Synthesis and efficacy of PPy/CS/GO nanocomposites for adsorption of ponceau 4R dye

Removal of food dyes using biological materials via adsorption: A review

It is alarming that synthetic food dyes (FD) are widely used in various industries and that these facilities discharge their wastewater into the environment without treating it. FDs mixed into industrial wastewater pose a threat to the environment and human health. Therefore, removing FDs from wastewater is very important. This review explores the burgeoning field of FD removal from wastewater through adsorption using biological materials (BMs). By synthesizing a wealth of research findings, this comprehensive review elucidates the diverse array of BMs employed, ranging from algae and fungi to agricultural residues and microbial biomass. Furthermore, this review investigates challenges in practical applications, such as process optimization and scalability, offering insights into bridging the gap between laboratory successes and real-world implementations. Harnessing the remarkable adsorptive potential of BMs, this review presents a roadmap toward transformative solutions for FD removal, promising cleaner and safer production practices in the food and beverage industry.

Hydrogels Based on Chitosan and Nanoparticles and Their Suitability for Dyes Adsorption from Aqueous Media: Assessment of the Last-Decade Progresses

Water is one of the fundamental resources for the existence of humans and the environment. Throughout time, due to urbanization, expanding population, increased agricultural production, and intense industrialization, significant pollution with persistent contaminants has been noted, placing the water quality in danger. As a consequence, different procedures and various technologies have been tested and used in order to ensure that water sources are safe for use. The adsorption process is often considered for wastewater treatment due to its straightforward design, low investment cost, availability, avoidance of additional chemicals, lack of undesirable byproducts, and demonstrated significant efficacious potential for treating and eliminating organic contaminants. To accomplish its application, the need to develop innovative materials has become an essential goal. In this context, an overview of recent advances in hydrogels based on chitosan and nanocomposites and their application for the depollution of wastewater contaminated with dyes is reported herein. The present review focuses on (i) the challenges raised by the synthesis process and characterization of the different hydrogels; (ii) the discussion of the impact of the main parameters affecting the adsorption process; (iii) the understanding of the adsorption isotherms, kinetics, and thermodynamic behavior; and (iv) the examination of the possibility of recycling and reusing the hydrogels.

Surfactant-supported organoclay for removal of anionic food dyes in batch and column modes: adsorption characteristics and mechanism study

This study aimed to create CTAB-modified bentonite organoclay (Bt@CTAB) by mixing the naturally occurring mineral bentonite (Bt) with the cationic surfactant cetyltrimethylammonium bromide (CTAB). Elemental analysis, N2 adsorption–desorption isotherm, scanning electron microscopy (SEM), FTIR spectroscopy, XRD, and thermogravimetric (TGA) analysis have been employed to analyze both the unmodified Bt and the Bt@CTAB organoclay. The dye sorption onto Bt@CTAB organoclay was investigated in the batch and column modes using aqueous solutions of anionic food dyes, viz., Sunset yellow FCF (E110), Azorubine (E122), and Ponceau 4R (E124) (individually or in a mixture). Experimental variables affecting the adsorption process, such as initial dye concentration, contact time, temperature, pH, and adsorbent dose, are evaluated. From the kinetic investigations, the adsorption of E110, E122, and E124 dyes well matched the pseudo-second-order kinetic model. E110 and E122 dyes adsorption onto Bt@CTAB attained equilibrium in 120 min while attained in 240 min for E124. The investigated food dyes were expected to achieve maximum adsorption efficiencies at concentration of 100 ppm of (E110 and E124) and 150 ppm of (E124), an adsorbent dosage of 0.4 gL−1, and an initial pH 5. In addition, Langmuir model best fits the sorption isotherm data, with the maximum adsorption capacity at 303 K being 238 mg/g, 248.75 mg/g, and 358.25 mg/g for E110, E122, and E124, respectively. The Bt@CTAB organoclay can be regenerated up to the 4th cycle successfully. The thermodynamic studies revealed the spontaneous and exothermic nature of the adsorption of these anionic dyes onto Bt@CTAB organoclay. The prepared cationic Bt@CTAB organoclay was successfully applied for the removal of E110, E122, and E124 from real water samples, synthetic effluents, and colored soft drinks with a recovery (R%) higher than 95%. The plausible adsorption mechanism of E110, E122, and E124 onto Bt@CTAB organoclay is proposed to be due to electrostatic interaction and hydrogen bond formation. Finally, the present study shows that Bt@CTAB organoclay may be employed efficiently and effectively to remove anionic food dyes from a wide range of real water and colored soft drinks.

Synergistic Effects of Graphene Oxide and Pesticides on Fall Armyworm, Spodoptera frugiperda

Fall armyworm Spodoptera frugiperda, a native insect pest in tropical and subtropical America, has rapidly spread to most parts of China and become a major pest of corn and other crops since invading in early January 2019. As an emergency and important control measure, chemical control of S. frugiperda has the advantages of quick effect and low cost. However, long-term and large-scale use of pesticides might pollute the environment and increase pest resistance. By improving the control effect and reducing the dosage of chemical pesticides, graphene oxide (GO) is used synergistically with insecticides to increase control efficacy to achieve low-cost and sustainable management of insect pests as a new type of synergist. In this study, graphene oxide was compounded with insecticides to form nanocomposites. To clarify pest physiological responses, the laboratory toxicity of graphene oxide-insecticide nanocomposites was measured on the larvae of S. frugiperda. The results demonstrated that GO could enhance the activity of four selected pesticides: chlorantraniliprole (Chl), beta cypermethrin (Bet), methoxyhydrazide (Met) and spinetoram (Spi). Compared with pesticides alone, the toxicity of Chl-GO, Bet-GO, Met-GO and Spi-GO mixtures to the third instar larvae of S. frugiperda increased by 1.56, 1.54, 2.53 and 1.74 times, respectively. The easy preparation and higher bioactivity of GO-pesticide nanocomposites indicated their promising application potential in pest control.

Polymeric biomolecules based nanomaterials: Production strategies and pollutant mitigation as an emerging tool for environmental application

The ever-exploding global population coupled with its anthropogenic impact has imparted unparalleled detrimental effects on the environment and mitigating them has emerged as the prime challenge and focus of the current century. The niche of nanotechnology empowered by composites of biopolymers in the handling of xenobiotics and environmental clean-up has an unlimited scope. The appositeness of biopolymer-nanoparticles (Bp-NPs) for environmental contaminant mitigation has received unique consideration due to its exclusive combination of physicochemical characteristics and other attributes. The current review furnishes exhaustive scrutiny of the current accomplishments in the development of Bp-NPs and biopolymer nanomaterials (Bp-NMs) from various polymeric biomolecules. Special attention was provided for polymeric biomolecules such as cellulose, lignin, starch, chitin, and chitosan, whereas limited consideration on gelatin, alginate, and gum for the development of Bp-NPs and Bp-NMs; together with coverage of literature. Promising applications of tailored biopolymer hybrids such as Bp-NPs and Bp-NMs on environmentally hazardous xenobiotics handling and pollution management are discussed as to their notable environmental applications.

Evaluation of sulfonated oxidized chitosan antifungal activity against Fusarium graminearum

Chitosan biomaterials are widely used in the biological area because of their broad-spectrum antibacterial activity. However, chitosan cannot be dissolved in a neutral solution, limiting its application in various fields seriously. In this study, water-soluble sulfonated oxidized chitosan (SOCS) with antifungal activity were prepared by oxidization and sulfonation. Its structure was clearly confirmed by spectroscopy data (FTIR, 1H NMR, ¹³C NMR) and elemental analysis. SEM images of OCS and SOCS revealed that there was a little curly and an irregular sheet-like morphologies on them which was attributed to the oxidation and sulfonation on CS. Moreover, the FTIR and NMR indicated that -OH on the CS was oxidized into -COOH on the OCS and -SO₃H groups on the SOCS. The EDS results of OCS and SOCS confirmed the presence of the oxygen element in OCS and the S element in SOCS. All studies confirmed the OCS and SOCS were synthesized successfully. Furthermore, the inhibitory activity of SOCS biocomposites against plant pathogenic fungi, (Fusarium graminearum), was investigated. The results showed that the SOCS have significant inhibitory effects on the mycelial growth of F. graminearum. The EC₅₀ value of SOCS against F. graminearum is 79.46 μg/mL. The research results presented above indicated that SOCS can be used as a candidate material for the control of plant pathogenic fungi, and can broaden the application of chitosan materials in plant protection and sustainable agriculture.Research highlightsSOCS showed better solubility in deionized water.The antifungal effect of SOCS dissolved in acetic acid was higher than that of CS dissolved in acetic acid.SOCS dissolved in water can cause an inhibitory effect on F. graminearum at lower concentrations.

In-situ hydrothermal synthesis of CNT decorated by nano ZnS/CuO for simultaneous removal of acid food dyes from binary water samples

The zinc sulfide/copper oxide-carbon nanotube nanocomposite (ZnS/CuO-CNT) was fabricated by using an in-situ hydrothermal synthesis method and was used for simultaneous ultrasound-assisted adsorptive removal of a binary mixture of ponceau 4R (P4R) and tartrazine (TA) acid food dyes from contaminated water. The as-synthesized ZnS/CuO-CNT was described by FESEM, XRD, FTIR, BET, and zeta potential analysis. The results included nested network morphology, high purity with the crystalline structure, oxygen-containing functional groups, mesoporous/micropores texture with cumulate interspace, specific surface area of 106.54 m2 g-1, and zero-point charge (pHzpc) of 5.3. In adsorption experiments, the simultaneous effect of main independent variables, including solution pH, adsorbent dosage, concentration of each dye, temperature, and sonication time on the removal efficiency of dyes was studied systematically using the central composite design (CCD) method based on response surface methodology (RSM). Also, the second-order multivariate equation was presented to determine the relationship between the removal efficiencies of P4R and AT dyes and six independent effective variables. The high correlation coefficient (R2 ≥ 0.99), significant p-value (P < 0.0001), and non-significant lack-of-fit (P > 0.05) showed the high accuracy, and validity of the proposed model to predict the removal efficiency of P4R and TA acid food dyes. The experimental removal efficiency for P4R and TA dyes was found to be 98.45 ± 2.54, and 99.21 ± 2.23, respectively. Also, the Langmuir maximum adsorption capacity for P4R and TA dyes was determined to be 190.1 mg g-1 and 183.5 mg g-1, respectively. Finally, the adsorbent's reusability was tested for six periods and could be reused repeatedly without significant reduction in adsorption performance.

Recent advances in Ponceau dyes monitoring as food colorant substances by electrochemical sensors and developed procedures for their removal from real samples

Ponceau dyes are one of the food coloring materials that are added to various pharmaceutical, health and food products and give them an appearance. These dyes contain contaminants such as Benzidine, 4-Aminobiphenyl, and 4-Aminoazobenzene that are safe in small amounts, but they are not approved by the US Food and Drug Administration (US-FDA) for human consumption. This study comprehensively was reviewed the properties, applications, chemistry, and toxicity of Ponceau dyes as food colorant substances. Electroanalysis of Ponceau dyes was discussed in detail, and the various electrochemical sensors used to detect and monitor these dyes as food colorant were examined. The applied methods of removing and degradation of these dyes in municipal and industrial wastes were also discussed. Conclusions and future perspectives to motivate future research were also explored.

Selective Removal of Perfluorobutyric Acid Using an Electroactive Ion Exchanger Based on Polypyrrole@Iron Oxide on Carbon Cloth

Perfluorobutyric acid (PFBA) is one type of perfluoroalkyl and polyfluoroalkyl substances (PFASs) and is widely used as an industrial compound. The removal of PFBA has attracted considerable scientific interests in recent decades because it causes environmental pollution and human diseases. Currently, the adsorption method has been used commonly to remove PFASs from wastewater. However, it is usually limited by the inevitable "secondary waste" produced in this treatment process. In this work, PFBA can be effectively removed by synergistic electrical switching ion exchange (ESIX) and a new type of nanostructured ion exchanger. Herein, the nanostructured ion exchanger has been designed and synthesized by coating a polypyrrole (PPy)@Fe₂O₃ nanoneedle on carbon cloth (PPy@Fe₂O₃ NN-CC). Results show that the PPy@Fe₂O₃ NN-CC nanocomposite enhances ion exchange speed and efficiency, which ensures its high adsorption capacity and rapid regeneration property, thereby reducing secondary waste. Moreover, ESIX based on the PPy@Fe₂O₃ NN-CC nanocomposite has high selectivity for adsorption of PFBA over other common anions in water, such as Cl^-, SO₄^2-, and NO₃^-.

Nanocomposite hydrogel based on sodium alginate, poly (acrylic acid), and tetraamminecopper (II) sulfate as an efficient dye adsorbent

In this study, a novel nanocomposite hydrogel (NCH) was prepared by in situ crosslinking and radical polymerization of acrylic acid (AA) in the presence of sodium alginate (Na-Alg), followed by loading of Cu²⁺ ions and reaction with ammonia. The main advantage of the synthesized NCH is the high adsorption of dye due to the large contact area. The structure of the NCH was studied by FT-IR spectroscopy, TEM, and SEM. TEM showed that the size of nanoparticles is about 5-30 nm. The adsorption of dye was studied by changing the different factors. The removal efficiency of Crystal Violet (CV) and Malachite Green (MG) was found to be more than 96% at concentration of 10 mg/L and pH = 6. The dye adsorption on the NCH is well described by Freundlich isotherm and pseudo-second-order kinetic models. The reusability experiments showed that about 95% of the initial adsorption was obtained after eight cycles.

Graphene-Based Materials Immobilized within Chitosan: Applications as Adsorbents for the Removal of Aquatic Pollutants

Graphene and its derivatives, especially graphene oxide (GO), are attracting considerable interest in the fabrication of new adsorbents that have the potential to remove various pollutants that have escaped into the aquatic environment. Herein, the development of GO/chitosan (GO/CS) composites as adsorbent materials is described and reviewed. This combination is interesting as the addition of graphene to chitosan enhances its mechanical properties, while the chitosan hydrogel serves as an immobilization matrix for graphene. Following a brief description of both graphene and chitosan as independent adsorbent materials, the emerging GO/CS composites are introduced. The additional materials that have been added to the GO/CS composites, including magnetic iron oxides, chelating agents, cyclodextrins, additional adsorbents and polymeric blends, are then described and discussed. The performance of these materials in the removal of heavy metal ions, dyes and other organic molecules are discussed followed by the introduction of strategies employed in the regeneration of the GO/CS adsorbents. It is clear that, while some challenges exist, including cost, regeneration and selectivity in the adsorption process, the GO/CS composites are emerging as promising adsorbent materials.

Chiral poly(amide-imide)/ZnS nanocomposite as a new adsorbent for simultaneous removal of cationic dyes from aqueous solution

A new adsorbent, poly(amide-imide)/zinc sulfide nanocomposite (PAI/ZnS NC), was fabricated and identified by Fourier-transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, field emission-scanning electron microscopy, and transmission electron microscopy. Then, the obtained NC was applied for the simultaneous removal of auramine O (AO) and rhodamine B (RB) dyes from aqueous solution via the interactions of hydrogen bonding, π– π stacking, and Lewis acid–base interaction. The effects of operational variables including pH, PAI/ZnS NC mass, AO and RB concentration, and sonication time on removal efficiency were examined and optimized values were found to be 8.0, 16 mg, 11 mg L−1, and 6 min, respectively. The adsorption capacities of PAI/ZnS NC for the removal of AO and RB dyes were found to be 70.92 and 91.74 mg g−1, respectively. Ultraviolet–visible spectrophotometer was used to determine the amount of residual dye in solution. Fitting the experimental equilibrium data to isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich reveals the suitability of the Langmuir model with high correlation coefficients ( R2 = 0.998 for AO and R2 = 0.999 for RB). Pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models applicability was tested and the pseudo-second-order equation controls the kinetics of the adsorption process. Furthermore, this study establishes that PAI/ZnS NC can be successfully applied as a low-cost adsorbent and conserve its high efficiency after nine cycles for the removal of AO and RB dyes.

Recent Developments in Chitosan-Based Adsorbents for the Removal of Pollutants from Aqueous Environments

The quality of water is continuously under threat as increasing concentrations of pollutants escape into the aquatic environment. However, these issues can be alleviated by adsorbing pollutants onto adsorbents. Chitosan and its composites are attracting considerable interest as environmentally acceptable adsorbents and have the potential to remove many of these contaminants. In this review the development of chitosan-based adsorbents is described and discussed. Following a short introduction to the extraction of chitin from seafood wastes, followed by its conversion to chitosan, the properties of chitosan are described. Then, the emerging chitosan/carbon-based materials, including magnetic chitosan and chitosan combined with graphene oxide, carbon nanotubes, biochar, and activated carbon and also chitosan-silica composites are introduced. The applications of these materials in the removal of various heavy metal ions, including Cr(VI), Pb(II), Cd(II), Cu(II), and different cationic and anionic dyes, phenol and other organic molecules, such as antibiotics, are reviewed, compared and discussed. Adsorption isotherms and adsorption kinetics are then highlighted and followed by details on the mechanisms of adsorption and the role of the chitosan and the carbon or silica supports. Based on the reviewed papers, it is clear, that while some challenges remain, chitosan-based materials are emerging as promising adsorbents.

High-performance two-dimensional montmorillonite supported-poly(acrylamide-co-acrylic acid) hydrogel for dye removal

High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal was investigated. Montmorillonite cooperated with acrylamide and acrylic acid via polymerization, hydrogen-bond, amidation and electrostatic interactions to form the three-dimensional reticular-structured hydrogel with the free entrance for macromolecules. Adsorption tests revealed that the efficient removal (97%) for methylene blue at high concentration (200 mg/L) could be achieved via a small dose of hydrogel (0.5 g/L) within a short time (20 min). The excellent adsorption performance was profited from the electronegative surface and fully exposed reaction sites of two-dimensional montmorillonite, which could save the treatment cost and promote the removal effect compared with the conventional adsorbents. The adsorption process of methylene blue onto hydrogel could be fitted by both the pseudo-first-order and pseudo-second-order kinetics models, and the adsorption isotherm corresponded to the Sips model. The mechanism analysis based on Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements illustrated that the reaction between carboxyl groups and methylene blue molecules as well as the cation-exchange enabled the hydrogel performing extraordinary adsorption efficiency.

Potentiality of the Phoma sp. inactive fungal biomass, a waste from the bioherbicide production, for the treatment of colored effluents

The potentiality of Phoma sp. inactive fungal biomass, waste from the bioherbicide production, was evaluated for the treatment of colored effluents containing Acid Red 18 (AR 18) dye. The batch experiments were performed to evaluate the following parameters: pH of the solution (2-10), dye concentration (50-200 mg L^-1), adsorbent dose (0.5-2.5 g L^-1), contact time (0-180 min) and temperature (298-328 K). The batch experiments using a synthetic dye solution revealed that Phoma sp. was efficient at pH of 2.0, 298 K and using a dosage of 1.25 g L^-1. The process was fast, being the equilibrium reached within 180 min. The maximum value of biosorption capacity was 63.58 mg g^-1, being the process favorable and exothermic. From the fixed bed assays, breakthrough curves were obtained, presenting a mass transfer zone of 7.08 cm and breakthrough time of 443 min. Phoma sp. was efficient to decolorize a simulated effluent, removing more than 90% of the color. From the obtained results, it can be concluded that Phoma sp. inactive biomass is a low-cost option to treat colored effluents in continuous and discontinuous biosorption modes. These indicate that Phoma sp. of inactive biomass is an option for the treatment of colored effluents.

Adsorption behavior and mechanism of β-cyclodextrin–styrene-based polymer for cationic dyes

These figures show that the cyclodextrin polymer was synthesized successfully and possessed good thermal stability.