a b s t r a c tIn this work, the potential of biomass waste, pomegranate (Punica granatum) peel (PP) as low cost adsorbent for adsorption of methylene blue (MB) from aqueous solution was studied. The physicochemical properties of PP were characterized using instrumental analyses such as CHNS-O analyzer, Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and point of zero charge (pH pzc ) analysis. Batch mode adsorption studies were conducted by varying operational parameters such as adsorbent dosage (0.02-0.16 g), solution pH 3-11, initial MB concentrations (50-300 mg/L), and contact time (0-390 min). The equilibrium data was found to better fit with Langmuir isotherm model compare to Freundlich model. The maximum adsorption capacity, q max of PP for MB was 200 mg/g at 303 K. The kinetic study revealed that the present system obeyed pseudo-second-order (PSO) model. The thermodynamic adsorption parameters, standard enthalpy (ΔH°), standard entropy (ΔS°), and standard free energy (ΔG°) showed that the adsorption of MB onto PP surface exothermic and spontaneous under the experimented conditions. All results mentioned above indicate that the PP can feasibly employ for the elimination of MB from aqueous solution.

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Synthesis, spectral characterization, lethal dose (LD 50 ) and acute toxicity studies of 1,4-Bis(imidazolylazo)benzene (BIAB)

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In the present study, the Myristica fragrans shells (MFS) was used as low-cost bio adsorbent for the removal of Rose Bengal (RB) dye from aqueous solutions. The characteristics of MFS powder were studied before and after adsorption using different techniques such as Fourier transform Infrared spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), BET and BJH surface area analysis, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Batch adsorption was adopted to evaluate the effect of various parameters on the removal of RB such as; time of contact (5–75 min), initial dye concentration (10–50 mg L–1), adsorbent dose (0.1–1.7 g L–1) and pH (3–12). The results revealed that the coverage of MFS surface by RB molecules involved the formation of ester bond (esterification), and the pore diameter decreased from 190.55 to 2.43 nm when adsorption of RB onto MFS surface occurred. Experimental adsorption data were modelled using isotherm models including Langmuir, Freundlich, and Temkin. Temkin isotherm demonstrated to be the best isothermal model, and the results indicate that the adsorption of Rose Bengal on MFS surface follows pseudo second-order kinetics model. The adsorption of dye at different pH media showed that the esterification process was more preferred in acidic solution.