Olugbenga Oludayo Oluwasina

Performance of bonded boards using lignin-based resins

Abstract Lignin was extracted from some underutilized plant materials using soda–anthraquinone and soda–anthraquinone–ethanol pulping chemicals. Soda–anthraquinone–ethanol gave higher lignin yield, ranging from 44.47% to 50.41% versus 39.40% to 47.92% of soda-anthraquinone. The isolated lignin was used as a partial substitution for phenol in preparation of lignin-phenol-formaldehyde. The free formaldehyde of the resins ranges from 0.25% to 0.67% versus 1.23% of phenol-formaldehyde (PF) resin used as control. The bonding effectiveness of the resin was evaluated when used as glue for board preparation. The density of the board ranges from 333.54 Kg/m3 to 363.84 Kg/m3. The result revealed that Musa sapientum-, Musa parasidiaca- and Tithonia diversifolia- soda–anthraquinone-derived resins, and soda-anthraquinone–ethanol-derived resin of M. parasidiaca and T. diversifolia had boards with better modulus of rupture (MOR) and modulus of elasticity (MOE) than the board obtained using PF resin.

Carboxymethyl chitosan zinc supplement: Preparation, physicochemical, and preliminary antimicrobial analysis

Abstract Enrichment of carboxymethyl chitosan with zinc provides alternative means of producing aqueous soluble chitosan-based material with antimicrobial and essential trace element properties. The change in FTIR spectra of bands at 3,266 and 3,106 cm−1 of the carboxymethyl chitosan from a strong to a weak band confirmed the formation of carboxymethyl chitosan zinc supplement. From the EDX result, elemental composition of carboxymethyl chitosan is 52.89% carbon, 39.34% oxygen, 0.38% sodium, 0.54% aluminum, 2.61% calcium, and 4.19% aluminum, while carboxymethyl chitosan zinc supplement recorded 49.55% carbon, 40.40% oxygen, 1.28% sodium, 2.37% nitrogen, and 6.40% zinc. The XRD spectrum of carboxymethyl chitosan showed a lower peak intensity as compared with that of its zinc supplement. The antibacterial activities showed that carboxymethyl chitosan zinc supplement was active against all tested bacterial having recorded 6.00, 5.00, 3.00, 7.00, and 6.00 zone of inhibition (mm), respectively, against Staphylococcus aureus, Bacillus cereus, Pseudomonas syringae, Pseudomonas aeruginosa, and Escherichia coli, while carboxymetyhl chitosan was active only against S. aureus (6.00 mm). Antifungal activities revealed that carboxymethyl chitosan zinc supplement had higher zone of inhibition (mm) 42.22, 40.00, 37.78, and 48.88 mm against Collectotrichum falcritum, Rhzoctonia solani, Colletotrihum lindematianum, and Trichhoderum rubrum, while carboxymethyl chitosan recorded 26.66, 18.88, 15.88, and 22.22 respectively. The combination of aqueous solubility and antimicrobial activities of the zinc-supplemented carboxymethyl chitosan prepared should make it a good replacement for carboxymethyl chitosan in various industrial applications like food, cosmetics, biomedical, and pharmaceutical.

Synthesis and Application of Carboxymethyl Cellulose from Gliricidia sepium and Cola gigantea

Carboxymethyl cellulose (CMC) was prepared from Gliricidia sepium and Cola gigantea cellulose with yields of 1.59 g/g and 1.76 g/g, respectively. The pH of the products were weakly acidic (6.47 and 6.54, respectively). The sodium chloride content was 0.22 for C. gigantea CMC and 0.27 for G. sepium CMC, while the degree of substitution was 0.46 and 0.51, respectively. The swelling capacity of G. sepium CMC was 802%, which was higher than the 519% of C gigantea CMC. Fourier transform infrared (FTIR) spectroscopy confirmed that the products were CMC, and a thermogravimetric analysis (TGA) confirmed that C. gigantea CMC was more stable than G. sepium CMC. Detergent fortified with G. sepium CMC had better performance than C. gigantea CMC in terms of cleaning action and emulsion index, and it competed favorably with a detergent fortified with commercial grade CMC.

Performance of Carbon Nanotube/Polysulfone (CNT/Psf) Composite Membranes during Oil–Water Mixture Separation: Effect of CNT Dispersion Method

Effect of the dispersion method employed during the synthesis of carbon nanotube (CNT)/polysulfone-infused composite membranes on the quality and separation performance of the membranes during oil–water mixture separation is demonstrated. Carbon nanotube/polysulfone composite membranes containing 5% CNT and pure polysulfone membrane (with 0% CNT) were synthesized using phase inversion. Three CNT dispersion methods referred to as Method 1 (M1), Method 2 (M2), and Method 3 (M3) were used to disperse the CNTs. Morphology and surface property of the synthesized membranes were checked with scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, respectively. Separation performance of the membranes was evaluated by applying the membrane to the separation of oil–water emulsion using a cross-flow filtration setup. The functional groups obtained from the FTIR spectra for the membranes and the CNTs included carboxylic acid groups (O–H) and carbonyl group (C=O) which are responsible for the hydrophilic properties of the membranes. The contact angles for the membranes obtained from Method 1, Method 2, and Method 3 were 76.6° ± 5.0°, 77.9° ± 1.3°, and 77.3° ± 4.5°, respectively, and 88.1° ± 2.1° was obtained for the pure polysulfone membrane. The oil rejection (OR) for the synthesized composite membranes from Method 1, Method 2, and Method 3 were 48.71%, 65.86%, and 99.88%, respectively, indicating that Method 3 resulted in membrane of the best quality and separation performance.