Application of novel organic acid-modified biosorbent in the sequestration of aqueous zinc ion

Alhagi graecorum (AG) is an invasive plant with a massive/robust root structure that can grow up to 12 feet into the ground. The present study exploited the rich cellulosic content in this ‘AG’ root for the synthesis of a novel biosorbent (‘MA’). This low-cost biosorbent, with high carboxyl content of 447.22 (m eq/100 g sample) was utilized for aqueous zinc ion sequestration. The surface functional groups and textural characteristics required for an efficient heavy metal binding were identified on ‘MA’ using Fourier transform infrared spectroscopy and scanning electron microscopy. Sip isotherm emerged as the model of best fit for equilibrium studies; hence, Zn (II) ion sorption onto ‘MA’ is believed to occur via a hybrid blend of homogeneous monolayer and heterogeneous multilayer adsorption. Meanwhile, the Elovich (SNE = 1.0429), intraparticle diffusion (SNE = 1.0205) and pseudo-first order (SNE = 1.0455) provided the best fitting for 200, 400 and 600 mg/L adsorption system, respectively. The maximum adsorption capacity of 188.67 mg/g was recorded at optimum adsorption conditions, with the predominance of the electrostatic and electron donor–acceptor interaction mechanism. The abundant surface oxygenous functional groups on ‘MA’ positively influenced its adsorption capacity, thus making it a promising biosorbent for aqueous Zn (II) uptake.