Articles

This study presents a comparative investigation of two common catalysts - p-toluene sulfonic acid (p-TSA, a strong organic Brønsted acid) and aluminum chloride (AlCl 3 , a Lewis acid) over non-catalyst one in the polycondensation of succinic acid (SA) with 1,3-propane diol (PDO) to form poly (trimethylene succinate) (PTSu). Reaction parameters (temperature, catalyst loading, and time) were systematically varied to evaluate catalyst efficiency with respect to (i) degree of polymerization, (ii) the rate of reaction of polycondensation, (iii) esterification rate, (iv) order of the reaction, and (v) activation energy of the reaction. Analytical techniques included FTIR & 1 H NMR. Mechanistic differences between Brønsted and Lewis acid catalysis are discussed. Results (representative data and trends are provided) indicate that p-TSA yields faster initial esterification and higher final molecular weights under identical conditions. In contrast, the AlCl 3 catalyst exhibits similar activity to the p-TSA catalyst. Among the non-catalyst, p-TSA, and AlCl 3 catalysts, the p-TSA and AlCl 3 catalysts performed well in the polycondensation reaction over the non-catalyst one.

The adsorption process investigates the adsorption kinetic of ciprofloxacin onto banana peels-based activated carbon (BPAC) with a batch process. The pyrolysis method prepared the banana peel-based activated carbon (BPAC). XRD investigated the crystallinity of the BPAC. The effect of shaking time, pH, concentration of BPAC, concentration of ciprofloxacin in aqueous solution, and time duration. The maximum removal percentage of ciprofloxacin from its aqueous solution was 98.7 %. In the kinetic study, the pseudo-first and second-order linear and non-linear equations were fitted with experimental data using the origin LAB program. The pseudo-first-order linear equation R 2 values have an R 2 of 0.9103. In contrast, the R 2 values of the linear equations about pseudo-second-order of types I, II, III, and IV are 0.9982, 0.9968, 0.9986, and 0.9886, respectively. Considering the R 2 values, linear pseudo-second-order types III & IV are preferable for ciprofloxacin elimination from its aqueous solution.

The article presents low-cost activated charcoal as an adsorbent in the adsorption process for the removal of malachite green from aqueous solution by batch process. To find the optimum condition of the process, contact time, shaking rate, concentration of malachite green, and concentration of activated charcoal were examined. The malachite green was removed up to 98.9%. The adsorption isotherms were studied to check the performance of the adsorbent. Langmuir, Freundlich, Temkin, Hill De Boer, and Dubinin-Radushkevich adsorption isotherms were studied and compared to which one was suitable in the process. The adsorption process with the activated charcoal adsorbent followed suitably with the order of the Dubinin-Radushkevich > Langmuir > Hill De Boer> Temkin > Freundlich models. According to a kinetic study, the adsorption process was second order. In thermodynamic studies, we obtained negative values of ΔG, ΔS, and ΔH. The negative ΔH and ΔS values suggest that enthalpy contributes more than entropy in producing negative ΔG values. The negative ΔG values of malachite green adsorptions indicate that is a favorable and spontaneous process. The negative value of ΔH ensures the adsorption process is characterized as chemical adsorption and exothermic. The negative ΔS value indicates that randomness decreases at the solid–solution interface during the adsorption of MG by activated charcoal. The surface morphology of the Activated charcoal ensured the adsorption process. The results indicate that the adsorption process is exothermic, spontaneous, and favorable. So, activated charcoal might be useful for removing the malachite green dye from the aqueous solution.