Tuning N-methyl-d-glucamine density in a new radiation grafted poly(vinyl benzyl chloride)/nylon-6 fibrous boron-selective adsorbent using the response surface method

Abstract

A new adsorbent containing boron-selective groups was prepared by radiation induced grafting of vinyl benzyl chloride (VBC) onto nylon-6 fibers followed by functionalisation with N-methyl-D-glucamine (NMDG). The density of glucamine loaded in the adsorbent was tuned by optimisation of the reaction parameters such as NMDG concentration, reaction temperature, reaction time and degree of grafting using response surface methodology (RSM) employing Box–Behnken design (BBD). The optimum parameters for achieving the maximum glucamine density (1.7 mmol g⁻¹) in the adsorbent are 10.6%, 81 °C, 47 min and 121% for the NMDG concentration, reaction temperature, reaction time and degree of grafting (DG), respectively. The deviation between the optimum experimental and predicted glucamine density is found to be 1.2% suggesting the reliability of RSM in predicting the yield and optimising the functionalisation reaction parameters. The chemical composition, morphology and structure of the NMDG-containing fibrous adsorbent were studied using Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The thermal properties were determined using differential scanning calorimetry (DSC) and the thermal stability was evaluated by thermogravimetric analysis (TGA). Considering the physico-chemical properties of the fibrous adsorbent and the preliminary results of boron adsorption, it can be suggested that this adsorbent is a promising candidate for boron removal.