Adsorption of Reactive Red 195 from aqueous medium using Lotus (Nelumbo nucifera) leaf powder chemically modified with dimethylamine: characterization, isotherms, kinetics, thermodynamics, and mechanism assessment

Acidified groundnut cake for enhanced bio adsorption of anionic textile dye Reactive Red 195

This study focuses on the improvement of bioremediation of textile dye Reactive Red 195 using agro-industrial waste, groundnut oil cake (GNOC) obtained after oil-pressing. The treatment of GNOC with 1 N H2SO4 had resulted in physiochemical changes on the insoluble porous adsorbent, which improved their adsorption efficiency. The dye removal efficiency increased from 55% to 94% on acidification of GNOC. The raw groundnut oil cake (RGNOC) and acid-treated groundnut oil cake (AGNOC) were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction, and zeta potential. The rate and efficiency of dye adsorption were examined using adsorption kinetics and isotherm models. The results confirm that acid-treated GNOC eliminates impurities, alter the surface functional groups, and significantly increase porous surface areas of RGNOC. The investigation of key factors such as contact time, initial concentration of dye, static/agitation impact, particle size, and adsorbent dose had significantly influenced adsorption capacity of GNOC. Adsorption of dye fits best into the Langmuir model and equilibrium data of dye on AGNOC was explained by psuedo-second-order reaction with maximum adsorption capacity of 12.65 mg/g. This emphasis AGNOC has a very excellent potential to remove the textile dye Reactive Red dye from industrial effluent.

Selective adsorption of single and binary dyestuffs by citrus peel: Characterization, and adsorption performance

The powdered citrus peel, which has been replaced with sodium hydroxide, was used in this study to test how well methylene blue and reactive black 5 dyestuff absorbed one or both. To find out about the texture and surface chemistry of modified citrus peel, Fourier transform infrared spectroscopy and scanning electron microscope analyses were carried out. Fourier transform infrared spectroscopy data revealed the presence of amphoteric radicals on the modified citrus peel surface, indicating the effective adsorption of methylene blue and reactive black 5. Many parameters affecting the batch adsorption process, such as modified citrus peel dose (0.1-0.5 g), pH (2-10), time (20-80 min), stirring speed (60-180 rpm), and temperature (20-45 °C), were studied. It is seen that the physical effect is at the forefront, homogeneous monolayer adsorption occurs, and the process fits the Langmuir and pseudo first order models for dyestuffs. Thermodynamic modeling showed that the adsorption of methylene blue and reactive black 5 was spontaneous and endothermic. At pH 2, an adsorption capacity of 0.67 mg/g and a removal efficiency of 66.86% were achieved for reactive black 5. For methylene blue at pH 6, the adsorption capacity was 4.34 mg/g, and the decolorization rate was 87%. The decreases in the removal rates of dyestuffs in the binary system indicate that they are affected by their simultaneous presence in the solution. The results proved that modified citrus peel can be useful for dyestuff removal in single or binary systems, although the removal capacity of modified citrus peel is highly dependent on methylene blue and reactive black 5.

Annona glabra L. Seeds: An Agricultural Waste Biosorbent for the Eco-Friendly Removal of Methylene Blue

The seeds of Annona glabra L., an invasive plant in Vietnam, were first employed as a new biosorbent for the adsorption of methylene blue (MB) from aqueous media. The characterizations of the material using FT-IR, SEM, nitrogen adsorption-desorption analysis, and point of zero charge reveals that it possesses a rough and irregular surface, various polar functional groups, and pHpzc of 5.5. Certain adsorption conditions including adsorbent dose, solution pH, contact time, and initial concentration of MB were found to affect adsorption efficiency. The kinetic data are well fitted with pseudo-second-order model with the adsorption rate of 0.002 g mg-1 min-1 and initial rate of 4.46 mg g-1 min-1. For the adsorption isotherm, three nonlinear models were used to analyze the experiment data, including Langmuir, Freundlich, and Temkin. The results indicate that the Langmuir model best describes the adsorption of Annona glabra L. seeds powder (AGSP) with a maximum adsorption capacity of 98.0 mg g-1. The investigation underpins the adsorption mechanism, whereby the electrostatic attraction between positively charged MB and negatively charged surface of AGSP is expected to be the predominant mechanism, together with hydrogen bonding and pi-pi interaction. These results make AGSP an interesting biosorbent concerning its environmental friendliness, cost-effectiveness, and relatively high dye adsorption capacity.

Isolation and characterization of microcrystalline cellulose from an agro-waste tamarind (Tamarindus indica) seeds and its suitability investigation for biofilm formulation

The exploration of potential bio-fillers for bio-film application is a promising approach to ensure biodegradable, eco-friendly, good-quality materials with high-performance applications. This is a comprehensive study executed to establish the utility of an agro-waste Tamarindus indica seeds for microcrystalline cellulose production and to assess its feasibility for biofilm fabrication. The extraction was carried out through consecutive chemical-mediated alkalization, acid hydrolysis and bleaching. The isolated microcrystalline cellulose from Tamarindus indica seeds (TSMCC) was characterized through chemical, thermal and morphological characterization to validate the cellulose contribution, thermal resistance, and compatibility of the material. The physical parameters as density and yield percentage were assessed to evaluate its light-weight utility and economic productivity. These examinations revealed that TSMCC has good specific properties such as high cellulose content (90.57 %), average density (1.561 g/cm3), feasible average roughness (12.161 nm), desired particle size (60.40 ± 21.10 μm), good crystallinity (CI-77.6 %) and thermal stability (up to 230 °C); which are worthwhile to consider TSMCC for bio-film formulation. Subsequently, bio-films were formulated by reinforcing TSMCC in polylactic acid (PLA) matrix and the mechanical properties of the bio-films were then studied to establish the efficacy of TSMCC. It is revealed that the properties of pure PLA film increased after being incorporated with TSMCC, where 5 %TSMCC addition showed greater impact on crystalline index (26.16 % to 39.62 %), thermal stability (333oc to 389 °C), tensile strength (36.11 ± 2.90 MPa to 40.22 ± 3.22 MPa) and modulus (2.62 ± 0.55GPa to 4.15 ± 0.53GPa). In light of all promising features, 5 % TSMCC is recommended as a potential filler reinforcement for the groundwork of good quality bio-films for active packaging applications in future.