Use of Vegetable Fibers for PRB to Remove Heavy Metals from Contaminated Aquifers—Comparisons among Cabuya Fibers, Broom Fibers and ZVI

Abstract

The Zero Valent Iron (ZVI) is the material most commonly used for permeable reactive barriers (PRB). For technical and economic reasons, hoter reactive substances usable in alternative to ZVI are investigated. The present study takes into account a vegetable fibers, the cabuya, investigating its capacity to retain heavy metals. The capacity of the cabuya fibers to adsorb heavy metals was verified in laboratory, by batch and column tests. The batch tests were carried out with cabuya and ZVI, using copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb). The results obtained by the cabuya fibers showed a very high adsorption capacity of heavy metals and resulted very similar to those obtained for the broom fibers in a previous study. The high value of the absorption capacity of the cabuya fibers was also confirmed by the analogous comparison made with the results of the batch tests carried out with ZVI. Column tests, using copper, zinc and cadmium, allowed to determine for the cabuya fibers the maximum removal percentage of the heavy metals considered, the corresponding times and the time ranges of the release phase. For each metal considered, for a given length and three different times, the constant of degradation of cabuya fibers was determined, obtaining values very close to those reported for broom fibers. The scalar behavior of heavy metal removal percentage was verified. An electron microscope analysis allowed to compare, by SEM images, the characteristics of the cabuya and broom fibers. Finally, to investigate the chemical structure of cabuya and broom fibers, the FTIR technique was used, obtaining their respective infrared spectra.

Adsorption Performance Analysis of Alternative Reactive Media for Remediation of Aquifers Affected by Heavy Metal Contamination

“…Some authors [ 33 , 61 , 62 ] found the following main composition: cellulose 63–80%, lignin 10.1–17%. In comparison with Spanish broom ( Spartium junceum ), which exhibits 6.6% of lignin content [ 63 ] and for which Fallico et al [ 59 , 64 ] and Arias et al [ 60 ] highlighted significant adsorption capacity for heavy metals, we observed a larger lignin content in cabuya fibers. Depending on the fiber type, namely row or elementary (i.e., subjected to further extraction procedure from the row fibers), different measurements are available in literature (e.g., [ 65 , 66 , 67 , 68 ]).…”

Adsorption capability of brewed tea waste in waters containing toxic lead(II), cadmium (II), nickel (II), and zinc(II) heavy metal ions

“…In general, when 1/n < 0.5 the experiment system is readily executed. The experiment system only becomes challenging when 1/n > 0.5 51 . In this study, 1/n was less than 0.5 when the Pb, Cd, Zn and Ni ions were adsorbed onto BTW, suggesting that the adsorption of the Pb, Cd, Ni and Zn ions with BTW was easily conducted.…”

Removal Behavior of Methylene Blue from Aqueous Solution by Tea Waste: Kinetics, Isotherms and Mechanism

“…Generally, when 1/ n is less than 0.5, the adsorption process would be easily carried out. Adsorption process is difficult when the 1/ n is larger than 0.5 [ 4 , 5 ]. In this research, the 1/ n is less than 0.5 when MB was adsorbed onto tea waste, suggesting that adsorption behavior of methylene blue on tea waste easily performed.…”

“…The Temkin isotherm model assumes that the heat of adsorption of all the molecules in the layer decreases linearly with coverage due to adsorbent–adsorbate interactions and mainly describes the chemisoprtion process which dominated through electrostatic adsorption [ 4 , 5 ]. In this investigation, the correlation coefficient of Temkin model was larger than 0.95, revealing that electrostatic interaction was an important mechanism between tea waste and methylene blue.…”

“…The priority research focuses on the choice of the adsorbent and the investigation of mechanism. Biomass is an ideal material for adsorbent owing to its wide availability and low cost, especially biomass based on agricultural and forestry residues [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ].…”