Search

To evaluate the competence of garlic peel (GP) as a low-cost bio-adsorbent, GP was chemically modified with sodium carbonate (Na2CO3) and hydrochloric acid, and used to adsorb Congo red (CR). The surface morphology, chemical characterization and structural information of the adsorbents were studied by scanning electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy. The impact of different adsorption settings on the removal effectiveness of CR by sodium carbonate-treated garlic peel (Na2CO3-GP) was also studied. The optimum conditions for effective adsorption of CR by Na2CO3-GP is found to be pH of 7, 90 minutes of equilibrium contact duration, 50 mg/L of initial CR concentration, 200 revolutions per minute of stirring (RPM), 0.10 g/mL of adsorbent dosage, and temperature of 298 K. As indicated by Langmuir isotherm, monolayer adsorption occurs at a maximum capacity of 52.6 mg/g for Na2CO3-GP. Adsorption kinetic studies suggest chemisorption, the process follows a pseudo-second-order model and thermodynamics of adsorption specifies that the process is spontaneous. The results explicitly show that Na2CO3-GP can be an effective bio-adsorbent for the removal of CR. [ABSTRACT FROM AUTHOR]

Addition of organic solvents is known to change the properties of amphiphiles through modification of bulk phase. Amitriptyline hydrochloride (AMT) is a tricyclic amphiphilic drug which is usually used as an antidepressant. In drug delivery, the cloud point (CP) of the drug is an important parameter. This article discusses the effects of ethanol–water (EtOH–WR) compositions on the energetic parameters, such as changes in Gibbs energy of clouding (ΔsG0), enthalpy of clouding (ΔsH0), and entropy of clouding (TΔsS0) of AMT-additive systems. Monovalent alkali halide salts, cationic conventional surfactants, and gemini surfactants were used as additives in the EtOH–WR mixed media whose compositions were varied between 0 and 15% (w/w). The ΔsG0 values are positive for all the additives and the values decrease with the rise in mole fractions of the additives. The ΔsH0 and TΔsS0 were noted to be positive except for KF in 15% EtOH–WR mixed media. [ABSTRACT FROM AUTHOR]

• Interactions of cationic surfactant DTAB with congo red (CR) dye in the presence of electrolyte/non-electrolyte. • Electrolyte decreases the cmc of DTAB, whereas non-electrolyte increases it. • The micellization of DTAB + CR + MgCl 2 /urea is entropically driven. • Absorbance of CR augments with [DTAB] and it increases further with MgCl 2 /urea. To investigate the interactions between congo red (CR) dye and dodecyltrimethylammonium bromide (DTAB) surfactant in aqueous, electrolytic (MgCl 2) and non-electrolytic (urea) solutions, conductometric, tensiometric and spectroscopic methods were used. Conductivity and surface tension measurements were performed to evaluate the critical micelle concentration (cmc) values of the cationic surfactant, DTAB. The change in Gibb's energy (Δ G m 0) , enthalpy (Δ H m 0) , and entropy (Δ S m 0) of micellization were also calculated. The cmc value of DTAB was found to drop in the presence of CR dye and a further decrease was noticed in the presence of MgCl 2 , while the values augmented when urea was present. Due to the interruption of the structured water molecules encasing the hydrophobic groups of the DTAB, the cmc values augmented with an increase in temperature. The presence of MgCl 2 led to a greater degree of ionization (α) of DTAB micelles. For all of the systems under study, the values of Δ G m 0 and Δ H m 0 were found to be negative. The - T Δ S m 0 values, which were noted to be higher than Δ H m 0 values suggest that the gain in entropy possibly be the prime factor that governs the process of micellization. Many of the CR dye molecules were drawn into DTAB micelles as their concentrations in the system were amplified, as evidenced by the absorbance values in UV–Vis spectroscopic studies. [ABSTRACT FROM AUTHOR]