Decolorization Of Organic Dyes Research Articles

Eco-Friendly Cost-Effective Formation of Copper Oxide Nanostructures and its Prodigious Potential for Environmental Remediation Applications

<p>The proliferation of environmental pollution, particularly from hazardous industrial dyes, poses a significant threat to ecosystems and aquatic life. This study uses extract from Nerium oleander leaves as a natural capping and reducing agent to produce copper oxide nanoparticles (CuO NPs), an ecologically acceptable way to tackle this problem. The CuO nanoparticles have improved physicochemical characteristics, as shown by their average crystalline size of 15.56 nm and decreased particle size of 31.84 nm. Additional studies such as SEM, EDX, TEM, and zeta potential were accomplished and revealed the spherical structure; an elevated negative zeta potential of -25.6 mV was observed on the surface property. The photodegradation efficacy of these bio-synthesized CuO NPs was assessed against various industrial dyes, including Rhodamine 6G, Malachite Green, Eosin Yellow, and Reactive Black. The results demonstrated exceptional degradation efficiencies, with rates of up to 97.48%, 99.54%, 89.73%, and 89.33% respectively. The decolorization of organic dyes presented a visual cue that the degradation process was progressing. Notably, using Nerium oleander leaves as reducing agents contributed to the nanoparticles' stability, making them suitable for repeated cycles of photocatalysis. This research underscores the potential of green synthesis methods and highlights the vital role of plant-based reducing agents in advancing environmentally friendly nanomaterials for wastewater treatment and environmental remediation. The findings offer a promising pathway toward sustainable and eco-friendly solutions to mitigate the environmental impact of hazardous industrial dyes, fostering responsible industrial practices and preserving aquatic ecosystems.</p>

Accelerated Decoloration of Organic Dyes from Wastewater Using Ternary Metal/g-C3N4/ZnO Nanocomposites: An Investigation of Impact of g-C3N4 Concentration and Ni and Mn Doping

Wastewater from many sectors that contains hazardous organic pollutants exacerbates environmental contamination. Consequently, outstanding photocatalytic substances that can successfully degrade hazardous substances are needed to provide pollution-free water. From this perspective, zinc oxide/g-C3N4-based composites are desirable due to their low cost, strong reactivity, and environmental friendliness. So, in the current investigation, sequences of Mn/g-C3N4/ZnO (Mn/GZ) and Ni/g-C3N4/ZnO (Ni/GZ) nanocomposites (NCs) containing different concentrations (wt.%) of g-C3N4 were made via the co-precipitation process. The chemical makeup and morphological characteristics of the produced composites were ascertained via the techniques of transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), photoluminescence (PL), and UV spectrophotometry. Methyl orange (MO) and Eriochrome Black T (EBT) dyes were used as target pollutants to assess the composite materials’ photocatalytic effectiveness. Compared to g-C3N4/ZnO and g-C3N4, the produced Mn/GZ and Ni/GZ NCs displayed better photocatalytic activity. The improved photocatalytic efficiency of the Ni/GZ and Mn/GZ NCs might be credited to synergistic interactions at the g-C3N4 and ZnO interface that result in a more efficient separation and conduction of photo-induced charges. Furthermore, the Ni/Mn atoms act as the facilitators to improve electron–hole pair separation and conduction in NCs. The nanocomposites were found to be incredibly stable, with consistently high dye decoloration efficiency over five catalytic cycles. Hence, Ni/GZ and Mn/GZ could potentially be very effective and adaptable photocatalysts for the photocatalytic decoloration of wastewater pollutants.

Textile‐Bound Copper Silicate as a New Peroxidase‐Like Nanozyme for Organic Dye Decolorization

AbstractCopper silicate (CS) bound to a nonwoven textile was prepared using a very simple procedure employing water glass as a precursor and subsequent copper sulfate treatment. Peroxidase‐like activity of the textile‐based CS derivative was detected for the first time. This new nanozyme was employed for the decolorization of three model organic dyes: Bismarck brown Y, Congo red, and methylene blue. Both adsorption and peroxidase‐like dye degradation were involved during the decolorization process.

Synthesis and characterization of a new hybrid nanocomposite based on di-substituted heteropolyanion-quantum dots as a high-performance nanocatalyst for organic dye removal from wastewater

In this manuscript, a new hybrid nanocatalyst (PMo10Ni2/ZnS@CS) based on di-substituted heteropolyanion (PMo10Ni2) and ZnS quantum dot was synthesized via the hydrothermal method. PMo10Ni2/ZnS@CS is a candidate for removal of environmental pollutants. The synthesized hybrid nanocatalyst was analyzed by TEM, UV-vis, FT-IR, XRD, and EDX techniques. The results of XRD analysis showed the average crystallite size of the PMo10Ni2/ZnS@CS nanocomposite particles is about 33 nm, which was consistent with the TEM results. The nano-catalytic activity of PMo10Ni2/ZnS@CS hybrid nanocomposite was investigated in photocatalytic decolorization of organic dyes. The experimental results showed that the inorganic-organic hybrid nanocomposite (PMo10Ni2/ZnS@CS) had excellent photocatalytic efficiency with 98% dye removal. The recovery of the photocatalyst in the decolorization process was investigated and the results indicate a reduction of photocatalytic power after the second and third stage recovery, respectively. In the present study, PMo10Ni2/ZnS@CS was proposed as a heterogeneous nanocatalyst with broad nanocatalytic applications of dye removal.

Polydopamine-Bi2WO6-Decorated Gauzes as Dual-Functional Membranes for Solar Steam Generation and Photocatalytic Degradation Applications.

The dual-functional Bi2WO6/polydopamine (PDA)-modified gauze membrane has been developed for applications in photocatalytic degradation and solar steam generation. Two types of membrane were prepared by changing the growth sequence of Bi2WO6 nanomaterials and PDA on gauze substrates. The spatial distribution of Bi2WO6 and polydopamine has a great influence on light absorption, photocatalytic degradation, and solar steam generation performances. Bi2WO6 photocatalysts can absorb short-wavelength light for the photocatalytic decoloration of organic dyes. The photothermal polydopamine can convert light into heat for water evaporation. Besides, the gauze substrate provides water transport channels to facilitate water evaporation. The morphology, surface chemistry, and optical properties of Bi2WO6-PDA modified gauzes were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance spectra. The photothermal properties, wetting properties, and solar steam generation rates of the composite films were also studied. Degradation of 96% of indigo carmine was achieved after being irradiated for 120 min in the presence of G/PDA/BWNP. The water evaporation rates of the G/BWP/PDA sample under the irradiation of an Xe lamp (light intensity = 1000 W/m2) reached 1.94 kg·m−2·h−1.

Decolorization of organic dyes in water using non-thermal plassma

Decolorization of azo dye methyl orange (MO) in aqueous solution was performed using non-thermal plasma in a dielectric barrier discharge device with the coaxial configuration. The results show that the average H2O2 accumulation rate is 0.73 mg/min (under the condition: discharge voltage 18 kV, solution volume of 500 ml, liquid flow rate of 100 ml/min, O2 flow rate of 0.5 l/min). The influence of parameters, including the liquid flow rate, gas flow, initial dye concentration on the decolorization efficiency has been studied on the batch processing model After 12 minutes of plasma treatment of MO solutions with initial concentrations of 100, 200, 300, 400 and 500 mg/l, the decolorization efficiencies were of 94.2%, 84.5%, 80.1%, 70.5% and 61.6%, respectively. In particular, after 48 minutes of the operation, decolorization efficiency was over 99% in all samples, which shows that the energy efficiency increases as the initial concentration of MO increases.

Immobilization of nZVI particles on cotton fibers for rapid decolorization of organic dyes

Immobilization of nZVI particles on cotton fibers for rapid decolorization of organic dyes

Fe/N-doped carbon magnetic nanocubes toward highly efficient selective decolorization of organic dyes under ultrasonic irradiation

Fe/N-doped carbon magnetic nanocubes (Fe/N–C MNCs) were feasibly fabricated through in situ thermal transformations of Prussian blue nanocubes (PB NCs) in an inert atmosphere, and the resultant composite employed as the heterogeneous noble-metal-free catalyst possessed satisfactory catalytic performance in hydrogen peroxide activation. By examining the properties of Fe/N–C MNCs, we demonstrate for the first time that the catalyst could act in synergy with ultrasonic irradiation and accelerate the selectivity of the degradation reaction of dyes. The degradation efficiency of the organic positively charged dye (methylene blue) is significantly increased after ultrasonic irradiation addition, probably owing to charge matching between a positively charged dye and the Fe/N–C MNCs. Interestingly, organic pollution degradation mainly follows a non-radical pathway. Furthermore, singlet oxygen (1O2) is predominantly produced by Fe/N–C MNCs on H2O2 activation, and it is the contributor to catalytic degradation instead of hydroxyl and/or superoxide anion radicals. Moreover, the Fe/N–C MNCs exhibit excellent stability and reusability. These findings offer interesting insights into the potential application of functional noble-metal-free materials in catalysis and wastewater remediation under ultrasonic radiation.

Reutilization of Fe-containing tailings ore enriched by iron(iii) chloride as a heterogeneous Fenton catalyst for decolorization of organic dyes.

In this study, the Fe-containing tailings (Fe-TO) ore was reutilized and enriched with FeCl3 as a heterogeneous catalyst for the Fenton process to degrade the organic dyes from aqueous solution. The determinants of the heterogeneous catalytic Fenton system which included iron modification ratio, solution pH, catalyst dosage, H2O2 dosage and initial concentration of organic dyes were systematically investigated. The modification ratio of 15% (w/w of iron), pH of 3, MFe-TO15 dosage of 0.5 g L−1 and H2O2 dosage of 840 mg L−1 were chosen as the best operational conditions for Fenton oxidation of organic dyes. The decolorization efficiency of both MB and RhB by MFe-TO15/H2O2 was higher than that of Fe-TO/H2O2 by about two times. The kinetic study showed the degradation of organic dyes well fitted the pseudo-first-order kinetic model with apparent constant rate values (Kd) following the same sequence as the degradation efficiency of organic dyes. The degradation mechanism of dyes could be attributed to adsorption due to the good-development in textural properties of the iron modified catalyst (MFe-TO) with an increase in BET surface area, pore volume and pore diameter of, respectively, 2, 5 and 5 times and leaching iron through homogeneous Fenton reaction. However, the oxidation process occurring on the MFe-TO15's surface by heterogeneous Fenton reaction which enhanced decomposition of H2O2 for continuous generation of hydroxyl radicals was the main mechanism. The key role of *OH radical in oxidation of organic dyes was further ascertained by the remarkable drop in the decolorization of both organic dyes when the various radical-scavengers, including tert-butanol and chloride were supplemented into Fenton systems. A good stability of the catalyst was obtained through leaching test with low leaching iron ratio. The applied modified catalyst remained stable through three consecutive runs. From these findings, it can be concluded that the modified material can be applied as a feasible, inexpensive and highly effective catalyst for removal of persistent organic compounds from wastewater.

Degradation of organic dyes by persulfate using liquor grain-derived N,P-codoped mesoporous carbon as metal-free catalyst

Exploring facile and available approaches for resource utilization of liquor grains is in high demand for the brewing industry. Herein, we demonstrate a one-step blending method followed by heat treatment to prepare N,P-codoped mesoporous carbons (P/NMCs) using liquor grains as the carbon source, nano-SiO2 as a template, and KH2PO4 as an extra phosphorus precursor. N2 adsorption/desorption, Raman spectra, X-ray diffraction, Fourier transform infrared spectra, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the textural properties and surface chemistry of P/NMCs. Results showed that the P/NMCs that were prepared with a larger amount of the phosphorus precursor demonstrated much higher catalytic activity for persulfate activation. The enhanced catalytic activity is ascribed to the relatively large specific area and the greater amount of active surface groups that are induced by N,P-codoping. Decolorization of organic dyes reached ∼95 % under a broad operating pH range (3.0–11.0). Quenching tests with different radical scavengers revealed that degradation of organic dyes was controlled by a surface-bound radicals process and not by a free radical pathway.

One-step synthesis of Cu–SBA-15 under neutral condition and its oxidation catalytic performance

The ordered mesoporous material Cu–SBA-15 was synthesized under neutral condition via a one-step method that uses hydroxyl radicals instead of inorganic acid. The obtained samples were systematically analyzed by XRD, SEM, TEM, UV–vis DRS, ICP–OES, N 2 adsorption, and NH 3 –TPD. The adsorption and oxidation catalytic properties of SBA-15 were also investigated via the oxidative decolorization of organic dyes as a model reaction. Results illustrated that Cu–SBA-15 has an ordered mesoporous structure with homogeneous pore distribution and acid sites with a Cu/Si molar ratio of 0.034. Cu 2+ ions incorporate homogeneously into the framework of the mesoporous silica rather than be at the extra-framework position in the form of CuO nanoparticles. Acetate ions not only accelerate the nucleation and crystallization of mesoporous silica but also contribute to the doping of Cu ions into the SBA-15 framework. Cu–SBA-15 materials exhibit a favorable catalytic activity in the oxidation degradation of organic dyes compared with CuO and Cu ion-exchanged Al–SAB-15. • Cu-SBA-15 mesoporous materials were synthesized under neutral condition via a one-step method. • Cu 2+ ions prefer incorporating into the framework to loading on the surface of the mesoporous silica. • Cu-SBA-15 exhibits the preferable oxidation catalytic performance in contrast to CuO and Cu 2+ /Al-SAB-15.

Photocatalytic decolorization of three commercial dyes using a new heteropolyoxotantalate catalyst.

The decolorization of commercial dyes is still a pertinent issue since these azo dyes are relatively resistant to conventional biological treatment methods. It is well known that polyoxometalates can absorb light in UV–Vis range that delivers electrons to the reducible species resulting in the decomposition of organic compounds. In this paper, we present the third heteropolyoxotantalate under conventional synthetic conditions in the presence of hydrogen peroxide. The compound has been thoroughly characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis and powder X-ray diffraction. The polyanion incorporates two 3-peroxotantalo-2-phosphate clusters that are linked together by four oxygen bridges. In addition, the photocatalytic activities of the title compound 1a were investigated. After 270 min irradiation, about 90% of Rhodamine B (RhB) was removed in the presence of 1a while the degradation of RhB could be negligible in the absence of 1a, indicating it can be a promising catalyst candidate for decolorization of organic dyes. Also, photocatalytic experiment for hydrogen generation was studied, and the results show that the H2 evolution rate is 3383 µmol h−1 g−1 for compound 1a (100 mg) over 6 h with the corresponding turnover number of 432.

The efficient, fast and facile decolorization of organic dyes homogeneously catalyzed by iron octacarboxylic phthalocyanine

To remove the harmful dye contaminants via an efficient, facile and low energy consumption route is a grave challenge in current chemical industry. Though the great progresses of TiO2 photocatalysis and enzymatic degradation have been witnessed, the strategy for satisfying the above requirements is still worth exploring. Herein, we develop a biomimetic catalysis strategy for the fast decolorization of organic dyes catalyzed by iron octacarboxylic phthalocyanine (FeOCPc) complexes assisted with tert-butyl hydroperoxide (BuOOH). Methyl orange (MO) and methylene blue (MB) were used as the model pollutants and experimental results show that the decolorization degree of 25 mg/L MO could achieve 100% within 20 min and 80% for 25 mg/L MB within 30 min. The molar ratio for FeOCPc/MO and FeOCPc/MB is 0.146 and 0.142, respectively. Interestingly, other than the high-valent iron-oxygen active species, tert-butyl peroxyl radicals and hydroxyl radicals were detected as the active species generated during the catalytic oxidation by the electron paramagnetic resonance (EPR) measurement. This work not only provides a distinctive biomimetic catalysis system of FeOCPc–BuOOH for the fast bleaching of dye pollutants, but also proposes the new insight on a mechanism based on the cooperation catalysis of iron-oxygen active species, tert-butyl peroxyl radicals and hydroxyl radicals.

Morphology and phase control of hierarchical copper sulfide superstructures as efficient catalyst

Morphology and phase have significant role in the performance of catalysts. Herein, we fabricated various novel and highly hierarchical flower-like copper sulfide superstructures of CuS and Cu1.8S phase through self-assembly of nanoplates or nanosheets via solvothermal reaction by adjusting the ratio of precursors and the type of solvent (i.e. 2-propanol, methanol, and mixed 2-propanol: water). Subsequently, the growth mechanism of superstructures was systematically investigated. These results demonstrate that the copper sulfide superstructures display surface area, morphology, and phase-dependent catalytic activity for decolorization of organic dye in an aqueous medium. Additionally, the rose like CuS structures showed the highest rate constant and reusability property. Thus they could be useful for environmental pollution cleanup as an efficient catalyst.

Microwave synthesis of ZnO nanoparticles using longan seeds biowaste and their efficiencies in photocatalytic decolorization of organic dyes.

Crude water extract of the ground longan seeds which have been disposed in a large amount annually in Northern Thailand has been used in a simple and rapid microwave synthesis of ZnO nanoparticles. The particles were characterized by the UV-vis spectroscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction, electron diffraction, energy dispersive X-ray spectroscopy, and transmission electron microscopy and revealed to be pure hexagonal phase. Influences of zinc precursor in the extract, microwave power, and irradiation time on particle sizes were studied. The use of 800W and 30 cycles of the microwave irradiation provided the ZnO particles of 10-100nm in size with an active surface area, a band gap energy, and a zero-point charge of 35m2·g-1, 3.42eV, and pH7.7, respectively, after the calcination. Photocatalytic efficiencies of the synthesized particles were evaluated through the decolorization of methylene blue, malachite green, methyl orange, and orange II, and proved to be on par with commercially available titanium dioxide (Arroxide®P-25) under the same conditions. The use of the longan seeds biowaste as a sustainable supply of natural reagents for the green synthesis of ZnO nanoparticles which can be employed further for waste water treatment of the local textile dyeing industry is therefore presented. Graphical Abstract.

Facile synthesis of copper ions chelated sand via dopamine chemistry for recyclable and sustainable catalysis

Metal-based catalysts present highly efficient catalytic activities towards organic dyes and their intermediates for color removal. However, several issues are needed to be addressed urgently for their large-scale practical applications, such as the cost, stability and recyclable use of these catalysts. In this work, we developed a facile approach to chelate Cu ions on the polydopamine-coated sand (Cu-PDA@Sand) and investigated their catalytic properties towards the decoloration of organic dyes or intermediate including 4-nitrophenol (4-NP), methylene blue (MB), and congo red (CR). Our results found that the copper ions from Cu-PDA@Sand were the mixture of Cu (I) and Cu (II), and the molar fraction of Cu (I) over Cu (II) was increased from the original 3:2 to 4:1 in the presence of NaBH4. The reduction of these organic dyes or intermediate followed the first order kinetics, and the apparent reduction rate kapp of CR was larger than that of MB and 4-NP under similar conditions. Additionally, the optimized kapp of 4-NP could reach to 1.28 min−1, which is much higher than the reported results from literature. The recyclability test of Cu-PDA@Sand showed that the reduction efficiency of Cu-PDA@Sand maintained 100% during the successive 20 cycles. Additionally, Cu-PDA@Sand was demonstrated to present long-term stability and catalytic activities after soaking Cu-PDA@Sand in water for 30 days. Our research demonstrated that the easy-prepared low-cost Cu-PDA@Sand catalyst would have a great potential in the practical applications for color removal of the dye-containing wastewater.

Green biosynthesis of silver nanoparticles decorated on multi-walled carbon nanotubes using the extract of Pistacia atlantica leaves as a recyclable heterogeneous nanocatalyst for degradation of organic dyes in water

In this study, the extract of Pistacia atlantica leaves is used to modify the surface of multi walled carbon nanotubes (MWCNTs) for in situ reduction and immobilization of Ag nanoparticles. The resultant nanocatalyst, i.e. MWCNTs@ S. Lavandulifolia/Ag, is characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma (ICP). The MWCNTs@ S. Lavandulifolia/Ag nanocomposite can be employed for decolorization of organic dyes (MO and MB) as a heterogeneous, highly effective and low-cost catalyst. Furthermore, this catalyst can be recycled and reused for 5 times without significant loss of efficiency.

Synergy effects of the complexation of a titania and a smectite on the film formation and its photocatalyst' performance

A clay mineral (synthetic hectorite) was complexed with titanium dioxide (anatase with the average particle size of 20 nm) as a film on a glass substrate for photocatalyst application. The mass ratio of the hectorite to the anatase was optimized to be 1(hectorite):10(anatase) to obtain homogeneous coatings. The photocatalytic decolorization of organic dyes (methyl orange and methylene blue) by UV irradiation was examined as a model reaction to find a synergy effect of the hybridization, an efficient methylene blue decomposition in an acidic solution.

Synthesis of 3D mesoporous alumina from natural clays for confining CdS nanoparticles and enhanced photocatalytic performances

Abstract A spatial confinement effect of CdS nanoparticles in mesoporous alumina, which is synthesized through evaporation-induced self-assembly (EISA) method, post-impregnation approach and microwave irradiation process, was investigated to verify the enhanced catalytic activity and stability with less aggregation of CdS crystallites during decoloration of organic dyes under visible-light irradiation. In this work, we utilize inexpensive natural clays for preparing mesoporous alumina via evaporation-induced self-assembly method, and used as the host for confining CdS nanoparticles to suppress the crystallite growth and aggregation. The loading amount and grain size of CdS nanoparticles significantly altered catalytic activity and stability. CdS clusters confined inside the mesoporous channels provided abundant reactive sites for photocatalytic reaction through spatial confinement effect, quantum size effect and sulfide-support interaction, thus greatly enhancing the reaction activity. CdS/MAl composites have large special surface area, strong visible light absorption and high quantum yields. CdS/MAl-25 photocatalyst has exhibited remarkably enhanced visible light photoactivities as compared to other catalysts, and the overall decoloration rate was up to 97.5% after visible light irradiation for 60 min. The CdS/MAl composites exhibit potential applications in the wastewater treatment under visible light irradiation.

Fast Electrochemical Method for Organic Dye Decolorization Using Recycled Li-Ion Batteries

In this paper, the application of recycled Li-ion battery spent cathodes (LIB-SC) combined with a NaHCO3/H2O2 system is presented for the first time in the literature as an alternative for the degradation of potentially toxic organic molecules. The model pollutant choice was methylene blue molecule. The spent cathode composition corresponds to LiCoO2, which was proved by the XRD and EDX. Regarding the decolorization of methylene blue solution, the addition of NaHCO3, in comparison with only H2O2, reduces the complete decolorization time by 96%. This reduction occurs because the radical CO 3 . is more stable than OH. In this way, the application of the system proposed in this article is aimed at solving two major global problems: the disposal of cell phone batteries and the pollution of liquid effluents.