scanning electron microscopy. Both nanoparticles also showed high thermal stability and pH-dependent surface charges. The human serum albumin adsorption protocol was optimized using a central composite rotatable design. Nanoparticle mass, pH, and albumin concentration were the most influential variables. Avrami's fractional order and Freundlich isotherm models best fitted the data for human albumin adsorption kinetic and isotherm studies for Fe3O4@TEOS and Fe3O4@TEOS@BSA, and the maximum adsorption capacities were 11.93 and 14.89 mg g−1, respectively. The protein desorption was influenced by the pH of samples and eluent volume. Electrophoresis in a polyacrylamide gel containing sodium dodecyl sulfate showed different patterns of serum protein bands when consecutive depletions were performed. The Fe3O4@TEOS showed greater affinity for HSA and efficiency in depletion. The process was versatile, and the depleted albumin proportion could be controlled by the nanoparticle masses. The proposed method is a powerful sample preparation technique for rapid, reliable, and specific depletion of albumin.

Flash combustion prepared Sm and Co doped Sr hexaferrite for environmental applications

AbstractNanotechnology is offering solutions to water contamination issues, as new techniques are needed to improve the removal of harmful compounds from water bodies. Despite previous reviews on this topic, nanotechnology is paving the way for more effective water treatment methods. Understanding the substitute influence of divalent Co2+ and rare earth elements Sm3+ on the structure, magnetic, and removal efficiency of hexagonal ferrites requires an understanding of a sequence of SrFe12O19, SrFe11.5Co0.5O19, Sr0.95Sm0.05Fe12O19, and Sr0.95Sm0.05Fe11.5Co0.5O19 M-type hexagonal ferrites were prepared using the flash technique. The XRD examination revealed that the crystallized material formed a single M-type hexagonal phase. The characteristics of M-type hexagonal ferrites include absorption bands with low wavenumbers in the FTIR curves between 400 to 1000 cm−1. There was a variation in magnetic characteristics with the replacement of Sm3+ and Co2+ doping, possibly due to the spin canting impact created by rare earth Sm3+ and Co2+ ions. The goal of the research is to explore the potential of doping magnetic hexaferrites and its influence in wastewater treatment. Various parameters, such as pH and contact duration, that influence the adsorption of lead ions from aqueous solutions were also examined. At pH 7 and 25 °C after 70min, the maximal removal efficiency of the Sr0.95Sm0.05Fe11.5Co0.5O19 was found to be 99%. Magnetic separation was carried out by applying an external magnetic field using a permanent magnet. The strong magnetization of the ferrites (51–58 emu/g) enabled the rapid separation of the magnetic particles from the solution, with over 95% of the ferrite particles being recovered within 10 to 70 min. The Freundlich isotherm model fitted all the isotherm data. Adsorption kinetics were explained by the pseudo-first-order, pseudo-second order, and intraparticle diffusion models. The investigated samples’ adsorption capacity remained efficient till 5 cycles.

Zn/Cr-MOFs/TiO2 Composites as Adsorbents for Levofloxacin Hydrochloride Removal.

The Zn/Cr-MOFs/TiO2 composites were synthesized using the solvothermal method. XRD, FTIR, and SEM techniques were utilized to characterize the Zn/Cr-MOFs/TiO2 composites employed for simulating levofloxacin hydrochloride in wastewater. The impact of the mass of the Zn/Cr-MOFs/TiO2 composite, concentration of levofloxacin hydrochloride, solution pH, and temperature on the adsorption performance was investigated. Experimental findings indicated that at pH 6, the maximum removal efficiency of levofloxacin hydrochloride by the Zn/Cr-MOFs/TiO2 composite was achieved at 88.8%, with an adsorption capacity of 246.3 mg/g. To analyze the experimental data, both pseudo-first-order and pseudo-second-order kinetics models were applied, revealing that the pseudo-second-order model provided a better fit to the data. Additionally, Langmuir and Freundlich isotherm models were used to study equilibrium adsorption behavior and showed good agreement with both kinetic modeling and Langmuir isotherm analysis results. These observations suggest that monolayer adsorption predominates during the removal process of levofloxacin hydrochloride by Zn/Cr-MOFs/TiO2 composites.

Adsorption and catalytic degradation of Light green SF by magnetic PEI-modified carbon nanotubes composites

Treatment of colored effluent is necessary for the textile industry. In this study, a magnetically recyclable composite (MnFe2O4@cCNTs-PEI) was prepared by coprecipitation and grafting methods, and its efficiency for removal of light green SF (LG) from solution assessed via the adsorption and advanced oxidation techniques. The experimental results indicated that the maximum adsorption capacity of MnFe2O4@cCNTs-PEI towards LG could reach 371 mg‧g−1 at solution pH 3 and 303 K. The adsorption equilibrium results could be well fitted by Koble-Corrigan, Temkin, and Freundlich isotherm models whereas the adsorption kinetic process follows the Elovich equation and Double Constant model. This implies the adsorption process be heterogeneous multimolecular layer adsorption, accompanied by heterogeneous diffusion. The adsorption process was spontaneous, endothermic and entropy increasing which was majorly controlled by the electrostatic attraction and π-π stacking mechanisms. MnFe2O4@cCNTs-PEI can catalyze and activate H2O2 to achieve a heterogeneous Fenton-like degradation of LG. MnFe2O4@cCNTs-PEI as a catalyst could achieve a higher removal rate of LG (90 %) within a broad pH range (3–10) which could be ascribed to the presence of active radical species such as ‧OH and 1O2. After three adsorption and degradation regeneration cycles, the removal rate of LG was still higher than 60 %. It is potential for MnFe2O4@cCNTs-PEI to be economically viable for practical applications.

Green Removal of Basic Fuchsin Using Fibers from Reed Leaves

This study investigates the adsorptive capacity of a novel lignocellulosic material derived from reed leaves for the removal of Basic Fuchsin, a cationic dye, from aqueous solutions through batch adsorption experiments. The experimental data showed that the adsorbent demonstrated effective dye removal, with the adsorption kinetics following a pseudo-second-order model and the equilibrium data best described by the Freundlich and Temkin isotherm models. The Langumir model shows the maximum capacity adsorption was 37.59 mg.g-1 Moreover, thermodynamic analysis indicated that the adsorption process was non-spontaneous and exothermic, highlighting the potential for optimizing conditions to enhance dye uptake and sustainability in wastewater treatment applications. In addition, characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller surface area analysis (BET) confirmed that the adsorbent possessed an amorphous structure with a surface area of 2.42 m².g-1 and the presence of mesoporous features. Lignocellulosic materials such as reed leaf adsorbents, effectively remove hazardous dyes from wastewater offering a sustainable solution to pollution.

Advanced chitosan-based composites for sustainable removal of Congo red from textile wastewater

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

Investigation on novel chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) and its potential application for organic dyes removal from aqueous solution

Chitosan, a natural polysaccharide, has attracted considerable attention as an environmentally friendly and highly efficient adsorbent for dye removal. It is usually produced by deacetylation or partial deacetylation of chitin. However, conventional sources of chitin and chitosan are limited, prompting the need for alternative sources with improved adsorption capabilities. Herein, this study focuses on exploring a novel chitin and chitosan source derived from the dung beetle and evaluates its potential for organic dye removal from aqueous solutions. The research involves the extraction and characterization of chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) using various analytical techniques, including SEM, FT-IR, TGA, XRD, NMR, deacetylation degree and elemental analysis. The chitosan obtained was used for the formation of hydrogels with sodium alginate via cross-linking with calcium chloride. And then the prepared hydrogels were evaluated for its adsorption capacity through batch adsorption experiments using methylene blue as a model pollutant. The adsorption capacity for methylene blue was 1294.3 mg/g at room temperature with solution pH = 12, MB concentration of 1800 mg/L. Furthermore, the kinetics of the adsorption process were analyzed using pseudo-first-order and pseudo-second-order models to understand the rate of adsorption. The maximum adsorption capacities were determined using Langmuir and Freundlich isotherm models. This study provides valuable insights for the development of sustainable dye adsorption technologies, specifically investigating a novel chitosan source derived from the dung beetle.

Adsorption characteristics and mechanisms of individual and a quinary mixture of heavy metal ions on novel CoFe2O4-BiFeO3 nanosorbents in water

Application of CoFe2O4-BiFeO3 nanocomposites (CFO-BFO NCs) in highly adsorptive removal of heavy metal ions (Pb(II), Co(II), Cu(II), Cd(II) and Zn(II)) by individual and simultanoeous adsorption were investigated for the first time in the present study. The characterization of CFO-BFO NCs were analyzed by using XRD, VSM, SEM, TEM and BET techniques. The CFO-BFO NCs powder consists of characteristic peaks of BFO and CFO without any trace of other crystalline phases; they were uniformly dispersed with a size of about 3–5 nm, much smaller than single – phase CFO (10–25 nm) and BFO (5–10 µm) with the surface area of 84.93 m2/g; remanence and coercivity were 14.33 emu/g, 1.99 emu/g and 195 Oe, respectively, significantly decreased compared to CFO but significantly increased compared to BFO. The single or simultaneous adsorption of a quinary mixture of Pb(II), Co(II), Cu(II), Cd(II) and Zn(II) on CFO-BFO NCs followed the Freundlich isotherm model and the pseudo-second-order kinetic model. Adsorption capacity of single heavy metal ions were in the order Pb(II) > Co(II) > Cu(II) > Cd(II) > Zn(II) while the simultaneous adsorption was in the order Pb(II) > Cu(II) > Co(II) > Zn(II) > Cd(II). The maximum adsorption capacities (qmax) of each ion in the case of simultaneous adsorption were smaller than that for cases of the single adsorption but the total qmax of ions mixture was much higher than the highest qmax of single adsorption. The simultaneous adsorption of heavy metal ions is the competition, the best selectivity is Pb(II) and the strongest competition is Cd(II), the adsorption ability reduces as the charge and radius of interfering cation increase and the ionic strength increases. The regeneration and reuse ability were good, while the adsorption efficiency slightly decreased over three recycles. The adsorption increased slightly as temperature increased. The adsorption process was spontaneous and endothermic. Adsorption of heavy metal ions on CFO-BFO NCs consists of both electrostatic and chemisorption. The applicability for real sample is good. Our results demonstrate that the CFO-BFO NCs is a prospective adsorbent to remove Pb(II), Co(II), Cu(II), Cd(II) and Zn(II) from aqueous environment.

Evaluation of Adsorption Ability of Lewatit® VP OC 1065 and Diaion™ CR20 Ion Exchangers for Heavy Metals with Particular Consideration of Palladium(II) and Copper(II).

The adsorption capacities of ion exchangers with the primary amine (Lewatit® VP OC 1065) and polyamine (Diaion™ CR20) functional groups relative to Pd(II) and Cu(II) ions were tested in a batch system, taking into account the influence of the acid concentration (HCl: 0.1-6 mol/L; HCl-HNO3: 0.9-0.1 mol/L HCl-0.1-0.9 mol/L HNO3), phase contact time (1-240 min), initial concentration (10-1000 mg/L), agitation speed (120-180 rpm), bead size (0.385-1.2 mm), and temperature (293-333 K), as well as in a column system where the variable operating parameters were HCl and HNO3 concentrations. There were used the pseudo-first order, pseudo-second order, and intraparticle diffusion models to describe the kinetic studies and the Langmuir and Freundlich isotherm models to describe the equilibrium data to obtain better knowledge about the adsorption mechanism. The physicochemical properties of the ion exchangers were characterized by the nitrogen adsorption/desorption analyses, CHNS analysis, Fourier transform infrared spectroscopy, the sieve analysis, and points of zero charge measurements. As it was found, Lewatit® VP OC 1065 exhibited a better ability to remove Pd(II) than Diaion™ CR20, and the adsorption ability series for heavy metals was as follows: Pd(II) >> Zn(II) ≈ Ni(II) >> Cu(II). The optimal experimental conditions for Pd(II) sorption were 0.1 mol/L HCl, agitation speed 180 rpm, temperature 293 K, and bead size fraction 0.43 mm ≤ f3 < 0.6 mm for Diaion™ CR20 and 0.315-1.25 mm for Lewatit® VP OC 1065. The maximum adsorption capacities were 289.68 mg/g for Lewatit® VP OC 1065 and 208.20 mg/g for Diaion™ CR20. The greatest adsorption ability of Lewatit® VP OC 1065 for Pd(II) was also demonstrated in the column studies. The working ion exchange in the 0.1 mol/L HCl system was 0.1050 g/mL, much higher compared to Diaion™ CR20 (0.0545 g/mL). The best desorption yields of %D1 = 23.77% for Diaion™ CR20 and 33.57% for Lewatit® VP OC 1065 were obtained using the 2 mol/L NH3·H2O solution.