Direct extraction of chitosan from snail shells by natural deep eutectic solvent

The processes involved to extract chitosan biopolymers from natural resources often employ hazardous chemicals and long processing time. This work provides a sustainable direct extraction method of chitosan from snail shells. Previous attempts using acetogenin in graviola extracts succeeded in the extraction of chitosan from marine shells. However, the slow reaction has prompted the addition of hydrogen bond acceptor solution into the graviola extract. Choline chloride is an excellent hydrogen bond acceptor mixed with acetogenin as hydrogen bond donor to form natural deep eutectic solvent (NADES) for the direct extraction of chitosan. Chitosan obtained from this method has a degree of deacetylation of 91% and a molecular weight of 481 kDa with fiber-like morphology. The direct extraction of chitosan from NADES consisting of choline chloride and acetogenin has proven to extract chitosan with comparable properties to commercial chitosan

Photocatalytic Hydrogen Production from Water on Ga, Sn-doped ZnS under Visible Light Irradiation

Zinc sulfide (ZnS) has been reported to act as a photocatalyts to reduce water to hydrogen. However, ZnS could not work under visible light irradiation due to its large band gap energy. In order to improve the performance of ZnS, Ga and Sn were doped to ZnS. The series of Ga(0.1),Sn(x)-ZnS with various amounts of Sn (x) was prepared by hydrothermal method. XRD patterns suggested that the addition of Ga might reduce the crystallinity of ZnS, suggesting that Ga might inhibit the crystal growth or agglomeration of ZnS. On the other hand addition of Sn did not much affect the structure of the Ga(0.1)-ZnS. The DR UU-visible spectra confirmed the red shift of the absorption edge with the addition of Ga due to the reduced band gap energy, while the addition of Sn did not much shift the absorption edge of the Ga(0.1)-ZnS to longer wavelength. FESEM images showed that all the prepared samples have sphere-shaped particles and no remarkable change was observed with the addition of Ga or Sn. The photocatalytic hydrogen production from water was carried out at room temperature in the presence of sacrificial agent under visible light irradiation. While ZnS did not show activity under visible light, all the prepared Ga(0.1)-ZnS and Ga(0.1),Sn(x)-ZnS samples exhibited photocatalytic activity for hydrogen production. The highest hydrogen production was achieved on Ga(0.1),Sn(0.01)-ZnS, which activity was ca. three times higher than that of the single doped Ga(0.1)-ZnS. This study clearly showed that Sn acted as a good co-dopant to increase the photocatalytic activity of Ga(0.1)-ZnS for hydrogen production from water under visible light irradiation

Catalytic Performance of Copper-Manganese Supported on Activated Carbon Synthesized by Deposition-Precipitation Method

CuMnx/activated carbon (AC, x = 0.1, 0.2, 0.5 and 1) nanoparticles were prepared by deposition-precipitation method. The catalytic performance of CuMnx/AC catalysts were studied for the oxidation of benzyl alcohol to benzaldehyde. The molar ratio of Mn plays an important role in the catalytic performances. The optimum amount of Mn is 0.1 with the highest benzyl alcohol conversion of 63 %

Bimetallic Cu-Ni nanoparticles supported on activated carbon for catalytic oxidation of benzyl alcohol

A series of bimetallic copper-nickel (CuNix, x = 0.1, 0.2, 0.5 and 1) nanoparticles supported on activated carbon (AC) were prepared by deposition-precipitation method for the oxidation of benzyl alcohol to benzaldehyde using hydrogen peroxide as oxidising agent. Analyses by means of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) confirmed that Cu and Ni was successfully added on the surface of activated carbon. CuNi1/AC showed the best catalytic activity for the oxidation of benzyl alcohols to the corresponding aldehyde within a short reaction period at 80 °C. The catalytic performance is significantly enhanced by the addition of equal amount of Ni as compared to the monometallic counterpart. This result indicates the synergistic effect between Ni and Cu particles in the catalytic oxidation reaction. © 2017 Elsevier Lt

Research based Learning through Immersive Face to Face Interaction

Group project for PRK1026 Chemistry II was implemented as researchbased learning through immersive face to face interaction among students and facilitator. The main activities include planning by writing proposal, conducting laboratory activities, interpretation of scientific data, followed by producing a scientific article. All pre-university students are required to complete this project as a team which cover topics related to Chemistry Learning Units in Semester Two

Assessment of Practical and Scientific Writing Skills for Pre-University Students through Project-Based Learning

Chemistry is one of the STEM (science, technology, engineering, and mathematics) subjects that has been perceived as an unattractive subject among students due to its scientific theories and practices in a laboratory. Practical and scientific writing skills are two crucial components in chemistry courses, including at the Pre-University level, thus requiring educators to design activities that integrate both skills in chemistry learning. This article describes the assessment using a projectbased learning approach to assess students’ practical and scientific writing skills for the Organic Chemistry course at the Universiti Malaysia Sarawak Foundation in Science program. A total of 72 PreUniversity science students participated in a Chemistry Group Project assessment. The students were divided into 6 groups and asked to write a proposal on the basis of a chosen title, conduct laboratory work, collect data, and prepare a final report. The assessment was conducted in a single semester from learning week 1 to learning week 17. Results of this study were collected through the submitted proposal, final reports, practical sessions, and students’ feedback. Students obtained good marks for practical and scientific writing with average marks of 84.9% and 84.4%, respectively. The results revealed that implementing the Chemistry Group Project as project-based learning leads to increased performance in practical and scientific writing skills and social skills among Pre-University students. Therefore, the Chemistry Group Project should be conducted as one of the learning activities and practical approaches at the Pre-University level