The impact of the different types of acid solution on the extraction and adsorption performance of chitin from shrimp shell waste.

The properties of chitin-based adsorbents varied among studies since they are influenced by different factors, such as the types of base and acid used to extract the chitin. Therefore, this works aimed to investigate the impact of four different acid solutions on the extraction and properties of chitin from shrimp shell waste, and to evaluate the adsorption performance of the obtained chitin on removing dye from an aqueous solution. The result showed that H2SO4, HCl, and HNO3 could remove high minerals from the shrimp shell, while the effect of CH3COOH was inferior. The Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) indicated that the extracted chitin was α-amorphous structure, regardless of the type of acid solution. However, the type of acid solution influenced the crystallinity index of the extracted chitin. The Scanning Electron Microscope (SEM) showed both fibrillar material and porous structures. In addition, the chitin extracted through demineralization using H2SO4 was more effective in removing RBBR dye from aqueous solution, followed by HCl, HNO3, and the last, CH3COOH treatment. The performances of chitin-based adsorbent could be attributed to the strength of acid solution used to remove mineral during the extraction process and the obtained pore structures.

Cigarette Butt Waste as Material for Phase Inverted Membrane Fabrication Used for Oil/Water Emulsion Separation.

The increasing rate of oil and gas production has contributed to a release of oil/water emulsion or mixtures to the environment, becoming a pressing issue. At the same time, pollution of the toxic cigarette butt has also become a growing concern. This study explored utilization of cigarette butt waste as a source of cellulose acetate-based (CA) polymer to develop a phase inverted membrane for treatment of oil/water emulsion and compare it with commercial polyvinylidene difluoride (PVDF) and polysulfone (PSF). Results show that the CA-based membrane from waste cigarette butt offers an eco-friendly material without compromising the separation efficiency, with a pore size range suitable for oil/water emulsion filtration with the rejection of >94.0%. The CA membrane poses good structural property similar to the established PVDF and PSF membranes with equally asymmetric morphology. It also poses hydrophilicity properties with a contact angle of 74.5°, lower than both PVDF and PSF membranes. The pore size of CA demonstrates that the CA is within the microfiltration range with a mean flow pore size of 0.17 µm. The developed CA membrane shows a promising oil/water emulsion permeability of 180 L m-2 h-1 bar-1 after five filtration cycles. However, it still suffers a high degree of irreversible fouling (>90.0%), suggesting potential future improvements in terms of membrane fouling management. Overall, this study demonstrates a sustainable approach to addressing oil/water emulsion pollution treated CA membrane from cigarette butt waste.

Analytical Methods for Determination of Non-Nutritive Sweeteners in Foodstuffs.

Sweeteners have been used in food for centuries to increase both taste and appearance. However, the consumption of sweeteners, mainly sugars, has an adverse effect on human health when consumed in excessive doses for a certain period, including alteration in gut microbiota, obesity, and diabetes. Therefore, the application of non-nutritive sweeteners in foodstuffs has risen dramatically in the last decade to substitute sugars. These sweeteners are commonly recognized as high-intensity sweeteners because, in a lower amount, they could achieve the same sweetness of sugar. Regulatory authorities and supervisory agencies around the globe have established the maximum amount of these high-intensity sweeteners used in food products. While the regulation is getting tighter on the market to ensure food safety, reliable analytical methods are required to assist the surveillance in monitoring the use of high-intensity sweeteners. Hence, it is also necessary to comprehend the most appropriate method for rapid and effective analyses applied for quality control in food industries, surveillance and monitoring on the market, etc. Apart from various analytical methods discussed here, extraction techniques, as an essential step of sample preparation, are also highlighted. The proper procedure, efficiency, and the use of solvents are discussed in this review to assist in selecting a suitable extraction method for a food matrix. Single- and multianalyte analyses of sweeteners are also described, employing various regular techniques, such as HPLC, and advanced techniques. Furthermore, to support on-site surveillance of sweeteners' usage in food products on the market, non-destructive analytical methods that provide practical, fast, and relatively low-cost analysis are widely implemented.

Understanding the adsorption of ionic liquids onto zeolite ZSM-5 from aqueous solution: experimental and computational modelling.

Ionic liquids are considered as emergent pollutants as these compounds possess high persistence in aqueous solution and toxicity toward aquatic organisms. In this work, the adsorption equilibrium of 27 ionic liquids, with different cation head groups, alkyl chain lengths, and anions, onto ZSM-5 was measured experimentally at several compositions and at temperature 298.15 K and 0.1 MPa. The extensive number of ionic liquids studied allows a comprehensive study on the impact of adsorbate chemical structures toward their adsorption process. The gathered experimental results show that the anions have a dominant effect, when compared to the cation head group and the alkyl chain length, in ruling the adsorption of ionic liquids from aqueous solution onto ZSM-5. The adsorption isotherms reveal that the adsorption process is a combination between Langmuir and Freundlich behaviors, with the latter leading the general process. Moreover, computational modelling using COSMO-RS demonstrates the existence of several molecular forces that rule the adsorption process, reinforcing the idea that the ionic liquid anion rules the adsorption. The results collected in the present work provide new understanding on the molecular mechanism for the development of efficient adsorbents for removal and recovery of ionic liquids from aqueous solution.

Ion speciation: a key for the understanding of the solution properties of ionic liquid mixtures.

Recently, combinations of two (or more) ionic liquids, known as ionic liquid mixtures, have become popular and have a broad range of applications. However, the fundamental knowledge on the molecular interactions that exist in ionic liquid mixtures is far from being understood. In this work, the experimental measurement of the water activity coefficient and computational modelling using Conductor-like Screening Model for Real Solvent (COSMO-RS) were carried out to get an insight into the molecular interactions that are present in ionic liquid mixtures in aqueous solution. The results show that the combination of two ionic liquids of different basicity in aqueous solution allows fine tuning of the water activities, covering a wide range of values that could replace several pure fluids. This is an important feature resulting from the unexpected ion speciation of the ionic liquid mixtures in aqueous solution.

Systematic study of the thermophysical properties of imidazolium-based ionic liquids with cyano-functionalized anions.

In the past few years, ionic liquids (ILs) with cyano-functionalized anions have shown to be improved candidates for electrochemical and separation applications. Nevertheless, only scattered data exist hitherto and a broad analysis of their structure-property relationship has yet to be attempted. Therefore, in this work, a systematic study of the densities, viscosities and refractive indices of imidazolium-based ILs with cyano-functionalized anions was carried out at 0.1 MPa within a broad temperature range (from 278 to 363 K). The ILs under study are based on 1-alkyl-3-methylimidazolium cations (alkyl = ethyl, butyl and hexyl) combined with the [SCN](-), [N(CN)2](-), [C(CN)3](-) and [B(CN)4](-) anions. The selected matrix of cation/anion combinations allows us to provide a detailed and comprehensive investigation of the influence of the -CN group through an analysis of the thermophysical properties of the related ILs. The results show that, regardless of the cation, the densities decrease with an increase in the number of cyano groups or anion molecular weight. Moreover, for a fixed cation and temperature, the refractive index of the ILs decreases according to the rank: [SCN](-) > [N(CN)2](-) ≈ [C(CN)3](-) > [B(CN)4](-). On the other hand, no clear trend was observed for the viscosity of ILs and the respective number of -CN groups. The viscosity dependence on the cyano-functionalized anions decreases in the order: [SCN](-) > [B(CN)4](-) > [N(CN)2](-) > [C(CN)3](-). The isobaric thermal expansion coefficient, the derived molar refraction, the free volume, and the viscosity energy barrier of all compounds were estimated from the experimental data and are presented and discussed. Finally, group contribution models were applied, and new group contribution parameters are presented, extending these methods to the prediction of the ILs properties.