Dye In Aqueous Solution Research Articles

Synthesis and investigation of optical properties and enhancement photocatalytic activity of TiO2-SnO2 semiconductor for degradation of organic compounds.

Industrial wastewater treatment using UV irradiation in combination with oxidants or catalysts (TiO2) has attracted attention as a promising substitute for conventional methods. Studying the preparation and characterization of TiO2-SnO2 nanocomposites with different ratios, as well as their use in the enhanced photocatalytic degradation of acid red 37 dye in aqueous solution under UV irradiation as a model pollutant, are the goals of the research. The crystalline structures of the prepared nanomaterials were confirmed by XRD and the surface morphology of the samples was studied by TEM. The elemental compositions of the catalysts were confirmed by EDAX. The optical properties of the powder samples were analyzed with UV-Vis spectroscopy and their band gaps were estimated. The photocatalytic degradation was investigated using several advanced oxidation techniques using a batch photoreactor. The TiO2-SnO2 (90:10) nanocomposite showed the best degradation efficiency.

Fabrication of Multifunctional Green-Synthesized Copper Oxide Nanoparticles Using Rumex vesicarius L. Leaves for Enhanced Photocatalytic and Biomedical Applications

Recently, the use of plant extracts has emerged as an innovative approach for the production of various nanoparticles. Enhancing green methods for synthesizing copper oxide (CuO) nanoparticles (NPs) is a key focus in the field of nanotechnology. This study presents a novel and eco-friendly synthesis of CuO NPs using Rumex vesicarius L. leaf extracts, offering a cost-effective and efficient method. The synthesized CuO NPs were evaluated for their cytotoxic effects against human cervical carcinoma (HeLa) cells, as well as their photocatalytic and antimicrobial activities. The morphology, size, and structural properties of the CuO NPs were characterized using various analytical techniques. X-ray diffraction (XRD) analysis confirmed the pure crystalline structure of the CuO NPs with a size of 19 nm, while transmission electron microscopy (TEM) showed particle sizes ranging from 5 to 200 nm. The photocatalytic performance of the CuO NPs was assessed through the photodegradation of crystal violet (CV) and methylene blue (MB) dyes under UV light. The NPs exhibited excellent decolorization efficiency, effectively degrading dyes in aqueous solutions under irradiation. Furthermore, the green-synthesized CuO NPs displayed strong antibacterial and antifungal activities against a variety of human pathogens. They also demonstrated significant dose-dependent cytotoxicity against the HeLa cancer cell line, with an IC50 value of 8 ± 0.54 μg/mL.

La-supported SnO2–CaO composite catalysts for efficient malachite green degradation under UV–vis light

This study presents the development and optimization of La@SnO2–CaO composite catalysts for efficient photocatalytic degradation of malachite green dye in aqueous solutions under UV–vis light irradiation. The catalysts were prepared via conventional incipient-wetness impregnation and thoroughly characterized using advanced analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, N2 adsorption–desorption analysis, and scanning electron microscopy. To optimize photodegradation efficiency, the effects of three independent factors were systematically investigated using response surface methodology: Temperature, pH, and Sn/Ca molar ratio. Our results reveal optimal conditions for maximum dye degradation: pH 7, Sn/Ca molar ratio of 0.33, and a process time of 35 min, resulting in a maximum photodegradation efficiency of 98.80% for malachite green dye. Notably, visible light exhibited a more pronounced effect on dye degradation compared to UV light over time, with visible light achieving 25% greater dye removal after 60 min of illumination. Furthermore, the catalyst showed excellent recyclability, retaining 85% of its initial activity after five consecutive cycles. These findings contribute significantly to the development of sustainable methods for dye removal from wastewater and highlight the potential of La@SnO2–CaO composite catalysts in environmental remediation processes, particularly in treating textile industry effluents.

Development of an eco-friendly geopolymer mortar using slag and fly ash with high bentonite content for thermal and environmental applications

The construction industry is exploring the use of low-cost waste materials to create eco-friendly geopolymer mortar binders. Our study aims to develop various environmentally friendly geopolymer mortar mixes for thermal and adsorption applications using natural materials like bentonite and industrial by-products such as ground-granulated blast furnace slag and fly ash. Ternary geopolymer mortar pastes are prepared using equimolar amounts of slag (GBFS) and fly ash (FA), with 6%, 8%, 10%, and 12% weight of bentonite (BC) from the total geopolymer weight to study the bentonite replacement effect. The prepared mortar are tested for their physico-chemical, mechanical, adsorption, and thermal stability properties (300 °C to 900 °C). The adsorption behavior of eco-friendly geopolymer mortar mixes against crystal violet dye in aqueous solutions is also identified. The study found that adding 6% bentonite to the slag/fly ash-based geopolymer mortar mix yielded the highest mechanical characteristics. Moreover, all the ternary geopolymer mortar mixes exhibited excellent thermal stability up to 900 °C. In adsorption study, the results indicated that the mortar mixes had excellent capacities and adhered well to the Freundlich isotherm model, suggesting potential applications in treating wastewater. Using bentonite in slag/fly ash geopolymer mortar offers a sustainable, cost-effective, and heat-resistant alternative to traditional cement binders.

Crowding for Confinement: Reversible Isomerization of First-Generation Donor-Acceptor Stenhouse Adduct Derivatives in Water Modulated by Thermoresponsive Dendritic Macromolecules.

Mimicking nature, the reversible isomerization of hydrophobic dyes in aqueous solutions is appealing for bio-applications. Here, we report on the reversible isomerization of first-generation solvatochromic donor-acceptor Stenhouse adducts (DASAs) in water within dendritic matrices, realized either through the dendronization of DASAs or the incorporation of DASA pendants into dendronized copolymers. These dendritic macromolecules contain three-fold dendritic oligoethylene glycols (OEGs), which afford the macromolecules water-solubility and unprecedented thermoresponsive behavior. The thermoresponsive behavior of both dendronized DASAs and dendronized copolymers is dominated by the peripherals of dendritic OEGs. However, the hydrophilicity of the acceptor from DASA moieties also play a role in mediating their thermal phase transitions, and more importantly, tailor the hydrophobic interactions between dendritic OEGs and DASA moieties. Intriguingly, dendritic topologies contribute confinement to encapsulate the DASA moieties through crowding effects, and cooperative interactions from the crowded dendritic OEGs modulate the DASA moieties with different isomerization in aqueous media. The thermally induced collapse of dendritic OEGs, accompanied by the aggregation of dendritic macromolecules, leads to the formation of hydrophobic domains, which exert enhanced crowding effects to efficiently encapsulate the DASA moieties. Compared to the low molar mass of dendronized DASAs, thermally collapsed dendronized copolymers can efficiently retard the hydration of DASA pendants through cooperation between neighboring dendritic OEGs and afford the DASA pendants with better confined microenvironments to mediate their isomerization recovery by up to 90% from a cyclic charged (hydrophilic) state into a noncharged (hydrophobic) linear state in water. This dendritic confinement exhibits excellent fatigue resistance after several cycles of alternating photo-irradiation and thermal annealing at elevated temperatures.

Physical and enhanced photocatalytic MO dye degradation behaviour of Zn doped β-Ga2O3 microrods

This work explored the effects of Zn doping on the structural, micrographic, optical and photocatalytic behaviour of gallium oxide (β-Ga2O3) microrods. The X-ray diffractogram (XRD) and Raman spectral analyses confirmed the monoclinic structure of β-Ga2O3, with a shift to lower angles in the XRD pattern indicating Zn incorporation into the Ga2O3 lattice. The Scanning electron microscopy (SEM) images revealed a rod-like shape, with the diameter decreasing from 604 nm to 573 nm with Zn doping. Further analysis using TEM, HR-TEM, SAED, EDX, and elemental mapping confirmed the shape, crystallinity, crystal structure, and elemental distribution. The interplanar spacings were measured as 0.4 and 0.2 nm, corresponding to the (002) and (−311) planes of β-Ga2O3. UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) showed a slight shift in the absorption edge, while photoluminescence (PL) analysis demonstrated strong UV and weak visible light emission. Photocatalytic results revealed a high efficiency of dye degradation,(i.e) 98 % (20 ppm) and 89 % (30 ppm) against methyl orange (MO) dye aqueous solution over 150 min, with a rate constant of 0.02/min and 0.01/min, respectively for 1.5 wt% Zn doping. This suggests that the Zn-doped material holds promise as a photocatalyst for wastewater treatment applications.

Lattice Distortion Creates Enhancements in Photocatalytic and Electrocapacitive Performance of Sol–Gel‐Derived Cu‐Doped NiTiO3

A remarkable 35% enhancement in the photocatalytic and electrocatalytic abilities of an ilmenite nickel titanate (NiTiO3) material is reported. This boost in catalytic performance is achieved by simply creating a static distortion in the rhombohedral unit cell by replacing a small proportion of a small‐size nondegenerate Ni (69 pm) with a large‐size degenerate Cu (73 pm). The materials are synthesized by using a simple sol–gel method. The appropriate doping amount of Cu facilitates the better separation of intrinsic charge carrier pairs by inhibiting their recombination. The photocatalytic and electrochemical activities of durable materials in aqueous MB dye (10 ppm) and KOH (1 molar) electrolyte solutions are found to be directly associated with this improvement in inherent charge carrier transfer characteristics. The enhanced photodissociation of MB dye (42–56%) and specific capacitance (381–450 F g−1) in a KOH (1 molar) electrolyte are in full accord with the investigations carried out using crystallographic and optoelectronic analysis, charging–discharging measurements, and electrochemical impedance (EIS) spectroscopy investigations. Same material with high textural surface areas or controllable particle morphologies might show a far better photo/electrocatalytic performance in a variety of practical applications.

Production of Porous Silica from Rice Husk Using Cetyltrimethylammonium Bromide to Remove Dyes in Aqueous Solution

Production of Porous Silica from Rice Husk Using Cetyltrimethylammonium Bromide to Remove Dyes in Aqueous Solution

Murexide retention and antibacterial performance of semiconductor copolymer/magnetic iron oxide hybrid nanocomposites synthesized via one pot in-situ chemical oxidative polymerization

Herein, semiconductor-magnetic hybrid nanocomposites, poly(vanillin-co-thiophene)/magnetic iron oxide (PVTO-Fe3O4), were successfully synthesized via single-step in situ chemical oxidative polymerization in the presence of different weight percentages of magnetic iron oxide nanoparticles Fe3O4 NPs (3, 6, and 9 wt%). Whereas the Fe3O4 NPs were prepared via an environmentally friendly, modified co-precipitation method, and their physicochemical characteristics were comprehensively analyzed using various analytical techniques. The adsorption behavior of the resulting samples towards murexide dye in aqueous solutions was investigated, along with their antibacterial efficacy against both gram-positive (Staphylococcus aureus and Bacillus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The adsorption study revealed that the nanocomposite containing 9 wt% Fe3O4 NPs achieved the highest removal efficiency for MX (approximately 87.41 %) and exhibited a maximum adsorption capacity of approximately 100.7 mg/g, surpassing many adsorbents reported in the literature. Optimization experiments identified the optimal conditions as 40 mg of adsorbent dose, 40 mL of MX solution (125 mg/L), pH 5, and 160 min contact time. The adsorption kinetics followed pseudo-second-order kinetics, and the adsorption isotherm fitted well with the Freundlich model. Moreover, the nanocomposite was efficiently recovered from the solution using an external magnet, highlighting its potential for practical applications. Antibacterial testing revealed significant antibacterial effectiveness of PVTO and its nanocomposites against both gram-positive and gram-negative bacteria, with a minimum inhibition zone of 20 mm.

Green Synthesis Study: Adsorption of Congo Red Dye with Selenium Nanoparticles Obtained from Prunus Armeniaca L. Leaf Waste

AbstractIn this study, it was aimed to remove Congo Red (CR) dye in aqueous solution by biosynthesized Selenium Nanoparticles from Prunus armeniaca L. (PAL‐SeNPs) leaf wastes by green synthesis method. The characteristic structure of PAL‐SeNPs was determined by UV‐vis spectroscopy, X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), energy dispersive X‐ray (EDX), fourier transform infrared spectroscopy (FTIR), thermogravimetry‐differential thermal analysis (TGA‐DTA), dynamic light scattering (DLS), zetasizer, and point of zero charge (pHpzc). The effects of pH, adsorbent amount, time, initial concentration, and temperature were investigated by batch adsorption studies. 2 different kinetic and 4 isotherm models were tested and error analysis functions were determined for the most suitable model. Accordingly, the particle size, crystallinity, pHpzc value and average surface charge of PAL‐SeNPs were determined as 9.969 nm, 48.50 %, 3.47, and −23.6 mV, respectively. Also, the most suitable kinetic and isotherm models for the removal of CR dye with PAL‐SeNPs were found as Pseudo‐second‐order and Freundlich, with R2 values of 0.996, respectively. Also, where the optimum pH was 7.00, the maximum adsorption capacity was calculated as 96.59 mgCR/gPAL‐SeNPs. The results obtained show that environmentally friendly and low‐cost PAL‐SeNPs produced by the green synthesis method are a suitable alternative for the removal of CR dye.

Copper-PANI-graphite HB2 composite for eco-friendly efficient degradation of textile dyes: Advancements in wastewater treatment enhanced by solar radiation

This research aimed to assess the potential of Cu50PANI@UG composite for sunlight drive photocatalytic dye degradation, targeting specifically Thymol Blue (TB) and Black NT (BNT) dyes and their mixture (DM). The Cu50PANI@UG composite was successfully synthesized via electropolymerization in acetonitrile/sulfuric acid mixture under atmospheric conditions. Photocatalytic experiments were conducted by exposing aqueous dye solutions to sunlight. N,N-dimethyl-p-nitrosoaniline (RNO) served as a molecular probe for detecting hydroxyl radicals (•OH). Additionally, experiments capturing free radicals were performed to identify active components, with a concomitant proposal of plausible degradation reaction mechanism for the Photo-Fenton-Like degradation into the Cu50PANI@UG composite + H2O2 + hv reaction system. Various operating parameters affecting dye degradation were evaluated, including catalyst dosage (from 0.27 to 0.67 g L−1), H2O2 concentration (from 16 to 64 mM), pH (from 3.0 to 9.0), and dye concentration (from 25 to 100 mg L−1). Optimization of key parameters such as pH, catalyst dosage, and H2O2 concentration was conducted. The highest degradation efficiency, ca. 100% of DM dye, was achieved within 35 min under optimized conditions, using Cu50PANI@UG composite as a catalytic precursor. These conditions were determined as follows: Catalyst dosage = 0.67 g L−1, pH = 3.0–6.0, H2O2 = 32–64 mM, and irradiation time of 35 min. The degradation percentage under the Response Surface Methodology (RSM) was utilized as a statistical tool to correlate influential parameters. Four consecutive reusability trials were performed to assess catalyst stability.

Development of composite ultrafiltration membrane from fly ash microspheres and alumina nanofibers for efficient dye removal from aqueous solutions

In this work, a novel type of ultrafiltration ceramic membranes with the support based on fine fly ash microspheres and selective layer based on the alumina nanofibers with an aluminosilicate binder is proposed. The average pore sizes of the support and selective layer are 0.46 μm and 29 nm, respectively. The membrane is characterized by the compressive strength of 96 MPa and water permeability of 207 L m−2 h−1 bar−1. It is shown that the binder provides structural stability of selective layer and adhesion to the support. With increasing the binder content, the water permeability increases, reaches maximum, and then slightly decreases. The developed membranes are used for ultrafiltration of Blue Dextran dyes aqueous solutions with molecular weights of 70 kDa and 500 kDa and concentrations of 50 and 100 mg/L. The dyes rejection varies in the range 97–99 %, while the permeate flux is 100–140 L m−2 h−1 at the transmembrane pressure of 4 bars. The dye retention occurs via adsorption at the initial stage, which leads to the narrowing of pore size. Further, the dye filtration proceeds mainly due to size effects. The proposed membranes can be employed for dye removal from wastewater, and also allow chemical modification by carbon coating to be employed in electrochemically assisted ultrafiltration. The developed methodology promotes the recycling of thermal energy waste and introduces novel approaches to combine waste and synthesized raw materials in the production of low-cost ceramic membranes.

Regulating the Surface State of Carbon Dots as Ultrahigh-Capacity Adsorbents for Water Treatment.

Adsorption is one of the most widely researched and highly effective methods for mitigating the environmental threat posed by recalcitrant dyes in aqueous solutions. This paper presents a solvent-free synthesis method for the rapid and large-scale production of nitrogen (N) and phosphorus (P) co-doped carbon dots (N, P-CDs) which possess specific surface states and outstanding dye adsorption properties. Compared to the undoped CDs, the N, P-CDs not only exhibit a higher yield of solid-state luminescence but also endow them with the efficient adsorption and removal of Congo red (CR) from water. Due to the synergistic effects of π-π stacking, hydrogen bonding and electrostatic attraction, the N, P-CDs exhibit an ultra-high adsorption capacity (3118.87mgg-1) and a removal efficiency (97.4%, at 500mgL-1) for CR, and also display excellent selective adsorption in both single-dye and dual-dye systems. This method offers a rational strategy for synthesizing novel CDs-based adsorbents for CR, which provides a demonstration for future dye adsorption studies and practical wastewater treatment applications of CDs.

ADSORPTION OF TEXTILE DYE ACID GREEN 42 (AG42) ON ACTIVATED CARBON FROM CHICKEN EGGSHELLS (CAC30)

The present work is a contribution to the valorization of chicken eggshells, an abundant waste product in Cote dIvoire, as a credible alternative to commercial activated carbon.Chemicalactivation of the precursorwascarriedoutwith30%phosphoricacidfor24h of contactin a ratio of 200 g of material to 100 mL of acid, and calcined at 600°C for 1h. The surface of the activated carbon obtained was studied using the BET (Brunauer-Emmett and Teller) method, which consists in establishing the adsorption isotherm for nitrogen N2. The results reveal a specific surface area of 5.42 m2.g-1, 65.68% of micropores and a pHzc of 7.40. Chemical characteristics determined by Boehms method indicate the basic nature of the surface. The elemental composition is dominated by oxygen(50.53%),calcium(30.78%)andcarbon(11.33%).The experiments demonstrated that the removalof AG42by adsorption on CAC30 is influenced by contact time, activated carbon mass, solution pH, and initial concentration and temperature of the dye aqueous solution. Adsorption kinetics followed the pseudo-second-order model and the isotherm is described by the Langmuir model. The thermodynamic study revealed the spontaneous (ΔG < 0) and exothermic (ΔH < 0) nature of dye adsorption, with a well-organized distribution of dye molecules at the adsorption sites (∆S°< 0).

Toxicological assessment of reactive blue 19 dye aqueous solutions under UV-LED light

Abstract The dye-contaminated industrial effluent causes serious health issues when it gets mixed with underground water without primary treatment. The current project was designed to treat reactive blue-19 dye aqueous solutions in the presence of hydrogen peroxide (H2O2) and titanium dioxide (TiO2) under UV-LED light. The characterization of the photocatalyst was carried out via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) for structure, purity, and surface study. The effect of various factors such as pH, TiO2 dose, UV-LED light exposure time, H2O2, and dye concentration, on the degradation rate and cytotoxicity reduction was evaluated and optimized through the Response Surface Methodology (RSM). The maximum degradation of dye solution and chemical oxygen demand (COD) reduction was achieved at 98.81 and 86.22 %, respectively for 50 ppm solution, using UV-LED/H2O2(3 %)/TiO2(6 g/L) hybrid process. The toxicity evaluation through the Allium cepa test demonstrated a 62.40, 65.2, and 56.97 % increase in root length (RL), root count (RC), and mitotic index (MI), respectively, following treatment with the UV-LED/H₂O₂/TiO₂ combined process for 150 min. The hemolytic and brine shrimp tests revealed a reduction in toxicity up to 92.18 and 84.08 %, respectively, after applying the same treatment. Additionally, the Ames test indicated up to 80.94 % reduction in mutagenicity for TA98 and an 84.04 % reduction for TA100 strain when dye samples were treated with UV-LED light in the presence of H₂O₂ and TiO₂ for 150 min. The findings suggested that UV-LED light in conjunction with H2O2 and TiO2 can be a useful tool for the degradation and detoxification of toxic pollutants found in textile wastewater.

Preparation of efficient adsorbent for methylene blue and Congo red by co-hydrothermal of red mud with food waste compost

Herein, a novel red mud-carbon composite (RFBC) was prepared through co-hydrothermal treatment of red mud with food waste compost, and its adsorption property was evaluated on Methylene blue (MB) and Congo red (CR), selected model dyes in aqueous solution. The adsorption process conformed to pseudo-second-order kinetic, intraparticle diffusion, and the Redlich-Peterson isotherm models. RFBC exhibited a maximum sorption of 124.06 mg·g-1 for MB and 2959.35 mg·g-1 for CR at 298 K. Isothermal and thermodynamic studies demonstrated that adsorption of MB and CR by RFBC were spontaneous and exothermic, governed by physisorption and chemisorption. Furthermore, the possible adsorption mechanisms are pore filling, electrostatic attraction, hydrogen bonding, and π-π interactions. After five consecutive adsorption-desorption cycles were completed, the RFBC demonstrated an adsorption efficiency exceeding 70 % in relation to dyes, affirming its exceptional reusability. This study suggested this red mud-carbon composite had high potential as a novel and promising adsorbent for dye removal from wastewater.

Effects of Surfactants on the Aggregation of 6,6'-Disubstituted Thiacarbocyanine Dyes in Aqueous Solutions

The aggregation properties of a number of 6,6'-substituted thiacarbocyanine dyes were studied by spectral-fluorescent methods: T-304, T-306, T-307, T-336 and, for comparison, thiacarbocyanine Cyan 2, which has no substituents in the 6,6'-positions, in aqueous buffer solutions and in the presence of various types of surfactants. The method of moments was used to characterize the absorption spectra (band positions, width, shape). Substituents in the 6,6'-positions significantly increase the ability of dyes T-304, T-306, T-307, T-336 to aggregation (dimerization, as well as to the formation of disordered aggregates with broad low-intensity absorption spectra). The introduction of surfactants leads to rearrangement of the spectra associated with the complex nature of the equilibria between monomers and aggregates of various structures (including surfactant molecules, if present), in particular, with a decrease in the contribution of disordered aggregates. However, the decomposition of dimeric aggregates of 6,6'-substituted cyanines is observed only at very high surfactant concentrations (~20 CMC and higher, where CMC is the critical micelle concentration). At the same time, the passing of surfactant concentrations through CMC does not significantly affect the spectral-fluorescent properties of the dyes, which is probably due to rather strong interactions of the dyes with individual surfactant molecules and premicellar associates of surfactants.

A highly efficient Co-based catalyst for peroxymonosulfate activation for rapid degradation of RhB over a wide pH range

Cobalt-based materials have been demonstrated to be effective heterogeneous catalysts for peroxymonosulfate activation in degrading many refractory organic pollutants. In this study, a new cobalt-based catalyst was prepared using cobalt chloride hexahydrate (CoCl2·6H2O) as the Co2+ source, 2,3-pyrazine dicarboxylic acid and 3,6-DI-4-pyridyl-1,2,4,5-tetrazine (4-PYTZ) as ligands. This catalyst was employed as a peroxymonosulfate activator for the degradation of Rhodamine B(RhB). The results indicated that the prepared Co-based catalyst can effectively degrade RhB dye in aqueous solution by activating peroxymonosulfate (PMS). Specifically, when the initial concentration of RhB was 20 mg/L, its degradation rate exceeded 98 % within merely 9 min. The factors influencing the activation of PMS by the Co-based catalyst were examined, including PMS concentration, reaction temperature, solution pH, and the concentration of organic pollutants. Stability and reusability tests demonstrated that the prepared catalyst exhibited good stability, with the degradation rate of RhB remaining above 97 % after four repetitive experiments. Free radical quenching experiments and electron paramagnetic resonance (EPR) analyses revealed that sulfate radicals (SO4−) and hydroxyl radicals (OH) are the primary reactive radicals accountable for the degradation process. Additionally, it displayed excellent adaptability over a wide pH range, particularly within the pH levels ranging from 5 to 9. This study demonstrates that the prepared Co-based catalyst can serve as a stable and effective option for degrading organic dyes in wastewater treatment applications.

Graphene oxide with different oxygen content produced from natural and synthetic graphite sources for methylene blue sorption

Graphene oxide (GO) is of great interest due to its unique structure and properties and potential applications, including water purification. In this work, we report the synthesis of GO samples with different oxidation degree from two different sources of graphite using Hummers method. Natural flake graphite with a high degree of crystallinity, and synthetic fine powder graphite were used. All produced materials were characterized by CHNS analysis, X-Ray Diffractive analysis (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). It was shown that the oxidation process for natural and synthetic graphite sources proceeds in different ways. The factors, affecting for the structure and properties of GO are the degree of crystallinity and the lateral size of the graphite flakes. The sorption activity of underoxidized, normally oxidized and overoxidized GO was compared toward the methylene blue (MB) dye in aqueous solution. The most efficient sorption was registered for GO produced from synthetic graphite with the use of 2.0 and 4.5 wt. eq. KMnO4. The sorbents removed 94 % and 100 % of MB from the solution, respectively, in approximately 10 min. Our results reveal that the structure and sorption properties of GO can be tuned by varying the oxidation degree as well as the graphite source, which may open the way to new developments in the GO-based materials applications.

Lead Oxide Modified Graphite Electrodes for Electrochemical Degradation of Congo Red Dye in Aqueous Solution

Lead Oxide Modified Graphite Electrodes for Electrochemical Degradation of Congo Red Dye in Aqueous Solution