Abstract
Polysaccharides are renewable biodegradable natural materials and are accounted for to control the formation of hybrid silica nanocomposites by sol gel process. The synthesis of templated silica xerogel essentially includes two critical steps of hydrolysis and polycondensation reaction that are started by catalyst and silica precursor solution. Aside from this Saponification guar-graft-polyacrylonitrile (s-GG-g-PAN) as a copolymer are included in the precursor solution for providing a novel templating environment for silica matrix formation. The s-GG-g-PAN acts as a template for the silica produced in the blended framework because of the hydrogen bonding between the hydroxyl groups at silanols and hydroxyl group and carbonyl groups at the copolymer surface. Connected silanol groups can further hydrolyze and after that take part in the condensation reaction. Accordingly, the s-GG-g-PAN template gets trapped inside the resulting silica system, which on calcining at 900 °C is lost, producing pores of shape and size of the template. The surface area and pore volume of the developed templated silica xerogel have been determined. The surface area and pore volume of the template silica xerogel (H900) were observed to be (240 m2 g−1) and (0.286 ccg−1) respectively. The conditions for the adsorption by adsorbent had been enhanced, and kinetics and thermodynamic studies were performed. The best result in terms of lead adsorption was obtained with templated silica xerogel calcined at 900 °C. The % Pb2+ removal is observed to be 96% when H900 adsorbent was treated under ideal adsorption states of measurements 0.05g dose, 500mgL−1 Pb2+ concentration, time 2 h, pH 5 at 30 °C. The adsorption information fitted satisfactorily to Langmuir isotherms, showing unilayer adsorption. In view of the Langmuir model, Qmax was calculated to be 2000 mgg−1. Theadsorption demonstrated pseudo-second-order kinetics. The thermodynamic study revealed the endothermic and spontaneous nature of the adsorption. The adsorbent demonstrated good thermal stability and high reusability. The present study highlights the possibility of silica xerogel derived from saponified guar gum-grafted poly (acrylonitrile) toward its potential application as superior adsorbent for removal of Pb2+ from aqueous solution.
Highlights
Polysaccharides are renewable biodegradable natural materials and are accounted for to control the formation of hybrid silica nanocomposites by sol gel process
The surface morphology of the templated xerogel (H900) nanocomposite and Pb2+-loaded templated xerogel (H900) nanocomposite was examined by a scanning electron microscopy (SEM) (TESCAN VEGA, Czech Republic) under a 20-kV electron acceleration voltage coupled with energy dispersive (EDS) for elemental examination
Templated silica xerogel (H900) adsorbent (50 mg) was Results and discussion The synthesis of templated silica xerogel essentially includes two critical steps of hydrolysis and polycondensation reaction that are started by catalyst and silica precursor solution
Summary
Polysaccharides are renewable biodegradable natural materials and are accounted for to control the formation of hybrid silica nanocomposites by sol gel process. Prolonged exposure to heavy metals such as cadmium, copper, lead, nickel, and zinc can cause deleterious health effects in humans (Harrison and Laxen 1981). Lead is one of the heavy metal that is non-essential and occurs naturally in the earth. Exposure to lead can occur in contaminated air, water, dust, food, or consumer products. Lead in drinking water can likewise bring about an assortment of antagonistic health impacts. The required Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) action level for lead in general industry and the construction industry is a time-weighted average (TWA) of 30 μg/m3 over 8-h. Young children are vulnerable to the toxic effects of lead and can suffer profound and permanent adverse health effects; it causes moderated development of the brain, learning issues, debilitated hearing, conduct issues (for example, hyperactivity), nerve and/or mind harm, extreme lethargies, and even demise. Lead can even create nephrotoxicity, neurotoxicity, circulatory strain, and unfriendly consequences for the hematological and cardiovascular systems in adult (Harrison and Laxen 1981; Hua et al 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
