Morphological synthesis of boehmite nanoparticles utilizing xanthan gum: A nature-based directing agent effect optimization

• Boehmite nanoparticles were synthesized morphologically under Taguchi designed experiments. • Effect of xanthan gum (as a nature-based structural directing agent) on the morphology of the aluminum hydroxide particles was optimized for the first time. • CaCl 2 added to the reaction solution was evaluated in order to shape alteration. • Addition of CaCl 2 results in the formation of rod-shaped γ-AlOOH particles, where the length of the nanorods extends to 120 nm. Boehmite nanoparticles (BNPs) were synthesized using a simple hydrothermal approach to attain optimal crystallite size, utilizing a novel directing agent. The synthesis process employed solutions of aluminum nitrate and urea, with a particular focus on the use of an environmentally friendly surfactant/bio-directing agent, namely xanthan gum. The effect of four key parameters, including the molar concentration of xanthan gum, the ratio of urea to aluminum nitrate molar concentrations (U/N ratio), reaction time, and the molar concentration of calcium chloride, was investigated using Taguchi design. Characterization of the samples was carried out through XRD, FESEM, EDX, and BET analyses revealing the presence of the boehmite pattern in all samples. The minimum crystallite size was achieved under optimized conditions (xanthan gum molar concentration of 2 mM, U/N molar ratio of 4, the reaction time of 12 h, and CaCl 2 molar concentration of 1 mM) measured 10.76 nm with a specific surface area of 63.779 m 2 /g.