Pusat Pengajian Kejuruteraan Kimia - Monograf

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Zinc removal from the industrial wastewater using activated carbon synthesized from mangrove
(2021-06-01)
Samsudin, Nur Fitri Syafiqah
Most of wastewater effluent contains dangerous heavy metals that must be appropriately handled. Heavy metal pollution is a serious problem in developing countries, as most industrial operations have increased heavy metal contamination in lakes, rivers, and other water sources. Thus, a substantial amount of research has been performed on low-cost adsorbents to examine their potential in heavy metal removal. As a result, a summary and assessment of mangrove as a low-cost adsorbent have been completed in this report. This study assesses the potential of activated carbon derived from mangroves for the removal of a specific heavy metal, zinc. Aside from that, the examination of the key factors that impact heavy metal removal, which are the effect of temperature, initial concentration, and contact duration on heavy metal removal, is also being examined. The adsorption capacity increased with the increase of initial concentration of Zn2+ from 1 ppm to 7 ppm resulted in an increase in adsorption capacity from 0.1604 mg/g to 1.1627 mg/g. As the temperature raised from 30°C to 60°C, the adsorption capability of Zn2+ were decreased indicating the process was exothermic. The capacity for Zn2+ adsorption reduced from 1.241 mg/g to 1.1627 mg/g as the temperature increased. For adsorption isotherm model, Freundlich isotherm model at temperature of 60°C is more suitable to describe Zn2+ adsorption on mangrove activated carbon due to higher correlation coefficient, R2 value at 0.5984. The correlation coefficient, R2 from the pseudo second order model for Zn2+ adsorption was 0.9959 which is higher than pseudo-first order model, 0.9695. This indicate that pseudo-second order is more suitable more kinetic adsorption model for Zn2+ adsorption.
The effect of carbon dots on conductive ink as a vitamin c electrochemical sensor
(2021-06-01)
Lee, Mun Yi
The demand for portable and disposable electrochemical sensors using conductive ink is increasing due to its flexibility and conductivity. With the recent discovery of carbon dots and its conductivity improvement, it can be modified as an additives in the conductive ink to see its effect as an electrochemical sensor towards vitamin C. In this study, an easy and inexpensive fabrication of unsupported sensor strips using carbon black (CB) as filler and alternate different binder such as polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA) was fabricated. The conductive ink prepared was casted on non-woven cloth using membrane casting tool and allowed to cured. It was then cut into standard sizes for characterization as well for cyclic voltammetry (CV) for vitamin C detection. The optimum of the conductive ink was 6:4 (m:m) CB: PVA, with higher molecular weight (MW) and hydrolysis degree (DH) of PVA. Crosslinking of PVA was not needed as it will decrease the conductivity of the ink. The lowest resistivity obtained for CB/PVA and CB/PMMA sensor strips were 0.357 ± 0.03 Ω·cm and 2.735 ± 0.2 Ω·cm which show CB/PVA conductive ink has more potential than CB/PMMA conductive ink and even commercial ink. The blending of carbon dots (CDs) was able to decrease the resistivity at optimum amount. However, CB/PVA sensor strip was not able to produce any oxidation and reduction peak in CV showing its non-responsiveness towards detection of vitamin C while CB/PMMA sensor strip was able to measure the vitamin C presence with limit of detection (LOD) of 0.622 mM and linear range of 5 – 15 mM. CDs was coated on CB/PVA and CB/PMMA sensor strips surface but only adhere to CB/PMMA which may due to porous structure of CB/PMMA sensor strip while detaching of CDs observed for CB/PVA. The CDs coated on the surface was able to decrease the resistance up to 36% for both sensor strips and increase the background current of CB/PMMA CV response showing improved conductivity. However, the peak current response decreased due to repulsion reaction of same negative charge of vitamin C and the carboxyl groups on CDs surface. Therefore, the CDs modification was deduced only suitable for detecting positive charge analyte. The proposed sensor strips exhibited great stability with a 10-cycles CV run in neutral, acidic but decent performance in alkaline condition.
Synthesis, characterization and fouling evaluation on superhydrophobic coating modified using carbon soot
(2021-07-01)
Mohd Hanapi, Muhamad Syafik
Superhydrophobic coating is an idea that imitate the surrounding nature, whichn has the biggest advantage in corrosion prevention on metals. This is because the surface of contact and liquid can be minimized so it can offer great resistance to humid surrounding. This thesis are to know the superhydrophobic can be achieve surface on the carbon soot from candle flames. The samples later are being dipped into PVDF/Acetone mixture to improve superhydrophobic contact. Carbon Soot(CS) that coating the glass slides which are obtained as hydrophobic state. It is collected from general uses candles to prove the hydrophobic behaviour from the carbon soot collected. Micropipette are being used to drop a few of droplets on the surface to check the contact angle occurred on the surface of carbon soot. The polymer used are 0.8g of Polyvinylidene Fluoride (PVDF) are mixture properly and continuously until it achieved perfect dilute in 80ml of Acetone based. The dip-coating process are in the constant Withdrawal/Drawing (W/D) at 40 mm/s and taking at 4 mins. The drying process are done in whole day time at room temperature. The contact angle on the both surfaces of samples can be obtained through Microscopic lens. As conclusion, carbon soot from candles can achieve hydrophobic and can achieve superhydrophobic with mixture of PVDF/Acetone in certain conditions.
Synthesis of porous cellulose beads intercalated with calcium carbonate nanoparticles from sodium hydroxideurea solution for dye adsorption
(2021-07-01)
Gan, Wei Chee
Dyes have become widely used in the textile industry over the last few decades and generates 200,000 tonnes of dye waste annually. Considering the situation, the adsorption process by using biodegradable alpha-cellulose (α-cellulose) is chosen for removing dye from wastewater due to its economic feasibility and absence of secondary pollution. However, a low degree of substitution occurs since this effect of α-cellulose's supramolecular structure is less reachable to reagents. Thus, the goals of this study are to synthesise and characterise porous cellulose beads (PCBs) for methylene blue (MB) dye removal, and to study the effects of calcium carbonates (CaCO3) nanoparticles incorporated on PCBs properties and MB dye removal. In this study, PCBs with various amounts of CaCO3 nanoparticles (0.01 wt%, 0.03 wt% and 0.05wt%) as green-based adsorbents were successfully fabricated. When the incorporation of 0.05 wt% of CaCO3 nanoparticles on PCBs, the increment of maximum removal efficiency (R) of MB from 88.12% to 97.04% at the adsorbent dosage of 0.06 g and equilibrium time of 3 hr. The experimental data of adsorption kinetic studies on MB using PCBs samples were imitated by pseudo-second-order, with R2 values of higher than 0.99, demonstrating that the adsorption process is governed by chemisorption. The maximum adsorption capacity of PCBs with 0.05 wt% of CaCO3 nanoparticles loading determined by pseudo-second-order was 4.91 mg/g. As a result, the findings of this study resulted in a simple and effective method for producing PCBs with CaCO3 nanoparticles loading.
Synthesis of pet mwcnts electrospun nanofiber with polyester fiber support for methylene blue removal
(2021-06-01)
Steven Ling, Guang Hu
Occurrence of water pollution including contamination of dyes and heavy metals causes the quality of water to decrease significantly. One of the major dyes found in the wastewater is methylene blue (MB). The purposes of this study were to synthesis polyethylene terephthalate/multi-walled carbon nanotubes (PET/MWCNTs) electrospun nanofiber with polyester fibers(PES) as support and to investigate its adsorption performance on MB. The method to synthesis PET/MWCNTs electrospun nanofiber was using electrospinning process method. There are three major parameters such as contact time, adsorbent dosage and initial dye concentration were to be evaluated through batch mode experiment. The optimum contact time obtained for adsorption was 1440 minutes. PES+PET/MWCNTs had adsorption capacity of 0.3398 mg/g and removal efficiency of 13.63% which had better performance as compared to PES having adsorption capacity of 0.2529 mg/g and removal efficiency of 11.62%. The adsorption capacity showed a decreasing trend and the MB removal percentage showed an increasing trend when the adsorbent dosage increased. However, there was an increment in adsorption capacity and a reducing trend in MB removal percentage when the initial dye concentration increased. For adsorption isotherm, it was found that Langmuir isotherm model is relevant with the experimental data as compared to Freundlich and Temkin isotherm model. Pseudo-second-order kinetic model was more favourable in providing the details of the kinetic studies in MB adsorption. Thus, PET/MWCNTs electrospun nanofiber can be a potential adsorbent in removing MB dye from wastewater.

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