Vermicompost as a natural adsorbent material: characterization and potentialities for cadmium adsorption

Abstract

Amostras de vermicomposto (material húmico) foram submetidas à caracterização por espectroscopia de infravermelho, difractometria de raios-X, termogravimetria, microscopia eletrônica, entre outras; adicionalmente, foi determinada a capacidade de troca catiônica (CTC). Empregou-se planejamento fatorial para estudar os mecanismos de interação da espécie Cd 2+ com os sítios adsortivos do vermicomposto e, posteriormente, foi avaliada a máxima capacidade adsortiva de cádmio empregando isoterma de Langmuir. A caracterização revelou que o vermicomposto exibe CTC tão elevada quanto 72,9 meq por 100 g, grande área superficial (substância porosa), grupos quelantes e máxima capacidade adsortiva para Cd (38,6 mg g -1 ) em pH 5,0. Esta potencialidade foi explorada em análises de amostras sintéticas e reais (água mineral) apresentando concentrações de cádmio próximas a 5 µg L -1 e requerendo etapas de pré-concentração. Um fator de enriquecimento de 100 foi obtido.Vermicompost (humic material) samples were submitted to characterization by infrared spectroscopy, X-ray diffractometry, thermogravimetric analysis, electron microscopy etc. In addition, its cation exchange capacity (CEC) was determined. Factorial experiments were designed in order to elucidate the interaction mechanisms between Cd 2+ and the adsorptive sites of vermicompost. The maximum adsorptive capacity for cadmium was evaluated by a Langmuir isotherm. The characterization revealed that vermicompost exhibits high CEC values (ca. 72.9 meq per 100 g), high surface area (porous material), chelating groups and a maximum adsorptive capacity for Cd (38.6 mg g , requiring a preconcentration step. An enrichment factor of 100 was attained.

Evaluation of sugar-cane bagasse as bioadsorbent in the textile wastewater treatment contaminated with carcinogenic congo red dye

“…4). Following literature recommendations (Pereira and Arruda, 2003), the isotherm was linearized and the maximum adsorptive capacity of cane bagasse for the congo red dye was established at 4.43 mg/g, which was a satisfactory value when compared to other congo red adsorbents such as red mud (4.05 mg/g) (Namasivayam and Kavitha, 2002) and activated carbon (6.7 mg/g) (Namasivayam and Arasi, 1997). It must be highlighted that the maximum adsorptive capacity described was calculated from the batch experiments, which could not be totally extrapolated to dynamic systems, as those based on percolation columns.…”

Use of Vermicompost for the Removal of Toxic Metal Ions of Synthetic Aqueous Solutions and Real Aqueous Waste

“…Thus, the destination of the vermicompost enriched with the execution of this study will be object of future investigations, which will be based on procedures already tested. In this context, previous studies 9 pointed out that metallic cations adsorbed in the vermicompost can be completely desorbed by percolation of acidic eluents, as 1 mol L -1 HNO3 solution. As for the recovery of desorbed metal ions, the literature 18 points to successful reuse alternatives in the scope of practical classes.…”

“…In turn, 44.4 ± 0.7 % (wt./wt.) of ashes highlight the use of soils in the vermicompost production 9 . 10 , whose values are (mg L -1 ): 0.2 (Cd), 1.0 (Cu), 1.0 (Mn), 2.0 (Ni), 0.5 (Pb) and 5.0 (Zn).…”

“…Vermicompost sample was characterized 9 for pH, humidity, total organic matter, and ashes. All analyses were performed in triplicate.…”

Review on the Removal of Metal Ions from Effluents Using Seaweeds, Alginate Derivatives and Other Sorbents

“…bentonite, kaolinite, montmorillonite, wollastonite) (CELIS et al, 2000;PRADAS et al, 1994), human hair and teeth (HELAL et al, 2002;TAN et al, 1985), leaf mould (SHARMA and FORSTNER, 1994), sand (AWAN et al, 2003), metal oxides (Al, Fe, Mn -oxides) (BAILEY et al, 1992;TRIVEDI andAXE, 2001), vermicompost (PEREIRA andARRUDA, 2003), xanthate (FLYNN et al, 1980;JAWED and TARE, 1991), and zeolites (e.g., clinoptilolite and chabazite) (GENÇ-FUHRMAN, 2007;LEPPERT, 1990;KALLO, 2001;OLIVEIRA et al, 2004).…”