Comparative Adsorption Behavior of Ibuprofen and Clofibric Acid onto Microwave Assisted Activated Bamboo Waste

The adsorption behavior of two representative pharmaceutically active compounds and widespread used drugs (ibuprofen and clofibric acid) were evaluated using a relatively abundant and inexpensive material, bamboo waste, as adsorbent prepared via ZnCl₂ activation process followed by microwave heating. The Langmuir, Freundlich, Dubunin–Raushkevich, and Temkin models were applied to describe the adsorption isotherm for the two systems. The goodness of curve fitting in the various models was done in accordance with linear regression coefficients and various error functions. The Langmuir isotherm model was applicable for describing the binding data for both ibuprofen (IBP) and clofibric acid (CA) onto activated bamboo waste (ABW) with the following order of adsorption capacity: IBP (278.55 mg·g^–1) > CA (229.35 mg·g^–1). The Gibbs free energy of −6.15 and −5.56 kJ mol^–1 estimated for IBP and CA onto ABW unravelled the spontaneous nature of this adsorbent toward these adsorbates. Both pH and temperature exhibited a remarkable effect on the adsorption of IBP and CA. Adsorption kinetic data for IBP and CA showed that the processes obeyed pseudo-second-order kinetic expression and diffusion in micropore and mesopore was the potential rate-controlling step. The desorption of IBP using methanol was very effective with more than 96% of IBP desorbed from ABW within 10 min to allow the reusability of the adsorbents. In contrast, methanol was less effective for CA as only 60% desorption was possible with the solvent. Certain physicochemical and spectroscopic characterization, viz., macro- and microanalysis, Bohem titration, pHp_ZC, Drift method, SEM-EDS, surface area, porosity, and FTIR were analyzed in an attempt to better understand the adsorption process

Donor−π–Acceptor-Type Configured, Dimethylamino-Based Organic Push–Pull Chromophores for Effective Reduction of Mild Steel Corrosion Loss in 1 M HCl

In this work, donor−π–acceptor-type four crystalline compounds have been tested for the first time to restrict the corrosion of mild steel in 1 M HCl. The details of the compounds are: C1, 4-<i>N</i>,<i>N</i>-dimethylamino-β-nitrostyrene; C2, 2-(4-(dimethylamino) benzylidene)­malononitrile; C3, ethyl 2-cyano-3-(4-(dimethylamino) phenyl)­acrylate; and C4, methyl 2-cyano-3-(4-(dimethylamino)­phenyl)­acrylate. The corrosion inhibition potentials of the compounds have been primarily investigated by electrochemical techniques, such as linear polarization resistance, Tafel polarization curves, and electrochemical impedance spectroscopy. The secondary investigation is performed by scanning electron microscopy, fluorescence surface imaging, spectroscopic techniques (UV–visible and Fourier transform infrared spectroscopy), and X-ray diffraction patterns. The results disclosed that 50 mg L^–1 of the compounds (1–4) in 1 M HCl provided the maximum inhibition efficiency as 93% (1), 88% (2), 82% (3), and 86% (4). The function of the compounds as corrosion inhibitors is explained with equilibrium corrosion potential, adsorption isotherms, and the frontier molecular orbital energies of the compounds (<i>E</i>_HOMO and <i>E</i>_LUMO) estimated by cyclic voltammetry curves and UV–visible spectra