Synthesis and characterization of copper nanoparticles using different concentration of rice straw

New copper nanoparticles (CuNPs) have been synthesized via chemical reduction method in the presence of rice straw as supports and seaweed as a stabilizer. Characterizations of the CuNPs were carried out using UV-visible spectroscopy (UV-vis), Fourier Transform Infrared (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray (EDX). The UV-vis adsorption spectra confirm the formation of CuNPs through the peaks of the surface plasmon resonance (SPR) bands around 500 to 600 nm. Morphological characterization showed the formation of a spherical structure of the CuNPs. Similarly, EDX spectra showed that the nanoparticles produced are copper based. The size of nanoparticles formed by this method was controlled easily by using different concentration of rice straw.Keywords: Chemical Reduction, Copper Nanoparticle, Rice Straw; Seawee

Thermal and mechanical responsiveness of some 4-substituted benzonitriles

Thesis (PhD)--Stellenbosch University, 2018.ENGLISH ABSTRACT: This work is based on three publications. The first manuscript describes the large volumetric thermal expansion of an organic cocrystal over a wide range of temperature (100–300 K). The novel organic multicomponent crystal (cocrystal) (ABN·2DMABN) consisting of 1:2 molar ratio of 4-aminobenzonitrile (ABN) and 4-(dimethylamino)benzonitrile (DMABN) was prepared. It shows linear positive thermal expansion (PTE) along all its three principal axes over the temperature range 100–300 K, which is exclusively dependent on the intermolecular interactions that govern the crystal packing. The associated volumetric thermal expansion coefficient (αv) of 222 MK-1 is the largest reported to date for a cocrystal over such a wide temperature range. The second manuscript explains the mechanical response/behaviour of a rigid small organic molecule, 4-bromobenzonitrile (4-BBN) that has been crystallised using sublimation under dynamic vacuum (0.02 mbar). Interestingly, the crystals show highly flexible plastic behaviour and bends along two orthogonal faces under mechanical stress− a rare phenomenon, resulting in helical twisting, or coiling, which is also rare for crystals of such rigid small organic molecules. The third manuscript discusses the thermal behaviour of the purely organic material 4-aminobenzonitrile (ABN). The single crystals of ABN undergo reversible thermosalience upon cooling from 300 to 100 K and subsequent heating to 300 K. In this study we have demonstrated that the release of accumulated strain in these crystals upon cooling, which results in rapid structural rearrangement, is due to the interplay between the directional and non-directional intermolecular interactions in the system.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaa

Removal of organic pollutant (pyrene) from aqueous solution using coordination polymer of [Cu(Pic)2(H2O)2]·H2O (CP-1) as adsorbent

CITATION: Tella, A. C., et al. 2019. Removal of organic pollutant (pyrene) from aqueous solution using coordination polymer of [Cu(Pic)2(H2O)2]·H2O (CP-1) as adsorbent. Applied Water Science, 9:159, doi:10.1007/s13201-019-1039-0.The original publication is available at https://link.springer.comENGLISH ABSTRACT: Adsorptive removal of organic pollutant (pyrene) was carried out using coordination polymer [Cu(Pic)2(H2O)2]·H2O (CP-1) (where “Pic” represents picolinic acid), which was prepared from copper acetate monohydrate and picolinic acid. The compound was characterized by spectroscopic techniques, SEM, elemental and thermal analyses and X-ray crystallographic analysis. The crystal structure of CP-1 shows a centrosymmetric triclinic space group P-1 in which a = 5.0924 (4) Å, b = 7.5172 (6) Å, c = 9.0965 (8) Å. The Cu²͘⁺ ion is seen to have an octahedral geometry, which is bonded to oxygen atoms from the picolinic acid and nitrogen atoms from the pyridine rings. Pyrene adsorption from aqueous media was studied with the prepared adsorbent (CP-1). The kinetic model was observed to be second order, and the sorption data fitted best into the Langmuir model. The absorbent, CP-1, was shown to have a 90.91 mg/g adsorption capacity (maximum) for pyrene in this study at 25 °C. Compound CP-1 can thus be presented as a potential adsorbent in the treatment of pyrene-polluted water.https://link.springer.com/article/10.1007/s13201-019-1039-0Publisher's versio