Eco-friendly synthesis of a novel adsorbent from sugarcane and high-pressure boiler water.

The development of industrial process in line with the circular economy and the environmental, social and corporate governance (ESG) is the foundation for sustainable economic development. Alternatives that make feasible the transformation of residues in added value products are promising and contribute to the repositioning of the industry towards sustainability, due to financial leverage obtained from lesser operational costs when compared with conventional processes, therefore increasing the company competitivity. In this study, it is presented a promising and innovative technology for the recycling of agro-industrial residues, the sugarcane bagasse and the high-pressure water boiler effluent, in the development of a low-cost adsorbent (HC-T) using the hydrothermal carbonization processes and its application in the adsorption of herbicide Diuron and Methylene Blue dye from synthetic contaminated water. The hydrothermal carbonization was performed in a Teflon contained inside a sealed stainless-steel reactor self-pressurized at 200°C, biomass-to-effluent (m/v) ratio of 1:3 and 24 h. The synthesized material (HC) was activated in an oven at 450°C for 10 min, thus being named adsorbent (HC-T) and characterized by textural, structural and spectroscopic analyses. The low-cost adsorbent HC-T presented an 11-time-fold increase in surface area and ∼40% increase in total pore volume in comparison with the HC material. The kinetic and isotherm adsorption experiment results highlighted that the HC-T was effective as a low-cost adsorbent for the removal of herbicide Diuron and Methylene Blue dye from synthetic contaminated waters, with an adsorption capacity of 35.07 (63.25% removal) and 307.09 mg g-1 (36,47% removal), respectively.

Direct Synthesis of HKUST-1 onto Cotton Fabrics and Properties.

Metal-organic frameworks are crystalline nanostructures formed by a metal interspersed by an organic binder. These metal-organic materials are examples of nanomaterials applied to textile material in search of new functionalized textiles. Cotton is a cellulosic fiber of great commercial importance, and has good absorption capacity and breathability; however, due to these characteristics, it is susceptible to the development of microorganisms on its surface. This work aims to analyze how the direct synthesis of HKUST-1 in cotton fabric modifies the chemical and physical properties. The material obtained was characterized by scanning electron microscopy to obtain its morphology, by spectrophotometry CIE L*a*b* to verify the color change, by a biological test to verify its resistance to microorganisms and, finally, by a unidirectional traction test to verify the change in its mechanical resistance. Thereby, it was possible to observe the formation of MOFs with the morphology of nanorods, and also, with regard to HKUST-1 in the cotton fabric, when applied, an elimination percentage higher than 99% was observed for both bacteria, E. coli and S. aureus. The presence of MOF was detected even after washing, however, the loss of 75% in the mechanical resistance of the material makes its potential for textile finishing unworkable.

Enhanced removal of bisphenol A using pine-fruit shell-derived hydrochars: Adsorption mechanisms and reusability.

We synthesized NaOH-activated hydrochars via hydrothermal carbonization (HTC) of Brazilian pine fruit shells at HTC residence times of 24, 48, and 72 h. The hydrochars were used as adsorbents to remove bisphenol A (BPA) from aqueous solutions. The surface area of the samples can reach up to 2220 m2 g-1, and the maximum adsorption of BPA onto the surfaces was achieved at a pH of 7.0 (708 mg g-1). Adsorption occurred mainly via monolayer formation with a low retention time of the adsorbate (τ) on the surfaces, indicating that the BPA molecules reached the already occupied active sites and returned after undergoing heat exchange (τ > 0). Adsorption is an endothermic spontaneous process that results in a balance between entropic and enthalpic contributions. In such a reaction, ΔG°< 0, even with ΔH°> 0, the process occurs with an important increase in the entropy. The desorption was more efficient with ethanol and methanol than with HCl, NaOH, and NaCl owing to the dipole-dipole forces between the adsorbate and the alcohols. Additionally, the low desorption efficiency using acid, base, and salts can be attributed to competitive effects between the desorption agents and the active sites of the adsorbents.

Surface Modification of Polyester Fabrics by Ozone and Its Effect on Coloration Using Disperse Dyes.

Polyester fibers (PES) are the most consumed textile fibers due to their low water absorption; non-ionic character and high crystallinity. However, due to their chemical structure, the chemical interactions between polyester, finishing products, and dyes are quite challenging. We report on the use of ozone to modify the surface of polyester fibers with the goal of improving the interaction of the modified surface with finishing compounds and dyes. We used C.I. Disperse Yellow 211 to dye ozone-treated polyester fabrics and evaluated the effects of ozone treatment using FTIR-ATR, Raman spectroscopy, SEM imaging, rubbing tests, and capillarity measurements. We evaluated the dyeing performance via color analysis, and determined the dyeing kinetics. Experimental results indicate that the modification of polyester fabrics with ozone is a feasible pre-treatment that improves dyeing efficiency allowing better solidity of color and a decrease in the amount of dye required.