Adsorption and identification of traces of dyes in aqueous solutions using chemically modified eggshell membranes

Enhanced decontamination of cationic and anionic dye from aqueous solutions using Hybrid ultrasonicated eggshell biochar nanomaterial: Statistical optimization model, techno-economic and sustainable approach

This study explored the synthesis of a green hybrid ultrasonicated eggshell biochar adsorbent (HUEBA) for the decontamination of cationic methylene blue (MB) and anionic methyl orange (MO). The hybrid material's morphological structure and physicochemical properties were examined using SEM, TEM, BET, FTIR, XRD, and point of zero charge techniques. Batch adsorption studies in decontamination of dye pollutants at varying dosages, pH, concentrations, temperatures, and time were performed. The produced material demonstrated outstanding performance against the sorption of MB and MO, achieving 85.49 and 53.45%, respectively, at an equilibration time of 2 h. Response surface methodology (RSM) optimization demonstrated satisfactory predictability for MB removal efficiency, with the importance of the model's validity confirmed through analysis of variance (p < 0.05) and R2 value of 0.99. Optimized conditions (236 mg/100 mL adsorbent dosage and 233 min adsorption time) resulted in over 99.9% decontamination of the initial 61 mg/L of MB dye. The validation of the sorption process with numerical isotherm models demonstrated Langmuir recorded a better fit than Freundlich at R2 of 0.9888 and 0.9939 mg/g with MB and MO, respectively. Moreover, the monolayer sorption capacities were 99.80 and 73.53 mg/g. The kinetics studies fitted the pseudo-second order and Elovich model against both dyes, revealing chemisorption processes. The thermodynamic studies exhibited exothermic, spontaneous, favourable and random for the sorption of both dye pollutants. The postulated mechanism of decontamination of MB and MO revealed electrostatic interaction, π-π electron stacking and hydrogen bridging. Hence, it is an outstanding material for decontaminating organic pollutants from wastewater systems.

Modified Urtica dioica Leaves as a Low-Cost and Effective Adsorbent for the Simultaneous Removal of Pb(II), Cu(II), Cd(II), and Zn(II) from Aqueous Solution

This study investigates the simultaneous adsorption of Pb(II), Cu(II), Cd(II), and Zn(II) ions from aqueous solutions using Urtica dioica leaves (UDLs) modified with sulfuric acid, followed by heat treatment to enhance adsorptive properties. The heat treatment significantly increased the adsorbent's specific surface area to 451.93 m2·g-1. Batch adsorption experiments were performed to determine the influence of the contact time, pH of the aqueous solution, adsorbent dosage, temperature, and initial metal concentration on the adsorption efficiency. The material (modified UDLs) was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). Maximum removal efficiencies were determined as 99.2%, 96.4%, 88.7%, and 83.6% for Pb(II), Cu(II), Cd(II), and Zn(II) ions, respectively. Adsorption isotherms and kinetics revealed that the process follows the Langmuir equation and pseudo-second-order models, indicating monolayer adsorption and chemisorption mechanisms. Furthermore, thermodynamic analysis indicated that the adsorption processes are spontaneous and endothermic in nature. The influence of competing ions on the adsorption of multiple heavy metals was also discussed. The results suggest that sulfuric acid and heat-treated Urtica dioica leaves can offer a promising, low-cost, and eco-friendly adsorbent for removing heavy metal ions from contaminated water.

Unveiling the emerging trends of egg components-based biodegradable food packaging development: A comprehensive review

Food packaging plays a crucial role in the food supply chain by aiding in food preservation and reducing food losses throughout the distribution process. The extensive, unregulated utilization, and waste mismanagement of food packaging materials made up of conventional petroleum-based plastics has led to a significant environmental crisis. Egg components-based food packaging has attracted considerable attention from the global packaging industry as a viable alternative to synthetic polymers due to its biodegradability, sustainability, and health-related benefits. This comprehensive review explores the composition and properties of egg components (eggshell, eggshell membrane, egg white, and egg yolk), and recent advancements in biodegradable packaging films derived from them. Additionally, it introduces the characteristics of these films and their applications in food, highlighting their biodegradability, sustainability, and suitable mechanical, barrier, thermal, optical, antioxidant, and antimicrobial properties as substitutes for traditional synthetic polymers. The utilization of various egg components in the packaging industry is a safe, non-toxic, cost-effective, and economical approach. However, it was found that incorporating active compounds from natural sources into packaging films, as well as composite films composed of egg components combined with other biopolymers, resulted in superior properties, compared to single component films. Moreover, the application of novel technologies in film development has proven to be more effective than conventional methods. These innovative egg components-based packaging films can be optimized and commercialized for use as packaging materials for food products.

Highly Porous Hydroxyapatite/Graphene Oxide/Chitosan Beads as an Efficient Adsorbent for Dyes and Heavy Metal Ions Removal

Dye and heavy metal contaminants are mainly aquatic pollutants. Although many materials and methods have been developed to remove these pollutants from water, effective and cheap materials and methods are still challenging. In this study, highly porous hydroxyapatite/graphene oxide/chitosan beads (HGC) were prepared by a facile one-step method and investigated as efficient adsorbents. The prepared beads showed a high porosity and low bulk density. SEM images indicated that the hydroxyapatite (HA) nanoparticles and graphene oxide (GO) nanosheets were well dispersed on the CTS matrix. FT-IR spectra confirmed good incorporation of the three components. The adsorption behavior of the obtained beads to methylene blue (MB) and copper ions was investigated, including the effect of the contact time, pH medium, dye/metal ion initial concentration, and recycle ability. The HGC beads showed rapid adsorption, high capacity, and easy separation and reused due to the porous characteristics of GO sheets and HA nanoparticles as well as the rich negative charges of the chitosan (CTS) matrix. The maximum sorption capacities of the HGC beads were 99.00 and 256.41 mg g⁻¹ for MB and copper ions removal, respectively.

The use of eggshell membrane for the treatment of dye-containing wastewater: Batch, kinetics and reusability studies

The worldwide consumption of eggs is very high, leading to about 250,000 tons of eggshell membrane (ESM) waste annually. The present research thus investigated the potential use of ESM as an inexpensive and abundant adsorbent for Reactive Red 120 (RR120) in aqueous solutions, a widespread hydrophilic azo dye used in the textile industry. The chemical structure and morphology of ESM were characterized using various spectroscopic methods, including scanning electron microscopy, Fourier transform infrared spectroscopy, and elemental analysis. It was found that natural ESM has a porous structure and surface functional groups that are suitable for the adsorption of the target molecules. The impact of the operating conditions, including the variation in the pH and temperature, on the RR120 sorption capacity and mechanisms of ESM was also analyzed. The maximum monolayer adsorption ability of ESM for RR120 was found to be 191.5 mg/g at 318 K, and the sorption process was spontaneous and endothermic. The adsorption of RR120 onto ESM was significantly influenced by the solution pH and the use of NaOH as eluent, indicating that the driving force for this adsorption was electrostatic attraction. Subsequent desorption experiments using 0.1 M NaOH resulted in satisfactory recovery efficiency. Kinetic, isothermic, and thermodynamic analysis was also conducted to support the experimental findings. The experimental results for the adsorption kinetics of ESM were fitted by a pseudo-second-order model. In conclusion, ESM has the potential to be utilized as an eco-friendly and cost-effective adsorbent for the removal of RR120 from aqueous solutions.

Advances in application of cotton-based adsorbents for heavy metals trapping, surface modifications and future perspectives

Cotton-based adsorbents (CBAs) are promising materials for combating the problem of heavy metal pollution of environmental waters. This is ascribed to the low cost, abundance, biodegradability and efficiency of CBAs. Herein we review the adsorption of heavy metals (HMs) onto CBAs. We found that several surface modifications were employed to improve the efficiency of the CBAs. These modifications were effected via thermal, physical and chemical means to obtain activated carbons, biochars, ionic liquids, aerogels, hydrogels, chitosans and nanoparticle-derived CBAs. The CBAs exhibited maximum HMs uptake as low as 0.002 mg/g to as high as 505.6 mg/g. Although, the cotton-derived activated carbons and biochars exhibited enhanced HM uptake from that of the unmodified CBAs, they were less efficient than CBAs modified by other methods. Recent chemical, ionic liquid, chitosan and nano-derived CBAs were the most efficient, with high uptake and fast kinetic removal. However, the nanoparticle-based adsorbents are preferred to the chemically modified forms, due to the possibility of secondary pollution and the noxious effect of the latter to the environment. Findings showed that chemical treatment produced CBAs most efficient for As(V), Pb(II) and Fe(III), while ionic liquid CBA was more efficient for Cu(II) and Ni(II). Nano-based treatment was suitable for the uptake of Co(II), Zn(II), Pb(II) and Cd(II), while the chitosan based adsorbent was viable for Hg(II). Isotherm and kinetic evaluation of CBAs mostly conformed to the Langmuir and pseudo-second order models, respectively. Spontaneous adsorption of HMs onto CBAs was deduced from thermodynamic analysis, with endothermic and exothermic characteristics. Over 88% desorption of HMs was obtained from the CBAs studied with good average reusability from 3 to 20 cycles. We also discussed the directions for future research.

Synthesis of silver nanoparticles utilizing various biological systems: mechanisms and applications-a review

The evolving technology of nanoparticle synthesis, especially silver nanoparticle (AgNPs) has already been applied in various fields i.e., electronics, optics, catalysis, food, health and environment. With advancement in research, it is possible to develop nanoparticles of various size, shape, morphology, and surface to volume ratio utilizing biological systems. A number of different agents and methods can be employed to develop choice based AgNPs using algae, plants, fungi and bacteria. The use of plant extracts to produce AgNPs appears to be more convenient, as the method is simple, environmental friendly and inexpensive, also requiring a single-step. The microbial synthesis of AgNps showed intracellular and extracellular mechanisms to reduce metal ions into nanoparticles. Studies have shown that different size (1-100 nm) and shapes (spherical, triangular and hexagonal etc.) of nanoparticles can be produced from various biological routes and these diverse nanoparticles have various functions and usability i.e., agriculture, medical-science, textile, cosmetics and environment protection. The present review provides an overview of various biological systems used for AgNP synthesis, its underlying mechanisms, further highlighting the current research and applications of variable shape and sized AgNPs.