Biological, chemical and mathematical sciences

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Browsing Biological, chemical and mathematical sciences by Subject "Adsorption"

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    Amine-functionalized kenaf as carbon dioxide adsorbent in pressure swing adsorption system
    (Universiti Teknologi Malaysia, 2016) Zaini, Nabilah
    Kenaf (Hibiscus Cannabinus L.) that belongs to the family of Malvaceae is abundantly grown in Malaysia since 2006 to replace tobacco plantation as it is inexpensive, easy to grow, and biodegradable. The use of kenaf as adsorbent is seen as an attractive and innovative method, and it has been used for various adsorptions. Adsorption is a promising technology that has the ability to capture carbon dioxide (CO2), the predominant contributor of global climate change. Inspired by the established and well–known amine–based absorption process of carbon capture and storage technology, the development towards new adsorbent by introducing amine functional group has been studied. Therefore, this study explores the potential of modified kenaf as adsorbent by incorporating amine functional group on the surface and investigates the CO2 adsorptive characteristics of amine–modified kenaf adsorbent using pressure swing adsorption system (PSA). The preparation of amine–modified kenaf was conducted via the incipient wetness impregnation technique. The physical and structural characteristics of amine–modified kenaf were determined via micromeritics 3 flex, field emission scanning electrons microscopy, energy dispersive x–ray, Fourier transform infrared spectroscopy, and thermogravimetric analyzer. The results show that the types of amine, amine loading concentration, and impregnation time affect the physical and structural properties of kenaf and thus affecting the capability for capturing CO2. Screening of various types of amines via PSA revealed that tetraethylenepentamine (TEPA) has recorded the highest CO2 adsorption (0.914 mmol/g). Further examination on amine loading divulged that kenaf to TEPA ratio of 1:2 presents the highest CO2 adsorption (2.086 mmol/g) with 5 hour impregnation time. To examine the utilization of amine–modified kenaf adsorbent in PSA system, pressure bed, adsorption time, and feed flowing rate were evaluated. The result revealed that these parameters affect the gas adsorption of amine–modified kenaf adsorbent. The regeneration study had shown that kenaf adsorbent could sustain the repeated adsorption/desorption cyclic operations. This study also found that physical and chemical adsorption occurred during the adsorption of CO2 on raw kenaf and amine–modified kenaf. Thus, amine–modified kenaf adsorbent has high potential to be used as low–cost CO2 agro–based adsorbent hence inducing towards innovative material in the field of gas adsorption
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    Fabrication and characterization of nylon 6, 6, polysulfone and polystyrene electrospun fibre membranes for adsorption of bisphenol a in water
    (Universiti Teknologi Malaysia, 2022) Jasni, M. Jasmin Fathi
    The presence of new emerging pollutants (NEPs) residue in wastewater effluents, surface water and drinking water even after being subjected to the conventional treatment methods is an emerging concern. Hence, a few advanced technologies were introduced, such as pressure-driven membranes, for example, nanofiltration (NF) and reverse osmosis (RO). However, their performance has been limited due to high-pressure requirement and low permeate flux, leading to high operational costs. In this study, the utilization of the electrospun fibre membranes (EFMs) was explored as they possesses several advantages, such as the lower operating pressure requirement and ability to produce higher permeate flux that is favourable for adsorption technology. The nylon 6, 6 (Ny), polysulfone (PSf) and polystyrene (PSty) EFMs were fabricated by using the electrospinning technique and used for the adsorption of bisphenol A (BPA), acetaminophene (ACTP), sulfamethoxazole (SMX) and ibuprofen (IBP). The optimum conditions, such as applied voltage, flow rate and inner diameter of needle of the electrospinning process for: i) Ny (26 kV, 0.4 mL/h, 0.50 mm), ii) PSf (15 kV, 2.5 mL/h, 0.50 mm) and iii) PSty (16 kV, 1.6 mL/h, 0.60 mm) are considered achieved when continuous and stable streaming jet without any dripping and clogging with minimal beaded fibres is observed. The field emission scanning electron microscopy (FESEM) result showed that the average fibre diameter of Ny, PSf and PSty EFMs was measured at 98, 1291 and 1575 nm, respectively. The contact angle analysis of Ny EFM revealed a hydrophilic character, while PSf and PSty EFMs exhibited hydrophobic character. Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of hydroxyl groups in the BPA molecule, carbonyl and amine groups in Ny EFM and sulfonyl groups in PSf. These results demonstrated that the hydrogen bonding probably could be formed between Ny and PSf EFM with the BPA molecules, thus facilitating the BPA adsorption. When compared to ACTP, SMX, and IBP, the adsorption of BPA by Ny EFM was more effective. The adsorption of BPA in ultrapure water (UPW) by using five layers of Ny EFM was 96%, and the permeate volume of BPA solution was recorded at 193 mL after 30 mins of operation. The result also showed that both composites of Ny+PSf and Ny+PSty EFMs enhanced the permeate volume of BPA solution, which was recorded at 454 and 290 mL, respectively, after 30 mins of operation. The experiment for membrane regeneration and reusability for composites of Ny+PSf and Ny+PSty EFMs through three cycles of BPA adsorption in UPW was successful. This good performance was due to the BPA adsorption showing a consistent performance throughout the three cycles of operation. However, the volume of permeate BPA solution for both composites of Ny+PSf and Ny+PSty EFMs decreased from the first to the third operation cycle, from 454 to 150 mL and 290 to 119 mL, respectively. Additionally, the membrane regeneration and reusability for composite of Ny+PSf EFM through three cycles of BPA adsorption in tap water was also successful with the adsorption of 98 - 99% throughout the three cycles of operation. Meanwhile, the volume of permeate BPA solution was consistent, recorded at 348, 352 and 365 mL during the first, second and third cycles of operation, respectively. The successful BPA adsorption makes the Ny+PSf EFM composite a promising and suitable candidate for use in advanced water filtration systems.