Dye pollutants from research laboratories are one of the major sources for environmental contamination. In the present study, a nutraceutical industrial fennel seed spent (NIFSS) was explored as potential adsorbent for removal of ethidium bromide (EtBr) from aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Through batch experiments, the operating variables like initial dye concentration, adsorbent dosage, temperature, contact time, and pH were optimized. Equilibrium data were analyzed using three number of two-parameter and six number of three-parameter isotherm models. The adsorption kinetics was studied using pseudo-first order and pseudo-second order. The diffusion effects were studied by film diffusion, Webber-Morris, and Dumwald-Wagner diffusion models. The thermodynamic parameters; change in enthalpy (ΔHº), entropy (ΔSº), and Gibbs free energy (ΔGº) of adsorption system were also determined and evaluated.

In this article, we report an ecofriendly technique for the preparation of silver nanoparticles (AgNPs) using seed extract of Foeniculum vulgare, and the evaluation of their antibacterial activity. UV-visible spectroscopy, SEM and FTIR analysis were used to characterize the morphology and crystalline phase of AgNPs. Reduction of silver ions using seed extract of Foeniculum vulgare resulted in the synthesis of nanoparticles. The seed extract showed an absorption peak at 475 nm in UV-VIS spectrum corresponding to the plasmon resonance of silver nanoparticles. FTIR spectrum showed the involvement of amides and amines in capping and reduction of silver nanoparticles. Antibacterial activity was screened using synthesized silver nanoparticles against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The AgNPs showed potent antibacterial activity against different types of bacteria. The results confirmed that Foeniculum vulgare is a potential bio-resource/biomaterial for synthesizing AgNPs with applications in antibacterial agents. K e y w o r d s Antibacterial assay BiosynthesisFoeniculum vulgare Silver nanoparticles How to cite this article:

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The economic viability of adsorbing crystal violet (CV) using pepper seed spent (PSS) as a biosorbent in an aqueous solution has been studied. A parametrical investigation was conducted considering parameters like initial concentration of dye, time of contact, pH value, and temperature variation. The analysis of experimental data obtained was carried out by evaluating with the isotherms of Freundlich, Sips, Tempkin, Jovanovic, Brouers–Sotolongo, Toth, Vieth–Sladek, Radke–Prausnitz, Langmuir, and Redlich–Peterson. The adsorption kinetics were studied by implementing the Dumwald-Wagner, Weber-Morris, pseudo-first-order, pseudo-second-order, film diffusion, and Avrami models. The experimental value of adsorption capacity ( Q m = 129.4   mg   g − 1 ) was observed to be quite close to the Jovanovic isotherm adsorption capacity ( Q m = 82.24   mg   g − 1 ) at ( R 2 ), coefficient of correlation of 0.945. The data validation was found to conform to that of pseudo-second-order and Avrami kinetic models. The adsorption process was specified as a spontaneous and endothermic process owing to the thermodynamic parametrical values of Δ G 0 , Δ H 0 , and Δ S 0 . The value of Δ H 0 is an indicator of the process’s physical nature. The adsorption of CV to the PSS was authenticated from infrared spectroscopy and scanning electron microscopy images. The interactions of the CV-PSS system have been discussed, and the observations noted suggest PSS as a feasible adsorbent to extract CV from an aqueous solution.