Preparation of thermally recyclable ?-alumina nanoparticles from boehmite for adsorption of anionic dyes: Spectrophotometric study, structural characterization and industrial experience

gamma-Alumina powders were produced from the calcination of pseudo-boehmite for scavenging anionic blue (RS 150), and red (RB 133) dyes. The effects of calcination temperature, soaking time, pH, and nanoparticle dosage on dye adsorption were investigated to fabricate a reusable adsorbent. The mentioned dyes can be efficiently adsorbed over the gamma-alumina nanoparticles if the calcination conditions, and pH are identified correctly. The powder calcined at 700 C within 30 min inherently exhibited a high affinity towards blue dye at pH 5.0, while the proper adsorption towards red dye was achieved at pH 2.0. The maximal blue, and red dye adsorption capacities were determined to be 303, and 417 mg L-1, respectively. Although the calcination of boehmite at 1,000 C led to the higher chemical resistance, the specific surface area significantly decreased from 202 to 126 m(2) g(-1), causing a significant drop in the adsorption of blue dye due to an increase in pore diameter, 6 nm. Importantly, the adsorptive performance of produced powder was stable with ten times thermal regeneration. Based on results obtained for the treatment of industrial textile wastewater, the fabricated gamma-alumina powder is promising material to adsorb the anionic dyes.