Synthesis, characterization, kinetics and adsorption properties of Pt-Co@GO nano-adsorbent for methylene blue removal in the aquatic mediums using ultrasonic process systems

Preparation magnetic graphene oxide/diethylenetriamine composite for removal of methylene blue from aqueous solutions

Graphene oxide (GO) and its derivatives have several applications in many areas such as environmental and energy materials, water treatment and biomedical technologies. Because of having various polar groups on its surface, GO is considered as an excellent adsorbent. However, for many applications such as adsorption of pollution from aqueous solutions, chemical functionalization of graphene oxide is often a necessary requirement. In the present study, a new composite from graphene oxide, diethylenetriamine (DETA) and silica coated MnFe2O4 nanoparticles (GO/DETA/MnFe2O4@SiO2) was prepared. The structure, thermal stability and magnetic properties of the composite were studied by FT-IR, XRD, SEM, EDS, VSM and TGA spectroscopic methods. The prepared composite showed magnetic property with a saturation magnetization of 3.0 emu/g. The adsorption properties of GO/DETA/MnFe2O4@SiO2 composite for methylene blue (MB) in aqueous solution were studied using batch method. The effects of important parameters on the surface adsorption process of MB, including pH, contact time, adsorbent dosage and initial dye concentration were investigated. The adsorption isotherm was in accordance with Langmuir model showing surface homogeneity of the adsorbent. According to the Langmuir analysis, the maximum adsorption capacity (qm) of GO/DETA/MnFe2O4@SiO2 composite for MB was found to be 243.91 mg/g. The kinetic studies showed that the adsorption was pseudo first-order process. In addition, the thermodynamic studies indicated the adsorption was spontaneous and endothermic process.

One-pot synthesis of g-C3N4/N-doped CeO2 nanocomposites and their potential visible light-driven photocatalytic degradation of methylene blue dye

In the pursuit of efficient photocatalytic materials for environmental applications, a new series of g-C3N4/N-doped CeO2 nanocomposites (g-C3N4/N-CeO2 NCs) was synthesized using a straightforward dispersion method. These nanocomposites were systematically characterized to understand their structural, optical, and chemical properties. The photocatalytic performance of g-C3N4/N-CeO2 NCs was evaluated by investigating their ability to degrade methylene blue (MB) dye, a model organic pollutant. The results demonstrate that the integration of g-C3N4 with N-doped CeO2 NCs reduces the optical energy gap compared to pristine N-doped CeO2, leading to enhanced photocatalytic efficiency. It is benefited from the existence of g-C3N4/N-CeO2 NCs not only in promoting the charge separation and inhibits the fast charge recombination but also in improving photocatalytic oxidation performance. Hence, this study highlights the potential of g-C3N4/N-CeO2 NCs as promising candidates for various photocatalytic applications, contributing to the advancement of sustainable environmental remediation technologies.

High efficiency removal of methyl blue using phytic acid modified graphene oxide and adsorption mechanism

Phytic acid modified graphene oxide (PGO) has encouraging prospect in environmental application. Herein, PGO was fabricated with a simple hydrothermal method and used as adsorbent to remove methyl blue (MB). Elaborate inspection based on the hard-soft acid-base (HSAB) principle, spectroscopic characterization, as well as batch adsorption and fitting were conducted to unravel the adsorption mechanism. Results show, PGO efficiently adsorbs 89.08 mg·g-1 of MB in 22 min. HSAB principle proposes, high electron transfer (ΔN) and energy lowering (ΔE) induce covalent bond (chemical interaction), while low ΔN and ΔE induce electrostatic effect (physical interaction). Accordingly, both the first and second strongest interaction occurs between PA moiety and MB: π electrons of MB flows towards O atom in OH and O(-O-) of PA, respectively. Yet the third strongest interaction happens between GO moiety and MB: electron of O atom in OH group of GO flows towards N atom of MB. Above top three interactions are characterized by prominent ΔN and ΔE implying the formation of covalent bond. However, other interactions yield low ΔN and ΔE, suggesting the presence of electrostatic effect. HSAB principle conclusion was substantiated by FTIR and UV-Vis analyses. These findings confirm that PA modification enhances the adsorption affinity of graphene oxide. Thereby, chemical adsorption induced by physical interaction is proposed. This work may inspire the design of efficient adsorbent based on PGO framework for environmental restoration.

In situ preparation of TiO2/f-MWCNT catalyst using Pluronic F127 assisted sol-gel process for sonocatalytic degradation of methylene blue

In this study, titanium dioxide- Pluronics @F127/functionalized -multi walled carbon nanotubes (TiO₂-F127f-/MWCNT) nanocatalysts were prepared, characterized, and used in methylene blue (MB) degradation under ultrasonic conditions. The characterization studies were performed using TEM, SEM, and XRD analyses to reveal the morphological and chemical properties of TiO₂-F127/MWCNT nanocatalysts. To detect the optimum parameters for MB degradation using TiO₂-F127/f-MWCNT nanocatalysts, several experimental parameters were conducted at various conditions such as different temperatures, pH, catalyst amount, hydrogen peroxide (H₂O₂) concentration, and various reaction contents. Transmission electron microscopy (TEM) analyses showed that TiO₂-F127/f-MWCNT nanocatalysts consisted of a homogenous structure and have a 12.23 nm particle size. The crystalline particle size of TiO₂-F127/MWCNT nanocatalysts was found to be 13.31 nm. Scanning electron microscope (SEM) analyses revealed the surface structure of TiO₂-F127/f-MWCNT nanocatalysts turned to be modified after TiO₂ loaded on MWCNT. Under the optimum conditions; pH: 4, MB concentration: 25 mg/L, H₂O₂ concentration: 30 mol/L, reaction time: and catalyst dose: 24 mg/L, chemical oxygen demand (COD) removal efficiency reached a maximum of 92%. To detect the radical effectiveness, three scavenger solvents were tested. Reuse experiments revealed that TiO₂-F127/f-MWCNT nanocatalysts retained 84.2% catalytical activity after 5 cycles. Gas chromatography-mass spectrometry (GC-MS) was successfully used to identify the generated intermediates. In addition, the GC-MS was successfully used to identify produced intermediates. Based on the experimental results, it has been suggested that •OH radicals are the main active species responsible for the degradation reaction in the presence of the TiO₂-F127/f-MWCNT nanocatalysts.

Pseudomonas alcaliphila NEWG-2 as biosorbent agent for methylene blue dye: optimization, equilibrium isotherms, and kinetic processes

In comparison to physicochemical and chemical methods, microbial dye biosorption is regarded as an eco-effective and economically viable alternative and is a widely applied method due to its high efficiency and compatibility with the environment. Therefore, the idea of this study is to clarify to what extent the viable cells and the dry biomass of Pseudomonas alcaliphila NEWG-2 can improve the biosorption of methylene blue (MB) from a synthetic wastewater sample. The array of Taguchi paradigm has been conducted to ascertain five variables affecting the biosorption of MB by broth forms of P. alcaliphila NEWG. The data of MB biosorption were familiar to the predicted ones, indicating the precision of the Taguchi model's prediction. The maximum biosorption of MB (87.14%) was achieved at pH 8, after 60 h, in a medium containing 15 mg/ml MB, 2.5% glucose, and 2% peptone, with sorting the highest signal-to-noise ratio (38.80). FTIR spectra detected various functional groups (primary alcohol, α, β-unsaturated ester, symmetric NH2 bending, and strong C-O stretching) on the bacterial cell wall that participated in the biosorption of MB. Furthermore, the spectacular MB biosorption ability was validated by equilibrium isotherms and kinetic studies (the dry biomass form), which were derived from the Langmuir model (qmax = 68.827 mg/g). The equilibrium time was achieved in about 60 min, with 70.5% of MB removal. The biosorption kinetic profile might be adequately represented by pseudo-second order and Elovich models. The changes in the bacterial cells before and after the biosorption of MB were characterized using a scanning electron microscope. As realized from the aforementioned data, the bacterium is a talented, effective, eco-friendly, and low-cost bio-sorbent for the decolorization and remedy of an industrial effluent containing MB from an aqueous environment. The current outcomes in the biosorption of MB molecules promote the use of the bacterial strain as viable cells and/or dry biomass in ecosystem restoration, environmental cleanup, and bioremediation studies.

Enhanced photocatalytic degradation of malachite green dye by highly stable visible-light-responsive Fe-based tri-composite photocatalysts

A novel visible-light-sensitive ZnVFeO₄ photocatalyst has been fabricated by the precipitation method at different pH values for the enhanced photocatalytic degradation of malachite green (MG) dye as a representative pollutant under visible light irradiation at neutral pH conditions. The structure and optical characteristics of the prepared photocatalysts were investigated by XRD, FTIR, N2 adsorption-desorption, TEM, diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) analyses. In addition, the photocatalytic activity of ZnVFeO₄ photocatalysts superior the efficiency to be more than that of the mono and bi-metal oxides of iron and iron zinc oxides, respectively. The best sample, ZnVFeO₄ at pH 3, significantly enhances the degradation rate under visible light to be 12.7 × 10^-3 min^-1 and can retain a stable photodegradation efficiency of 90.1% after five cycles. The effect of the catalyst dose and the initial dye concentration on the photodegradation process were studied. This promising behavior under visible light may be attributed to the low bandgap and the decreased electron-hole recombination rate of the ZnVFeO₄ heterostructures. The scavenger experiment confirmed that the hydroxyl radicals induced the MG photodegradation process effectively. Hence, the ZnVFeO₄ is a reliable visible-light-responsive heterostructure photocatalyst with excellent potential for the photodegradation of organic pollutants in wastewater treatment.

Synthesis and application of AuNi@AC nano adsorbents for the removal of Maxilon Blue 5G azo dye from aquatic mediums

In this research, gold-nicel supported on activated carbon (AC) nanoadsorbent (AuNi@AC) synthesized by following a series of physicochemical procedures was prepared for the removal of Maxilon Blue 5G (MB) which is a cationic textile dye. Experimental studies based on parameters specifically pH, contact time, nano catalytic adsorbent particle, initial MB dye concentration and temperature effect were conducted in aqueous solutions in a batch system. AuNi@AC nanoadsorbents (NAs) reached the equilibrium in 30 min under optimum conditions in adsorption of the dye. The pseudo-first, second-order, and intra-particle diffusion models were tested to evaluate a the experimental results. Adsorption kinetics were found to be represented by the pseudo-second-order model, and the maximum adsorption capacity (q_max.) was calculated to be 542.90 mg/g (or 2.041 mmol/g). The synthesized magnetic AuNi@AC nanoadsorbent showed a high-efficiency reusability effect of about 64% after five reuse runs. Also, thermodynamic function parameters such as activation energy (Ea), Gibbs free energy (ΔG *), and entropy (ΔS *) were investigated in the sorption study. After all evaluation of data, it was concluded that the novel AuNi@AC nanoadsorbent could be considered as an effective support material for the removal of various organic pollutants in aquation solution especially for the removal of MB.

Fabrication of activated carbon supported modified with bimetallic-platin ruthenium nano sorbent for removal of azo dye from aqueous media using enhanced ultrasonic wave

Herein, activated carbon supported modified with bimetallic-platin ruthenium nano sorbent (PtRu@AC) was synthesized by a thermal decomposition process and used in the removal of methylene blue (MB) from aqueous solutions. The synthesized nano sorbents were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS) spectroscopic techniques. The data obtained from characterization studies showed that PtRu@AC nano sorbent was highly crystalline and in a form of PtRu alloy with a monodispersed composition. The results indicated that the maximum adsorption capacity (qemax) for the removal of MB with PtRu@AC under optimum conditions was detected to be 1.788 mmol/g (569.4 mg/g). The experimental kinetic results of the study revealed that the adsorption of methylene blue was found to be more compatible with the false second-order model compared to some tested models. Calculations for thermodynamic functions including enthalpy change (ΔHo), entropy change (ΔSo), and Gibbs free energy change (ΔGo) values were performed to get an idea about the adsorption mechanism. As a result, the synthesized PtRu@AC nano adsorbent was detected as a highly effective adsorbent material in the removal of MB from aquatic mediums.

Congo red dye removal from aqueous environment by cationic surfactant modified-biomass derived carbon: Equilibrium, kinetic, and thermodynamic modeling, and forecasting via artificial neural network approach

Herein, it was aimed to optimize, model, and forecast the biosorption of Congo Red onto biomass-derived biosorbent. Therefore, the waste-orange-peels were processed to fabricate biomass-derived carbon, which was activated by ZnCl₂ and modified with cetyltrimethylammonium bromide. The physicochemical properties of the biosorbents were explored by scanning electron microscopy and N₂ adsorption/desorption isotherms. The effects of pH, initial dye concentration, temperature, and contact duration on the biosorption capacity were investigated and optimized by batch experimental process, followed by the kinetics, equilibrium, and thermodynamics of biosorption were modeled. Furthermore, various artificial neural network (ANN) architectures were applied to experimental data to optimize the ANN model. The kinetic modeling of the biosorption offered that biosorption was in accordance both with the pseudo-second-order and saturation-type kinetic model, and the monolayer biosorption capacity was calculated as 666.67 mg g^-1 at 25 °C according to Langmuir isotherm model. According to equilibrium modeling, the Freundlich isotherm model was better fitted to the experimental data than the Langmuir isotherm model. Moreover, the thermodynamic modeling revealed biosorption took place spontaneously as an exothermic process. The findings revealed that the best ANN architecture trained with trainlm as the backpropagation algorithm, with tansig-purelin transfer functions, and 14 neurons in the single hidden layer with the highest coefficient of determination (R² = 0.9996) and the lowest mean-squared-error (MSE = 0.0002). The well-agreement between the experimental and ANN-forecasted data demonstrated that the optimized ANN model can predict the behavior of the anionic dye biosorption onto biomass-derived modified carbon materials under various operation conditions.

A green and sensitive guanine-based DNA biosensor for idarubicin anticancer monitoring in biological samples: A simple and fast strategy for control of health quality in chemotherapy procedure confirmed by docking investigation

Drug efficiency can be considerably boosted while adverse effects can be reduced by precisely monitoring the concentration of anti-cancer drugs. Thus, one of the most important parameters for human health is the monitoring and detection of anticancer drugs during chemotherapy treatment. Herein, a glassy carbon electrode (GCE) was modified by Pt- and Pd-incorporated ZnO nanoparticles-decorated single-wall carbon nanotubes (Pt-Pd-ZnO/SWCNTs) nanocomposites, and ds-DNA (Calf Thymus) that was a biological recognition element, and it was aimed to be utilized as an ultrasensitive and effective electroanalytical biosensor for idarubicin (IDR) monitoring. Various physicochemical characterization techniques including transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS) were used to investigate the morphology and structure of the Pt-Pd-ZnO/SWCNTs nanocomposite, which was produced via straightforward chemical precipitation combined with the one-pot method. The layer-by-layer modification technique was implemented to fabricate the ds-DNA/Pt-Pd-ZnO/SWCNTs/GCE to be further utilized as a voltammetric sensor for sensitive monitoring of idarubicin in biological fluids and pharmaceutical substances. The electroanalytical method implemented to detect idarubicin was based to detect the ds-DNA's guanine base signal on the surface of the modified electrode in the absence and presence of the anticancer drug. The results explicated that the developed biosensor performed well in determining idarubicin in concentrations ranging from 1.0 nM to 65 μM, with a detection limit of 0.8 nM. The idarubicin detection ability of the modified electrode in real samples was evaluated, and the recovery data was acquired in the range of 98.0% and 104.75%. In the final step, the preferential intercalative binding mode of idarubicin drug with ds-DNA was approved by molecular docking study. This study paves the way for engineering highly sensitive DNA biosensors to be employed in the monitoring of anticancer drugs by combining the benefits of nanocomposites and valuable information of a molecular docking study.

Charge-driven interaction for adsorptive removal of organic dyes using ionic liquid-modified graphene oxide

A facile approach is presented to synthesize the ionic liquid-grafted graphene oxide (GO-ImOH) for fast and efficient adsorptive removal of cationic dyes. A coupling reaction between the hydroxyl terminal of imidazolium ionic liquid and the carboxylic group of GO, yielded the GO-ImOH hybrid material. The higher surface negative charge (-32 mV) and excellent dispersibility make the GO-ImOH an efficient adsorbent for cationic dyes. The GO-ImOH showed excellent removal efficiency for methylene blue (cationic dye), whereas it could adsorb only 22% methyl orange (anionic dye). The GO-ImOH displayed significantly higher adsorptive removal capacity for cationic dye compared to that of GO adsorbent. The chemical and structural features of GO-ImOH and spectroscopic analyses (FTIR and Raman) of pristine and recovered GO-ImOH adsorbent suggested multiple adsorptive interaction pathways (electrostatic, π-cation, π-π interactions, and hydrogen linkages) between the GO-ImOH adsorbent and the dye molecules. The work paves a new direction for the development of ionic liquids-modified 2D nanomaterials for efficient and fast adsorptive removal of organic pollutants, where the adsorptive sites on the surface of 2D nanomaterials can be tuned by selecting the desired functionalities from a diversified library of cations and anions of ionic liquids.

Nano-adsorbents an effective candidate for removal of toxic pharmaceutical compounds from aqueous environment: A critical review on emerging trends

Advancements in medical research has resulted in the modernization of healthcare facilities, subsequently leading to a higher level of production and usage of pharmaceuticals to sustain better quality of life. Pharmaceutical active compounds (PhACs) possess high genotoxicity and eco-toxicity thus presenting numerous side effects to living beings on long-term exposure. The fate and toxicity of PhACs were explored in detail, aiming to elucidate their occurrence and transmission in wastewater treatment systems (WWTPs). Adsorption of pharmaceutical compounds using Nano-adsorbents has gained momentum in recent years owing to their low-cost, high surface area and effectiveness. This review has been conducted in order to widen the utilization of Nano adsorbents in the adsorption of pharmaceutical compounds with a focus on the aqueous environment. The synthesis routes and properties of Nano-adsorbents for removal of PhACs were assessed in a comprehensive way. The recovery and reuse ability of nano-adsorbents also forms an integral part of its application in the removal of PhACs and has hence been delineated.

Photocatalytic Degradation of the Light Sensitive Organic Dyes: Methylene Blue and Rose Bengal by Using Urea Derived g-C3N4/ZnO Nanocomposites

In this study, we report the fabrication of graphitic carbon nitride doped zinc oxide nanocomposites, g-C3N4/ZnO, (Zn-Us) by using different amount of urea. They were further characterized by X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman, UV-vis, Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) techniques. The prepared nanocomposites were used as photocatalysts for the mineralization of the light sensitive dyes Methylene Blue (MB) and Rose Bengal (RB) under UV light irradiation, and corresponding photo-mechanism was proposed. Benefiting from these photocatalytic characteristics, urea derived g-C3N4/ZnO photocatalysts have been found to have excellent photodegradation activity against the MB and RB for 6 h and 4 h, respectively. Under the given experimental conditions, the degradation percentage of fabricated Zn-Us were shown ~90% for both model dyes. Compared to cationic MB dye, anionic RB dye is more actively degraded on the surface of prepared photocatalysts. The results obtained can be effectively used for future practical applications in wastewater treatment