Simultaneous ultrasonic-assisted removal of malachite green and methylene blue from aqueous solution by Zr-SBA-15

Tuning the Acid-Base Properties of Lignin-Derived Carbon Modulated ZnZr/SiO2 Catalysts for Selective and Efficient Production of Butadiene from Ethanol

The direct selective conversion of ethanol to butadiene (ETB) is a competitive and environmentally friendly process compared to the traditional crude cracking route. The acid-base properties of catalysts are crucial for the direct ETB process. Herein, we report a rationally designed multifunctional lignin-derived carbon-modulated ZnZr/SiO2 (L-ZnZr/SiO2) catalyst with suitable acid-base properties for the direct ETB reaction. A variety of characterization techniques are employed to investigate the relationship between the acid-base properties and catalytic performance of the multifunctional lignin-modulated ZnZr/SiO2 catalysts. The results revealed that the rationally additional lignin-modulated carbon enhances both the acidity and basicity of the ZnZr/SiO2 catalysts, providing a suitable acid-base ratio that boosts the direct ETB reactivity. Meanwhile, the 1% L-ZnZr/SiO2 catalyst possessed ethanol conversion and butadiene selectivity as high as 98.4% and 55.5%, respectively, and exhibited excellent catalytic stability.

Adsorptive removal of malachite green dye from aqueous solution using Rumex abyssinicus derived activated carbon

The potential for malachite green dye saturated effluent to severely affect the environment and human health has prompted the search for effective treatment technologies. Thus, this study was conducted with the goal of developing activated carbon from Rumex abyssinicus for the adsorptive removal of malachite green dye from an aqueous solution. Unit operations such as drying, size reduction, impregnation with H3PO4, and thermal activation were used during the preparation of the activated carbon. An experiment was designed considering four main variables at their respective three levels: initial dye concentration (50, 100, and 150 mg/L), pH (3, 6, and 9), contact period (20, 40, and 60 min), and adsorbent dosage (0.05, 0.01, and 0.15 g/100 mL). Optimization of the batch adsorption process was carried out using the Response Surface methodology's Box Behnken approach. The characterization of the activated carbon was described by SEM for surface morphology with cracks and highly porous morphology, FTIR for multi-functional groups O-H at 3506.74 cm-1 and 3290.70 cm-1, carbonyl group stretching from aldehyde and ketone (1900-1700 cm-1), stretching motion of aromatic ring C=C (1543.12 cm-1), stretching motion of -C-H (1500-1200 cm-1), vibrational and stretching motion of -OH (1250.79 cm-1), and vibrational motion of C-O-C (1049.32 cm-1), pHpzc of 5.1, BET for the specific surface area of 962.3 m2/g, and XRD for the presence of amorphous structure. The maximum and minimum dye removal efficiencies of 99.9% and 62.4% were observed at their respective experimental conditions of (100 mg/L, 0.10 mg/100 mL, pH 6, and 40 min) and (100 mg/L, 0.15 mg/100 mL, pH 3, and 20 min), respectively. Langmuir, Freundlich, Toth, and Koble-Corrigan models were used to evaluate the experimental data, in which Koble-Corrigan model was found to be the best fit with the highest value of R2 0.998. In addition to this, the kinetic studies were undertaken using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Boyd models, and as a result, the pseudo-second-order model proved to have a better fit among the kinetic models. The kinetics and isotherm analysis revealed that the nature of the adsorption to be homogenous and monolayer surfaces driven by chemosorption. Furthermore, the thermodynamics study revealed the nature of adsorption to be feasible, spontaneous, and endothermic. On the other hand, the reusability study depicted the fact that the adsorbent can be utilized for five cycles with a negligible drop in the removal efficiencies from 99.9 to 95.2%. Finally, the low-cost, environmentally benign, and high adsorption capacity of the adsorbent material derived from Rumex abyssinicus stem could be used to treat industrial effluents.

Activation of bisulfite by LaFeO3 loaded on red mud for degradation of organic dye

In this study, red mud (RM) was used as a support for LaFeO₃ to prepare LaFeO₃-RM via the ultrasonic-assisted sol-gel method for the removal of methylene blue (MB) assisted with bisulfite (BS) in the aqueous solution. Characterization by scanning electron microscopy and the Brunauer-Emmett-Teller method indicated that LaFeO₃-RM exhibited a large surface area and porous structure with a higher pore volume (i.e. 10 times) compared with the bulk LaFeO₃. The XRD, XPS and FTIR results revealed that the support of porous RM not only dispersed LaFeO₃ particles but also increased Fe oxidation capability, oxygen-containing functional groups and chemically adsorbed oxygen (from 44.3% to 90.3%) of LaFeO₃-RM, which improved the catalytic performance in structure and chemical composition. MB was removed through the synergistic effect of adsorption and catalysis, with MB molecules first absorbed on the surface and then degraded. The removal efficiency was 88.19% in the LaFeO₃-RM/BS system under neutral conditions but only 27.09% in the LaFeO₃/BS system. The pseudo-first-order kinetic constant of LaFeO₃-RM was six times higher than that of LaFeO₃. Fe(III) in LaFeO₃-RM played a key role in the activation of BS to produce SO 4 ⋅ - by the redox cycle of Fe(III)/Fe(II). Dissolved oxygen was an essential factor for the generation of SO 4 ⋅ - . This work provides both a new approach for using porous industrial waste to improve the catalytic performance of LaFeO₃ and guidance for resource utilization of RM in wastewater treatment.

Optimization of dyes and toxic metals removal from environmental water samples by clinoptilolite zeolite using response surface methodology approach

The present study aimed to remove crystal violet (CV), malachite green (MG), Cd(II), and Pb(II) from an aqueous solution using clinoptilolite zeolite (CZ) as an adsorbent. Response surface methodology (RSM) based on central composite design (CCD) was used to analyze and optimize the process parameters, such as pH, analyte concentration, adsorbent amount, and sonication time. Quadratic models with the coefficient of determination (R2) of 0.99 (p < 0.0001) were compared statistically. The results revealed that the selected models have good precision and a good agreement between the predicted and experimental data. The maximum removal of contaminants was achieved under optimum conditions of pH = 6, sonication time of 22 min, the adsorbent amount of 0.19 g, and analyte concentration of 10 mg L-1. The reusability test of the adsorbent showed that the CZ adsorbent could be used 5 times in water and wastewater treatment processes. According to the results of interference studies, the presence of different ions, even at high concentrations, does not interfere with the removal of contaminants. Applying the CZ adsorbent on environmental water samples revealed that CZ adsorbent could remove CV, MG, Cd(II), and Pb(II) in the range of 84.54% to 99.38% and contaminants present in industrial effluents. As a result, the optimized method in this study can be widely used with high efficiency for removing CV, MG, Cd(II), and Pb(II) from water and wastewater samples.

Green biosynthesis of magnetic iron oxide nanoparticles using Mentha longifolia for imatinib mesylate delivery

In this work, the rapid, facile, and eco-friendly green process was introduced in the preparation of β-cyclodextrin/magnetic iron oxide nanoparticles by using the aqueous Mentha longifolia extracts of Mentha longifolia. The obtained nanoparticles were characterised by Fourier transform infrared spectroscopy, x-ray powder diffraction, field emission scanning electron microscope, and thermogravimetric analysis. Also, effective factors on the synthesis of magnetic nanocomposites including temperature, concentration of the Mentha longifolia extract, and concentration of FeSO₄ solution were optimised by Taguchi design. Moreover, important effective parameters on the adsorption efficiency; such as adsorbent dosage, pH, contact time, and temperature were investigated. The prepared magnetic nanocomposite was applied as a nanocarrier for imatinib mesylate delivery. In vitro studies confirmed imatinib mesylate release over 6 h. The nanocarrier showed pH-dependent imatinib mesylate release with higher drug release at simulated cancer fluid (pH = 5.6) compared to neural fluid (pH = 7.4). Moreover, the sorption isotherms and kinetics for the magnetic nanocomposite were fitted into Langmuir and pseudo-second order models, respectively. Based on the thermodynamic results, the adsorption of imatinib mesylate onto the nanoadsorbent was found to be spontaneous and exothermic.

Effective mitigation of single-component and mixed textile dyes from aqueous media using recyclable graphene-based nanocomposite

The present study reported the synthesis and utilization of a graphene-based hybrid nanocomposite (MnFe₂O₄/G) to mitigate several synthetic dyes, including methylene blue, malachite green, crystal violet, and Rhodamine B. This adsorbent was structurally analyzed by several physicochemical techniques such as X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, Raman spectroscopy, N₂ adsorption-desorption isotherm measurement, point of zero charge, and Boehm titrations. BET surface area of MnFe₂O₄/G was measured at 382.98 m²/g, which was substantially higher than that of MnFe₂O₄. MnFe₂O₄/G possessed diverse surface chemistry properties with the presence of many functional groups such as carboxylic acid, phenolic, lactone, and basic groups. MnFe₂O₄/G was used to remove synthetic dyes in the aqueous media. The effect of many factors, e.g., concentration (5-50 mg/L), pH (4-10), dose (5-20 mg), and temperature (25-45 °C) on adsorption performance of MnFe₂O₄/G was conducted. Kinetic, isotherm, intraparticle, and thermodynamic models were adopted for investigating adsorption phenomenon of dyes on MnFe₂O₄/G. The maximum adsorption capacity of dyes over MnFe₂O₄/G was found as Rhodamine B (67.8 mg/g) < crystal violet (81.3 mg/g) < methylene blue (137.7 mg/g) < malachite green (394.5 mg/g). Some tests were performed to remove mixed dyes, and mixed dyes in the presence of antibiotics with total efficiencies of 65.8-87.9% after 120 min. Moreover, the major role of π-π stacking interaction was clarified to gain insight into the adsorption mechanism. MnFe₂O₄/G could recycle up to 4 cycles, which may be beneficial for further practical water treatment.

Rapid and Efficient Removal of Anionic Dye in Water Using a Chitosan-Coated Iron Oxide-Immobilized Polyvinylidene Fluoride Membrane

Anionic dyes are one of the most serious contaminants in water as these molecules are known to be toxic to many living organisms. Herein, we report the development of functionalized polyvinylidene fluoride membranes modified with chitosan-coated iron oxide nanomaterials (Fe-PVDF) for the efficient treatment of anionic dye-contaminated water. Aqueous solutions of anionic dyes could be captured rapidly by passing through the functionalized membrane under reduced pressure. Under neutral conditions, Fe-PVDF showed a maximum removal capacity of 74.6 mg/g for Evans blue (EB) through the adsorption process. In addition, the adsorption capacity was significantly enhanced up to 434.78 mg/g under acidic conditions. The adsorption process for EB matched well with the Langmuir model, indicating monolayer adsorption of the dye to the membrane surface. Moreover, Fe-PVDF can be reusable by a simple washing step in an alkaline solution, and thus, the composite membrane was applied several times without a significant decrease in its adsorption performance. The same composite membrane was further applied to the removal of five other different anionic dyes with high efficiencies. The adsorption mechanism can be explained by the electrostatic interaction between the positively charged chitosan and the negatively charged dye as well as the affinity of the sulfate groups in dye molecules for the surface of the iron oxide nanoparticles. The easy preparation and rapid decolorization procedures make this composite membrane suitable for efficient water treatment.

Adsorptive decontamination of doxycycline hydrochloride via Prosopis juliflora activated carbon: Parameter optimization and disposal study

This study deals with the removal of doxycycline hydrochloride (DOX) antibiotic, from aqueous environment by using Prosopis juliflora activated carbon (PJAC). PJAC was synthesized by chemical activation and pyrolysis of Prosopis juliflora. It was characterized by employing Fourier transform infrared spectroscopy (FTIR), scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX), X-ray diffraction analysis (XRD), and Brunauer-Emmett-Teller (BET) techniques. The specific surface area, pore volume, and pore diameter were evaluated as 320.45 m² /g, 0.176 cm³ /g, and 2.65 nm, respectively. Different functional groups (O-H, C-O, C=C, C-N, and C-C) present on PJAC promoted the adsorption of DOX. The influence of various adsorption parameters suggested by central composite design (CCD) model was determined using response surface methodology (RSM), and interactive effects of these were optimized. The thermodynamic and kinetic studies performed at optimized conditions, exhibited that adsorption was spontaneous and endothermic. The experimental data were well described with Langmuir, Redlich-Peterson, and Freundlich isotherm models while kinetics data were well described by pseudo second order. The excellent interactions between the PJAC and DOX resulted maximum adsorption capacity as 57.11 mg/g. The adsorption mechanisms was dominated by π - π interactions and hydrogen bonding. Moreover, almost complete encapsulation of DOX was achieved by stabilization of exhausted PJAC. PRACTITIONER POINTS: A wild harmful plant Prosopis juliflora was used to synthesize a low-cost and eco-friendly bio-sorbent PJAC. Adsorptive ability of PJAC was quantified for adsorption of DOX antibiotic from its aqueous solution. DOX uptake on PJAC was mainly governed by л-л EDA interactions and hydrogen bonding.

From Microurchins to V2O5 Nanowalls: Improved Synthesis through Vanadium Powder and Fast, Selective Adsorption of Methylene Blue

Research on synthesizing micro- and nanosized materials directly from metals has attracted considerable attention because of its simplicity, ability to synthesize in large quantities, and high uniformity. This study proposes a simple method to synthesize high-uniformity or high-density V₂O₅ microurchins and nanowalls directly from vanadium powder. Remarkably, the synthesis condition of 60 °C for 1 h is considered to be an optimal condition to convert metals into micro- or nano-oxides. The as-synthesized V₂O₅ nanowalls can adsorb nearly 90% of methylene blue in the dark in 3 min. The adsorption selectivity of these samples with several pigments is investigated.

Direct synthesis of dimethyl ether from CO2 hydrogenation over a highly active, selective and stable catalyst containing Cu–ZnO–Al2O3/Al–Zr(1 : 1)-SBA-15

A green and sustainable method to valorize CO2 into dimethyl ether on a very active and stable CZA/Al–Zr(1 : 1)-SBA-15 trifunctional catalyst.

Recent developments in metal-doped SBA-15 catalysts for heterogeneous catalysis and sustainable chemistry

The development of new advanced sustainable materials for heterogeneous catalysis requires control of the structural parameters of the active sites. Mesoporous silica, especially SBA-15, has some unique and important features such as highly ordered mesopores, greater hydrothermal stability, greater wall thickness, large surface area, and adjustable pore volume. All these properties render it a promising material for catalysis, adsorption, supporting materials, biomedical applications, and environmental remediation. However, pure SBA-15 lacks acidic characteristics, which hinders its catalytic activity. Therefore, the functionalized SBA-15 improves the catalytic activity for versatile applications. Thus, in this study, we attempted to summarize the synthesis procedures, various functionalization processes, and application of metal-modified SBA-15 in organic synthesis, fine chemical synthesis, photocatalysis, and decontamination of water. Furthermore, the physicochemical properties, sustainability, and efficacy are discussed in detail for future reference and scope of studies.

Response surface methodology optimizing the adsorptive removal of azithromycin using mesoporous silica SBA-15: Mechanism, thermodynamic, equilibrium, and kinetics modeling studies

The objective of this research was to study an effective adsorbent for removing azithromycin (AZT) from industrial wastewater. AZT is an antibiotic used for many diseases remedy, but it is a pollutant to our environment; therefore, its residual should be removed from wastewater. The mesoporous SBA-15 silica as an efficient adsorbent was prepared by the hydrothermal method. The surface of mesoporous SBA-15 plays a significant role in the removal process; therefore, the characterization of the adsorbent was accomplished by several techniques. The batch system has been used, and the effect of four essential variables: pH (3-10), drug concentration (20-200 mg L^-1), sorbent weight (0.2-2 g L^-1), and temperature (20-40 °C) were investigated on the AZT removal efficiency by response surface methodology (RSM). The isotherm results were found to be in proper compliance with the isotherm model of Freundlich. In the kinetics part of this study, the experimental outcomes were fitted to the equation model of pseudo-second-order. The calculation of thermodynamic parameters shows that the removal process is spontaneous and endothermic. Upon the results, the vast surface area, the active functional groups, reusability, stability, and inexpensively make the mesoporous SBA-15 a suitable candidate for removal of AZT and similar antibiotics.

Investigating Methylene Blue Removal from Aqueous Solution by Cysteine-Functionalized Mesoporous Silica

In this study, mesoporous silica nanoparticles (MSNs) were synthesised using the Stober method and functionalised with cysteine (MSN-Cys) for removal of Methylene Blue (MB) from aqueous solution using the batch method. The adsorbent nanoparticles were characterised by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), FTIR, BET, and TGA. Several influential factors on the adsorption of MB onto the surface of MSN-Cys particles were investigated, including pH, initial concentration, and contact time. The adsorption capacity of MB from aqueous solution increased from circa 70 mg/g MSN-Cys in acidic media to circa 140 mg/g MSN-Cys in basic media. Adsorption isotherms and kinetic models of adsorption were used to clarify the adsorption process. The measured adsorption isotherm was fitted with a Freundlich model for all solutions, and the kinetic model was determined to be pseudo-second-order.

Drug delivery of amoxicillin molecule as a suggested treatment for covid-19 implementing functionalized mesoporous SBA-15 with aminopropyl groups

SARS-CoV-2 is a novel coronavirus that was isolated and identified for the first time in Wuhan, China in 2019. Nowadays, it is a worldwide danger and the WHO named it a pandemic. In this investigation, a functionalization post-synthesis method was used to assess the ability of an adapted SBA-15 surface as a sorbent to load the drug from an aqueous medium. Different characterization approaches were used to determine the characterization of the substance before and after functionalization such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), nitrogen adsorption–desorption porosimetry (Brunauer–Emmett–Teller) BET surface area analysis, and thermal gravimetric analysis (TGA). Batch adsorption testing was carried out in a single adsorption device to find the impact of multiple variables on the drug amoxicillin charge output. The following parameters were studied: 0–72 hr. contact time, 20–120 mg/l initial concentration, and 20–250 mg of NH₂-SBA-15 dose. The outcomes from such experiments revealed the strong influence and behavior of the amino-functional group to increase the drug's load. Drug delivery outcomes studies found that amoxicillin loading was directly related to NH₂-SBA-15 contact time and dose, but indirectly related to primary concentration. It was observed that 80% of amoxicillin was loaded while the best release test results were 1 hour and 51%.

Fabrication of a Smartphone-Based Spectrophotometer and Its Application in Monitoring Concentrations of Organic Dyes

In this study, an in-house constructed paper-based spectrophotometer is presented and demonstrated for detecting three organic dyes, namely, methylene blue, malachite green, and rhodamine B, and monitoring the efficiency of their removal from a wastewater sample with Sistan sand as a costless adsorbent. The compact design and light weight of this simple spectrophotometer delivered portability, with materials costing less than a dollar. Spectral analysis of the captured images was performed using free downloadable software from the Google Play store. The main experimental parameters affecting the efficiency of dye adsorption including pH, sorbent dosage, initial dye concentration, and contact time were investigated and optimized using the Taguchi design experimental method. Validation experiments were performed using a standard commercial bench-top spectrophotometer, and results were compared in terms of analytical performance, speed, and cost of analysis. The smartphone-based spectrometer was able to measure accurately, as confirmed using the commercial spectrometer, with enhanced sensitivity for methylene blue and rhodamine B. The combination of the high spectral accuracy of the paper-based spectrophotometer, together with sand as a readily accessible sorbent, enabled us to develop a powerful yet simple approach and tool for the removal and monitoring of dyes within wastewater samples, which is potentially available to everybody who owns a smartphone.

Fabrication of Ceramsite Adsorbent from Industrial Wastes for the Removal of Phosphorus from Aqueous Solutions

A more applicable adsorbent was fabricated using industrial wastes such as red mud, fly ash, and riverbed sediments. The heavy metal inside the raw materials created metal hydroxy on the adsorbent surface that offered elevated adsorption capacity for phosphorus. The required equilibrium time for the adsorption is only 10 min. The theoretical maximum adsorption capacity of the adsorbent was 9.84 mg·g−1 inferred from the Langmuir adsorption isotherm. Higher solution pH favored phosphorus adsorption. Kinetics study showed that the adsorption could be better fitted by the pseudo-second-order kinetic model. The presence of coexisting anions had no significant adverse impact on phosphorus removal. The speciation of the adsorbed phosphorus indicated that the adsorption to iron and aluminum is the dominating adsorption mechanism. Moreover, a dynamic adsorption column experiment showed that, under a hydraulic time of 10 min, more than 80% of the phosphorus in the influent was removed and the surplus phosphorus concentration was close to 0.1 mg L−1. The water quality after adsorption revealed its applicability in real treatment. Consequently, the adsorbent synthesized from industrial wastes is efficient and applicable due to the high efficiency of phosphorus removal and eco-friendly behavior in solutions.

New MOF/COF Hybrid as a Robust Adsorbent for Simultaneous Removal of Auramine O and Rhodamine B Dyes

In this study, by hybridization of zinc-based metal-organic framework-5 (MOF-5) and melamine-terephthaldehyde-based intergrade two-dimensional π-conjugated covalent organic framework (COF), a novel MOF-5/COF (M5C) hybrid material was prepared and characterized by Fourier transform infrared, field emission scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. MOF-5 has a well-defined cubic structure, and the proposed COF has an orderly and spherical nanosize shape. The prepared MOF-5/COF was applied as an effective adsorbent for rapid and high-efficient simultaneous removal of auramine O (AO) and rhodamine B (RB) cationic dyes via electrostatic, H-bonding, Lewis acid-base interactions, and π-π stacking from aqueous solution. The effect of experimental parameters such as pH, M5C mass, contact time, and AO and RB dyes concentration was investigated for removal efficiency and optimized. The M5C adsorbent showed an adsorption capacity of 17.95 and 16.18 mg/g for AO and RB dyes, respectively, at pH 9.5. The adsorption study of AO and RB dyes by M5C comprises both isotherm and kinetic studies. The equilibrium adsorption data followed by Langmuir isotherm and the adsorption kinetic process were found to be a pseudo-second-order model. The robustness adsorption efficiency of MOF/COF hybrids can be attributed to the formation of amide bonds between COF and MOFs, which improve the stability of the adsorbent.