A sustainable process for adsorptive removal of methylene blue onto a food grade mucilage: kinetics, thermodynamics, and equilibrium evaluation.

Adsorption of dyes onto natural materials like polysaccharides is considered a green chemistry approach for remediation of wastewater. In this work, the polysaccharide isolated from the corm of Colocasia esculenta (L.) Schott or taro tuber (CEM) was utilized for removing methylene blue (MB) from aqueous solution by batch adsorption method. The CEM adsorbent was characterized by FTIR spectroscopy, Brunauer-Emmett-Teller (BET), and scanning electron microscopy (SEM). The solution pH and adsorbent dose have been found to have a significant positive correlation with the adsorptive removal efficiency of CEM for MB dye. The removal efficiency of CEM was found to be 72.35% under the optimum conditions; 20 mg/L initial concentration of dye, 120 mg of adsorbent dose, solution pH 8.5, 311.2 K temperature and 80 min contact time. The adsorption of MB onto CEM followed best the Freundlich isotherm and pseudo-second-order kinetics. The adsorption was thermodynamically favorable and was endothermic in nature. The desorption/adsorption data justifiably indicated the reuse capability of CEM adsorbent for MB adsorption. Hence, CEM may be regarded as an eco-friendly and cost-effective natural adsorbent for MB dye removal from aqueous solution.

Carbon nanoprobe derived from Nyctanthes arbor-tristis flower: Unveiling the surface defect-derived fluorescence.

Dual Emissive (green and blue) Carbon dots (C-Dots) aka g-CD and b-CD were synthesized using flowers of Nyctanthes arbortristis as the sole precursor via hydrothermal method without the aid of any external passivating agent. In the present report, the effect of time and temperature on the hydrothermal reaction was evaluated in order to modulate the surface defects that could lead to dual emissions. To gauge the nature, size, morphology, and optoelectronic characteristics, the C-Dots were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and Fluorescence spectroscopy. The fluorescence studies of both the Carbon Dots revealed their excitation-dependent emission characteristics with the bathochromic shift. Furthermore, both g-CD and b-CD could effectively be utilized as efficient fluorescent probes for the selective and sensitive detection of Fe3+. These fluorescent nanoprobes could selectively detect Fe3+ over a wide range of concentrations (3 µM to 100 µM) with limit of detection (LOD) as low as 0.06 µM and 0.70 µM respectively. These tuneable Carbon Dots having wider solubilities would open a new avenue as Nanosensors for real-time applications.

Isolation, characterization, and microwave assisted surface modification of Colocasia esculenta (L.) Schott mucilage by grafting polylactide.

Mucilage (represented as CEM) is abundantly present in Colocasia esculenta (L.) Schott or taro and is a water-soluble neutral polysaccharide that can act as a binder, thickening agent, and matrix agent in the pharmaceutical fields of research. Presence of hydroxyl groups on its surface structure allows chemical modification. This study describes in details the synthesis and characterization of its graft copolymer with polylactide (CEM-g-PLA). The polymerization has performed using both the microwave irradiation and conventional methods. Ring opening polymerization of lactide onto the mucilage carried out in presence of stannous octoate as catalyst in chloroform medium produced CEM-g-PLA copolymer under optimum condition. The structure of CEM-g-PLA copolymers obtained from both the methods were comprehensively characterized for their physicochemical and thermal properties by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), differential scanning colorimetric (DSC), thermo-gravimetric analysis (TGA/DTG) and Dynamic light scattering (DLS) measurements. Grafting of lactide onto CEM backbone has changed its water absorption capacity, solubility and swelling power, morphology, crystalline structure, and thermal property of the mucilage. The newly synthesized CEM-g-PLA copolymer may find potential applications in wastewater treatment and for sustained and controlled drug delivery systems.