Removal of Remazol brilliant violet textile dye by adsorption using rice hulls

Sonophotocatalytic Degradation of Fast Yellow AB and Remazol Brilliant Violet-5R by Using Ag-Impregnated ZnO as a Photocatalyst

The fundamental aim of this project was to assess the sonophotocatalytic degradation of textile dyes mostly eluted from industries into wastewater. Such a pretreatment of wastewater makes the water suitable for drinking and irrigation purposes and thereby helps protect the ecosystem. The main objective of this research was to degrade real samples and laboratory-prepared samples sonophotocatalytically using a silver-impregnated ZnO photocatalyst. Reactive dyes, including Fast Yellow AB (FY AB) and Remazol Brilliant Violet-5R (RBV-5R), were degraded via this technique under optimum and enhanced conditions. The photocatalyst was synthesized through a wet impregnation process and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, and UV/vis spectroscopy to examine the morphology, composition, and functional groups of the photocatalyst. Parameters including pH, dosage, dye concentration, scavengers, and effects of oxidizing agents were considered. Under optimal conditions, the degradations were 95.7 and 88.9% for RBV-5R and FY AB, respectively, in 60 min. The pH and oxidizing agents played important roles in the degradation process. Only 43.8 and 32.5% of RBV-5R and FY AB, respectively, were degraded in the absence of an oxidizing agent. With the addition of oxidizing agents, 95.7 and 88.9% of RBV-5R and FY AB degradation occurred, respectively. The optimal pH values for RBV 5-R and FY-AB were 8 and 12, respectively. A comparison between the photocatalytic and sonophotocatalytic processes revealed degradation efficiencies of 41 and 33% for RBV-5R and FY-AB, respectively, by the photocatalytic process. Therefore, results indicate the productivity of the sonophotocatalytic degradation process.

Biogenic Amine Sensing Based on Rosamine a N-Methylpyridinium Derivative Supported on Silica Materials from Rice Husk

In this work new rosamine-silica composites were prepared and their sensing ability towards different amines was assessed. Rice husk wastes were used as a biogenic silica source. Silica was extracted by thermal treatment, before rice husk ash and after acid leaching with citric acid-treated rice husk ash. Mesoporous material (SBA-15) was also prepared using the extracted silica. The prepared materials were characterized by several techniques such as FTIR, XRD, SEM and N₂ adsorption. The materials were then used as adsorbents of the chromophore N-methylpyridinium rosamine (Ros4PyMe). The obtained loaded composites were tested in solution for amines sensing (n-butylamine, aniline, putrescine and cadaverine). The detection studies were analyzed by fluorescence and revealed 40% and 48% quenching in fluorescence intensity for the composite Ros4PyMe@SBA in the presence of the biogenic amines cadaverine and putrescine, respectively. The composite was also sensitive in the powder form, changing the color from violet to pale pink in the presence of putrescine vapors with a fast response (around 2 min), the process being reversible by exposure to air.

Brazilian Agro-industrial Wastes as Potential Textile and Other Raw Materials: a Sustainable Approach

The Brazilian agro-industrial chain generates about 291 million/tons/year of wastes, which, if inadequately destinated, could originate social and environmental risks. There is a growing need for the use of alternative raw materials to replace that originated from fossil resources in the Brazilian industry. Renewable materials play an important role on the sustainability of ecosystems and materials’ circularity. The issue has acquired importance in light of recent bio-based agro-fiber development potential applications. Considering sustainability guidelines, this study aimed to analyze the main Brazilian agro-industrial waste crops (temporary and permanent) as important sources of natural fibers and other raw materials. A systematic review of the literature (SRL) about Brazilian researches, based on concepts of industrial ecology, and the creation of a bibliometric analysis network were carried out. The agricultural biomass related to the main crops presents characteristics making them suitable to be applied for textiles, as natural fibers and polymers, in biosorbents for industrial effluents, and cellulose obtention and reinforcement material in composites. Thus, scientific investment in researches on materials and technology development are necessary to provide applications that could meet current and future demands and expand the scope of new materials for sustainability.

Performance of treatment schemes comprising chromium-hydrogen peroxide-based advanced oxidation process for textile wastewater

The present study investigated the performance of a chromium-based advanced oxidation process using chromium (as Cr³⁺ or Cr⁶⁺) and H₂O₂ for the treatment of synthetic and simulated textile wastewaters. With the Cr³⁺/H₂O₂ system, the maximum total organic carbon (TOC) and color removals from the synthetic dye wastewater (Remazol Brilliant Violet 5R dye concentration = 100 mg/L) were 75% and 99%, respectively, within 30 min duration ([Cr³⁺]:[H₂O₂] = 1:30, stoichiometric H₂O₂ dose = 2.01 ml/L and pH = 7). Whereas the same catalyst and oxidant combination resulted in chemical oxygen demand (COD) and color removals of ~ 46%, and 84%, respectively, after 3 h of reaction at the optimized reaction conditions (i.e., [Cr³⁺]:[H₂O₂] = 1:50, stoichiometric H₂O₂ dose = 11.6 ml/L and pH = 7) from the simulated textile wastewater (initial pH = 10.2, and COD = 1820 mg/L). Further, the addition of stoichiometric H₂O₂ dose to the pretreated wastewater and pH adjustment increased the overall COD removal to 77%. Both oxidation and precipitation reactions were found responsible for organics removal from the wastewater. The other alternative involving activated carbon adsorption as second step, was not found as effective as the above scheme. The data on COD removal from simulated textile wastewater could be fit adequately in the retarded first-order kinetic model. Based on the COD and color removal results and preliminary cost analysis, this can be suggested that the Cr³⁺/H₂O₂ oxidation process followed by pH adjustment and further H₂O₂ treatment was the best option for the removal of COD and color from the simulated combined textile wastewater.

Removal of hazardous dye from aqueous media using low-cost peanut (Arachis hypogaea) shells as adsorbents

In the present article, an attempt is made for simple, low-cost, and efficient removal of Auramine dye using peanut (Arachis hypogaea) shells as adsorbents. Two different forms of adsorbents distilled water washed peanut shells (DPS) and NaOH treated peanut shells (NPS) were used as adsorbents. Both the adsorbents were studied using BET, pH_PZC , FTIR, SEM, TGA, and XRD characterization techniques. Adsorption parameters such as effect of contact time, pH, initial dye concentration, adsorbent dose, and temperature were also assessed. Isotherm analysis at optimum conditions showed Langmuir fitted better with a q_m value of 96.15 mg/g for DPS and 294.12 mg/g for NPS; while in kinetic analysis, pseudo-second order was superior. Thermodynamics study stated that adsorption process was endothermic in nature. Overall outcomes establish that the two forms of peanut shells, DPS, and NPS were excellent in removal of Auramine dye and are low cost also as preparation cost of DPS and NPS is 68.73 INR and 106.19 INR per kg, respectively. PRACTITIONER POINTS: Removal of Auramine dye from aqueous media using different forms of peanut (Arachis hypogaea) shells as adsorbents is discussed. q_m (Langmuir) using DPS and NPS were found to be 96.15 and 294.12 mg/g, respectively. Preparation cost of DPS was 68.73 INR per 1 kg, whereas for NPS it was 106.19 INR per 1 kg.

Adsorption of Remazol Brilliant Violet-5R Textile Dye from Aqueous Solutions by Using Eggshell Waste Biosorbent

Based on the well-known excellent adsorbent ability of chicken eggshells, the adsorptive capacity and mechanism of Remazol Brilliant Violet-5R (RBV-5R) dye by eggshell was investigated. Exploiting the high surface-area-to-volume ratio and porous structure of this natural adsorbent, the developed procedure showed to be useful for the efficient adsorption of RBV-5R dye from contaminated water. The protocol was thoroughly optimized by investigating the effect of the dye concentration, biomass-contaminated water ratio, particle size of the adsorbent, pH and temperature, as they are key factors in the efficiency of the dye removal process. The eggshell material was characterized by different types of microscopy techniques (stereo, polarization, SEM) as well as elemental analysis (element distribution mapping, EDX), Raman spectroscopy and BET-surface density measurements. EDX, FTIR and Raman spectroscopy proved the presence of the adsorbed dye on the surface of the biomaterial. It was shown that under optimal conditions, the environmentally friendly and inexpensive eggshell could be a reliable adsorbent for Remazol dye removal from wastewater.

Effect of Carbon Nanostructures and Fatty Acid Treatment on the Mechanical and Thermal Performances of Flax/Polypropylene Composites

Four different strategies for mitigating the highly hydrophilic nature of flax fibers were investigated with a view to increase their compatibility with apolar polypropylene. The effects of two carbon nanostructures (graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs)), of a chemical modification with a fatty acid (stearic acid), and of maleated polypropylene on interfacial adhesion, mechanical properties (tensile and flexural), and thermal stability (TGA) were compared. The best performance was achieved by a synergistic combination of GNPs and maleated polypropylene, which resulted in an increase in tensile strength and modulus of 42.46% and 54.96%, respectively, compared to baseline composites. Stearation proved to be an effective strategy for increasing the compatibility with apolar matrices when performed in an ethanol solution with a 0.4 M concentration. The results demonstrate that an adequate selection of surface modification strategies leads to considerable enhancements in targeted properties.

Synthesis, and characterization of chitosan bearing pyranoquinolinone moiety for textile dye adsorption from wastewater

A novel compound was synthesized by the reaction of the amino group of the chitosan with the formyl group of pyrano[3,2-c]quinoline-3-carboxaldehyde moiety, which produced chitosan modified with a Schiff base (chitosan Schiff base). The structure of the newly prepared composite was elucidated. Chitosan Schiff base was used to remove the textile anionic remazol red (RR) dye from wastewater. The kinetic data and adsorption isotherm were best fitted by the pseudo-second-order kinetic model and the Freundlich isotherm, respectively. Thermodynamic parameters were calculated. Chitosan Schiff base resulted in 100% removal of carcinogenic dye at 2 min only with q_m 344.8 mg/g, and may do the same for other anionic reactive dyes, thus avoiding secondary pollution.