Novel Adsorbent Material from Plinia cauliflora for Removal of Cationic Dye from Aqueous Solution.

The food industry is responsible for the generation of large amounts of organic residues, which can lead to negative environmental and economic impacts when incorrectly disposed of. The jaboticaba peel is an example of organic waste, widely used in industry due to its organoleptic characteristcs. In this study, residues collected during the extraction of bioactive compounds from jaboticaba bark (JB) were chemically activated with H3PO4 and NaOH and used to develop a low-cost adsorbent material for the removal of the cationic dye methylene blue (MB). For all adsorbents, the batch tests were carried out with the adsorbent dosage of 0.5 g L-1 and neutral pH, previously determined by 22 factorial design. In the kinetics tests, JB and JB-NaOH presented a fast adsorption rate, reaching equilibrium in 30 min. For JB-H3PO4, the equilibrium was reached in 60 min. JB equilibrium data were best represented by the Langmuir model and JB-NaOH and JB-H3PO4 data by the Freundlich model. The maximum adsorption capacities from JB, JB-NaOH, and JB-H3PO4 were 305.81 mg g-1, 241.10 mg g-1, and 122.72 mg g-1, respectively. The results indicate that chemical activations promoted an increase in the volume of large pores but interacted with functional groups responsible for MB adsorption. Therefore, JB has the highest adsorption capacity, thus presenting as a low-cost and sustainable alternative to add value to the product, and it also contributes to water decontamination studies, resulting in a zero-waste approach.

Sphagnum perichaetiale Hampe biomass as a novel, green, and low-cost biosorbent in the adsorption of toxic crystal violet dye.

In this study, the Sphagnum perichaetiale Hampe biomass was collected, characterized, and used as a biosorbent in the removal of crystal violet from water. The chemical and morphological results suggest that even after minimal experimental procedures, the biomass presented interesting properties regarding the adsorption of contaminants. Results of adsorption showed that the pH was not a relevant parameter and the best adsorbent dosage was 0.26 g L-1. The kinetic results presented an initial fast step and the equilibrium was reached after 180 min. For the equilibrium data, the best adjustment occurred for the Sips model, reaching a maximum adsorption capacity of 271.05 mg g-1 and the removal percentage obtained in the maximum adsorbent dosage was 97.11%. The thermodynamic studies indicated a reversible process and that the mass-transfer phenomena is governed by the physisorption mechanism. In addition to its great performance as a biosorbent, Sphagnum perichaetiale biomass also presents economic and sustainable benefits, as its production does not require costs with reagents or energy, usually used in chemical and physical activation. The reversible process indicated that the biosorbent could be reused, decreasing the costs related to the treatment of the effluents. Thus, Sphagnum perichaetiale biomass can be considered an efficient low-cost and eco-friendly biosorbent.