High Dye Concentration Research Articles

Experimental and Theoretical Evaluation of a Commercial Luminescent Dye for PVT Systems

Combining photovoltaic (PV) and photo-thermal (PT) energy collection strategies in a single system can enhance solar energy conversion efficiencies, leading to increased economic returns and wider adoption of renewable energy sources. This study focuses on incorporating a commercial luminescent organic dye (BASF Lumogen F Red 305) into ethylene glycol to explore its potential for PVT applications. The optical and electrical characteristics of the working fluid were evaluated at different temperatures under direct solar irradiance. Pristine ethylene glycol reduced the maximum PV cell temperature by 10 °C. The inclusion of luminescent dye at various concentrations further reduced the maximum temperature, with the lowest concentration achieving a 7 °C decrease compared to pristine ethylene glycol. The highest dye concentration (0.50 wt%) resulted in a significant temperature reduction of 12 °C. While electrical conversion efficiencies decreased with increasing dye concentration, all concentrations exhibited higher fill factors compared to the bare PV cell during the 100-min illumination period. A ray-tracing model was employed to analyze the behavior of the luminescent dye and quantify transmitted energy for electricity and thermal energy production. Different concentrations showed varying energy outputs, with lower concentrations favoring electrical energy and higher concentrations favoring thermal energy. Economic assessment revealed the viability of certain concentrations for specific countries, highlighting the trade-off between thermal and electrical energy generation. These findings provide valuable insights for PVT system applications in different geographical and economic contexts.

Alkaline-thermal hydrolysate of waste activated sludge as a co-metabolic substrate enhances biodegradation of refractory dye reactive black 5

Aromatic azo dyes possess inherent resistance and are known to be carcinogenic, posing a significant threat to human and ecosystems. Enhancing the biodegradation of azo dyes usually requires the presence of co-metabolic substrates to optimize the process. In addressing the issue of excessive waste activated sludge (WAS) generation, this study explored the potential of utilizing alkaline-thermal hydrolysate of WAS as a co-metabolic substrate to boost the degradation of reactive black 5 (RB5) dyes. The acclimated microbial consortium, when supplemented with the WAS hydrolysate obtained at a hydrolysis temperature of 30 °C, achieved an impressive RB5 decolorization efficiency of 90.3% (pH = 7, 35 °C) with a corresponding COD removal efficiency of 45.0%. The addition of WAS hydrolysate as a co-substrate conferred the consortium with a remarkable tolerance to high dye concentration (1500 mg/L RB5) and salinity levels (4–5%), surpassing the performance of conventional co-metabolic sugars in RB5 degradation. 3D-EEM analysis revealed that protein-like substances rich in tyrosine and tryptophan, present in the WAS hydrolysate, played a crucial role in promoting RB5 biodegradation. Furthermore, the microbial consortium community exhibited an enrichment of dye-degrading species, including Acidovorax, Bordetella, Kerstersia, and Brevundimonas, which dominated the community. Notably, functional genes associated with dye degradation and intermediates were also enriched during the RB5 decolorization and biodegradation process. These findings present a practical strategy for the simultaneous treatment of dye-containing wastewater and recycling of WAS.

Preparation, catalytic efficiency and mechanism of Fe3O4/HNTs heterogeneous Fenton-like catalyst

In situ anchor of Fe3O4 nanoparticles (NPs) onto the external surface of natural halloysite nanotubes (HNTs) was achieved by a simple one-pot solvothermal method. The Fe3O4/HNTs composites were characterized by XRD, SEM, TEM, FT-IR, VSM, and N2 adsorption-desorption. Characterization results showed that the magnetic Fe3O4 NPs formed tightly on the external surface of HNTs with good dispersion. Fe3O4/HNTs composites exhibited typical ferromagnetic property determined by VSM tests and could be recovered by an external magnet. Degradation experiments were conducted using the active dye RhB as the target probe to evaluate the Fenton-like catalytic efficiency of Fe3O4/HNTs composites obtained under different preparation conditions. The experimental results indicated that the degradation efficiency of RhB could reach more than 98 % within 10 min reaction time, when the initial pH was 3.5, initial RhB concentration was 100 mg L−1, H2O2 concentration was 1.96 mmol L−1, and catalyst dosage was 0.5 g L−1, realizing the rapid degradation of high concentration dye. Comparative investigations revealed that the Fenton-like catalytic efficiency of Fe3O4/HNTs for degrading high concentration RhB was much higher than that of Fe3O4 NPs. The heterogeneous Fenton-like catalytic mechanism of Fe3O4/HNTs was elucidated. Hydroxyl radicals (•OH) and superoxides radicals (•O2-) dominated the RhB degradation in the Fe3O4/HNTs-H2O2 system.

Efficiently elimination of high concentration dye pollutants by Ph-C≡C-Cu/nanoparticles hybrids

For the requirement of industrial printing and dyeing wastewater treatment, this work designed and synthesized a serious of Ph-C≡C-Cu/nanoparticles (NPs) hybrids for highly efficient removal of dye pollutants. Among them, Cu2O/Ph-C≡C-Cu shows the most excellent adsorption ability and considerable stability. The prepared Cu2O/Ph-C≡C-Cu hybrids were detailedly studied, demonstrating a different growth mode of Ph-C≡C-Cu on the surface of Cu2O, which provides increased surface area and adsorption sites exposure. The highest adsorption capacity of MO achieved 629.1 mg/g at 20 wt% Cu2O/Ph-C≡C-Cu hybrid, which is about 10 and 30 time higher than those of raw Ph-C≡C-Cu and Cu2O. Moreover, it is even 3 times higher than the famous adsorbent activated carbon. This is because that the adsorption mode of MO on the surface of Cu2O/Ph-C≡C-Cu hybrid is demonstrated to be chemical adsorption by the kinetic analysis, while it is mainly physical adsorption on the surface of activated carbon. Besides, Cu2O/Ph-C≡C-Cu hybrid also shows good stability and universality at the condition of basic room temperatures (0–50 °C), pH of 5–11, anions (NO3− and HCOO−) and other dyes (congo red, malachite green and sunset yellow) co-existence. This work indicates that 20 wt% Cu2O/Ph-C≡C-Cu is an effective and prospective adsorbent for treating the printing and dyeing industrial wastewater.

Tuning of Morphological and Antibacterial Properties of Poly(3,4-ethylenedioxythiophene):Peroxodisulfate by Methyl Violet.

This study demonstrates a one-step synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of the methyl violet (MV) dye. The structural properties of PEDOT:peroxodisulfate were studied using Raman and MALDI-TOF spectroscopies. The use of the MV dye in the polymerization process resulted in a change in the typical irregular morphology of PEDOT:peroxodisulfate, leading to the formation of spherical patterns. SEM and TEM analyses revealed that increasing the dye concentration can produce larger spherical aggregates probably due to the hydrophobic and π-π interactions. These larger aggregates hindered the charge transport and reduced the electrical conductivity. Interestingly, at higher dye concentrations (0.05 and 0.075 M), the PEDOT:peroxodisulfate/MV films exhibited significantly improved antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the PEDOT:peroxodisulfate films with the incorporated MV dye exhibited a well-defined and repeatable redox behavior. The remarkable amalgamation of their optical, electrochemical and antibacterial properties provides the PEDOT:peroxodisulfate/MV materials with an immensely diverse spectrum of applications, including in optical sensors and medical devices.

Phytoremediation of high concentration of ionic dyes using aquatic plant (Lemna minor): A potential eco-friendly solution for wastewater treatment

Wastewater pollution poses a significant threat to the environment and human health. Recent studies have shown a disturbing increase in the levels of water contamination. However, phytoremediation is a low-cost, eco-friendly and effective technology that utilizes plants to treat wastewater. In this study, duckweed (Lemna minor) used for phytoremediation to address the high concentration of ionic dyes in contaminated water. The findings of this study were remarkable, with Lemna minor showing impressive results in reducing both Methylene Blue (up to 99%) and Congo red (up to 25%) after a 24-day period. Furthermore, the relative growth rate of the plants was analyzed, revealing that the growth rate of Lemna minor was higher after exposure to methylene blue than it was for Congo red. This study also employed FTIR to analyze the characteristics of the plant sorption process. Overall, this study highlights the effectiveness of using phytoremediation with duckweed for treating wastewater contaminated with dyes. The results provide a strong foundation for further research into using plants for treating water pollution.

Investigation of Effective Removal of Auramine O Dye by Pyracantha Coccinea Biosorbent: Isotherm and Kinetics

In this study, the effect of biosorbent dosage (0.1-0.4 g/L), dye pH (3.0-9.0) and initial dye concentration (50-500 mg/L) on synthetic Auramine O (AU-O) dye removal of biosorbent produced from Pyracantha coccinea (PC) plant by physical modification was investigated and the dye removal behavior of the biosorbent was investigated by kinetic and isotherm experiments. In the batch experiments, it was observed that as the adsorbent quantity was raised from 1 g/L to 4 g/L at a consistent dye concentration, the adsorption capacity declined from 69.25 mg/g to 22.73 mg/g. The adsorption capacities of AU-O dye at concentrations of 50 mg/L and 100 mg/L were determined to be 22.350 mg/g and 72.35 mg/g at 200 mg/L, respectively. The reason why there was no significant increase in adsorption capacity at higher dye concentrations (250-500 mg/L) was that at constant amount of biosorbent, the change in adsorption capacity was minimal since the active sites of the biosorbent reached saturation. The adsorption capacity was determined to be 26.512 mg/g, 38.74 mg/g, and 44.07 mg/g at pH:3.0, pH:4.88, and pH:7.0, respectively. It has been determined that the adsorption capacity achieved at pH 9.0 (44.21 mg/g) was nearly equivalent to the adsorption capacity observed under neutral pH conditions. The adsorption mechanism is best explained by the Langmuir isotherm (qm:123.10 mg/g and R2:0.990) and the pseudo-second-order kinetic models (R2: 0.985) in the adsorption isotherm and kinetic research.

Tuning surface termination of CeO2 nanoparticles for adsorption of anionic dyes via urea content in a simple pyrolysis technique

CeO2 adsorbents with different terminated surfaces are fabricated by controlling urea content in simple pyrolysis methods. CeO2 adsorbent prepared with lower urea content is discovered to form a less positively charged surface with anoxic cerium-rich defect structures, inducing more difficult charge transfer in adsorbent interface and higher diffusion resistance in the interface of adsorbent and adsorbate. Thus, its adsorption isotherm is preferably fitted to Freundlich isotherms and its single adsorption site adsorbs multiple Congo red molecules, especially at higher dye concentrations. However, the adsorbent still has low adsorption ability. Oppositely, CeO2 adsorbent prepared with higher urea content induces forming a more positively charged surface with Ce-terminated structure due to higher Ce3+ concentration on its defect surface stabilized by Ce2O3 structure. CeO2 adsorbents with the Ce-terminated surface structures present easier charge transfer and lower diffusion resistance during dye adsorption. Significantly, they have much higher adsorption capacities of anionic dyes and their adsorption isotherm is better matched with Langmuir isotherms. Therefore, in the synthetic process of CeO2 adsorbents, urea content essentially regulates the arrangement structure of their terminated atoms, which greatly changes physicochemical properties of their terminal surfaces and influences the Congo red adsorption capacities.

To study on development and treatment of textile waste water by using microbiological processes and root-bed treatment in Jhunjhunu, Rajasthan

Textile wastes often have an intense color, with high concentrations of dyes, dyeing of various chemicals, additives, and some are non-biodegradable and toxic, mutagenic or carcinogenic. Therefore, it is essential to treat the waste water from the tissues to eliminate these substances before discharging them into the environment. In the present and in the last decades, in-depth research has been conducted on the elimination of dyes from different waste waters using chemical and biological treatment technologies or a combination of both. Therefore, the goal was to study the microbial community in the active tissue that worked well compared to the municipal for two seasons (winter and summer) sludge, and explain the differences observed by environmental variables bacterial taxonomy, phylogenetic tree, Chloroflexi, Choroid and Acidobacterias were more abundant in active sludge textile samples. In addition, reducing exfeated bacteria detected almost exclusively in the textile industry, while nitrification and denitrification of bacteria and phosphate accumulation bacteria were more abundant in the city. It was also clear that the textile microbial communities were more different than municipal, perhaps due to a wider variety of environmental stress to which microbial communities are subjected in textile purification plant. High salinity, high organic loads and a higher water temperature have been found as important variables that guide the composition of the microbial community.

Pit-mound microrelief on a forested slope drives infiltration and preferential flow after heavy rainfall – experiments with soil resistance monitoring and dye tracing

With the changing climate, short heavy rainfalls (SHRs) are becoming more frequent and intensive. The distribution of rainwater and subsurface runoff formation in forest soils can be strongly affected by soil disturbances and surface microrelief. Rainwater redistribution and the formation of preferential flow in response to natural and simulated SHRs were investigated in soil profiles on slopes forested by Norway spruce with a pit-mound microrelief formed by historical tree uprooting using two independent methods; soil electrical resistance monitoring and the application of dye tracer. In the deepest soil layers, resistance decreased in responses to natural SHRs on average by 46% in pits and by 11% on ‘smooth slope’ controls, reflecting the deeper redistribution of infiltrated water in pits. Dye tracing in the simulated rainfall revealed the formation of shallow biomat flow at the control plot. In contrast, the shallow lateral flow was focused by the pit and redirected into funnel flow underneath the pit bottom. The sum of medium and high dye concentration classes obtained with the support vector machine classification of profile photographs indicated a higher water entry into topsoil and subsoil layers in pit (44% and 31% of area, respectively) as compared to the control profile (16% and 8% of area, respectively). Leaving pit-mound microrelief as the natural legacy in forest soils can mitigate some of the negative hydrological effects of intensive forest management and may improve the water yields on forested slopes by redirecting shallow subsurface runoff and facilitating deep distribution of infiltrated water. Such beneficial effects of pit-mounds on the hydrology of forested slopes should be considered in future hydrological modelling and land management.

Influence of the azo-dye amaranth on the trophic structure of activated sludge in a model experiment.

The textile industry generates significant amounts of wastewater containing high concentrations of azo dyes. An important point in the process of purification of azo dyes is their influence on the activated sludge (AS) in wastewater treatment plants. Azo dyes, such as amaranth, play the role of xenobiotics. This article seeks to answer the question of how organisms manage to respond to xenobiotics remains very important and open, i.e., how they will react to toxic conditions. The aim of this research was to study how these changes are expressed in terms of the different trophic levels of AS. In our experiment, it was found that the dominant trophic units are significantly changed due to the xenobiotic entering the system. The data reveal the significant development of the bacterial segment (genusPseudomonasand azo-degrading bacteria) at times of large amaranth removal. In the most active phase of amaranth biodetoxification (48h), the culturable bacteria of the genus Pseudomonas change by about 40%, while the azo-degrading bacteria change by about 2%. Fauna organisms have a sharp change in the dominant groups-from attached and crawling ciliates and testate amoebas to the mass development of small and large flagellates. This is of great importance because micro- and metafauna play an important role in the detoxification process by ingesting some of the xenobiotics. This role is expressed in the fact that after dying, macro-organisms release this xenobiotic in small portions so that it can then be effectively degraded by adapting to the amaranth biodegradation bacteria. In this study, it is clear that all these events lead to a decline in the quality of AS. But on the other hand, these allow AS to survive as a microbial community, and the fauna segment does not disappear completely.

Encapsulation of Sorghum Leaf Red Dye: Biological and Physicochemical Properties and Effect on Stability.

The encapsulation of the 3-deoxyanthocyanidins (3-DXA) red dye, extracted from sorghum (Sorghum bicolor L.) leaves, was explored for food application. The extracts showed antioxidant activity at concentrations ranging from 803 to 1210 μg mL-1 and did not reveal anti-inflammatory or cytotoxic properties, indicating their potential for food application. Encapsulation was performed with two carrier agents (maltodextrin and Arabic gum) in different proportions (1:1, 2:1 and 1.5:2.5 (w/w)). The microparticles produced by freeze-drying and spray-drying were studied according to the concentration of the dye, the encapsulation efficiency, the process yield, the solubility and the colour of the powders. The dye extracts are released from the microparticles at different pHs. The variation in ratio composition of the 3-DXA encapsulation was assessed by principal component analysis (PCA) using data from ten physicochemical parameters. The results indicated that the maltodextrin at the 2:1 ratio had a higher dye concentration and total phenolic content (TPC) at pH 6. This ratio was selected to produce the microparticles by freeze-drying and spray-drying, and the particles were used in the temperature stability tests at pH 6. The results suggest that the freeze-drying process offers better protection to 3-DXA, with a degradation percentage of 22% during the heating period (80 °C for 18 h), compared to the non-encapsulated dye (48%). However, there were no significant differences between the two polymeric agents. The non-encapsulated 3-DXA was evaluated as control and lost 48% of the total colour with the same treatment. Red dyes from sorghum leaf by-products may constitute promising ingredients for the food industry and increase the value of this crop.

Nanoemulsion-based silver ion-selective optode based on colorimetrically silver ion-responsive ionic liquid-based dye.

In this study, we describe the fast-responsive nanoemulsion (NE)-based silver ion (Ag+)-selective optode based on colorimetrically silver ion-responsive ionic liquid-based dye (ILD). The ILD comprises purely functional sensing molecules, a protonated cationic merocyanine dye (KD-M13-H+) and an anionic Ag+ ionophore (BDM-SO3-), and thus, it can be used for highly sensitive silver ion (Ag+) sensing due to the extremely high content of dye in the organic phase (ionic-liquid phase). However, during the Ag+ sensing, the cationic merocyanine dye is converted into electrically neutral form by deprotonation of the dye, which leads to the conversion of liquified dye into solid form in the organic phase, which makes the response time slower when ILD is used for poly(vinyl chloride) (PVC) membrane-based ion-selective optode, especially for sensing of high Ag+ concentration. To solve this problem, we focused on the use of the nano-emulsification technique. The response time of the ILD-based nanoemulsion (NE) was considerably shorter (1s) compared to that of the ILD-based PVC membrane (a few minutes) owing to the large surface area and excellent diffusivity of the emulsion. The ILD-based NE contained a very high dye concentration (833mmolkg-1) and exhibited approximately 12 times higher sensitivity than that of the plasticizer-based conventional NE. In the cation measurements, the ILD-based NE responded to Ag+ via a cation-exchange mechanism and demonstrated a highly selective response to Ag+ (log [Formula: see text] = -3.0). ILD-NE was successfully applied to the detection of spiked Ag+ in a tap water sample with recoveries of 98 -103% with a relative standard deviation (RSD) of less than 5%. In comparison with NE based on non-ionic ionophores without charge, NE based on BDM-SO3- responded to lower Ag+ concentrations owing to the effect of negative charge on the binding property. The novel ILD-based NE was capable of highly sensitive, rapid, and selective Ag+ sensing, providing potential for analytical devices applicable to high-performance on-site analysis.

Analysis of the Capacity of the Fenton Process for the Treatment of Polluted Wastewater from the Leather Dyeing Industry.

In this work, the capacity of the Fenton oxidation process for the degradation of color and organic matter contained in the wastewater generated in the leather dyeing stage (WWDS) of an industrial tannery was evaluated. The wastewater characteristics included, among others, high toxicity (lethal concentration for Artemia salina, 24 h test, 50% of population = 93.71 ppm), high dye concentration (36 mg/L, yellow color), high chromium concentration (3.34 mg/L), and low biodegradability index (BOD5/COD ratio = 0.083). From an experimental design, the response surface methodology, and the multiobjective optimization analysis, the following optimal operating conditions were established: initial pH = 3.15, [Fe2+] = 0.981 mM, and [H2O2] = 5.38 mM. After 10 min of oxidation (determined from kinetic studies), it reached approximately 97% decolorization, COD reduction of approximately 82%, and TOC mineralization of approximately 92%. A synergistic effect of Fenton's reagents for TOC removal (S TOC = 0.8) and decolorization (S CN = 0.28) of the WWDS under study was confirmed experimentally. An increase in the biodegradability index, to a value of approximately 0.3, was confirmed. The cost of the treatment was estimated at 0.0112 USD/m3. Thus, the Fenton oxidation process allowed compliance with current Colombian environmental regulations and considerably improved the biodegradability and toxicity characteristics of the studied industrial effluent. It can be considered as an efficient alternative, easy to carry out on an industrial batch scale, and economically viable for the treatment of wastewater from the leather dyeing stage of an industrial tannery.

Efficient Labeling of Vesicles with Lipophilic Fluorescent Dyes via the Salt-Change Method.

Fluorescent labeling allows for imaging and tracking of vesicles down to single-particle level. Among several options to introduce fluorescence, staining of lipid membranes with lipophilic dyes provides a straightforward approach without interfering with vesicle content. However, incorporating lipophilic molecules into vesicle membranes in an aqueous solution is generally not efficient because of their low water solubility. Here, we describe a simple, fast (<30 min), and highly effective procedure for fluorescent labeling of vesicles including natural extracellular vesicles. By adjusting the ionic strength of the staining buffer with NaCl, the aggregation status of DiI, a representative lipophilic tracer, can be controlled reversibly. Using cell-derived vesicles as a model system, we show that dispersion of DiI under low-salt condition improved its incorporation into vesicles by a factor of 290. In addition, increasing NaCl concentration after labeling induced free dye molecules to form aggregates, which can be filtered and thus effectively removed without ultracentrifugation. We consistently observed 6- to 85-fold increases in the labeled vesicle count across different types of dyes and vesicles. The method is expected to reduce the concern about off-target labeling resulting from the use of high concentrations of dyes.

A fluorogenic method to directly observe transfer and distribution of influenza viral contents to target vesicles.

There is a long-standing interest in studying viral infection processes using bottom-up biophysical models to dissect various underlying molecular determinants. Fusion of enveloped viruses with cellular membranes and subsequent release of viral contents into the cytoplasm is a key event in the infection cycle. In case of influenza virus, fusion of the viral membrane is mediated by conformational changes of its surface protein hemagglutinin triggered by acidic pH within endosomes. Previously, content transfer assays have relied on fluorescence enhancement of an encapsulated self-quenched water-soluble dye upon fusion of the viral compartment with a target membrane. However these assays do not track the transfer of actual viral macromolecular contents, and suffer from drawbacks such as the need to use high concentration of the content dye which may have perturbative effects on the membranes. To overcome these limitations, we developed a method utilizing nucleic acid-binding dyes to directly observe the transfer of viral ribonucleoprotein complexes to target vesicles by total internal reflection fluorescence (TIRF) microscopy. The dyes were encapsulated within surface-tethered vesicles and the unlabeled virus particles were bound via sialic acid receptors. The fluorogenic nature of the dyes allowed background-free detection of fusion events when pH was dropped. We determined the kinetics of viral content transfer and found that it is slower than that of lipid mixing. We further employed a super-localization strategy to investigate to what extent the viral contents are transferred to the target vesicle through the fusion pore. Overall, our method allows observation of viral fusion events on a single-particle level and will provide the groundwork for development of biosensors for rapid quantification of fusogenic virus particles.

Carboxylated Graphene Oxide (c-GO) Embedded ThermoPlastic Polyurethane (TPU) Mixed Matrix Membrane with Improved Physicochemical Characteristics.

Water is an important component of our life. However, the unavailability of fresh water and its contamination are emerging problems. The textile industries are the major suppliers of contamination of water, producing high concentrations of heavy metals and hazardous dyes posing serious health hazards. Several technologies for water purification are available in the market. Among them, the membrane technology is a highly advantageous and facile strategy to remediate wastewater. Herein, the distinguished combination of pore-forming agents, solvent, and nanoparticles has been used to achieve improved functioning of the polymeric composite membranes. To do so, graphene oxide (GO) was fabricated via Hummer's technique and GO functionalization using chloroacetic acid (c-GO) was performed. Thermoplastic polyurathane (TPU) membranes having different concentrations c-GO were made using the phase inversion technique. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) was used to examine surface morphology, chemical functionalities on membranes surfaces, and crystallinity of membranes, respectively. The temperature-dependent behavior of c-GO composite membranes has been analyzed using DSC technique. The water contact angle measurements were performed for the estimation of hydrophilicity of the c-GO based TPU membrane. The improved water permeability of the composite membrane was observed with increasing the c-GO concentration in polymeric membranes. c-GO was observed as a potential candidate that enhanced membrane physicochemical properties. The proposed membranes can behave as efficient candidates in multiple domains of environmental remediation. Furthermore, the improved dye rejection characteristics of proposed composite membranes suggest that the membranes can be best suited for wastewater treatment as well.

Fabrication of cross-linked highly stable graphene oxide membrane for dye removal

ABSTRACT Clean water is essential to our health, community and economy, but also its availability remains a major challenge even today. Graphene oxide membranes have shown significant promise in addressing this problem. A great deal of research has been conducted and is still being done to produce a stable graphene oxide membrane with high permeability and rejection rate. In this study, a highly stable GO membrane was fabricated using a simple vacuum filtration technique by the addition of TRIS and PEG. This is the first paper to discuss the potential for this combination to remove dyes and how it can result in the formation of a stable membrane. The membranes were characterised in detail using various characterisation techniques such as XRD, XPS, AFM, etc., and their ability in dye removal was investigated using UV–Vis spectroscopy. The stability of the developed membranes was tested using ultrasonication, and it was found that the membranes could remove the organic dyes (MB and CR) even at high concentration of dye (20 ppm) and with rejection percentage of 95% for both dyes. Furthermore, the membranes showed good water permeability with a value of 183 Lm−2h−1bar −1 emphasising its high potential for water purification.

Synthesis of Graphene oxide/Porphyrin Nanocomposite for Photocatalytic Degradation of Crystal Violet Dye

AbstractA novel nanocomposite was synthesized by covalent functionalization of graphene oxide (GO) with 5,10,15,20‐tetrakis(4‐hydroxyphenyl)porphyrinatoiron (III) chloride (Fe−THPP) via an ester linkage. The synthesized nanocomposite was characterized by various techniques such as XPS, Raman spectroscopy, BET, IR, UV‐Visible, TGA, SEM, and EDX. The synthesized nanocomposite exhibited appreciable interaction with crystal violet (CV) dye with a detection limit of 2.6×10−6 μg/mL and binding constant of 35.93×103 ppm−1 which ensured the high concentration of CV dye on the surface of synthesized photocatalyst. The nanocomposite was effectively utilized in the photo‐degradation of CV dye under visible light irradiation. The photo‐degradation efficiency was remarkably high (93.45 %) with a low catalytic dosage of 0.4 mg/L within 80 minutes. The nanocomposite exhibited good stability and reusability and thereby can be used in the photocatalytic degradation processes to treat wastewater.

Natural calcium phosphates from circular economy as adsorbent phases for the remediation of textile industry waste-waters

Adsorption is one of the most important techniques for the remediation of textile industry wastewaters containing high concentrations of toxic dyes. Calcium phosphates (CaPs) have been advocated among the most promising adsorbent phases in virtue of their high dye adsorption potential, low production cost, and possible recovery from circular economy sources. In this paper, we investigated the application of synthetic CaPs (CaP–S) and two CaPs extracted from food by-products, namely from bone meal (CaP-BM) and fish bones (CaP-FM) for the removal of a model dye, copper phthalocyanine tri-sulfonic acid, also known as acid blue 185 (AB-185). All the materials were characterized from the physical-chemical point of view and used for the study of adsorption kinetic and isothermal adsorption of AB-185 at neutral, acidic and basic pH values. The best adsorption capacity was obtained for CaP–S, followed by CaP-BM and CaP-FM. Nonetheless, results showed that all the materials can be employed for removing AB-185 from wastewaters of textile industry, and we correlated dye removal efficiency to the adsorbent phase specific surface area (SSA) and ζ-potential, as well as to dye concentration and pH of wastewaters. Finally, as the process used to produce the studied CaPs affects their main final physical-chemical parameters and performance in terms of dyes removal, it is important to consider the variables of CaPs production process (e.g., temperature, time of treatment, grinding etc.), especially when CaPs are recovered from circular economy sources by thermal treatments of food-byproducts.