Low Cost Biosorbents: An alternative treatment for contaminated water

I. F. Sarabia-Meléndez1; M. S. Berber-Mendoza1*; O. Reyes-Cárdenas1; M. Sarabia-Meléndez1; A. Acosta-Rangel1

Correspondence: *. Corresponding Author: Sarabia-Meléndez, Irma Francisca. Universidad Autónoma de San Luis Potosí, Facultad de Ingeniería, Manuel Nava No. 8, Zona Universitaria, C.P. 78290, San Luis Potosí, S.L.P., México. Phone: +52(444)826 2339. E-mail: E-mail:


In the last few years, low-cost adsorbent materials for the removal of heavy metals (Pb, Cd, Mn and As) from contaminated water, have been successfully studied. The purpose of this paper was to compare the different types of bio-sorbent materials from agricultural and wood residues and the factors influencing the adsorption process in their removal capacity of heavy metals in aqueous means, such as duration of contact, the effects of pH, and temperature. This way, relevant information is presented, such that it will serve as a guideline for future research about the use of bio-sorbents in water treatment as an efficient, economic and eco-friendly alternative.

Received: 2017 October 19; Accepted: 2018 March 5

revbio. 2020 Mar 23; 5: e375
doi: 10.15741/revbio.05.e375

Keywords: Keywords: Heavy metals, adsorption, agricultural waste, wood waste.


Water is an essential element to maintain life in this planet. Even though it is an inextinguishable resource, its chemical composition varies throughout the Earth’s crust, which affects its suitability for domestic and industrial purposes. While groundwater represents 0.6 % of hydrological resources (Mehta et al., 2015), it is the main supplier of the population’s needs. Nonetheless, due to the fast growth of industry, the quality of this resource has been significantly reduced due to the industrial and agricultural wastewater discharges which contain heavy metals (Yan-bing et al., 2017), which once emitted, can remain in the environment during hundreds of years, and due to their toxic effect and their tendency to accumulate, represent a risk for humans and the environment.

Moreover, there is a variety of traditional methods that have been used in the removal of heavy metals, such as, ion exchange, reverse osmosis, filtration, electrochemical treatment, oxidation or reduction methods, chemical precipitation, and membrane technology, which have been proven effective for the elimination of contaminants, nevertheless, in some cases, there are disadvantages such as the generation of chemical toxic sludge whose confinement is costly, and none environmentally friendly (Fu & Wang, 2011; Lakherwal, 2014), besides being inefficient in the removal of metallic ions in concentrations of 0,01 to 0,1 g/L (Bulut & Tez, 2007). For this reason, it is necessary to look for low-cost, efficient alternatives that are environmentally friendly.

Adsorption represents one option. It is a process of mass transference through which a substance goes from a liquid phase to the surface of a solid, as a result of the affinity on the active sites of the adsorbent with the adsorbate, united by physical or chemical interaction, which can take place through complexing, coordination, chelation and ionic interchange (Pehlivan et al., 2008). Additionally, the adsorption capacity is affected by the properties of the adsorbent, such as specific and chemical area on the surface (Qomi et al., 2014). Currently, adsorption is considered as an effective, economical and eligible option for the treatment of waters (De Gisi et al., 2010). Among the most widely used adsorbents in the treatment of contaminated waters for purification, is activated carbon. Recently, the use of activated carbon fiber has stood out since it has a larger specific area which increases the speed of absorption (Zaini et al., 2010). Nonetheless, the use of activated carbon in the treatment of residual waters is sometimes limited because of its high cost. For this reason, attempts have been made to replace it with agricultural and industrial residues.

One alternative is biosorption, which is an ecological technology for the removal of heavy metals from water, easy to use, low cost, high efficiency, and with a minimum of sludge generation. Additionally, there is the possibility of regeneration of the biosorbent and recovering of metal (Das et al., 2014).

Biosorption can be defined as the ability of biomass to remove organic and inorganic species in aqueous solutions through a physio-chemical mechanism of sequestration (Akar et al., 2015). There are two types of biomass, living biomass (fungus, algae, bacteria) and dead biomass (agricultural residues, wood residues or wool residues). The use of dead biomass is frequently applied in this type of process (biosorption), since it requires no maintenance conditions; while the use of living biomass requires nutrients, and the toxicity of the biomass is likely to occur when entering into contact with contaminants, nevertheless, its potential on the removal of contaminants through bio-precipitation can be recognized (Park et al., 2010).

In order to consider a bio-sorbent as effective, it must have the following properties: low cost, little or no processing, naturally abundant or being a waste product (Bulut & Tez, 2007), high efficiency, affinity (in terms of equilibrium and kinetics), stable (mechanically and chemically), with recycling possibilities (Kleinübing et al., 2011), no production of secondary compounds, short operating time (Morosanu et al Venom., 2017), metal recovering (Das et al., 2014) and environmentally friendly (Nagy et al., 2017). Nevertheless, the adsorption capacity depends on the active sites of the material and the nature of the ions in solution to be eliminated (Taty-Costodes et al., 2003). Among the active sites, there are functional groups such as carboxyl, xylan, hydroxil, carbonyl, amino and phenolic compounds (Lodeiro et al., 2006; Han et al., 2006; Pehlivan et al., 2008; Jayakumar et al., 2015).

The capacity of adsorption of a metallic ion by a biomass, depends on those that affect the process of biosorption, amount which we find: pH of the solution, type of adsorbent material, stirring time, contact time, amount of adsorbent (Jayakumar et al., 2015; Djemmoe et al., 2016; Huang et al., 2015), stirring time (Daneshvar et al., 2017; Bulut & Tez, 2007), amount of adsorbent (Argun et al., 2007), temperature (Moubarik & Grimi, 2015), initial concentration (Das et al., 2014), ionic force and coexistence of other contaminants (Park et al., 2010; Larous et al., 2005).

pH is probably the most important factor in biosorption of metallic ions, for cations as well as anions, showing a different effect in both cases (Lodeiro et al., 2006). This is due to the surface charge of the bio-sorbent depending on the pH of the solution and its point of zero charge (PZC). When the surface charge of the adsorbent is zero, it is considered neutral and it is called PZC. The surface is charged positively below the PZC, and it can cause rejection of cations and attraction of anions. On the other hand, in low pH (pH = 2), the hydronium ion competes against the metallic ion for the sites of the bio-sorbent. When the value of pH is higher than PZC, the surface of the adsorbent is charged negatively and the functional groups (carboxyl, phenolic, phosphate, and amino) react with the metallic cations for their elimination from the solution (Taty-Costodes et al., 2003; Han et al., 2006; Moubarik & Grimi, 2015; Salazar- Rábago & Leyva-Ramos, 2016).

Temperature is another factor that most influences the efficiency of biosorption (Zeraatkar et al., 2016) and the interaction between the solute and the absorbent (Kleinübing et al., 2011). Nevertheless, in biosorbents such as algae, a very high temperature causes alteration on the surface and, therefore, a loss in the absorption capacity due to deterioration of biomass (Jayakumar et al., 2015; Park et al., 2010; Moubarik & Grimi, 2015). While in biosorbents coming from agricultural waste, at high temperatures, it has been demonstrated that it increases the absorption capacity of metallic ions, which could be due to the activity on the surface of the biosorbent in the same way that the kinetic energy of metallic ions is increasing with higher temperature (Park et al., 2010; Morosanu et al., 2017). In other studies, it has been found that the adsorption capacity diminishes with the increase of temperature, in these cases it is said to be an exothermic process (Huang et al., 2015).

Time of contact is a parameter considered for the adsorption of metallic ions upon the material. (Han et al., 2006; Pehlivan et al., 2008). In most cases they are left in contact until equilibrium is reached between the biosorbent and the metallic ion in solution. In order to determine the relationship between the adsorbate and the absorbent in equilibrium, different models of isotherms can be used. One of the mostly used models is the Freundlich model, which predicts the surface heterogeneity of the adsorbent (Ajmal et al., 1998). Meanwhile, the Langmuir model, which is also frequently used, is based on the adsorption on completely homogeneous surfaces with a single layer formation, where the interactions between adsorbed molecules are negligible (Larous et al., 2005). Both models of isotherms adequately adjust to the description of the adsorption aqueous systems. In this context, low cost, readily available materials have been studied, that have turned out effective, such as: bacteria, algae, fungi, natural residues (Park et al., 2010), materials and byproducts of industrial origin, such as operational waste, process waste and fermentation residue (Aksu et al., 2008; Han et al., 2006), agricultural waste (Huang et al., 2015). All of them promise to be, somehow, eco-friendly, besides being profitable in the elimination of metals from contaminated waters (Henriques et al., 2015). It has been determined that modifications of materials having different chemicals increase the removal of contaminants, however, such modifications can increase the cost of biosorbents (Park et al., 2010). For this revision, information from several studies of wood and agricultural waste were considered (Figure 1), taking into consideration feasibility and efficiency, as well as optimum conditions of operation for the removal of heavy metals with the intention of analyzing biomasses with a high adsorption potential for their application.

[Figure ID: f1] Figure 1.

Classification of agricultural and wood biomass, used for removal of heavy metals in aqueous solutions.

1. Removal by agricultural waste

A great variety of agricultural waste and byproducts have been explored for the elimination of heavy metals. Agricultural waste can be generated from several parts of plants, such as stems, leaves, flowers, fruit, peel, seeds and fruit pits, for example: sugarcane bagasse, coconut husk, palm oil, neem bark, pecan and walnut residue, by-products such as onion skin, palm kernel peel, (Pehlivan et al., 2008; Hegazi, 2013; Qomi et al., 2014; Huang et al., 2015), rice and wheat bran, brewer’s yeast (Han et al., 2006) and sawdust (Argun et al., 2007; Sciban et al., 2007). Due to their structure formed by natural biopolymers (cellulose) all these residues, heteropolysaccharides like hemicellulose, pectin, and lignin, (Anwar et al., 2010), besides having phenolic, amino, hydroxyl and carboxyl groups (Castro et al., 2011), can be used as biosorbents, and biosorption of this type of materials occurs when the functional groups unite with the metallic ions (Akar et al., 2015).

Some of the mechanisms for the adsorption of metals are chelation, complexing, and ionic interchange (Fu & Wang, 2011). The advantage with these biosorbents is the fact that they do not have to be produced specifically for that purpose, since they are agricultural or timber byproducts, available in large quantities (Sulyman et al., 2017), additionally they are low-cost and easily processed. Based on the above, agricultural residues represent a good alternative as a source of adsorbent materials for the treatment of residual waters (Okoro & Okoro, 2011) and specifically on the removal of heavy metals.

Table 1 shows the biosorption capacities of various types of agricultural residues, their temperature conditions, pH and duration of contact, as well as the type of isotherm to which the experimental data was related. This table shows that the adsorption capacities of biosorbents depends on the type of residue as much as on the conditions, and on the metallic ion found in the solution. The most widely used isotherms are Langmuir and Freundlich. It can also be noted that the maximum capacity of adsorption of metal onto the residues occurs between 3 and 7 pH, and the times of contact varied between 20 min up to 48 h, and temperatures went from 20 up to 35°C. Additionally, it can be appreciated that the residues that showed a higher adsorption capacity were: tea waste which removed 65 mg/g and 48 mg/g of Pb (II) and Cu (II) respectively, as well as sugar beet pulp which showed an absorption of 46.1 mg/g of Cd (II) and 35.6 mg/g of Zn (II) (Figure 1). Nevertheless, it is hard to decide, from the information above, which of these biomasses works better, since the conditions under which the studies were made, were not the same. However, what can be concluded is that the use of some agricultural residues is recommendable, since besides their physio-chemical properties and their affinity with metallic ions, it is clear that they are relatively cheap, readily available, and abundant. It has also been shown that they can be modified in order to increase their properties and removal capacities, however, more research is required regarding modeling, regeneration and metal recovery (Sud et al., 2008).

Table 1.

Agricultural waste materials used as low cost adsorbents.

Adsorbent Metal Removal
Isotherm* T °C pH References
Bagasse carbon Cd (II)
Zn (II)
1 h L, F 25 4.5 Mohan et al., 2002
Sugar beet pulp (SBP) Cu (II)
Zn (II)
60 min L 25 ± 1 5.5
Pehlivan et al., 2006
Fly ash (FA) Cu (II)
Zn (II)
60 min L 25 ± 1 5
Pehlivan et al., 2006
Carbon Henna leaves Cu (II)
Cr II)
90 min L, F 35 ± 2 7 Shanthi & Selvarajan, 2013
Tea waste Pb (II)
Cu (II)
90 min L, F 22±2 5-6 Amarasinghe & Williams, 2007
Oxidised coir Ni (II)
Zn (II)
Fe (II)
120 min L 35 6.5 Shukla et al., 2006
Sugar beet pulp Pb (II)
Cu (II)
Ni (II)
120 min L 20±0.5 6 Gerente et al., 2000
Sugar beet pulp Cd (II)
Pb (II)
70 min L, F 25±1 5.3 Pehlivan et al., 2008
Banana Peel Pb (II)
Cu (II)
20 min L 30 3 Castro et al., 2011
Beer yeast Pb (II)
Cu (II)
60 min L, F 20 5 Han et al., 2006
Mustard husk Pb (II)
Cd (II)
48 h L, F 6
Meena et al., 2008
Peels of banana Pb (II)
Cd (II)
20 min L 25 5
Anwar et al., 2010

TFN1*Isotherm Adsorption L=Langmuir and F= Freundlich.

Figure 2 Shows the removal capacity of agricultural waste according to the relationship species-metal.

[Figure ID: f2] Figure 2.

Agricultural waste species with more capacity of heavy metal adsorption.

2. Removal with wood residues

Another alternative material for adsorption of metals are the residues of the wood industry (sawdust) which are widely available, and often considered as waste (Qomi et al., 2014). Its structure is formed by primary components like cellulose (40-50 %), hemicellulose (20-40 %), and lignin (20-40 %) (Salazar-Rábago and Leyva-Ramos, 2016), besides secondary components like carbohydrates, phenolic groups, carboxyl groups, hydroxyl groups, sulfate, phosphate, and amino groups and extracts of fat and wax (Vásquez-Guerrero et al., 2016); the percentage of the composition of the structure is directly related to the species of wood from which the sawdust is produced (Ahmad et al., 2009). The physio-chemical properties of the previously mentioned adsorbent affect its removal capacity (Martín-Lara et al., 2016). Recently, the use of sawdust of various species of wood has caught the attention of several research studies, which, in some cases has been modified in its physio-chemical properties to increase its adsorption capacity through some of the following acids: Hydrochloric, sulfuric, phosphoric, tartaric, citric, or sodium hydroxide (Meena et al., 2008; Ofomaja et al., 2010). Table 2 shows different natural and modified residues of wood used in the removal of heavy metals.

Table 2.

Different wood waste materials used as adsorbents.

Adsorbent Metal Removal
Isotherm* T °C pH References
Sawdust of Meranti wood Cu (II)
Pb (II)
60 min L, F 30 6.6
Ahmad et al., 2009
Meranti sawdust Cu (II)
Cr (III)
Ni (II)
Pb (II)
120 min L, F, DR 30 6 Rafatullah et al., 2009
Sawdust of Pinus Sylvestris Cd (II)
Pb (II)
20 min L 25 Taty-Costodes et al., 2003
Sawdust Cu (II)
Pb (II)
24 h L, F 23 75 Yu et al.,2001
Papaya wood Cu (II)
Cd (II)
Zn (II)
60 min L, F - 5 Saeed et al., 2005
Mansonia wood sawdust Pb (II)
Cu (II)
- L, F 26 6 Ofomaja et al., 2010
KOH treated pine cone powder Cu (II)
Pb (II)
15 min L, F, DR 18 5 Ofomaja et al., 2010
Modified oak sawdust Cu (II)
Ni (II)
Cr (VI)
L, F, DR 20 483 Argun et al., 2007
Pine cone Fenton’s reagent Cd (II)
Pb (II)
90-105 min L 20 7 Argun et al., 2008
NaOH treated raw sawdust Cr (IV)
Pb (II)
Hg (II)
Cu (II)
48 h
L, F 30 6 Meena et al., 2008
Modified pine sawdust with citric acid Pb(II) 18.9-304 7 d L 25 5 Salazar-Rábago & Leyva- Ramos, 2016

TFN2*Isotherm Adsorption L=Langmuir, F= Freundlich and DR=Dubini-Radushkevich.

It is clear there is variation in the adsorption capacity of residues, both natural and modified, which will depend on the surface charge on the adsorbent and the pH of the solution. To a higher pH the surface charge will be negative, due to the deprotonation of the carboxyl and hydroxyl groups (Debnath et al., 2017); nevertheless, the temperature and duration of contact also influence on the removal of contaminants. Among the materials that showed a higher adsorption capacity is pine tree sawdust modified with citric acid which removed up to 304 mg/g of Pb (II) (Salazar-Rábago & Leyva Ramos, 2006), another case is the one treated with NaOH, which adsorbed 111.61 mg/g of Cr(II) and Pb(II), respectively (Meena et al., 2008), while Mansonia residue removed 51.81 mg/g and 42.37 of Pb (II) and Cu (II), respectively (Ofomaja et al., 2010) (see Figure 3). Like in some other residues, the most used models of isotherms of adsorption for the adjustment of experimental adsorption data were Langmuir and Freundlich (Singh et al., 2016). Argun et al. (2007), considers that modification causes diminishing of the amount of cellulose and hemicellulose, while increasing the proportion of lignin, which is favorable since it has proven that metals adsorb preferably to the latter. Figure 3 shows the capacity of removal of the different types of sawdust according to the relation species-metal.

[Figure ID: f3] Figure 3.

Wood waste with more adsorption capacity of heavy metals. Wood waste species.


Conventional treatments, in view of their high cost, turn out to be ineffective for the elimination of low concentrations of metals Figure 3. Wood waste with more adsorption capacity of heavy metals. Wood waste species. For this reason, the residues under study in this paper represent an alternative for the treatment of waters contaminated by heavy metals.

Modified agricultural waste proved to be more efficient on the removal of heavy metals, however, it is important to take into consideration the cost of the modification process.

The adsorption of heavy metals as well as any other contaminant, is conditioned by the type of material, the pH, temperature, and the duration of contact, besides, according to this revision, the metal must be taken into consideration and its species in aqueous solution for better removal of them.

The majority of the reported studies have been carried out in lots. More research that focuses on the factor affecting biosorption becomes necessary in order to make the economical processes in an industrial scale with the idea of recovering the metal and the regeneration of the industrial residue.

In general, the selective order of adsorbents by heavy metals is:

Pb (II) > Cd (II) > Cu (II) > Cr (II) > Zn (II) > Ni (II).

In view of the above, the assessed materials can be considered as an alternative treatment for the adsorption of metals in aqueous solution, in large quantities, for their effectiveness, availability and low cost.

fn1Cite this paper: Sarabia-Meléndez, I. F., Berber-Mendoza, M. S., Reyes-Cárdenas, O., Sarabia-Meléndez, M., Acosta-Rangel, A. (2018). Low Cost Biosorbents: An alternative treatment for contaminated water. Revista Bio Ciencias 5, e375. doi: https://doi.org/10.15741/revbio.05.e375


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