Preparation of lignin sulfonate-based mesoporous materials for adsorbing malachite green from aqueous solution

Abstract

In this study, lignin sulfonate-based mesoporous materials (LSMMs) were prepared and applied for removal malachite green (MG) from aqueous solution. Lignin sulfonate-g-poly (acrylic acid-r-acrylamide) was prepared by grafting poly(acrylic acid-r-acrylamide) onto a lignin sulfonate molecule followed by crosslinking. N2 adsorption/desorption indicated that the corsslinked lignin sulfonate-g-poly(acrylic acid-r-acrylamide) were mesoporous materials. The batch adsorption experiments of MG on LSMMs were carried out to evaluate the performance of the LSMMs. Results revealed that the maximum percentage adsorption of MG on the LSMMs is more than that of MG on the lignin sulfonate-based polymer without grafted copolymer with a maximum difference of 37% in the same adsorption conditions. pH, adsorbent dosage, initial MG concentration and temperature are just the parameters that could exhibit breathing effect to the adsorption process. The adsorption kinetics follows a pseudo-second-order kinetics, intra-particle diffusion is not the only rate-controlling step in the entire adsorption process, and the equilibrium adsorption data could be described well by the Langmuir isotherm equation. The adsorption process is endothermic, spontaneous and random. LSMMs can be used as low-cost adsorbent for refractory cationic organic dye in effluent.