Methylene Blue Adsorption Study on Microcline Particles in the Function of Particle Size Range and Temperature

In this paper, the adsorption process of methylene blue has been investigated on microcline particles as a function of particle size and temperature. The characterization of microcline in the particle size ranges of 1−71 μm and 71−315 μm gained by sieving was proved using X-ray diffraction (XRD) and scanning electron microscopy combined with energy-dispersive detector (SEM-EDS) in powder form, over laser diffraction measurements in aqueous suspension. The optimum dosage of adsorbent was 13.5 g/L in dye adsorption and the adsorption isotherms on both microcline size fractions were determined at this adsorbent concentration. The maximum adsorption capacities were in the range of 1.5–3.1 mg g−1 on microcline particles with supplementing evaluation of isotherms using the Langmuir model. Considering the problems of linearization of equations, the non-linear least-squares estimation can be strongly recommended for modeling adsorption-equilibrium. The adsorption isotherm determined at elevated temperature of 60−65 °C represents a breakpoint at around 20 mg L−1 of equilibrated dye concentration due to performing of a potential process of dye self-association. According to our experiments, the increase in temperature has an adverse effect on adsorption.