This research investigates commercial activated carbon (AC) potential to remove methyl orange (MO) dye removal from aqueous solution using a batch process. The AC material was characterized using FTIR spectroscopy and SEM analysis. The effect of the main operating parameters, such as the pH, adsorbent dosage, contact time, and initial dye concentration, was studied. MO removal could be accomplished within 30 min at a pH value of 3. The calculated maximum MO adsorption capacity onto activated carbon was 129.3 mg/g, while the removal efficiency was 97.8%. Adsorption results were analyzed by studying the Langmuir and Freundlich isotherm models. The MO adsorption data on activated carbon were better explained by the Langmuir isotherm than by the Freundlich isotherm. The pseudo-second-order kinetic model may have had an effect on the MO dye adsorption on AC material. This research showed that the commercial activated carbon can be used as an effective sorbent for MO removal from wastewater sample. Moreover, the AC material has good reusability and practical utilization capacities.

As the world transitions towards a more sustainable future, it is imperative to develop innovative solutions that address the pressing issue of plastic pollution. Microplastics, in particular, have become a significant concern due to their widespread presence in the environment and potential to interact with toxic pollutants. Organic compounds, which include a variety of harmful chemicals, such as pesticides and other industrial chemicals, are often released into the environment and can readily bind to microplastics. In this context, understanding the adsorption of organic compounds on microplastics is crucial for designing effective strategies to mitigate their environmental impacts. This study investigates the adsorption dynamics of organochlorine pesticides (OCPs) on polystyrene microplastics, exploring the influence of pH and contact time, as well as utilizing kinetic models and isothermal equations to elucidate the adsorption mechanism. The results suggest that the pH level has a negligible impact on the adsorption capacity of PS for OCPs. In contrast, the contact time plays a significant role in the amount of OCPs adsorbed onto the PS surface. Interestingly, a relatively short time of up to 6 h was sufficient to reach equilibrium. The adsorption of OCPs on PS follows a uniform pattern consistent with the Freundlich isotherm model, indicating a multilayer adsorption process. The use of kinetic models to describe the adsorption process was also found to be useful in understanding its mechanism. Specifically, the pseudo-second-order kinetic model proved to be a suitable descriptor for the adsorption process of organochlorine pesticides on PS. This study highlights the importance of understanding the interactions between microplastics and organic pollutants, which is crucial for developing sustainable solutions to mitigate the environmental impacts of plastic pollution, ultimately contributing to a more environmentally conscious future.

New research applications involving the use of cellulosic material derived from maize stalk for on-site treatment of leachate were evaluated for specific removal of Cu(II) and Fe(III) from real, highly polluted tailing pond and mine wastewater samples. Two major issues generated by anthropic mining activities were also tackled: wastewater metal content decrease to improve water quality and subsequently metal specific recovery, increasing the economic efficiency of metal production by using a green technology for residual management. Rapid saturation of the maize stalk mass determined in batch studies and the mine pilot experiment led to diminished metal concentrations in the second pilot experiment, where Cu(II) and Pb(II) from synthetic solutions were monitored in order to test biomaterial performances. In addition, in the second pilot experiment, maize stalk removed Pb(II) in the first 36 h, below the determination limit of the analytical method. The biomaterial bed in the column was saturated after 252 h of inflow solution. FTIR-ATR, TG and SEM techniques probed the interaction between maize stalk polar groups C=O, –OH, C–O and tailing water metallic ions by large FTIR band displacements, intensity decrease and shape changes, modification of thermal stability and by changes in the appearance of adsorbent microstructure images owing mainly to ion exchange mechanism.

Understanding the volatile flavor compounds present in commercial beverages is crucial for the food and beverage industries as these compounds significantly influence product perception and consumer acceptability. This paper aims to comprehensively analyze the composition of volatile organic compounds in various commercial beverages using targeted gas chromatographic–mass spectrometry (GC/MS) approaches. The study employs a screening method based on the Headspace-GC/MS technique to efficiently extract and identify volatile organic compounds found in commercial beverages. This methodology provides a rapid and reliable system for assessing the volatile profile of these beverages. The analysis reveals the presence of a total of 40 volatile organic compounds, including esters, terpenes/terpenoids, alkenes, aldehydes, aromatic hydrocarbons, and alcohols. Medium-chain esters were found to dominate the volatile profile of the beverages, suggesting a significant contribution to their fragrance and taste. This study offers valuable insights into the volatile profile of commercial beverages, creating awareness among consumers about the flavor components present in these products. By understanding the volatile composition, consumers can make informed choices regarding their beverage consumption. The comprehensive analysis provided by this research serves as a foundation for further studies related to flavor characterization and optimization in commercial beverages.

The large amounts of chrome-tanned leather waste (CLTW) produced annually can be valorized by applying circular economy principles in various fields due to the valuable substances contained (mainly collagen). The main problem for the direct valorization of these wastes is the presence in their composition of dangerous substances, such as chromium. Thus, before being used as raw material in new processes, chrome-tanned leather waste must be subjected to a preliminary stage of chromium removal. In this article, we propose to identify the optimal working conditions for the extraction of chromium ions from chrome-tanned hides in the presence of oxalic acid with various concentrations, at various temperatures and contact times, so that the degree of collagen hydrolysis is minimal. In this sense, the response surface methodology (RSM) method was used to optimize the working conditions, to maximize the efficiency of chrome extraction from the leather, and to minimize the efficiency of collagen hydrolysis: An undesirable process. To optimize both the extraction yield (%) and the degree of hydrolysis (%), the key operational variables, namely oxalic acid concentration (%), contact time (%), and temperature (°C), were systematically adjusted using the Box–Behnken design within the response surface methodology (RSM). The most favorable extraction conditions were identified at an oxalic acid concentration of approximately 7%, a contact time close to 120 min, and a temperature near 49 °C. Under these optimized parameters, the hydrolysis degree remained very low, around 0.38%, indicating minimal degradation during the process.

PH influences the reactivity of iron (II) minerals towards halogenated pollutants like hexachlorocyclohexanes (HCHs). To explore these incompletely understood interactions, we investigated the carbon isotope fractionation of the δ-HCH isomer during dehalogenation by iron sulfide at pHs spanning a pH range across slightly acidic to alkaline domains (5.8-9.6). The δ-1,3,4,5,6-pentachlorocyclohex-1-ene (δ-PCCH) was the intermediate degradation product, while benzene, monochlorobenzene (MCB), but especially 1,2-dichlorobenzene (1,2-DCB), and 1,2,4-trichlorobenzene (1,2,4-TCB), were the main degradation products of δ-HCH. These degradation products suggested dehydrochlorination as the main degradation pathway of δ-HCH by iron sulfide. Different kinetic experiments indicate that the rate constants (k_a) during dechlorination of δ-HCH by iron sulfide rose with pH: 0.003 d^-1 (pH 5.8) < 0.034 d^-1 (pH 8) < 0.085 (pH 9.3) < 0.286 d^-1 (pH 9.6). Upon Rayleigh model calculations, an enrichment factor (εC) of -7.8 ± 1.0 ‰ was calculated for δ-HCH dehalogenation by FeS at pH 8.0. This suggests an apparent kinetic isotope effect (AKIE_C) value of 1.049 ± 0.006 for dehydrohalogenation. The magnitude of the isotope effect from this paper furthermore supports dehydrohalogenation and opens the possibility to study the degradation of HCHs by iron (II) minerals containing FeS as mackinawite in oxygen-deprived environments.