Equilibrium, Kinetics, and Thermodynamics of Methylene Blue Adsorption by Pine Tree Leaves

The adsorption capacity of pine tree leaves for removal of methylene blue (MB) from aqueous solution was investigated in a batch system. The effects of the process variables, such as solution pH, contact time, initial dye concentration, amount of adsorbent, agitation speed, salt concentration, and system temperature on the adsorption process were studied. The extent of methylene blue dye adsorption increased with increase in initial dye concentration, contact time, agitation speed, temperature, and solution pH but decreased with increased in amount of adsorbent and salt concentration. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine tree leaves biomass was 126.58 mg/g at 30°C. The value of separation factor, R L , from Langmuir equation and Freundlich constant, n, both give an indication of favorable adsorption. The intrapartical diffusion model, liquid film diffusion model, double exponential model, pseudo-first and second order model were used to describe the kinetic and mechanism of adsorption process. A single stage bath adsorber design for the MB adsorption onto pine tree leaves has been presented based on the Langmuir isotherm model equation. Thermodynamic parameters such as standard Gibbs free energy (ΔG 0), standard enthalpy (ΔH 0), and standard entropy (ΔS 0) were calculated

Removal of cationic dye methylene blue (MB) from aqueous solution by ground raw and base modified pine cone powder

The adsorption capacity of raw and sodium hydroxide-treated pine cone powder in the removal of methylene blue (MB) from aqueous solution was investigated in a batch system. It was found that the base modified pine cone exhibits large adsorption capacity compared with raw pine cone. The extent of adsorption capacity was increased with the increase in NaOH concentration. Overall, the extent of MB dye adsorption increased with increase in initial dye concentration, contact time, and solution pH but decreased with increase in salt concentration and temperature for both the systems. Surface characteristics of pine cone and base modified pine cone were investigated using Fourier transform infrared spectrophotometer and scanning electron microscope. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity was found to be 129.87 mg g-1 at solution pH of 9.02 for an initial dye concentration of 10 ppm by raw pine cone. The base modified pine cone showed the higher monolayer adsorption capacity of 142.25 mg g-1 compared with raw pine cone biomass. The value of separation factor, RL, from Langmuir equation and Freundlich constant, n, both give an indication of favourable adsorption. The various kinetic models, such as pseudo-first-order model, pseudo-second-order model, intraparticle diffusion model, double-exponential model, and liquid film diffusion model, were used to describe the kinetic and mechanism of adsorption process. Overall, kinetic studies showed that the dye adsorption process followed pseudo-second-order kinetics based on other models

Using xanthated Lagenaria vulgaris shell biosorbent for removal of Pb(II) ions from wastewater

Chemically modified Lagenaria vulgaris shell was applied as a new sorbent for the removal of lead (II) ions from aqueous solution in a batch process mode. The influence of contact time, initial concentration of lead (II) ions, initial pH value, biosorbent dosage, particle size and stirring speed on the removal efficiency was evaluated. Biosorbent characterization was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four kinetic models (pseudo-first order, pseudo-second order, Elovich model and Intraparticle diffusion model) were used to determine the kinetic parameters. The experimental results were fitted to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models of isotherm. Pseudo-second order kinetic model and Langmuir isotherm model best fitted the experimental data. Sorption process is obtained to be fast and equilibrium was attained within 40 min of contact time. The maximum sorption capacity was 33.21 mg g−1. Biosorption was highly pH-dependent where optimum pH was found to be 5. The results of FTIR and SEM analysis showed the presence of new sulfur functional groups. This study indicated that xanthated Lagenaria vulgaris shell could be used as an effective and low-cost biosorbent for the removal of lead (II) ions from aqueous solution