Environmental remediation of selenium using surface modified carbon nano tubes - Characterization, influence of variables, equilibrium and kinetic analysis.

Selenium is targeted as a priority pollutant to be removed due to its high toxicity level and lethal effects. In this research, a novel nano sorbent was fabricated using ionic liquid on multiwalled carbon nanotubes (IL-MCNT) and employed for Selenium remediation from aqueous media. Besides solution pH, nanocomposite dosage, the initial selenium concentration, temperature and sorption time were also examined as operating variables. At optimal pH 2.0, 96% of the selenium was removed with maximum efficiency with 100 mg/L of IL-MCNT at 308 K, 45 min of contact time, and 110 g of IL-MCNT dosage. From kinetic studies, it appears that the Langmuir isotherm fits the observed data (R2 > 0.9813), supporting the hypothesis that monolayer attachment occurs. The Langmuir isotherm parameters are evaluated as qm = 125 mg/g and KL = 0.172 L/mg. As a result of testing several kinetic models, the pseudo-second-order model was the most suitable for experimental data (R2 > 0.9746). Scanning Electron Microscopy images, FTIR spectra, and thermogravimetric study were used to examine the synthesized nanomaterial.

Environmentally benign Prosopis juliflora extract for corrosion protection by sorption - Gravimetric, mechanistic and thermodynamic studies.

Environmentally benign plant extract compounds have gained significant attention in the corrosion prevention applications due to their biodegradability and eco-friendliness. The adsorptive corrosion control action of Prosopis juliflora plant extract was investigated using differential mass change experiments and the mechanism was validated using Tafel and Nyquist plots. The effect of green corrosion inhibitor concentration (0-800 ppm) on corrosion rate at different solution temperatures (305.15, 310.15 and 315.15 K) in 1 M HCl was studied. The corrosion inhibitor exhibited monolayer surface coverage and confirmed by Langmuir isotherm (R2 > 0.970). The negative values of Gibbs free energy (<20 kJ/mol) proved the electrostatic interaction between the inhibitor and metal surface. The enhanced energy barrier for the corrosion process was confirmed by changes in Ea in the presence of biomass-based inhibitor on the mild steel surface. Electrochemical impedance study proved that the double layer capacitance (Cdl) decreased and the resistance increased with increase in corrosion inhibitor concentration. The surface modifications on the metal were observed using scanning electroscope imaging. ATR studies were conducted for functional group identification of the corrosion inhibitor.