Zn(II) adsorption from synthetic solution and kaolin wastewater onto vermicompost

Abstract

The adsorption of Zn(II) from both synthetic solution and kaolin industry wastewater by cattle manure vermicompost was studied. The adsorption process was dependent on the various operating variables, viz., solution pH, particle size of the vermicompost, mass of vermicompost/volume of the Zn(II) solution ratio, contact time and temperature. The optimum conditions for Zn adsorption were pH 6.0, particle size of < or = 250 microm, 1 g per 10 mL adsorbent dose, contact time of 4h and temperature of 25 degrees C. Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated, with R(2) values from 0.95 to 0.99. In synthetic solution, the maximum adsorption capacity of the vermicompost for Zn(2+) ions was 20.48 mg g(-1) at 25 degrees C when the vermicompost dose was 1 g 10 mL(-1) and the initial adjusted pH was 2. The batch adsorption studies of Zn(II) on vermicompost using kaolin wastewater have shown the maximum adsorption capacity was 2.49 mg g(-1) at pH 2 (natural pH of the wastewater). The small values of the constant related to the energy of adsorption (from 0.07 to 0.163 L mg(-1)) indicated that Zn(2+) ions were binded strongly to vermicompost. The values of the separation factor, R(L), which has been used to predict affinity between adsorbate and adsorbent were between 0 and 1, indicating that sorption was very favorable for Zn(II) in synthetic solution and kaolin wastewater. The thermodynamic parameter, the Gibbs free energy, was calculated for each system and the negative values obtained confirm that the adsorption processes are spontaneous. The DeltaG degrees values were -19.656 kJ mol(-1) and -16.849 kJ mol(-1) for Zn(II) adsorption on vermicompost in synthetic solution at pH 6 and 2, respectively, and -13.275 kJ mol(-1) in kaolin wastewater at pH 2.

Removal of heavy metals by biosorption

“…A review of the literature has shown that there are only a few studies reporting the remediation of wastewaters containing heavy metals by vermicomposts. The efficiency of vermicompost for removing heavy metals from aqueous solutions or industrial effluents has not been studied in detail except to mention a few and namely Jordão et al (2002Jordão et al ( , 2009, Arruda (2003), Carrasquero Durán et al (2006), Jadia and Fulekar (2008) and Urdaneta et al (2008). These researchers found that metal concentrations in the purified effluents were below the maximum values established for waste discharges by the prevalent local standards.…”

“…Their results showed maximum adsorption values between 113.6 mg/g (33°C) and 123.5 mg/g (50°C), and the differences in the IR spectra at pH 3.8 and 7.0 in the region from 1,800 to 1,300/cm, were interpreted on the basis of the carboxyl acid ionization, which reduced the band intensity around 1,725/cm, producing signals at 1,550/cm and 1,390/cm of carboxylate groups. Jordão et al (2009) also studied the adsorption of Zn 2? from both synthetic solution and kaolin industry wastewater by cattle manure vermicompost.…”

A Study on Al(III) and Fe(II) Ions Sorption by Cattle Manure Vermicompost

“…Although the Al concentration in the wastewater reached up to 102 mg L −1 , the concentration of this metal seems to vary according to the time of sample collection. In a previous work, Jordão et al (2008) reported Al concentration in the kaolin wastewater from Mar de Espanha of 585 mg L −1 , while Fe concentration reached up to 710 mg L −1 . There is no maximum limit of Al concentration established by the Brazilian legislation for effluent discharges into water courses.…”

“…However, some metals are not strongly influenced on varying the particle size, while some are better adsorbed only onto smaller particles (Matos and Arruda 2003). Jordão et al (2008) reported that Zn(II) adsorption by cattle manure vermicompost was higher in the ≤250 fraction as compared with any other fraction studied. In the present study, the ≤250 fraction particle size was used in the Al(III) and Fe(II) adsorption experiments.…”

- Use of Aqueous Extracts from Vermicomposts or Teas in Suppression of Plant Pathogens

“…For example, compost incorporation enhances the stabilization of mine-associated soils, thus reducing symptoms of ecotoxicity (Gadepalle et al 2007;Tandy et al 2009b), although these remediative effects may be moderated or reversed in certain composts . Organic constituents of vermicomposts also have high-metal affinities (Pereira and Arruda 2003;Carrasquero Durán et al 2006), and there is an emerging interest in the use of vermicomposts for removing metals from industrial effluents (Jordão et al 2002(Jordão et al , 2007Jordão, Fernandes, Ribeiro, Nascimento, et al 2009). In these seminal studies vermicomposts were deployed as a cation-exchange matrix.…”