Heavy metal adsorption onto agro-based waste materials: A review

Demırbas, Ayhan

doi:10.1016/j.jhazmat.2008.01.024

Cited by 1,354 publications

(655 citation statements)

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“…It is now well established that the ability of a waste material to bind lead or, more generally, heavy metals is the result of a number of mechanisms, including surface adsorption, chemisorption, complexation, ion exchange, microprecipitation and metal hydroxide condensation (Demirbas, 2008). In order to understand the detailed mechanism by which metals are removed by adsorption, it is essential to identify the functional groups involved in binding.…”

Section: Discussionmentioning

confidence: 99%

“…Although specific studies on tea waste are lacking, charged and polar functional groups on the surface of proteins or of other cell-wall components (cellulose, hemicellulose, pectin, lignin) are considered to be the main responsible for metal removal (Basso et al, 2002;Pagnanelli et al, 2003). Metal-binding sites can replace hydrogen ions with metal ions or donate an electron pair to form metal complexes (Ofomaja and Ho, 2007;Demirbas, 2008).…”

Section: Discussionmentioning

confidence: 99%

“…The former occur between the positively charged lead ions and some negatively charged groups on the protein surface, while covalent bonds are formed between lead ions and N-, O-or C-protein terminals (Dutta et al, 2005;Ghering et al, 2005;Srinivas et al, 2007). Other potential lead-binding sites are the hydroxyl and carboxyl groups on the cellulose-based plant fibers (Zhou et al, 2005;Demirbas, 2008). Also the phenolic compounds contained in the tea leaf have a significant affinity for lead ions, which manifests itself in their capability of capturing these metal species from aqueous solutions (Yu et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, in recent years much research has been undertaken to develop comparably effective but less expensive adsorbents (Bailey et al, 1999;Babel and Kurniawan, 2003;Demirbas, 2008). An economical adsorbent is defined as one which is abundant in nature, or is a by-product or a waste from industry and requires little processing (Aksu and Isoglu, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Adsorption of Pb(II) on Spent Leaves of Green and Black Tea

Zuorro¹,

Lavecchia

2010

American Journal of Applied Sciences

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Problem statement:In recent years much attention has been focused on the use of biomass residues as low-cost adsorbents for the removal of heavy metal ions from contaminated waters. Spent tea leaves, an abundantly available material that is currently disposed of as a solid waste, are potentially suitable for such applications. Approach: To provide some information on the adsorption properties of tea waste, we evaluated the removal efficiency of lead ions by spent leaves of green and black tea. Batch adsorption experiments were made at 25 and 40°C at initial lead-ion concentrations between 0.01 and 2 g L −1 . Equilibrium data were analyzed by the Langmuir equation to evaluate the maximum adsorption capacity and the equilibrium constant. The adsorption characteristics of the two materials were also compared with those of coffee grounds, activated carbon and Fuller's earth. Results: Experimental data showed that removal efficiencies up to 98-99% can be achieved when using spent tea leaves as lead adsorbent. The results were only marginally affected by the type of tea waste. At low lead loading, the adsorption equilibrium was well described by the Langmuir equation, with a maximum adsorption capacity of 83-130 mg g −1 and an equilibrium constant ranging from 0.112-0.245 L mg −1 . A comparison with other adsorbents provided the following order for lead removal efficiency: Black tea, coffee grounds > green tea > Fuller's earth > activated carbon. Conclusion:The results from this study indicate that using spent tea leaves as an adsorbent may be an efficient and economical means for removing lead and, presumably, other heavy metal ions from aqueous solutions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adsorption of Pb(II) on Spent Leaves of Green and Black Tea

Zuorro¹,

Lavecchia

2010

American Journal of Applied Sciences

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“…The Langmuir and Freundlich isotherm models are only applicable to batch adsorption systems where sufficient time is provided to allow equilibrium occurs between the pollutant in solution and the pollutant adsorbed on the media. During the flow through the adsorbent, a large amount of pollutants is expected to come into contact with active surface sites and thus be retained on the surface of the adsorbing media [12]. The Langmuir and Freundlich equations are most widely used.…”

Section: Introductionmentioning

confidence: 99%

Isotherm adsorption studies of Ni(II) ion removal from aqueous solutions by modified carboxymethyl cellulose hydrogel

Anah

Astrini

2018

IOP Conf. Ser.: Earth Environ. Sci.

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Abstract. This paper reports the removal of nickel ions from aqueous solutions using carboxymethyl cellulose-graft-poly(acrylic acid) CMC-g-PAA hydrogel as an adsorbent. The hydrogel was prepared through graft copolymerization of acrylic acid monomer onto a carboxymethyl cellulose backbone in the presence of N,N'-methylenebisacrylamide as a crosslinking-agent using benzoyl peroxide initiator system. Isotherm for the adsorption of nickel on CMC-g-PAA hydrogel was developed and the equilibrium data fitted to the Langmuir and Freundlich isotherm models. The result showed that at pH of 5 and shaker speed of 100 rpm, Freundlich model was better fitted than Langmuir model, of which R 2 = 0.999 and R 2 = 0.935, respectively. The constant of Langmuir model was KL value = 0.003 and qmax = 1000 mg/g, whereas the constant of Freundlich model n = 1.2 and KF = 4.614. The CMC-g-PAA hydrogel before and after Ni(II) adsorption were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). IntroductionEnvironmental pollution by toxic metals arises from industries, agricultural effluents and waste disposal from various sources. Many industries such as metal plating facilities, mining operations and tanneries discharge waste containing heavy metal ions.As pollutants, heavy metals were intensively studied due to their significance from the point of view of persistence and toxicity. These toxic metals can cause accumulative poisoning, cancer, and brain damage when present at above the tolerance levels. The agencies for the environmental monitoring have set permissible limits for heavy metals levels in drinking water because of their harmful effects. The removal and rapid decontamination of heavy metals such as Cd, Pb, Cu, Ni, Hg become very important for the environmental remediation [1]. The World Health Organization has recommended strict controls on the percentages of various heavy metals in effluent waters [2].Hydrogels are water-swollen crosslinked network of hydrophilic polymer. Due to the hydrophilic groups in their backbone, hydrogels can imbibe large quantities of water and swells. The degree of hydrogel swelling is related to the degree of crosslinker, ionic strength of the solution, temperature, pH, and the presence and extent of hydrophilic groups such as -OH, -COOH, -NH2, -CONH2, and SO3H. These functional groups in the hydrogel networks can be utilized for the toxic metal ion removal. Hydrogels can also be modified with new functionalities or prepared as composites with clays and with other materials to increase the metal ion absorption capacities [3][4][5][6].

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Organo‐Clay Nanohybrid Adsorbents in the Removal of Toxic Metal Ions

Liu

2014

Nanomaterials for Environmental Protection

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Heavy metal adsorption onto agro-based waste materials: A review

Cited by 1,354 publications

References 112 publications

Adsorption of Pb(II) on Spent Leaves of Green and Black Tea

Adsorption of Pb(II) on Spent Leaves of Green and Black Tea

Isotherm adsorption studies of Ni(II) ion removal from aqueous solutions by modified carboxymethyl cellulose hydrogel

Organo‐Clay Nanohybrid Adsorbents in the Removal of Toxic Metal Ions

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