Competitive adsorption of acetaminophen and caffeine onto activated Tingui biochar: characterization, modeling, and mechanisms.

Tingui biochar (TB) activated with potassium hydroxide (TB-KOH) was synthesized in the present study. The adsorption capacity of TB-KOH was evaluated for the removal of acetaminophen and caffeine in monocomponent and bicomponent solutions. As a result, the study of the TB-KOH characterization as well as the adsorption kinetics, isotherm, thermodynamics, and a suggestion of the global adsorption mechanism are presented. TB-KOH was characterized through physical-chemical analysis to understand its surface morphology and how it contributes to the adsorption of these drugs. Furthermore, modelling using advanced statistical physical models was performed to describe how acetaminophen and caffeine molecules are adsorbed in the active sites of TB-KOH. Through the characterizations, it was observed that the activation with KOH contributed to the development of porosity and functional groups (-OH, C-O, and C = O) on the surface of TB. The monocomponent adsorption equilibrium was reached in 90 min with a maximum adsorption capacity of 424.7 and 350.8 mg g-1 for acetaminophen and caffeine, respectively. For the bicomponent solution adsorption, the maximum adsorption capacity was 199.4 and 297.5 mg g-1 for acetaminophen and caffeine, respectively. The isotherm data was best fitted to the Sips model, and the thermodynamic study indicated that acetaminophen removal was endothermic, while caffeine removal was exothermic. The mechanism of adsorption of acetaminophen and caffeine by TB-KOH was described by the involvement of hydrogen bonds and π-π interactions between the surface of TB-KOH and the molecules of the contaminants.

Novel activated carbon from Magonia pubescens bark: characterization and evaluation of adsorption efficiency.

In this work, the synthesis of activated carbon from the bark of the Magonia pubescens (known as Tingui) and its efficiency in the removal of diclofenac sodium through batch adsorption tests and physical-chemical characterizations were investigated. The phytotoxicity of this material was also evaluated through germination and root growth of Lactuca sativa seeds. According to the experimental design performed for the synthesis of Tingui carbon, the optimized temperature and residence time for the production of this adsorbent were 550 °C and 120 min, respectively. The equilibrium time was reached in 600 min and the theoretical model that best fitted the kinetic data was the Elovich model. The BET was the best fit for the adsorption isotherm dataThis indicates that the adsorption process of sodium diclofenac by activated carbon can occur by two different mechanisms, monolayer and/or multilayer adsorption, depending on the conditions employed in the process, such as temperature and adsorbate concentration. The thermodynamic study showed that the process was favourable and spontaneous in the temperature range evaluated. Furthermore, the characterizations showed by TG/DTG and FTIR analyses that the temperature throughout the process had a marked impact on the degradation of the organic constituents of the biomass and the appearance of distinct functional groups that contributed to the adsorption process of diclofenac sodium. Finally, the toxicity tests recognized that this adsorbent does not affect the germination of L. sativa species. Thus, this adsorbent may become a novel and viable option to be used in the removal of sodium diclofenac.

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.

Acetaminophen removal by calcium alginate/activated hydrochar composite beads: Batch and fixed-bed studies.

The occurrence of acetaminophen in surface water has been reported worldwide, indicating the need of alternative wastewater treatments. Activated hydrochar (AHC) is efficient for pharmaceuticals removal. Powdered AHC presents challenges that hamper its expansion. However, these issues can be overcome by adding polymers, such as alginate, in composite beads. Therefore, the present study aimed to develop and characterize alginate/brewer's spent grain AHC beads, applying them to acetaminophen adsorption in batch and fixed-bed experiments. The adsorbent presented a high surface area (533.42 m2 g-1) and Fourier-transform infrared spectroscopy (FTIR) showed that alginate assigned new functional groups to the composite. Batch studies revealed an endothermic behavior and maximum adsorption capacity of 165.94 mg g-1, with an equilibrium time of 240 min. The fixed-bed maximum adsorption capacity was 127.01 mg g-1, with a mass transfer zone of 5.89 cm. The importance of alginate for the adsorbent development has been successfully proven.

Biosorption mechanisms of cationic and anionic dyes in a low-cost residue from brewer's spent grain.

The brewer's spent grain (BSG) is a byproduct of the brewing industry produced in large quantities and with few ecological disposal options. The use of this low-cost residue was investigated for the removal of methylene blue (MB) and tartrazine yellow (TY) dyes. The BSG has been extensively characterized to obtain its physicochemical characteristics. Batch experiments were conducted to investigate the effects of biosorption parameters: initial pH, kinetics, equilibrium isotherms and adsorption thermodynamics. The characterization showed high carbon content and heterogeneous morphology with the presence of meso and macropores. The best experimental conditions were obtained as pH 11 for MB and pH 2 for TY. Kinetics resulted in an equilibrium time of 240 min for MB and 300 min for TY and was best represented by the pseudo-second order model. Different interaction mechanisms were suggested, such as electrostatic interactions, electron donors and electron acceptors, hydrogen bonds, π-π dispersion interactions and the dye molecules aggregation. Equilibrium data were better represented by Langmuir isotherm. The maximum adsorbed amount of MB and TY was 284.75 and 26.18 mg/g, respectively, in each better experimental condition. Through the thermodynamic analysis, it was observed that the adsorption of the dyes was spontaneous and favourable. MB is preferentially retained through chemisorption, whereas TY followed a physical process. Considering the characteristics and results found compared to the recent literature, it was verified that BSG can be used as an effective and innovative biosorbent for removal purposes of dyeing effluent.

Chitosan, alginate and other macromolecules as activated carbon immobilizing agents: A review on composite adsorbents for the removal of water contaminants.

Activated carbon (AC) is widely used in water treatment, however, it has some technical disadvantages, such as its high cost and difficulty to recover. To overcome these drawbacks, AC particles have been encapsulated within a polymeric support, mainly chitosan and alginate-based. The use of these biological macromolecules results in composites with lower-cost, superior mechanical properties, and higher number of functional groups, advantages that have been attracted the attention of the scientific community. However, the number of publications is relatively low, demonstrating an important research gap yet to be investigated. Thus, this paper aims to review the recent studies concerning the use of chitosan, alginate and other macromolecules as AC immobilizing agents, describing the synthesis methods, characterization analyses and adsorption studies, focusing on the main advantages, disadvantages, gaps and future perspectives. Throughout the review it was verified that the composites were able to remove several water contaminants, mainly dyes and heavy metals, with high efficiency. Synergistic effects were detected, indicating the role of both polymers and AC, which increased the spectrum of contaminants capable of being adsorbed. Finally, it was observed a gap in column experiments, suggesting that future studies are essential to elucidate the applications in the industrial perspective.

Activated hydrochar produced from brewer's spent grain and its application in the removal of acetaminophen.

Acetaminophen has shown a gradual increase in detection in surface waters. Although present in low concentrations, it should be removed to prevent deleterious effects. Thus, adsorption onto activated carbon is emphasized. Adsorbents may be produced by hydrothermal carbonization (HTC), an environmental-friendly process. Therefore, this work aimed to investigate the use of HTC, verifying its application in acetaminophen removal. Brewer's spent grain (BSG), its hydrochar (HC-BSG) and its activated hydrochar (AHC-BSG) were characterized. HTC provided material with high carbon content. Lignocellulosic breakdown has been demonstrated in HC-BSG and AHC-BSG, but in the latter it was more intense as a result of activation with KOH. Also, a high surface area was found in AHC-BSG (1512.83 m2 g-1), resulting in an adsorption of 318.00 mg g-1. The pseudo-second-order and Langmuir models were fitted to the experimental data. Therefore, HTC was effective as a pretreatment for AHC-BSG, resulting in significant acetaminophen removals.