A highly efficient and green adsorbent for anionic dyes synthesized from whole pine needles modified with glycidyltrimethylammonium chloride: synthesis, kinetic, and thermodynamic investigation

Functionalization of whole biowaste to develop new value-added materials by applying clean synthetic protocols is emerging as an attractive research area for a sustainable environment. Herein, we report the synthesis and detailed characterization of pine needles-glycidyltrimethylammonium chloride (G-PNs), which was accomplished by incorporating quaternized ammonium groups on the surface of pine needles by a polymer analogous reaction. As-synthesized G-PNs were explored as an adsorbent for the selective removal of anionic dyes, namely Congo red (CR) and methyl orange (MO) from their solutions. Adsorption capacity, kinetics, and thermodynamic behaviour of G-PNs with the dyes as a function of time, temperature, pH, and dye concentration were also analyzed. Various kinetic and adsorption isotherm models were used to identify the mechanism of the CR and MO adsorption process. The adsorption studies revealed a significantly high efficiency and selectivity of the adsorbent for anionic dyes with %removal of 94.76% and 93.96% for CR and MO, respectively. The adsorption process followed pseudo-second-order kinetic and Langmuir isotherm models with a maximum adsorption capacity (q m ) of 251.8 mg/g and 263.1 mg/g for CR and MO, respectively. Furthermore, after fifteen adsorption-desorption cycles, the effectiveness of the adsorbent for the dyes remained appreciable. Additionally, dye adsorption studies of G-PNs were also carried out for dye removal from real textile effluent. The use of bio-waste-based G-PNs thus resulted in environmentally friendly, cost-effective, biodegradable, and green material that has good potential for use in real samples to remove anionic dyes from the textile wastewater treatment. Graphical Abstract