Preparation of nanochitosan-STP from shrimp shell and its application in removing of malachite green from aqueous solutions

In this investigation, nanochitosan prepared from shrimp shells was functionalized using sodium triphosphate (STP) obtaining nanochitosan-STP and applied to remove malachite green from aqueous solutions. For characterization of the synthesized nanochitosan-STP, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were used. The nanochitosan-STP beads were prepared using a routing method and used as adsorbent. The effects of different parameters including pH, initial concentration of malachite green and adsorbent dosage on adsorption efficiency were studied to determine the optimum conditions for adsorption process. In the following, the adsorption process of malachite green in the batch system was examined to evaluate the fitness of data with Langmuir and Freundlich isotherm models in the batch adsorption system. The results showed that both Freundlich (R-2 = 0.96) and Langmuir models (R-2 = 0.94) logically described the adsorption trend. The maximum malachite green adsorption capacity was obtained 317.73 mg g(-1) by Langmuir model. The kinetic studies revealed that the pseudo-first-order and pseudo-secondorder kinetic models with R-2 values of 0.95 and 0.92, respectively, were fitted properly with the experimental results. However, in most cases, the pseudo-second order fitted better due to highly R-2 values and the maximum adsorption capacity predicted values (q(e2)) are more closed to experimental values (q(e) exp.). Based on the attained results, nanochitosan-STP can be a suitable adsorbent for removal of malachite green dye from aquaculture industry wastewaters due to low-cost, environmental friendly and lack of secondary polluting characteristics.