Adsorption mechanism of hexavalent chromium on electron beam-irradiated aged microplastics: Novel aging processes and environmental factors.

Microplastics are widely present in the natural environment and exhibit a strong affinity for heavy metals in water, resulting in the formation of microplastics composite heavy metal pollutants. This study investigated the adsorption of heavy metals by electron beam-aged microplastics. For the first time, electron beam irradiation was employed to degrade polypropylene, demonstrating its ability to rapidly age microplastics and generate a substantial number of oxygen-containing functional groups on aged microplastics surface. Adsorption experiments revealed that the maximum adsorption equilibrium capacity of hexavalent chromium by aged microplastics reached 9.3 mg g-1. The adsorption process followed second-order kinetic model and Freundlich model, indicating that the main processes of heavy metal adsorption by aged microplastics are chemical adsorption and multilayer adsorption. The adsorption of heavy metals on aged microplastics primarily relies on the electrostatic and chelation effects of oxygen-containing functional groups. The study results demonstrate that environmental factors, such as pH, salinity, coexisting metal ions, humic acid, and water matrix, exert inhibitory effects on the adsorption of heavy metals by microplastics. Theoretical calculations confirm that the aging process of microplastics primarily relies on hydroxyl radicals breaking carbon chains and forming oxygen-containing functional groups on the surface. The results indicate that electron beam irradiation can simultaneously oxidize and degrade microplastics while reducing hexavalent chromium levels by approximately 90%, proposing a novel method for treating microplastics composite pollutants. Gas chromatography-mass spectrometry analysis reveals that electron beam irradiation can oxidatively degrade microplastics into esters, alcohols, and other small molecules. This study proposes an innovative and efficient approach to treat both microplastics composite heavy metal pollutants while elucidating the impact of environmental factors on the adsorption of heavy metals by electron beam-aged microplastics. The aim is to provide a theoretical basis and guidance for controlling microplastics composite pollution.

Investigation into the characteristics of electron beam-aged microplastics and adsorption behavior of dibutyl phthalate.

Microplastics are increasingly prevalent in the environment, and their ability to adsorb various organic additives, posing harm to organisms, has attracted growing attention. Currently, there are no effective methods to age microplastics, and there is limited discussion on the subsequent treatment of aged microplastics. This study focuses on micro polyethylene (PE) and employs electron beam technology for aging treatment, investigating the adsorption and leaching behavior between PE and dibutyl phthalate (DBP) before and after aging. Experimental results indicate that with increasing doses of electron beam irradiation, the surface microstructure of PE worsens, inducing the generation of oxygen-containing functional groups on the surface of polyethylene. Comparative evaluations between electron beam aging and existing methods show that electron beam technology surpasses existing aging methods, achieving a level of aging exceeding 0.7 within an extremely short period of 1 min at doses exceeding 350 kGy. Adsorption experiments demonstrate that the adsorption between PE and DBP conforms to pseudo-second-order kinetics and the Freundlich model both before and after aging. The adsorption capacity of microplastics for DBP increases from 76.8 mg g-1 to 167.0 mg g-1 after treatment, exceeding that of conventional DBP adsorbents. Electron beam irradiation causes aging of microplastics mainly through the generation of ·OH, which lead to the formation of oxygen-containing functional groups on the microplastics' surface, thereby enhancing their adsorption capacity for DBP. This provides a new perspective for the degradation of aged microplastics and composite pollutants.

Fabrication of lignosulfonate-derived porous carbon via pH-tunable self-assembly strategy for efficient atrazine removal.

Herein, a straightforward protocol was developed for the one-pot synthesis of N-doped lignosulfonate-derived carbons (NLDCs) with a tunable porous structure using natural amino acids-templated self-assembly strategy. Specifically, histidine was employed as a template reagent, leading to the preparation of 10-NLDC-21 with remarkable characteristics, including the large specific surface area (SBET = 1844.5 m2/g), pore volume (Vmes = 1.22 cm3/g) and efficient adsorption for atrazine (ATZ) removal. The adsorption behavior of ATZ by NLDCs followed the Langmuir and pseudo-second-order models, suggesting a monolayer chemisorption nature of ATZ adsorption with the maximum adsorption capacity reached up to 265.77 mg/g. Furthermore, NLDCs exhibited excellent environmental adaptability and recycling performance. The robust affinity could be attributed to multi-interactions including pore filling, electrostatic attraction, hydrogen bonding and π-π stacking between the adsorbents and ATZ molecules. This approach offers a practical method for exploring innovative bio-carbon materials for sewage treatment.

Tecoma stans floral extract-mediated synthesis of MgFe2O4/ZnO nanoparticles for adsorption and photocatalytic degradation of coomassie brilliant blue dye.

Toxic organic dyes-containing wastewater treatment by adsorption and photocatalytic techniques is widely applied, but adsorbents and photocatalysts are often synthesized through chemical methods, leading to secondary pollution by released chemicals. Here, we report a benign method using Tecoma stans floral extract to produce MgFe2O4/ZnO (MGFOZ) nanoparticles for adsorption and photocatalytic degradation of coomassie brilliant blue (CBB) dye. Green MGFOZ owned a surface area of 9.65 m2/g and an average grain size of 54 nm. This bio-based nanomaterial showed higher removal percentage and better recyclability (up to five cycles) than green MgFe2O4 and ZnO nanoparticles. CBB adsorption by MGFOZ was examined by kinetic and isotherm models with better fittings of Bangham and Langmuir or Temkin. RSM-based optimization was conducted to reach an actual adsorption capacity of 147.68 mg/g. Moreover, MGFOZ/visible light system showed a degradation efficiency of 89% CBB dye after 120 min. CBB adsorption can be controlled by both physisorption and chemisorption while •O2- and •OH radicals are responsible for photo-degradation of CBB dye. This study suggested that MGFOZ can be a promising adsorbent and catalyst for removal of organic dyes in water.

Removal of Cd from solution and in-situ remediation of Cd-contaminated soil by a mercapto-modified cellulose/bentonite intercalated nanocomposite.

A novel intercalated nanocomposite of mercapto-modified cellulose/bentonite (LCS-BE-SH) was synthesized by high-speed shearing method in one step at room temperature, and was applied to remove Cd from solution and remediate Cd-contaminated soil. Results revealed that cellulose long-chain molecules have intercalated into bentonite nanolayers and interlayer spacing was increased to 1.411 nm, and grafting -SH groups improved adsorption selectivity, which enabled LCS-BE-SH to have distinct capability of Cd adsorption (qmax = 147.21 mg/g). Kinetic and thermodynamics showed that Cd adsorption onto LCS-BE-SH was well fitted by pseudo-second-order and Langmuir adsorption isotherm. Characterizations of the adsorbents revealed that synergistic effect of complexation (e.g., CdS, CdO) and precipitation (e.g., Cd(OH)2, CdCO3) mechanism played a major role in Cd removal. In soil remediation, application of LCS-BE-SH was most effective (67.31 %) in Cd immobilization compared to the control (8.85 %), which reduced exchangeable Cd from 37.03 % to 11.44 %. Meanwhile, soil pH, soil organic matter, available phosphorus, and enzyme activities (catalase, urease, and dehydrogenase) were improved LCS-BE-SH treatment. The main immobilization mechanism in soil included complexation (e.g., CdS, CdO) and precipitation (e.g., Cd(OH)2, Cd-Fe-hydroxide). Overall, this work applied a promising approach for Cd removal in aqueous and Cd remediation in soil by using an effective eco-friendly LCS-BE-SH nanocomposites.

Recent advances in boron removal in aqueous media. An approach to the adsorption process and process optimization.

The numerous oxidation states of the element boron bring great challenges in containing its contamination in receptor bodies. This scenario increases significantly due to the widespread use of boron compounds in various industries in recent years. For this reason, the removal of this contaminant is receiving worldwide attention. Although adsorption is a promising method in boron removal, finding suitable adsorbents, that is, those with high efficiency, and feasible remains a constant challenge. Hence, this review presents the boron removal methods in comparison to costs of adsorbents, reaction mechanisms, economic viability, continuous bed application, and regeneration capacity. In addition, the approach of multivariate algorithms in the solution of multiobjective problems can enable the optimized conditions of dosage of adsorbents and coagulants, pH, and initial concentration of boron. Therefore, this review sought to comprehensively and critically demonstrate strategic issues that may guide the choice of method and adsorbent or coagulant material in future research for bench and industrial scale boron removal.

Perspectives on Corrosion Inhibition Features of Novel Synthesized Gemini-Fluorinated Cationic Surfactants Bearing Varied Spacers for Acid Pickling of X60-Steel: Practical, and In Silico Calculations.

Through our present study, three novel Gemini-fluorinated cationic surfactants bearing different spacers (FSG6-2, FSG6-4, and FSG6-6) were synthesized, and their structures were explained via different spectroscopic instruments such as 1H, 13C, and 19F NMR spectra. The surface activity of the as-prepared surfactants was examined. The inhibiting influence of FSG6 molecules on the X60 steel corrosion in the pickling solution (HCl) was examined by diverse methods comprising electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and X-ray photoelectron spectroscopy (XPS) experimentations, and computational calculations. The inhibition effectiveness of FSG6 surfactants followed the order of 93.37% (FSG6-2) < 96.74% (FSG6-4) < 98.37% (FSG6-6) at 2.0 × 10-4 M. The FSG6 surfactants function as mixed-type inhibitors, according to PDP investigations. The H2O molecules that adsorbed on the steel interface were substituted with surfactant molecules, and the surfactant's inhibitory activity is likely caused by the improvement in an adsorptive layer on the steel substrate, as specified by the EIS results. The Langmuir isotherm describes the absorption of FSG6 molecules on the metal surface. The XPS investigations validate the steel interface's extremely protective nature. The mechanism of interaction between FSG6 molecules with an X60-steel employing the DFT calculations and MC simulations methods was also examined and discussed.

On the Use of Graphene Nanosheets for Drug Delivery: A Case Study of Cisplatin and Some of Its Analogs.

Graphene (GN) nanosheets have been widely exploited in biomedical applications as potential nanocarriers for various drugs due to their distinct physical and chemical properties. In this regard, the adsorption behavior of cisplatin (cisPtCl2) and some of its analogs on a GN nanosheet was investigated in perpendicular and parallel configurations by using density functional theory (DFT). According to the findings, the most significant negative adsorption energies (Eads) within the cisPtX2⋯GN complexes (where X = Cl, Br, and I) were observed for the parallel configuration, with values up to -25.67 kcal/mol at the H@GN site. Within the perpendicular configuration of the cisPtX2⋯GN complexes, three orientations were investigated for the adsorption process, namely, X/X, X/NH3, and NH3/NH3. The negative Eads values of the cisPtX2⋯GN complexes increased with the increasing atomic weight of the halogen atom. The Br@GN site showed the largest negative Eads values for the cisPtX2⋯GN complexes in the perpendicular configuration. The Bader charge transfer outcomes highlighted the electron-accepting properties of cisPtI2 within the cisPtI2⋯GN complexes in both configurations. The electron-donating character of the GN nanosheet increased as the electronegativity of the halogen atom increased. The band structure and density of state plots revealed the occurrence of the physical adsorption of the cisPtX2 on the GN nanosheet, which was indicated by the appearance of new bands and peaks. Based on the solvent effect outlines, the negative Eads values generally decreased after the adsorption process in a water medium. The recovery time results were in line with the Eads findings, where the cisPtI2 in the parallel configuration took the longest time to be desorbed from the GN nanosheet with values of 61.6 × 108 ms at 298.15 K. The findings of this study provide better insights into the utilization of GN nanosheets in drug delivery applications.

Biosorption of Cd+2 and Pb+2 by Exopolysaccharide Extracted from Lactobacillus fermentum 6b; Adsorption Isotherm and Kinetic Studies.

Background: In recent years, the biosorption of heavy metals by Lactobacillus strains has received attention from researchers. We aimed to remove of heavy metals lead and cadmium from L. fermentum 6b exopolysaccharide in 2021. Methods: Extracellular exopolysaccharide was first extracted from selected probiotic strain, and then the effect of variables such as pH, the extracted exopolysaccharide adsorbent dose, contact time, heavy metal concentration, and temperature on the adsorption rate was investigated. The adsorption isotherms of Langmuir and Freundlich were also examined. Pseudo-first and pseudo-second-order kinetics equations were also investigated for the desired surface adsorption. Results: The adsorption process at pH=6.5, contact time=80 min, pollutant concentration=100 mg.L-1, adsorbent dose (extracted exopolysaccharide) =1500 mg.L-1, temperature=35°C for cadmium; pH= 6, contact time=60 min, contaminant concentration of 100 mg.L-1, adsorbent dose (extracted exopolysaccharide) =1500 mg.L-1 temperature=of 35 °C for lead had optimum condition. The adsorption process corresponded to Freundlich isotherm with R2=0.958 and R2=0.988, and pseudo-second-order kinetic with R2=0.99 and R2=0.85 for cadmium and lead, respectively. Conclusion: The exopolysaccharide extracted from L. fermentum 6b isolate can have an acceptable removal potential for lead and cadmium heavy metals.

A comprehensive review on modelling the adsorption process for heavy metal removal from waste water using artificial neural network technique.

Water is the most necessary and significant element for all life on earth. Unfortunately, the quality of the water resources is constantly declining as a result of population development, industry, and civilization progress. Due to their extreme toxicity, heavy metals removal from water has drawn researchers' attention. A lot of scientific applications use artificial neural networks (ANNs) because of their excellent ability to map nonlinear relationships. ANNs shown excellent modelling capabilities for the water treatment remediation. The adsorption process uses a variety of variables, making the interaction between them nonlinear. Selecting the best technique can produce excellent results; the adsorption approach for removing heavy metals is highly effective. Different studies show that the ANNs modelling approach can accurately forecast the adsorbed heavy metals and other contaminants in order to remove them.

Removal of Methylene Blue from Aqueous Solutions by Surface Modified Talc.

In this study, raw talc powder surface modification was conducted, and the powder was modified in two different methods using acid washing and ball milling. Modified talc was characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In order to investigate the adsorption capacity of modified talc on dyes, adsorption experiments were carried out with methylene blue (MB) in aqueous solutions as the target contaminant. The findings of the characterization revealed that both modifications increased the adsorption capacity of talc, which was attributed to changes in specific surface area and active groups. The influence of process parameters such as contact time, pH, dye concentration, and adsorbent dosage on the adsorption performance was systematically investigated. Modified talc was able to adsorb MB rapidly, reaching equilibrium within 60 min. Additionally, the adsorption performance was improved as the pH of the dye solution increased. The isotherms for MB adsorption by modified talc fitted well with the Langmuir model. The pseudo-second-order model in the adsorption kinetic model properly described the adsorption behavior. The results show that the modified talc can be used as an inexpensive and abundant candidate material for the adsorption of dyes in industrial wastewater.

Effects of activated earth, activated alumina, and chitosan adsorption processes on thermal and rheological and chemical characteristics of menhaden oil.

The objective of this study was the effectiveness of using activated earth, activated alumina, and/or chitosan, either separately or in combination, as adsorbents to remove free fatty acids (FFA) and peroxides from unpurified menhaden oil (MO). Thermal and rheological properties of MO were also evaluated. Five different combinations of absorbents were used to purify MO: Processes 1-3 involved purifications of MO by 5% chitosan (wt/wt of oil), 5% activated earth, and 5% activated alumina, respectively, process 4 involved MO purification with a combination of 6.5% chitosan, 3.5% activated earth, and 5% activated alumina, and process 5 involved MO purification process with a combination of adsorbents of 9% chitosan, 1% activated earth, and 5% activated alumina. All the adsorption processes were conducted at 25°C. Purified MO and MO were evaluated for their fatty acid profile, FFA, peroxide value (PV), moisture content (MC), minerals, and color. Triplicate experiments were conducted, and data were statistically analyzed using α = 0.05. Processes 4 and 5 were effective in reducing PV, FFA, and MC in MO. Thermal properties indicated processes 4 and 5 produced purer MO than processes 1-3. All the oil samples became less viscous, and the flow behavior index of MO was close to 1 after the adsorption processes. This study demonstrated that adsorption processes that include chitosan, activated earth, and activated alumina could effectively improve MO quality.

Activated Carbon with Ultrahigh Specific Surface Derived from Bamboo Shoot Shell through K2FeO4 Oxidative Pyrolysis for Adsorption of Methylene Blue.

To effectively remove methylene blue (MB) from dye wastewater, a novel activated carbon (BAC) was manufactured through co-pyrolysis of bamboo shoot shell and K2FeO4. The activation process was optimized to a temperature of 750 °C and an activation time of 90 min based on its excellent adsorption capacity of 560.94 mg/g with a yield of 10.03%. The physicochemical and adsorption properties of BACs were investigated. The BAC had an ultrahigh specific surface area of 2327.7 cm2/g and abundant active functional groups. The adsorption mechanisms included chemisorption and physisorption. The Freundlich model could be used to describe the isothermal adsorption of MB. The kinetics confirmed that the adsorption of MB belonged to the pseudo-second-order model. Intra-particle diffusion was the main rate-limiting step. The thermodynamic study showed that the adsorption process was endothermic and temperature was beneficial for the improvement of adsorption property. Furthermore, the removal rate of MB was 63.5% after three cycles. The BAC will have great potential for commercial development for purifying dye wastewater.

Removal of chloride ion from drinking water using Ag NPs-Modified bentonite: Characterization and optimization of effective parameters by response surface methodology-central composite design.

The presence of chloride ion as an environmental pollutant is having a devastating and irreversible effect on aquatic and terrestrial ecosystems. To ensure safe and clean drinking water, it is vital to remove this substance using non-toxic and eco-friendly methods. This study presents a novel and highly efficient Ag NPs-modified bentonite adsorbent for removing chloride ion, a common environmental pollutant, from drinking water using a facile approach. The surface chemical properties and morphology of the pristine Na-bentonite and Ag NPs-Modified bentonite were characterized by field emission scanning electron microscopy (FESEM) and X-ray spectroscopy (EDX), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), and zeta potential (ζ). To achieve maximum chloride ion removal, the effects of experimental parameters, including adsorbent dosage (1-9 g/L), chloride ion concentration (100-900 mg/L), and reaction time (5-25 h), were examined using the Response Surface Methodology (RSM). The chloride ion removal of 90% was obtained at optimum conditions (adsorbent dosage: 7 g/L, chloride ion concentration: 500 mg/L, and reaction time: 20 h). The adsorption isotherm and kinetics results indicated that the Langmuir isotherm model and pseudo-second-order kinetics were found suitable to chloride ion removal. Additionally, the regeneration and reusability of the Ag NPs-modified bentonite were further studied. In the regeneration and reusability study, the Ag NPs-modified bentonite has shown consistently ≥90% and ≥87% chloride ion removal even up to 2 repeated cycles, separately. Thus, the findings in this study provided convincing evidence for using Ag-NPs modified bentonite as a high-efficiency and promising adsorbent to remove chloride ion from drinking water.

Occurrence and removal of benzotriazole and benzothiazole in drinking water treatment plants.

The occurrence and removal of four benzotriazoles (BTRs) and five benzothiazoles (BTHs) in drinking water treatment plants (DWTPs) and bottled water were investigated. The mean total BTR and BTH concentrations were 390 and 117 ng/L in raw water, 51.2 and 66.5 ng/L in treated water, and 0.758 and 48.4 ng/L in bottled water, respectively. Different distribution patterns were observed according to the water type, with the dominant BTR being 1H-BTR (mean: 57.8%) in raw water and a predominance of BTH in bottled water (mean: 84.6%). In the DWTPs, the mean removal of BTRs (90.9%) was better than that of BTHs (29.3%). The BTRs were efficiently removed in DWTPs, and in particular during adsorption processes. 5Cl-BTR had a high removal efficiency (75.7%) in the adsorption processes, followed by 5M-BTR (70.0%), 5,6-di-MeBTR (58.4%), and 1H-BTR (50.1%). By contrast, BTHs were not efficiently removed in DWTPs, although relatively high removal efficiencies were achieved with an ozonation process (43.1%) compared to other treatment processes. In treated drinking and bottled water, the hazard quotients (HQs) of the representative BTRs and BTHs were acceptable (defined as HQ < 1), with a safety margin of 2-5 orders of magnitude.

Synergistic effect of Fenton oxidation and adsorption process in treatment of azo printing dye: DSD optimization and reaction mechanism interpretation.

The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO4/H2O2) and heterogeneous (Fe2(MoO4)3/H2O2) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20-180 mg L-1), iron concentration (0.75-60 mg L-1), pH (2-10) and hydrogen peroxide concentration (1-11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

Adsorption Behavior of Toxic Carbon Dichalcogenides (CX2; X = O, S, or Se) on ß12 Borophene and Pristine Graphene Sheets: A DFT Study.

The adsorption of toxic carbon dichalcogenides (CX2; X = O, S, or Se) on ß12 borophene (ß12) and pristine graphene (GN) sheets was comparatively investigated. Vertical and parallel configurations of CX2⋯ß12/GN complexes were studied herein via density functional theory (DFT) calculations. Energetic quantities confirmed that the adsorption process in the case of the parallel configuration was more desirable than that in the vertical analog and showed values up to −10.96 kcal/mol. The strength of the CX2⋯ß12/GN complexes decreased in the order CSe2 > CS2 > CO2, indicating that ß12 and GN sheets showed significant selectivity for the CSe2 molecule with superb potentiality for ß12 sheets. Bader charge transfer analysis revealed that the CO2⋯ß12/GN complexes in the parallel configuration had the maximum negative charge transfer values, up to −0.0304 e, outlining the electron-donating character of CO2. The CS2 and CSe2 molecules frequently exhibited dual behavior as electron donors in the vertical configuration and acceptors in the parallel one. Band structure results addressed some differences observed for the electronic structures of the pure ß12 and GN sheets after the adsorption process, especially in the parallel configuration compared with the vertical one. According to the results of the density of states, new peaks were observed after adsorbing CX2 molecules on the studied 2D sheets. These results form a fundamental basis for future studies pertaining to applications of ß12 and GN sheets for detecting toxic carbon dichalcogenides.

A novel approach based on the ultrasonic-assisted microwave method for the efficient synthesis of Sc-MOF@SiO2 core/shell nanostructures for H2S gas adsorption: A controllable systematic study for a green future.

In this work, for the first time, novel Sc-MOF@SiO2 core/shell nanostructures have been synthesized under the optimal conditions of ultrasonic-assisted microwave routes. The final products showed small particle size distributions with homogeneous morphology (SEM results), high thermal stability (TG curve), high surface area (BET adsorption/desorption techniques), and significant porosity (BJH method). The final nanostructures of Sc-MOF@SiO2 core/shell with such distinct properties were used as a new compound for H2S adsorption. It was used with the systematic investigation based on a 2K-1 factorial design, which showed high-performance adsorption of about 5 mmol/g for these novel adsorbents; the optimal experimental conditions included pressure, 1.5 bar; contact time, 20 min; and temperature, 20°C. This study and its results promise a green future for the potential control of gas pollutants.

Application of Orange Peel Waste as Adsorbent for Methylene Blue and Cd2+ Simultaneous Remediation.

Pollution by dyes and heavy metals is one of the main concerns at the environmental level due to their toxicity and inefficient elimination by traditional water treatment. Orange peel (OP) without any treatment was applied to effectively eliminate methylene blue (MB) and cadmium ions (Cd2+) in mono- and multicomponent systems. Although the single adsorption processes for MB and Cd2+ have been investigated, the effects and mechanisms of interactions among multicomponent systems are still unclear. Batch experiments showed that in monocomponent systems, the maximum adsorption capacities were 0.7824 mmol g-1 for MB and 0.2884 mmol g-1 for Cd2+, while in multicomponent systems (Cd2+ and MB), both contaminants competed for the adsorption sites on OP. Particularly, a synergic effect was observed since the adsorption capacity of Cd2+ increased compared to the monocomponent system. Results of desorption and adsorbent reuse confirmed that the adsorbent presents good regeneration performance. The low cost of this material and its capacity for the individual or simultaneous removal of Cd2+ and MB in aqueous solutions makes it a potential adsorbent for polluted water treatment processes.

Green Synthesis of Zinc Oxide Nanoparticles Using Red Seaweed for the Elimination of Organic Toxic Dye from an Aqueous Solution.

This study aims to produce green zinc oxide nanoparticles (ZnO-NPs) derived from red seaweed (Pterocladia Capillacea) and evaluate their potential to absorb Ismate violet 2R (IV2R) ions from an aqueous solution. UV-vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and a Brunauer-Emmett-Teller surface area analysis (BET) were used to analyze the structural, morphological, and optical features of the synthesized nanoparticles. The change in color of the chemical solution revealed the formation of zinc oxide nanoparticles. The FTIR examination confirmed the synthesis of both Zn and ZnO nanoparticle powder, with a BET surface area of 113.751 m2 g-1 and an average pore size of 2.527 nm for the synthesized adsorbent. Furthermore, the maximum removal effectiveness of IV2R was 99% when 0.08 g ZnO-NPs was applied at a pH of 6, a temperature of 55 °C, and a contact time of 120 min. The dye adsorption capacity of the ZnO-NPs was 72.24 mg g-1. The adsorption process was also controlled by the Freundlich adsorption model and pseudo-second-order reaction kinetics. The adsorption of IV2R ions onto the ZnO-NPs could be represented as a nonideal and reversible sorption process of a nonuniform surface, according to Freundlich adsorption isotherms. In addition, the constant values of the model parameters were determined using various nonlinear regression error functions. Moreover, thermodynamic parameters such as entropy change, enthalpy change, and free energy change were investigated; the adsorption process was spontaneous and endothermic. The high capacity of the ZnO-NPs synthesized by red seaweed promotes them as promising substances for applications in water treatment for the removal of IV2R dye from aqueous systems.