Highly Selective Removal of Cationic Dyes from Wastewater by MgO Nanorods

Facile synthesis of TiO2@ZnO nanoparticles for enhanced removal of methyl orange and indigo carmine dyes: Adsorption, kinetics

Water pollution represents one of the most important problems affecting the health of living organisms, so it was necessary to work on the formation of active materials to get rid of pollutants. In this study, Titanium dioxide (TiO2) doping Zinc oxide (ZnO) nanocomposites were produced via simple sonication method at 500 Hz in ethanol medium. At different weight concentrations (2.5, 5, 7.5, and 10 %). The morphology, structure configuration, chemical bonding, crystalline phase, and surface properties of obtained nanocomposites were characterized via FESEM, BET, XRD, XPS, RAMAN and FTIR instrumentation. The nanocomposites were employed as an adsorbent to eliminate the methyl orange (MO) and Indigo Carmine (IC) dyes from an aqueous solution. Batch removal experiments revealed that the elimination of MO and IC dyes by the TiZnO surface was pH and doping Ti concentration-dependent, with maximum removal occurring at pH = 7 for MO and pH = 3 for IC contaminants at 10 % doping Ti concentration (Ti (10 %)@ZnO). Langmuir model fit the absorptive removal of MO and IC dyes into the Ti (10 %)@ZnO surface well. The maximal removal capacity of Ti (10 %)@ZnO nanocomposite was found to be 994.24 mg. g-1 for MO and 305.39 mg. g-1 for IC. The Ti (10 %)@ZnO nanocomposite showed remarkable high stability towards the removal of both dyes through consecutive four cycles.

Prediction and optimizing of methylene blue sequestration to activated charcoal/magnetic nanocomposites using artificial neutral network and response surface methodology

Green synthesized magnetic nanoparticles (MNPs) linked with activated charcoal (AC) (AC/Fe3O4 NCs) were exploited for methylene blue (MB) confiscation in this study. The AC/Fe3O4 NCs produced were characterized using TEM, FTIR, UV/Vis and XRD spectrometry. The Response-Surface-Methodology (RSM) was utilized to improve the experimental data for the MB sorption to AC/Fe3O4 NCs, with 20 experimental runs implemented through a central composite design (CCD) to assess the effect of sorption factors-initial MB concentration, pH and sorbent dosage effects on the response (removal-effectiveness). The quadratic model was discovered to ideally describe the sorption process, with an R2 value of 0.9857. The theoretical prediction of the experimental data using the Artificial-Neural-Network (ANN) model showed that the Levenberg-Marquardt (LM) had a better performance criterion. Comparison between the modelled experimental and predicted data showed also that the LM algorithm had a high R2 of 0.9922, which showed NN model applicability for defining the sorption of MB to AC/Fe3O4 NCs with practical precision. The results of the non-linear fitting (NLF) of both isotherm and kinetic models, showed that the sorption of MB to AC/Fe3O4 NCs was perfectly described using the pseudo-second-order (PSOM) and Freundlich (FRHM) models. The estimated optimum sorption capacity was 455 mg g-1. Thermodynamically, the sorption of MB to AC/Fe3O4 NCs was shown to be non-spontaneous and endothermic.

Effective removal of malachite green oxalate from aqueous solution using Newbouldia laevis husk/MWCNTs nanocomposite: equilibrium, kinetics, and thermodynamics

The discharge of colored effluent into water bodies is a big concern; hence, the current work was designed to fabricate a superior nanocomposite (NBM) using the Newbouldia laevis husk (NB) and functionalized multiwalled carbon nanotubes (f-MWCNTs) for the adsorption of malachite green oxalate (MGO). Brunauer-Emmett-Teller (BET) surface analysis was used to assess the specific surface area of NB (0.7699 m2 g-1) and NBM (94.006 m2 g-1). Fourier transform infrared spectroscopy (FTIR) was employed to determine the chemical moieties on the surface of the adsorbent. Field emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA) were used to analyze the surface morphology and the thermal behavior of the adsorbents. Essential factors of the adsorption process were investigated, and it was revealed that pH 6.0, adsorbent dose of 0.05 g, contact time 80 min, concentration of 100 mg dm-3 and maximum adsorption capacity of 35.78 mg g-1 (NB) and 69.97 mg g-1 (NBM) were the optimal parameters. The NB and NBM adsorption processes followed a pseudo-first-order kinetic model. The exothermic and endothermic adsorptive processes were noticed to be the best descriptions of MGO elimination by NB and NBM, respectively. The uptake of MGO by NB and NBM was best described by models of Freundlich and Langmuir isotherms. Besides, NBM demonstrated uptake efficiency that is >80% after the fourth adsorption/desorption cycle. As a result, NBM has a wide range of possible uses in environmental remediation.

Efficiency of magnesium oxide nanoparticle in contaminants removal from environmental water samples: Optimization through central composite design

This experimental study was conducted to synthesize magnesium oxide (MgO) nanoparticles and investigate their efficiency in removing arsenic, brilliant cresyl blue, and neutral red from aqueous solutions. The MgO nanoparticles were characterized using X-ray diffraction (XRD), energy dispersive X-ray (EDS), Fourier-transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) analyses. The results revealed that the synthesized MgO nanoparticles had a spherical structure with an estimated average size of approximately 30 nm. The influence of solution pH, concentration, adsorbent amount, type of eluent, and interference of interfering ions was examined and optimized for removing arsenic, brilliant cresyl blue, and neutral red. The optimal conditions for the removal process were determined as pH of 7, MgO amount of 0.037 g, ultrasonication time of 16 min, and concentration of 25 mg L-1. The experimental removal efficiencies of arsenic, brilliant cresyl blue, and neutral red in aqueous samples ranged from 88.49% to 96.03%. The results of eluent selection showed that ethanol had the highest removal efficiency of analytes from the absorbent surface. The reusability of the MgO adsorbent demonstrated its effective use for the continuous removal of arsenic, brilliant cresyl blue, and neutral red for at least four consecutive cycles. Overall, the results suggest that MgO nanoparticles could be an effective and cost-efficient adsorbent for removing arsenic, brilliant cresyl blue, and neutral red from real samples.

Nanocellulose-Based Ecofriendly Nanocomposite for Effective Wastewater Remediation: A Study on Its Process Optimization, Improved Swelling, Adsorption, and Thermal and Mechanical Behavior

A nanocellulose (NC)-based cross-linked adsorbent has been employed herein for the removal of dye pollutants (e.g., methylene blue) from the textile industry. The synthesized hydrogel was optimized to achieve the best concentrations of the adsorbent constituents, i.e., 1.55% guar gum, 1.46% NC, and 0.84% borax for achieving the maximum swelling index (SI, 3741.42%) and higher adsorption capacity (qe, 24.05 mg g-1). 98.8% of dye qe was achieved at optimal conditions of pH 8 within 30 min at 30 °C. Adsorption isotherms and kinetics investigations showed good correlation with the Freundlich adsorption isotherm model (R2 > 0.9889; ΔG° = -4.71; ΔH° = -12.30; ΔS° = -0.025) as well as the pseudo-second-order kinetics model, indicating multilayered and intricate adsorption mechanisms for dye removal. The study of thermodynamic parameters confirmed the exothermic nature of the adsorption process. The adsorption-desorption study of the resulting hydrogel exhibited 64.58% dye removal efficiency even after 4 consecutive cycles of reuse. Further, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction analysis revealed the surface morphology, functional moieties, thermal behavior, and crystallinity pattern of the hydrogel. Rheological analysis demonstrated pseudoplastic flow and improved mechanical behavior for the hydrogel. The current study found that the synthesized adsorbent with a higher SI and qe has a noticeable potential for the removal of dye pollutants from wastewater.

Synthesis of Kaolin-Supported Nickel Oxide Composites for the Catalytic Oxidative Degradation of Methylene Blue Dye

Organic dye contamination of water is a contributing factor to environmental pollution and has a negative impact on aquatic ecology. In this study, unsupported NiO and kaolin-supported NiO composites were synthesized by a one-step wet impregnation-precipitation method through the precipitation of nickel hydroxide onto locally accessible, inexpensive, and easily treated kaolin surfaces by using sodium hydroxide as a precipitating agent. The product was calcined at 500 °C and used for the catalytic oxidative degradation of methylene blue (MB) dye in an aqueous solution. The morphology, structure, and interactions of the synthesized materials were explored by SEM, XRD, and FT-IR spectroscopy. The characterization results revealed the fabrication and the growth of NiO on the kaolin surface. To determine the catalytic oxidative degradation performance of the catalyst, many experiments have been performed using the MB dye as a model dye. The catalytic degradation tests confirmed the importance of NiO and the high catalytic activity of the synthesized NiO/kaolin composite toward MB dye degradation. The oxidative degradation results showed that the optimized precursor amount on the kaolin surface could efficiently enhance the removal of MB dye. The kinetic investigation of the catalytic degradation of MB dye fitted the pseudo-first-order kinetic model. High removal efficiency was observed after eight reuse cycles, proving the exceptional stability and reusability of the composite. The catalytic process also proceeded with a low activation energy of 30.5 kJ/mol. In conclusion, the kaolin-supported NiO composite was established to be a favorable catalyst to degrade a model dye (MB) from an aqueous solution in the presence of inexpensive and easily available NaOCl with a catalytic efficiency of the material higher than 99% of the 20.3 mg catalyst within 6 min with an apparent rate constant, kapp, higher than 0.44625 min-1, which is far better than that of the unsupported catalyst with a kapp of 0.0926 min-1 at 10 mg dose in 20 min.

Facile synthesis of novel magnesium oxide nanoparticles for pesticide sorption from water

The quantum of pesticides in surface as well as drinking water has become a serious health hazard. In this experiment, magnesium oxide nanoparticles (MgO NPs) were synthesized using leaves of purple-colored rice variety (Crossa) and utilized for simultaneous removal of three pesticides, namely, thiamethoxam, chlorpyriphos, and fenpropathrin from water. The biogenic MgO NPs were characterized using SEM-EDX, FTIR, XRD, DLS, etc. The optimum synthesis parameters (1 M NaOH, 80 °C, and 2 h) resulted in maximum yield of MgO NPs (87.7 mg), minimum hydrodynamic diameter (35.12 nm), poly dispersity index (0.14) and mean zeta potential (-11 mV). Sorption data of the three pesticides fitted well with non-linear Langmuir and Freundlich isotherm models and non-linear pseudo-second-order kinetic model. The maximum adsorption capacity of MgO NPs for the three pesticides was 87.66 µg/mg, as obtained from the Langmuir isotherm model. Under optimum conditions (initial concentration, 40 mg/L; dose, 30 mg/30 mL; and pH, 9), 60.13, 80.53, and 92.49% removal of thiamethoxam, chlorpyriphos, and fenpropathrin was achieved with a 100% desirability, respectively. Thus, the biogenic MgO NPs could be an efficient adsorbent of pesticides and could be recommended for pesticide decontamination in water treatment plants and domestic water purifier systems.

Adsorption of Brilliant Green Dye onto a Mercerized Biosorbent: Kinetic, Thermodynamic, and Molecular Docking Studies

This study reports the valorization of pistachio shell agricultural waste, aiming to develop an eco-friendly and cost-effective biosorbent for cationic brilliant green (BG) dye adsorption from aqueous media. Pistachio shells were mercerized in an alkaline environment, resulting in the treated adsorbent (PS_NaOH). The morphological and structural features of the adsorbent were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, and polarized light microscopy. The pseudo-first-order (PFO) kinetic model best described the adsorption kinetics of the BG cationic dye onto PS_NaOH biosorbents. In turn, the equilibrium data were best fitted to the Sips isotherm model. The maximum adsorption capacity decreased with temperature (from 52.42 mg/g at 300 K to 46.42 mg/g at 330 K). The isotherm parameters indicated improved affinity between the biosorbent surface and BG molecules at lower temperatures (300 K). The thermodynamic parameters estimated on the basis of the two approaches indicated a spontaneous (ΔG < 0) and exothermic (ΔH < 0) adsorption process. The design of experiments (DoE) and the response surface methodology (RSM) were employed to establish optimal conditions (sorbent dose (SD) = 4.0 g/L and initial concentration (C₀) = 10.1 mg/L), yielding removal efficiency of 98.78%. Molecular docking simulations were performed to disclose the intermolecular interactions between the BG dye and lignocellulose-based adsorbent.

Magnetic Ionotropic Hydrogels Based on Carboxymethyl Cellulose for Aqueous Pollution Mitigation

In this work, stabilized ionotropic hydrogels were designed using sodium carboxymethyl cellulose (CMC) and assessed as inexpensive sorbents for hazardous chemicals (e.g., Methylene Blue, MB) from contaminated wastewaters. In order to increase the adsorption capacity of the hydrogelated matrix and facilitate its magnetic separation from aqueous solutions, sodium dodecyl sulfate (SDS) and manganese ferrite (MnFe₂O₄) were introduced into the polymer framework. The morphological, structural, elemental, and magnetic properties of the adsorbents (in the form of beads) were assessed using scanning electron microscopy (SEM), energy-dispersive X-ray analysis, Fourier-transform infrared spectroscopy (FTIR), and a vibrating-sample magnetometer (VSM). The magnetic beads with the best adsorption performance were subjected to kinetic and isotherm studies. The PFO model best describes the adsorption kinetics. A homogeneous monolayer adsorption system was predicted by the Langmuir isotherm model, registering a maximum adsorption capacity of 234 mg/g at 300 K. The calculated thermodynamic parameter values indicated that the investigated adsorption processes were both spontaneous (ΔG < 0) and exothermic (ΔH < 0). The used sorbent can be recovered after immersion in acetone (93% desorption efficiency) and re-used for MB adsorption. In addition, the molecular docking simulations disclosed aspects of the mechanism of intermolecular interaction between CMC and MB by detailing the contributions of the van der Waals (physical) and Coulomb (electrostatic) forces.

Dependency of Crystal Violet Dye Removal Behaviors onto Mesoporous V2O5-g-C3N4 Constructed by Simplistic Ultrasonic Method

This research examined the production of a V2O5-g-C3N4 nanocomposite to remove organic dyes from wastewater. To generate the V2O5-g-C3N4 nanocomposite, the sonication method was applied. The testing of V2O5-g-C3N4 with various dyes (basic fuchsin (BF), malachite green (MG), crystal violet (CV), Congo red (CR), and methyl orange (MO)) revealed that the nanocomposite has a high adsorption ability towards BF, MG, CV, and CR dyes in comparison with MO dye. It was established that the modification of pH influenced the removal of CV by the V2O5-g-C3N4 nanocomposite and that under optimal operating conditions, efficiency of 664.65 mg g−1 could be attained. The best models for CV adsorption onto the V2O5-g-C3N4 nanocomposite were found to be those based on pseudo-second-order adsorption kinetics and the Langmuir isotherm. According to the FTIR analysis results, the CV adsorption mechanism was connected to π–π interactions and the hydrogen bond.

Uptake of BF Dye from the Aqueous Phase by CaO-g-C3N4 Nanosorbent: Construction, Descriptions, and Recyclability

Removing organic dyes from contaminated wastewater resulting from industrial effluents with a cost-effective approach addresses a major global challenge. The adsorption technique onto carbon-based materials and metal oxide is one of the most effective dye removal procedures. The current work aimed to evaluate the application of calcium oxide-doped carbon nitride nanostructures (CaO-g-C3N4) to eliminate basic fuchsine dyes (BF) from wastewater. CaO-g-C3N4 nanosorbent were obtained via ultrasonication and characterized by scanning electron microscopy, X-ray diffraction, TEM, and BET. The TEM analysis reveals 2D nanosheet-like nanoparticle architectures with a high specific surface area (37.31 m2/g) for the as-fabricated CaO-g-C3N4 nanosorbent. The adsorption results demonstrated that the variation of the dye concentration impacted the elimination of BF by CaO-C3N4 while no effect of pH on the removal of BF was observed. Freundlich isotherm and Pseudo-First-order adsorption kinetics models best fitted BF adsorption onto CaO-g-C3N4. The highest adsorption capacity of CaO-g-C3N4 for BF was determined to be 813 mg. g−1. The adsorption mechanism of BF is related to the π-π stacking bridging and hydrogen bond, as demonstrated by the FTIR study. CaO-g-C3N4 nanostructures may be easily recovered from solution and were effectively employed for BF elimination in at least four continuous cycles. The fabricated CaO-g-C3N4 adsorbent display excellent BF adsorption capacity and can be used as a potential sorbent in wastewater purification.

Removal of Malachite Green Dye from Aqueous Solution by Catalytic Wet Oxidation Technique Using Ni/Kaolin as Catalyst

In this study, natural Algerian kaolin was used as a support and impregnated with nickel at different loading amounts (2 wt.%, 5 wt.%, and 7 wt.%) in order to prepare a supported catalyst. The wet impregnation technique was used in this preparation; nickel oxide (NiO) was the active phase precursor of the catalyst, and the catalysts were designated as follows: 2%, 5%, and 7% Ni/kaolin. These catalysts were put to the test in catalytic wet peroxide oxidation (CWPO) for degrading the organic contaminant malachite green dye (MG). Analytical techniques such as FTIR spectroscopy, X-ray diffraction, BET, and X-fluorescence were used to examine the structure, morphology, and chemical composition of the support and the produced catalysts. Several parameters, including temperature, catalytic dose, metal loading, hydrogen peroxide volume, and kinetic model were systematically investigated. The combination of improved parameters resulted in a significant increase in the catalytic activity, achieving a high removal rate of MG dye of 98.87%.

Sweep-Out of Tigecycline, Chlortetracycline, Oxytetracycline, and Doxycycline from Water by Carbon Nanoparticles Derived from Tissue Waste

Pharmaceutical pollution has pervaded many water resources all over the globe. The propagation of this health threat drew the researchers' concern in seeking an efficient solution. This study introduced toilet paper waste as a precursor for carbon nanoparticles (CRNPs). The TEM results showed a particle size range of 30.2 nm to 48.1 nm, the BET surface area was 283 m² g^-1, and the XRD pattern indicated cubical-graphite crystals. The synthesized CRNPs were tested for removing tigecycline (TGCN), chlortetracycline (CTCN), oxytetracycline (OTCN), and doxycycline (DXCN) via the batch process. The adsorption equilibrium time for TGCN, DXCN, CTCN, and OTCN was 60 min, and the concentration influence revealed an adsorption capacity of 172.5, 200.1, 202.4, and 200.0 mg g^-1, respectively. The sorption of the four drugs followed the PSFO, and the LFDM models indicated their high sorption affinity to the CRNPs. The adsorption of the four drugs fitted the multilayer FIM that supported the high-affinity claim. The removals of the four drugs were exothermic and spontaneous physisorption. The fabricated CRNPs possessed an excellent remediation efficiency for contaminated SW and GW; therefore, CRNPs are suggested for water remediation as low-cost sorbent.

Influence of Doping-Ion-Type on the Characteristics of Al2O3-Based Nanocomposites and Their Capabilities of Removing Indigo Carmine from Water

Globally, the continuous contamination of natural water resources is a severe issue, and looking for a solution for such a massive problem should be the researcher’s concern. Herein, Al2O3, Al2O3-CuO, Al2O3-NiO, and Al2O3-CoO were prepared via a simple and fast route, utilizing glucose as a capping material. All synthesis conditions were uniform to make the fabricated nanomaterials’ characteristics exclusively influenced by only the ion type. The SEM analysis showed that the particles of the synthesized Al2O3, Al2O3-CuO, Al2O3-NiO, and Al2O3-CoO were all less than 25 nm. The Al2O3-NiO showed the smallest particle size (11 to 14 nm) and the best BET surface area of 125.6 m2 g−1. All sorbents were tested for removing organic pollutants, as exemplified by indigo carmine (IGC) dye. The Al2O3-NiO possessed the highest adsorption capacity among the other sorbents for which it had been selected for further investigations. The IGC sorption reached equilibrium within 2.0 h, and the kinetic study revealed that the IGC removal by Al2O3-NiO nanocomposite fitted the FOM and the LFM. The sorbent showed an experimental adsorption capacity (qt) of 456.3 mg g−1 from a 200 mg L−1 IGC solution and followed the Langmuir model. The thermodynamic findings indicated an endothermic, spontaneous, and physisorption nature. The seawater and groundwater samples contaminated with 5.0 mg L−1 IGC concentrations were fully remediated using the Al2O3-NiO nanocomposite. The reuse study showed 93.3% average efficiency during four successive cycles. Consequently, prepared Al2O3-NiO nanocomposite is recommended for the treatment of contaminated water.

Enhanced adsorptive removal of indigo carmine dye by bismuth oxide doped MgO based adsorbents from aqueous solution: equilibrium, kinetic and computational studies

The IC adsorption mechanism on the Bi2O3 doped MgO nanosorbents occurred through the chemisorption process.