Adsorption Optimization of Acyclovir on Prepared Activated Carbon Swati Jain, 1,2 Pardeep Kumar, 2 Raj K. Vyas, 1 Prabhat Pandit 1 and Ajay K. Dalai 2 * 1. Department of Chemical Engineering, Malaviya National Institute of Technology, Jaipur 302 017, India 2. Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Canada Canadian pine cones (pine cone type I and pine cone type II) and deoiled canola meal were utilized as precursors for preparation of powdered activated carbons (PACs) using thermo‐chemical process. Physicochemical properties of the biomass and obtained adsorbents were evaluated. Prepared PACs were investigated for the adsorptive removal of acyclovir (ACV) from aqueous solutions. Pine cone type I PAC was found to have well developed pores and surface area. It was found to be suitable for removal of ACV from aqueous solution. Response surface methodology was used for the optimization of ACV adsorption on PAC prepared from pine cone type I and the development of predictive model. A second‐order polynomial equation fitted data well which indicated that the process variables such as temperature, pH and especially adsorbent dose had large impact on the ACV adsorption process. The optimum conditions for ACV removal were found to be 39 8C, pH 8 and 2 g/L of pine cone type I PAC dose. At these conditions, the removal of ACV was 90.3 %, which was close to the maximum predicted value of 92.5 %. Keywords: adsorption, acyclovir, activated carbon, central composite design, optimization INTRODUCTION A ntiviral drug, acyclovir (9‐{2‐hydroxyethoxymethyl} gua- nine) is a nucleoside analogue used in the therapy of herpes simplex virus and varicella zoster virus infections. [1] The acyclovir (ACV) concentration in effluents originating from pharmaceutical manufacturing plants was found to range typically from 154 to 2580 mg/L, [2a,b] which is high and can cause drug resistance to humans and aquatic lives. [3] In wastewater treatment plant influent, the concentration of ACV was reported to be in the range of 190–1800 ng/L and a lower concentration of ACV is also reported in river water. [4] It is found that ACV is excreted largely unchanged in the form of urine and feces from humans. [5] Prodrugs like valacyclovir, 2‐amino‐9‐[2‐hydroxyethoxy methyl]‐9H‐purine (A515U) also accumulate in ACV form [6,7] in environment thus increasing its concentration in wastewater. Thus, ACV like other pharmaceuticals finds its way into the environment through wastewater collection systems. [8] Its toxicity can lead to renal insufficiency, nausea, diarrhea, headache, tremors, delirium, and encephalopathy in humans. [9,10] The environmental release of ACV has raised an alarm due to its potential disturbance in the ecosystem. Its release and subsequent contact with pathogens results in the alteration of the genetic make‐up of pathogens [11] and increases the risk of viral resistance. Biological treatment methods have been reported to remove ACV from wastewater, but the compounds identified after biodegrada- tion were reported to be more toxic or persistent in environment than the parent compound. [12] Prasse et al. reported the removal of nine antiviral drugs including ACV from wastewater using conventional wastewater treatment process and elimination of nearly 97 % ACV. [4] Prasse et al. in a further study identified the transformation product (TP) as carboxy‐ACV after biological treatment of ACV. [12] They reported that TP present in the drinking water can cause damage to the nervous system. The integrated membrane bioreactor‐ozonation system and aerobic biological treatment have also been reported to remove ACV from waste- water. [2a,b] The TPs released after biological treatment and ozonation of ACV gave an impetus to carry out research work for a cleaner and more efficient technology, including adsorption. The treatment of pharmaceutical wastewaters and hazardous wastes with activated carbon is considered to be an effective method for the removal of these harmful compounds from waste aqueous solutions. [16a,b] Due to their highly porous structure and surface area, and easy availability, activated carbons are considered to be efficient for the removal of contaminants from wastewater. [17,18] However, com- mercial activated carbon prepared from non‐renewable and relatively conventional precursors, viz. high quality coal makes it an expensive adsorbent for water treatment processes. [19] Waste materials like bottom ash and deoiled soya can be used as such as biosorbents for removal of hazardous wastes from wastewater. [21a,b][22a,b] The disposal of waste materials has always been a matter of great concern for handling authorities, as the dumped materials are highly unsuitable for agricultural uses and as it makes the agricultural land barren and unproductive. [23] Various agricultural by‐products such as coconut shells, palm‐pith, wood chips, wheat straw, date pits, [24] rice husk, [25] oak sawdust, [26] and waste materials, [27,28] and also waste from agriculture, have been successfully used as low cost substrate for preparation of activated carbon. Since the performance of an adsorptive removal process is dependent on the quality and cost effectiveness of the adsorbent, the last decade has seen a continuous advancement in the development of effective and noble adsorbents in the form of activated carbon. [16a] Pine trees are dominant and widely distributed vegetation in Saskatchewan, Canada. Saskatchewan *Author to whom correspondence may be addressed. E‐mail address: ajay.dalai@usask.ca Can. J. Chem. Eng. 92:1627–1635, 2014 © 2014 Canadian Society for Chemical Engineering DOI 10.1002/cjce.22026 Published online in Wiley Online Library (wileyonlinelibrary.com). VOLUME 92, SEPTEMBER 2014 THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING 1627