Dye In Aqueous Medium Research Articles

Photocatalytic degradation of alizarin red dye in aqueous medium using carbon nanotubes/Cu–Ti oxide composites

ABSTRACTMultiwalled carbon nanotubes/copper and titanium oxides (MWNTs/Cu–Ti) and Cu–Ti composites were synthesized by wet chemical precipitation method and were used as photocatalysts for photodegradation of alizarin red dye in aqueous media. The morphological study presented that MWNTs are well covered by Cu–Ti. The formation of Cu–Ti was confirmed by energy dispersive X-rays (EDX) and X-rays diffraction (XRD). The MWNTs/Cu–Ti degraded about 92.51% within 180 min. The effect of other parameters like pH, catalyst dosage, and concentration of dye on the photocatalytic degradation was also studied. The activity of recovered and re-recovered catalysts was also studied.

Green synthesis of Terminalia arjuna-conjugated palladium nanoparticles (TA-PdNPs) and its catalytic applications

Synthesis of metal nanoparticles from the metal salts by reduction with plant extracts in water, without any additional stabilizing or capping agents is a green and eco-friendly method. In the present work, aqueous extract of the bark of Terminalia arjuna was utilized to synthesize T. arjuna-conjugated palladium nanoparticles (TA-PdNPs) from palladium chloride. The dark brown colour indicating the formation of TA-PdNPs appeared within 3 h without heating but, on heating colour appeared almost instantly. The synthesized TA-PdNPs are characterized by UV spectroscopy, HRTEM and XRD studies. The TA-PdNPs were utilized as efficient catalyst for Heck and Suzuki type C–C coupling reactions and degradation of organic dyes in aqueous medium at room temperature.Graphical abstract

Graphene Oxide-Chitosan Composite Material for Treatment of a Model Dye Effluent.

Graphene oxide (GO) was cross-linked with chitosan to yield a composite (GO-LCTS) with variable morphology, enhanced surface area, and notably high methylene blue (MB) adsorption capacity. The materials were structurally characterized using thermogravimetric analysis and spectroscopic methods (X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and 13C solid-state NMR) to support that cross-linking occurs between the amine groups of chitosan and the −COOH groups of GO. Equilibrium swelling studies provide support for the enhanced structural stability of GO-cross-linked materials over the synthetic precursors. Scanning electron microscopy studies reveal the enhanced surface area and variable morphology of the cross-linked GO materials, along with equilibrium and kinetic uptake results with MB dye in aqueous media, revealing greater uptake of GO-LCTS composites over pristine GO. The monolayer uptake capacity (Qm; mg g–1) with MB reveals twofold variation for Qm, where GO-LCTS (402.6 mg g–1) > GO (286.9 mg g–1). The kinetic uptake profiles of MB follow a pseudo-second-order trend, where the GO composite shows more rapid uptake over GO. This study reveals that the sorption properties of GO are markedly improved upon formation of a GO–chitosan composite. The facile cross-linking strategy of GO reveals that its physicochemical properties are tunable and versatile for a wider field of application for contaminant removal, especially over multiple adsorption–desorption cycles when compared against pristine GO in its highly dispersed nanoparticle form.

Hybrid Metal–Organic-Framework/Inorganic Nanocatalyst toward Highly Efficient Discoloration of Organic Dyes in Aqueous Medium

Nanoscale metal-organic frameworks (NMOFs) represent a unique class of solids with superior adsorption, mass transport, and catalytic properties. In this study, a facile and novel approach was developed for the generation of hybrid Cu-NMOF/Ce-doped-Mg-Al-LDH nanocatalyst through in situ self-assembly and solvothermal synthesis of a 2D Cu-NMOF, [Cu2(μ-OH)(μ4-btc)(phen)2] n·5 nH2O {H3btc, trimesic acid; phen, 1,10-phenanthroline}, on a cerium-doped Mg-Al layered double hydroxide (Ce-doped-Mg-Al-LDH) matrix. Self-assembly between Cu-NMOF nanocrystals and exfoliated LDH led to their nanoscale mixing and prevented the formation of aggregated Cu-NMOF nanoparticles. In the resulting hybrid nanostructure, Cu-NMOF nanocrystals (∼10-20 nm particle size) are anchored uniformly on a Ce-doped-Mg-Al-LDH's surface, possessing a dimension of several hundred nanometers. Catalytic activity of Cu-NMOF/Ce-doped-Mg-Al-LDH and Cu-NMOF was evaluated under ambient conditions in the reductive degradation (discoloration) of aqueous solutions of 4-nitrophenol (4-NP, model substrate) and a series of commercial organic dyes by applying sodium borohydride as a reducing agent. The Cu-NMOF/Ce-doped-Mg-Al-LDH nanocatalyst exhibited an outstanding catalytic activity toward degradation of 4-NP, with kapp (rate constant) of 0.03 and a catalyst TOF (turnover frequency) up to 7.1 × 103 h-1. Full and very quick discoloration of organic dyes {rhodamine B (RhB), methylene blue (MB), Congo red (CR), methyl orange (MO), and rhodamine 6G (R6G)} was also achieved with TOF values of up to 1.4 × 105/h. A superior activity of the hybrid nanocatalyst over Cu-NMOF can be regarded as a synergic effect among Cu-NMOF and Ce-doped-Mg-Al-LDH components, while the Ce-doped-Mg-Al-LDH carrier acts as a cocatalyst. The hybrid nanocatalyst can easily be recovered and reused successfully for the five consecutive reaction runs with the same catalytic performance. This study also shows that NMOFs can be easily incorporated onto conventional catalyst supports, resulting in hybrid nanocatalysts with a highly uniform structural architecture, controlled chemical composition, and excellent catalytic function.

Green Synthesis of Ag–NiO and Investigation of its Catalytic Activity for Degradation of Rhodamine B Dye in Aqueous Medium

Abstract The plants assisted green synthesis of nanoparticles have drawn a momentous importance worldwide. NiO is one the metal oxides researched comprehensively for decades and still has dominance in the field of photo-catalysis. In present study NiO and Ag–NiO were successfully prepared by a simple and environmentally friendly method using nickel nitrate, silver nitrate and leaves extract of Azadirachta indica L. plant as precursor materials. The prepared materials were characterized by XRD, SEM and TGA. Then the photo-catalytic efficiency of NiO and Ag–NiO were evaluated by aqueous phase photo-degradation of rhodamine B as a model pollutant under ultraviolet irradiations. About 40% and 96% of 200 mg/L (50 mL) degraded in 120 min at 40 °C over NiO and Ag–NiO as photo-catalyst respectively. The apparent rate constants were determined as 0.0109, 0.0165, 0.0175 and 0.0190 per min at 30, 40, 50 and 60 °C respectively. 14.6 kJ/mol was calculated as activation energy of reaction.

A Magnetic Adsorbent for the Removal of Cationic Dyes from Wastewater.

In this article, a study was presented on the adsorption activity of a new nanocomposite particle Fe3O4@1, which was synthesized by combining [Cu(HL)2]2H2[P2Mo5O23]·10H2O (1) (HL = 2-acetylpyridine semicarbazone) and Fe3O4 nanoparticles. Transmission electron microscopy and X-ray powder diffraction analyses revealed that Fe3O4@1 possessed high crystallinity with an average particle size of 19.1 nm. The adsorption activity of the as-prepared Fe3O4@1 was investigated by photometrically monitoring the removal of methylene blue, rhodamine B, safranine T, gentian violet, fuchsin basic, and methyl orange from aqueous solutions. Significantly, we could easily separate Fe3O4@1 from the reaction media by applying an external magnet. Furthermore, the recycling performance was observed using methylene blue, revealing the recyclability and high stability of Fe3O4@1. It was shown that Fe3O4@1 is a promising candidate material for adsorbing cationic dyes in aqueous media.

Photocatalytic Activity of Bismuth Ferrite Nanoparticles Synthesized via Sol-Gel Route

Abstract Nanosized, magnetically separable bismuth ferrite (BFO) nanoparticles, pertaining a crystallite size in the range of 14–15 nm were prepared via facile sol-gel technique. The product was characterized by scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The product was explored for the photocatalytic mineralization of rhodamine B (RB) dye in aqueous medium. The effect of different investigational parameters such as amount of photocatalyst, initial dye concentration and irradiation time on the photocatalytic degradation of RB was studied. The results reveal that the catalyst shows good degrading ability under normal pH and visible light conditions. BFO nanoparticles demonstrated a strong absorption ability in the visible-light region, which lead to efficient photocatalytic degradation of RB dye The reaction system was heterogeneous in nature in which the catalyst can be separated by a normal magnet.

Silver Nanoparticles Engineered Polystyrene‐Poly(N‐isopropylmethacrylamide‐acrylic acid) Core Shell Hybrid Polymer Microgels for Catalytic Reduction of Congo Red

AbstractPolystyrene‐poly(N‐isopropylmethacrylamide‐acrylic acid) [pSty‐p(NIpmam‐AC)] core shell microgels loaded with silver nanoparticles (NPs) as a recyclable catalyst for rapid reduction of Congo Red (CR) dye in aqueous medium is reported for the first time. Catalytic activity of Ag‐pSty‐p(NIpmam‐AC) core shell composite microgels is measured by adopting the reduction of CR as a benchmark reaction. Restriction of Ag NPs in single layered p(NIpmam‐AC) shell of Ag‐pSty‐p(NIpmam‐AC) core shell composite microgels enhances the diffusion of reactants to access the Ag NPs, surface during reaction with respect to previously reported core shell and homogenous composite microgels, and thus enhances the rate of CR reduction. The solid nonresponsive pSty core induces easy recyclability in core shell composite microgel catalysts. The effect of different reaction parameters such as amount of catalyst, concentration of NaBH4 and CR on the reaction completion time for CR reduction, as well as on the value of apparent rate constant (kapp), is also studied by keeping all other parameters constant, separately. Reduction efficiency of Ag‐pSty‐p(NIpmam‐AC) catalyst is also measured under different reaction conditions for the reduction of CR. A slight decrease in the percentage activity of Ag‐pSty‐p(NIpmam‐AC) catalyst is observed for up to four cycles for CR reduction. The reported Ag‐pSty‐p(NIpmam‐AC) composite microgel catalysts can be used to degrade other pollutants.

TiO2-GO nanocomposite for photocatalysis and environmental applications: A green synthesis approach

The present study reports a novel, simple, economic and ecofriendly method to synthesize Titanium dioxide (TiO2) nanoparticles using green alga Chlorella pyrenoidosa. Further, these TiO2 nanoparticles were deposited on GO sheets to form TiO2-GO nanocomposite. The crystalline information, morphological and optical properties of the synthesized TiO2-GO nanocomposite were studied using X-ray Diffraction (XRD), Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDX) and UV–Vis absorption spectroscopy. Crystal Violet (CV) dye was used as a model contaminant. The photocatalytic activity of TiO2 nanoparticles and the TiO2-GO nanocomposite were evaluated by the degradation of CV dye in aqueous medium under visible light. The result showed that the TiO2-GO nanocomposite exhibited higher photocatalytic efficiency compared to pristine TiO2 nanoparticles with three cycles reusability. The improved activity of the TiO2-GO nanocomposite might be attributed to enhanced charge separation, efficient charge transportation, extended light absorption range and increased adsorption of dye. This nanocomposite has a great potential in removing environmental contaminants and applicable in water purification.

Effective Removal of the Remazol Yellow GR Dye Using Cellulose Functionalized by Basic Groups

Adsorption has been researched attempting to minimize the pollution caused by dyes, which represents a serious environmental problem as contamination of surface and ground water. Therefore, cellulose and its modified forms with amine and thiols groups constitute a class of versatile adsorbents for the removal of anionic dyes in aqueous solution. In this context, this work reports the preparation of cellulose modified by ethylene sulfide and ethylenediamine (Cel-ESEN), through the reaction of the cellulose modified by ethylene sulfide (CEL-ES) and ethylenediamine (EN). Materials were characterized by elemental analysis, which showed in the Cel-ESEN matrix 10.12 ± 0.10%, 5.52 ± 0.06% of sulfur and nitrogen, respectively. Nuclear magnetic resonance in the solid state of 13C (13C NMR) showed, for the Cel-ESEN matrix, a peak related to CH2 groups from the molecules incorporated in the cellulose biopolymer. Crystalline Index obtained by X-ray diffraction (XRD) was in the order pure Cellulose > Cel-Cl > Cel-ES > Cel-ESEN. The adsorbent matrix (Cel-ESEN) was used in the removal of the remazol yellow GR (RY) dye in aqueous medium. Data obtained experimentally from kinetic study had the best adjustment to the proposed pseudo-second-order model. The adsorption process occurs in monolayer, is endothermic and thermodynamically favorable. Adsorption capacity of the modified material became 118 times higher than the starting material. These results suggest that the obtained biopolymer can be used as an alternative material to remove RY in aqueous solution.

Systematic study of graphene oxide production using factorial design techniques and its application to the adsorptive removal of methylene blue dye in aqueous medium

Water pollution is a serious environmental problem and coloured pigments are considered one of the greatest concerning contaminants. Graphene, a new two-dimensional material presenting high theoretical specific surface area, has been widely studied for applications in wastewater treatment. It was the aim of this work to study the feasibility of producing Graphene Oxide (GO) under different conditions, using Factorial Design techniques, so that it could be successfully applied in the adsorptive removal of Methylene Blue (MB) dye in aqueous medium. For GO production, the best conditions were achieved within 3 h of reaction and no ultrasonic bath, for a percentage removal of MB over 99%. Surprisingly, it was verified that ultrasonic bath and the increase in reaction time had negative effects under GO production process. For the adsorptive studies using the best samples produced, it was observed that the best pH value was 5.5, and the maximum adsorptive capacities predicted by the Langmuir model were approximately 365 and 504 mg.g−1, although this was not the model that best fit the experimental data. Unlike most previous works which reported MB adsorption onto GO occurs in mono-layers, in this study it was proved the process happens with formation of multiple layers, as the equilibrium data best fit the Temkin model. Both the physical nature and the spontaneity of the process were verified by the Gibbs free energy of adsorption. Equilibrium was reached very quickly in less than 10 min, and kinetics data were properly fitted to pseudo-second order model.

Role of optimization parameters in the production of nanoporous carbon from mandarin shells by microwave-assisted chemical activation and utilization as dye adsorbent

In this study, mandarin (Citrus reticulata) shells (MS) were used as a new precursor material for preparation of nanoporous carbon by chemical activation method with H3PO4 in the presence of microwave radiation. The obtained nanoporous carbon (MNC) was characterized using nitrogen adsorption-desorption isotherms, scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and Boehm titration analysis. When using impregnation ratio of 2.0 at 500 °C for 1 h, specific surface area of prepared MNC reached the maximum value, which is 1021 m2/g. Pore properties of MNC were strongly influenced by impregnation ratio, activation temperature and activation time. For industrial and environmental applications, MNC was tested towards the removal of basic blue 9 (BB9) and acid yellow 36 (AY36) dyes in aqueous media and compared with other carbon adsorbents. The high sorption capacities were 294 mg/g for BB9 and 417 mg/g for AY36. The results indicate that MNC could be regard as a valuable adsorbent to treatment dye pollutants.

Synthesis and characterization of polyvinyl pyrrolidone (PVP)-coated Fe3O4 nanoparticles by chemical co-precipitation method and removal of Congo red dye by adsorption process

The present paper deals synthesis of polyvinyl pyrrolidone (PVP)-coated magnetite nanoparticles by chemical co-precipitation method. The samples were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR) and Brunauer–Emmett–Teller (BET) methods. The surface area, pore volume and pore radius were calculated by the BET analysis. The EDX and FT-IR analysis demonstrated the fabrication of PVP-coated Fe3O4 NPs. The as-synthesized Fe3O4/PVP has successfully been used as an adsorbent for elimination of Congo red dye in aqueous medium.

Potential of amino-functionalized cellulose as an alternative sorbent intended to remove anionic dyes from aqueous solutions

Adsorption has been explored to minimize the pollution caused by dyes. This work relates the preparation of diethylenetriamine-modified cellulose (DetaCel) by reacting phthalic anhydride-modified cellulose (PhCel) with diethylenetriamine (Deta). Materials were characterized by Elemental Analysis and results showed a degree of incorporation of 5.55 ± 0.02 mmol of nitrogen per gram of modified material. The main bands observed for DetaCel by Fourier-Transform Infrared Spectroscospy (FTIR) were attributed to CN deformation (1330 cm−1) and NH stretching of amide (3400 cm−1), while Solid State Nuclear Magnetic Resonance of 13C (13C{1H}CP-MAS NMR) showed a signal at 164.6 ppm characteristic of amide group. Crystallinity index (CrI) obtained by X-Ray Diffraction (XRD) was 74.99 (Cel), 58.64 (PhCel) and 46.12% (DetaCel). Adsorbent matrices were employed to remove methyl orange (MO) and eosin (EY) dyes in aqueous medium. Data obtained experimentally from kinetic study had a better fit to the pseudo-first order, thus the adsorption process occurs in monolayer, with MO adsorption capacity by Cel and DetaCel of 2.19 and 65.45 mg g−1, respectively. For EY adsorption by Cel and DetaCel was 1.30 and 56.69 mg g−1, respectively. These results suggest that DetaCel can be used as an alternative potential for removal dyes in aqueous solution.

Potential of Cellulose Functionalized with Carboxylic Acid as Biosorbent for the Removal of Cationic Dyes in Aqueous Solution.

In the last decade, adsorption has been used to minimize the pollution caused by dyes, which represents a serious environmental problem. In this context, this work reports the preparation of phthalic anhydride-modified cellulose (PhCel), through the reaction of cellulose (Cel) with phthalic anhydride (Ph). The efficiency of the reaction was observed by elemental analysis, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetry/derivative thermogravimetry (TG/DTG). The adsorbent matrix (Cel and PhCel) was used in the removal of crystal violet (CV) and methylene blue (MB) dyes in aqueous medium. In the kinetic study, the experimental data obtained had the best fit to the pseudo-first-order model. In general, the isotherms obtained at different temperatures had a best fit to the model proposed by Langmuir, and the CV and MB adsorption process in adsorbent matrixes can be favored strictly by hydrogen bonds and/or electrostatic interactions for Cel and electrostatic interactions for PhCel.

Corrigendum to: Green Synthesis of CoFe2O4 and Investigation of its Catalytic Efficiency for Degradation of Dyes in Aqueous Medium

Corrigendum to: Green Synthesis of CoFe₂O₄ and Investigation of its Catalytic Efficiency for Degradation of Dyes in Aqueous Medium

Ag-Co3O4: Synthesis, characterization and evaluation of its photo-catalytic activity towards degradation of rhodamine B dye in aqueous medium

Abstract Synthesis, characterization of Co 3 O 4 and Ag-Co 3 O 4 composites and evaluation of their photo-catalytic activities towards photo-degradation of aqueous solution of rhodamine B dye under irradiation of visible light have been described in this paper. Co 3 O 4 was prepared by solid phase mechano chemical process using Co(NO 3 ) 2 ·6H 2 O and NH 4 HCO 3 as precursor materials. Ag was deposited on Co 3 O 4 from AgNO 3 using Calotropis gigantea extract as reducing agent. XRD, SEM and FTIR were used for characterization of prepared composites. Photo-catalytic efficiencies of as-prepared Co 3 O 4 and Ag-Co 3 O 4 were evaluated for aqueous phase photo-degradation of rhodamine B. It was found that deposition of Ag on Co 3 O 4 highly enhanced the photo-catalytic activity of Co 3 O 4 . Photo-catalytic degradation followed the Eley–Rideal mechanism. About 100% and 91% photo-degradation of 40 ml dye solution achieved at 313 K in 90 and 120 min over 0.05 g of Ag-Co 3 O 4 as photo-catalyst using 100 and 200 mg·L − 1 as initial concentration of dye respectively.

Degradation of Crystal Violet Dye by Fenton and Photo-Fenton Oxidation Processes

Abstract The oxidative degradation of CV dye in aqueous media has been evaluated using Fenton (Fe2+/H2O2) and photo-Fenton (Fe2+/H2O2/UV) processes. Various operational parameters like H2O2 dosages, Fe2+ dosages and [CV]0 were optimized of both Fenton and photo-Fenton processes for the removal of CV dye from aqueous media. Kinetic results indicated that photo-Fenton process (k obs=0.0097 min−1, t 1/2=71.45 min) is more effective than Fenton process (k obs=0.0074 min−1, t 1/2=93.66 min). Second order rate constant of ˙OH radical with CV dye was calculated to be 3.96×109 M−1s−1. De-methylated organic intermediates of CV dye detected by LC-MS and some other intermediates like CH3COO−, HCOO−, NH4 + and Cl− were identified by ion-chromatography.

Impregnation of activated carbon-TiO2 composite and its application in photodegradation of procion red synthetic dye in aqueous medium

Synthetic dyes are often used for textile dyeing process. The dye wastewater containing hazardous materials, toxic, and also harmful to the environment. Among the existing technologies,photodegradation using semiconductor catalyst is a promising alternative method. However, the weak adsorption capacity of photocatalyst is an issue for photocatalysis process. To overcome this lack, photocatalyst material needs to combine with an adsorbent. The composite was synthesized by combining the function of activated carbon as adsorbents and TiO2 as a catalyst. The objective of the study was to synthesize a composite of activated carbon and TiO2 through impregnation method. The activated carbon-TiO2 composite produced was characterized to determine the surface morphology and the elements contained in the composite by using SEM/EDX. The composite activity to photodegrade various concentrations of Procion red, as a model of synthetic dye, was also investigated. To compare the activity of activated carbon-TiO2 composite in degrading Procion red, different conditions were applied by using UV lamps, sunlight irradiation, and without irradiation (darkroom). The activated carbon-TiO2 composite was able to photodegrade of Procion red by UV light irradiated at optimum wavelength 530 nm. The highest photodegradation percentage of 58.9% and 71.7 % were obtained when using the activated carbon-TiO2 composite ratio of 3:7 and 1:1, respectively.

Degradation of toxic organic dyes in aqueous medium in greener ways: Exploring the utility of Indian Curry Leaf plant and the nanoparticles synthesized using it

Degradation of toxic organic dyes in aqueous medium in greener ways: Exploring the utility of Indian Curry Leaf plant and the nanoparticles synthesized using it