Removal of dyes using agricultural waste as low-cost adsorbents: a review

Appl Water Sci (2013) 3:773–790 DOI 10.1007/s13201-013-0117-y REVIEW ARTICLE Removal of dyes using agricultural waste as low-cost adsorbents: a review K. S. Bharathi • S. T. Ramesh Received: 31 March 2013 / Accepted: 7 June 2013 / Published online: 17 July 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com Abstract Color removal from wastewater has been a matter of concern, both in the aesthetic sense and health point of view. Color removal from textile effluents on a continuous industrial scale has been given much attention in the last few years, not only because of its potential toxicity, but also mainly due to its visibility problem. There have been various promising techniques for the removal of dyes from wastewater. However, the effectiveness of adsorption for dye removal from wastewater has made it an ideal alternative to other expensive treatment methods. In this review, an extensive list of sorbent literature has been compiled. The review evaluates different agricultural waste materials as low-cost adsorbents for the removal of dyes from wastewater. The review also outlines some of the fundamental principles of dye adsorption on to adsorbents. Keywords Dyes  Low-cost adsorbents  Adsorption  Wastewater treatment Introduction Dyes are widely used in industries such as textiles, rubber, plastics, printing, leather, cosmetics, etc., to color their products. As a result, they generate a considerable amount of colored wastewater. There are more than 10,000 commercially available dyes with over 7 9 105 tonnes of dye stuff produced annually. It is estimated that 2 % of dyes K. S. Bharathi (&)  S. T. Ramesh Department of Civil Engineering, National Institute of Technology, Tiruchirappalli 620 015, Tamil Nadu, India e-mail: S. T. Ramesh e-mail: produced annually is discharged in effluents from associated industries (Allen and Koumanova 2003). Among various industries, textile industry ranks first in usage of dyes for coloration of fiber. The total dye consumption of the textile industry worldwide is in excess of 107 kg/year and an estimated 90 % of this ends up on fabrics. Consequently, 1,000 tones/year or more of dyes are discharged into waste streams by the textile industry worldwide (Marc 1996). Discharge of dye-bearing wastewater into natural streams and rivers poses severe problems to the aquatic life, food web and causes damage to the aesthetic nature of the environment. Dyes absorb and reflect sunlight entering water and so can interfere with the growth of bacteria and hinder photosynthesis in aquatic plants. The problems become graver due to the fact that the complex aromatic structures of the dyes render them ineffective in the presence of heat, light, microbes, and even oxidizing agents and degradation of the dyes become difficult (Pearce et al. 2003). Hence, these pose a serious threat to human health and water quality, thereby becoming a matter of vital concern. Keeping the essentiality of color removal, concerned industries are required to treat the dye-bearing effluents before dumping into the water bodies. Thus, the scientific community shoulders the responsibility of contributing to the waste treatment by developing effective dye removal technique. Dyes can have acute and/or chronic effects on exposed organisms depending on the exposure time and dye concentration. Dyes can cause allergic dermatitis, skin irritation, cancer, mutation, etc. Dyes can be classified as (Mishra and Tripathy 1993): anionic (direct, acid and reactive dyes), cationic (basic dyes) and non-ionic (dispersive dyes). Many treatment processes have been applied for the removal of dye from wastewater such as: Fenton process 123 774 Appl Water Sci (2013) 3:773–790 (Behnajady et al. 2007), photo/ferrioxalate system (Huang et al. 2007), photo-catalytic and electrochemical combined treatments (Neelavannan et al. 2007), photo-catalytic degradation using UV/TiO2 (Sohrabi and Ghavami 2008), sono-chemical degradation (Abbasi and Asi 2008), Fentonbiological treatment scheme (Lodha and Chaudhari 2008), biodegradation (Daneshvar et al. 2007), photo-Fenton processes (Garcia-Montano et al. 2007), integrated chemical–biological degradation (Sundarjanto et al. 2006), electrochemical degradation (Fan et al. 2008), adsorption process (Tan et al. 2007; Hameed et al. 2007a, b), chemical coagulation/flocculation, ozonation, cloud point extraction, oxidation, nano-filtration, chemical precipitation, ionexchange, reverse osmosis and ultra-filtration (LorencGrabowsk and Gryglewic 2007; Malik and Saha 2003; Malik and Sanyal 2004; Banat et al. 1996). Among treatment technologies, adsorption is rapidly gaining prominence as a method of treating aqueous effluent. Some of the advantages of adsorption process are possible regeneration at low cost, availability of known process equipment, sludge-free operation and recovery of the sorbate (Kapdan and Kargi 2002). Activated carbon is the most widely used adsorbent for dye removal because of its extended surface area, micro-pore structures, high adsorption capacity and high degree of surface reactivity. However, commercially available activated carbon is very expensive and has high regeneration cost while being Table 1 Reported adsorption capacities qm (mg/g) of different agricultural wastes 123 exhausted. Furthermore, generation using solution produces a small additional effluent while regeneration by refractory technique results in a 10–15 % loss of adsorbent and its uptake capacity (Waranusantigul et al. 2003). This has lead to search for cheaper substances. Researchers are always in a hunt for developing more suitable, efficient and cheap and easily available types of adsorbents, particularly from the waste materials. Agricultural waste materials have little or no economic value and often pose a disposal problem. The utilization of agricultural waste is of great significance (Geopaul 1980). A number of agricultural waste materials are being studied for the removal of different dyes from aqueous solutions at different operating conditions. Agricultural waste includes coir pith (Namasivayam and Kavitha 2002), orange peel (Rajeswari et al. 2001), banana peel (Annadurai et al. 2002), rice husk (Malik 2003), straw (Kannan and Sundaram 2001), date pit (Banat et al. 2003a), oil palm trunk fiber (Hameed and El-Khaiary 2008a), durian (Durio zibethinus Murray) peel (Hameed and Hakimi 2008), guava (Psidium guajava) leaf powder (Ponnusami et al. 2008), almond shell (Ardejani et al. 2008), pomelo (Citrus grandis) peel (Hameed et al. 2008a), broad bean peel (Hameed and El-Khaiary 2008b), peanut hull (Tanyildizi 2011), Citrullus lanatus rind (Bharathi and Ramesh 2012). The adsorption capacity of these sorbents is listed in Table 1. Adsorbent Dye Coir pith Congo red Maximum adsorption capacity (mg/g) 2.6 References Namasivayam and Kavitha (2002) Orange peel Aid violet 19.88 Rajeswari et al. (2001) Banana peel Ric (...truncated)