Kinetics of Adsorption in Mercury Removal Using Cassava (Manhiot esculenta) and Lemon (Citrus limonum) Wastes Modified with Citric Acid1

Abstract

The high toxic concentrations of mercury in water bodies and its negative impact on the environment has resulted in the need for research on effective and low-cost methods for the treatment of industrial effluents, such as adsorption. This research compares the feasibility and viability of the adsorption abilities of cassava and lemon citric acid-modified peels. The results showed that the modified peel of cassava has a better adsorption ability compared to that of lemon. The kinetics models that best fit the experimental data were the Pseudo-second order model and the Elovich model for both modified biomasses. This means that the mechanism that controls the adsorption is a second order reaction, and also shows that the catalytic area of the adsorbent is heterogeneous; whereas the Freundlich isotherm describes better the adsorption process. In conclusion, the use of waste material is possible for Hg (II) removal. The study of chemical modifications is suggested to improve the adsorption percentages.

Biosorptive Decontamination of Acid Red-87 Dye from Wastewater byCitrus limonum Peels:Ecofriendly Approach

“…FTIR spectrum reveals the presence of amines, alcohol, carboxylic acid, hydroxyl groups, phenol, amino acids etc in both form of this peel. The peaks observed near 2900 cm -1 may be associated with the stretching vibrations of CH bond of methyl, methylene and methoxy groups [24][25][26][27]. Shifting of various peaks in below spectrum occurred after adsorption of dye molecules as is clear from (Fig.…”

“…These two components pyrolyzed into monomeric phenols, aromatic rings and piranose structures. Above 500 o C, a continuous weight loss was noticed, which may be attributed to slow decomposition of the remaining heavy components, which may consist of stable micronutrients like metal oxides [24][25][26][27].…”

“…In an earlier report, lemon peel has been evaluated as a potential adsorbent to remove methyl orange and Congo red [22]. We have also previously contributed the function of lemon peel [23], as low cost adsorbent to remove the Trypan Blue dye from aqueous solution [24].…”

Characterizing the Pequi Bark (Caryocar brasiliense Camb.) and Teak Sawdust (Tectona grandis) Biomasses in natura, or Modified with Citric Acid, According to Boehm's Methodology to Set the Basic and Acidic Groups

“…No entanto, os ensaios com as biomassas de casca de mandioca (Manhiot esculenta) e casca de limão (Citrus limonum), que foram modificadas com ácido cítrico, evidenciaram que a presença de grupos hidroxila e carbonila na superfície das biomassas garantem grande afinidade ao Hg(II), mostrando que a modificação favoreceu o processo de biossorção. 26 As capacidades de biossorção encontradas para o metal potencialmente tóxico Pb(II) não sofreram influência segundo a modificação com ácido cítrico, algo que também foi constatado para o íon Cd(II).…”

“…27 As biomassas in natura detiveram boas capacidades de biossorção devido ao fato de suas estruturas químicas serem compostas principalmente por biopolímeros como lignina, celulose e hemi-celulose, como foi verificada para as biomassas de casca de mandioca (Manhiot esculenta) e casca de limão (Citrus limonum) que detiveram alto potencial de remoção de íons Hg(II). 26 Entretanto quando se compara a capacidade de biossorção em relação à modificação das biomassas por ácido cítrico observa-se que, com exceção da biomassa serragem modificada, ambas as biomassas in natura apresentaram melhor capacidade de biossorção das espécies metálicas do que as modificadas.…”