Boron removal from aqueous solutions by chitosan/functionalized-SWCNT-COOH: Development of optimization study using response surface methodology and simulated annealing.

Boron contamination in water resources (especially drinking waters and agricultural land) is a major problem for the ecosystem. In this study, a novel synthesized chitosan/functionalized-SWCNT-COOH was prepared to separate boron (as boric acid) from aqueous solutions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis revealed that SWCNT was dispersed in chitosan homogenously. Moreover, this study has related to the constrained optimization problem with an engineering approach. Response surface method (RSM) with face-centered central composite design (FCCCD) was chosen for maximizing the adsorption capacity as well as determining optimal independent factors such as pH, adsorbent dose, and concentration of boric acid. The optimized response (adsorption capacity) was reached 62.16 mg g-1 under the optimal conditions (98.77 mg L-1 of boric acid concentration, pH of 5.46 and 76 min). The present study has indicated that the synthesized material can be used as an adsorbent for eliminating boric acid from aqueous solutions depending on its high adsorbent capacity to remove boron and has better performance than existing adsorbents. Furthermore, simulated annealing (SA) optimization technique was used to compare the findings of RSM. Moreover, the selected optimization techniques were compared with error functions. The optimal conditions derived from SA were 91.17 mg L-1 of boric acid concentration, pH of 5.86, and 76.17 min. The optimal adsorption capacity of SA was found to be 62.06 mg g-1. These results revealed that the predictions of the two models are very close to each other.