Effect of particle size, shape, and weight percentage of hydroxyapatite (HA) on rheological behaviour of polycaprolactone/hydroxyapatite (PCL/HA) composites

The aim of this study is to investigate the influence of hydroxyapatite’s (HA) particle size, shape, and variation of HA weight percentage on the rheological behaviour of polycaprolactone/hydroxyapatite (PCL/HA) composite. The composite was produced by melt blending process using a single screw extruder assisted with an ultrasonic wave with varied HA weight content (0 wt.%, 10 wt.%, 20 wt.%, 30 wt.% and 40 wt.%). Two types of HA were used, which are needle shape (HAN) and irregular shape (HAS). The rheological behaviour of the PCL/HA composite was investigated through the melt flow index (MFI) test at a varied temperature of 100, 110, and 120 °C. The result indicated that an increase of HA content decreases the MFI values of the PCL/HA composite. At similar content of HA, PCL/HAN composite has higher activation energy with lower MFI values compared to PCL/HAS composite. In conclusion, this study concluded that the particle size, shape, and weight percentage of HA significantly affect the rheological behaviour of PCL/HA composites.

Characteristics and oil sorption effectiveness of areca nut husk

Oil spill accident occur due to human carelessness and error during oil transportation, storage, and production of the hydrocarbon. Effect of oil spill can be either short or long term. It is not only affecting the environment but also marine life, economy, and social. Thus, effective recovery and control method must be carefully implemented to minimise the effect. There are various studies and technologies to mitigate the oil spill incident but mostly the techniques are very expensive, difficult and use of non-environmental friendly material. Hence, this study is conducted to study areca nut husk as a potential oil adsorbent for oil spill recovery. The characteristics of areca nut husk include morphological structures and chemical composition. The areca nut husk oil sorption effectiveness and capacity also been investigated. Areca nut husk were tested for both heavy crude oil and diesel adsorption. The result shows that the efficiency of oil sorption of areca nut husk toward heavy crude oil is 14.8% and it can be an alternative sorbent material to the current modern material. Meanwhile, the areca nut husk is not recommended to be used for diesel absorption activity for its low effectiveness (i.e., 2.04%) showed in this study.

Physico-mechanical and water absorption properties of LDPE/cassava starch film

Plastic waste is a global crisis, and Malaysia is the 8th worst country worldwide for plastic waste. With this trend, growing market demands for green product have imposed pressure on industries to find an alternative to petroleum-based plastic. Degradable plastic is introduced to overcome this limitation. The present work investigates degradable plastic film of low-density polyethylene incorporated with cassava starch (LDPE-CS). The compounding of the LDPE-CS was prepared via pre-mixing, blending, resin crushing, and film hot pressing. Film thickness, tensile strength, elongation, water absorption, and field test were conducted on the LDPE-CS and commercial LDPE (control). Experimental data of LDPE-CS and commercial LDPE films were evaluated and compared. Thickness of LDPE-CS film was 0.18 mm which was 51% thicker than the control film. Tensile strength and elongation of the LDPE-CS were 7.04 MPa and 5.39%, while control film was 12.77 MPa and 921.5%, respectively. The tensile strength and elongation of the LDPE-SC were significantly lower than the control film, which may be due to the weak interface between LDPE and starch. The water absorption test revealed that the LDPE-CS film absorbed water by 4.8%, which indicates its degradability in the water. The field test shows that the LDPE-CS is biodegradable and comparable with the commercial plant polybag in terms of its capability in planting.

Real-time indoor air quality monitoring association with humidity, temperature, and carbon monoxide level in the residential environment

Indoor Air Quality (IAQ) is the air quality in or around a building that can affect the comfort and health of building occupants. Polluted air contains toxic gases emitted by industry, vehicle emissions, and increased concentrations of harmful gases and particles in the atmosphere. The use of IoT can monitor IAQ reading levels and update IAQ real-time information parameters at different locations in the residential environment for the comfort and health of the occupants. The focus of this work is to measure the level of carbon monoxide (CO) as well as other important parameters such as temperature and relative humidity (RH) as recommended by ASHRAE 55-1992 and MS:1525. The developed system was built using NodeMCU as a microcontroller, MQ-7 to measure CO levels, and DHT22 sensor to measure the humidity and temperature levels. The experiment was conducted in a residential building located in Paya Jaras Tengah, Sungai Buloh, Selangor. The developed system was measured in three different locations, namely the living room, kitchen, and bedroom. In the morning, as the RH increased, the temperature also increased. Since the living room is located nearby the main road, the CO reading was higher than the other two locations, in which the highest value of 12 ppm was recorded. The results obtained showed that the system works well and can record the readings of RH, temperature, and CO level in the residential environment. Therefore, a reliable system can be developed to help the residential occupants monitor the level of IAQ in the house.

Emission level of air pollutants during 2019 pre-haze, haze, and post-haze episodes in Kuala Lumpur and Putrajaya

Nowadays, due to population growth and industrialisation, air quality in Malaysia is becoming a critical threat. Air pollution has become a serious issue due to its impacts on humans, animals, and the environment. Malaysia experienced air quality deterioration in 2019 when the episodes of haze happened from July to September. It was due to the local and transboundary sources such as vehicles, factories, power plants, and biomass burning from Sumatra. This study aims to differentiate the level of the potential air pollutants, examine the influence of meteorological factors on the potential air pollutants and determine the local and transboundary impact on the potential air pollutants during episodes of pre-haze, haze, and post-haze in Kuala Lumpur and Putrajaya in 2019. Secondary physical and data on meteorology were obtained from the continuous ambient air quality monitoring (CAQM) stations by the Malaysian Department of Environment (DOE). The data obtained from CAQM were physical: particulate matters (PM2.5 & PM10), carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), and level ozone (O3); as well as meteorological: temperature (T), relative humidity (RH), wind speed (WS) and wind direction (WDir). Overall, the particulate matter (PM2.5, PM10) and carbon monoxide which are the pollutants that involve the formation of haze in Kuala Lumpur and Putrajaya are higher during haze episodes compared to pre-haze and post-haze episodes while the other pollutants (NO2, SO2, O3) are fluctuated throughout the entire episode due to its sources and the influence of meteorological factors. The backward trajectory indicated that the air pollutants are influenced by wind direction from South West Malaysia (SWM) and North East Malaysia (NEM) throughout the entire year.

A short review on synthesis and characterisation of nano SiO2/TiO2 composite for insulation application

Silica dioxide (SiO2) and titanium dioxide (TiO2) are nanoparticle fillers that are widely incorporated into polymer matrix for thermal insulation application. Combination of both fillers in producing polymer nanocomposite is interesting to review. This paper reviews on the current and recent research on the method to incorporate the SiO2/TiO2 nanoparticles as the fillers into various polymer matrix such as direct mixing, intercalation, sol-gel and in situ polymerisation as well as the effect of nanofillers on the thermal properties, morphology studies, rheology behaviour, mechanical property, and conductivity (thermal and electrical) of the SiO2/TiO2 polymer nanocomposites. This paper also reviews the effect of SiO2/TiO2 nanoparticles to the polymer nanocomposites in term of dielectric properties as a potential electrical insulation material. SiO2 nanoparticles presented to be the best filler to enhance the dielectric properties compared to the TiO2. When both of nanofillers are incorporated into the polymer matrix, a better result in term of mechanical, thermal, and electrical insulation properties are produced.

Hazardous area classification for wheat flour processing plant

Dust explosion possibly occurs in common unit operations such as mills, grinders, dryers, and other modes of transport. The basic element for the setting of hazardous zone types consist of identifies release sources, determination of classification region of hazardous area, overviewing the basic operation in wheat flour processing plant with their specification requirement and use of a suitable code or calculations to determine area scope. Therefore, this analysis can be more elaborate by classifying the hazardous area into several areas using the International Electro Technical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres standard. Thus, wheat flour processing plant area classification can be categorized according to three zones based on the quantity of an explosion into atmosphere and its release frequencies which are zones 20, zones 21, and zones 22. From the results, it can be summarized that zone 20 is almost inside or closer one with the main equipment located near the ignition source which could lead to dust explosion, whereas zone 21 and zone 22 comes after zone 20 which is a less hazardous area as compared to zone 20 areas.

An overview of the extraction methods of plant-based natural antioxidant compounds

Natural antioxidants are widely used in food additives, application in functional foods or also known as ingredients that offer health benefits that extend beyond their nutritional value, and pharmaceutical. These natural antioxidants such as carotenoids, vitamins, and polyphenol can be obtained from fruit, vegetables, and traditional herbal medicines. However, there have several issues regarding the conventional extraction method to extract natural antioxidants compounds from food and medicinal plants such as require a large volume of solvent and long extraction time. Therefore, new green extraction methods such as microwave-assisted, ultrasound-assisted, pulsed electric field, enzyme-assisted, supercritical fluid, and pressurised liquid, technologies were studied to overcome these constraints. Thus, different types of extraction and their mechanism in natural antioxidant compounds extraction was further discussed in this study. Besides, the main classes, source of natural antioxidants and their health benefits also were presented in this paper.

Adsorption of anionic surfactant on surface of reservoir minerals in alkaline-surfactant-polymer system

Alkaline-surfactant-polymer (ASP) flooding is significant to the oil and gas industry due to synergistic interaction between alkaline, surfactant and polymer. However, chemical losses due to adsorptions of surfactant and polymer on the rock surface could lead to inefficiency of the process. There are also significant uncertainties on adsorption mechanism when surfactant is flooded with presence of alkaline and polymer. This study highlights the static adsorption tests using anionic sodium dodecyl sulphate (SDS), hydrolysed polyacrylamide (HPAM) and sodium carbonate (Na2CO3) as the surfactant, polymer and alkaline, respectively. Sand particles and kaolinite clay were used as the reservoir minerals. The adsorption tests were conducted at various surfactant concentrations ranging from 50 to 2000 ppm. Sodium chloride (NaCl) concentration was investigated from 0 to 2 wt.%, while the local sand and kaolinite was mixed in surfactant solution at a fixed mass to volume ratio of 1:5. The static adsorption test was conducted by shaking the mixture samples and centrifugation before analysing the supernatant liquid using UV-Visible spectrophotometer. The results showed that the surfactant adsorption was higher on kaolinite compared to sand particle. The higher the salinity, the higher the adsorption of surfactant due to higher ionic strength. The adsorption of SDS surfactant on sand particles and kaolinite was lesser in ASP system compared to the presence of surfactant solution alone. Thus, it can be concluded that the presence of polymer and alkaline in ASP solution have great potential to reduce the surfactant adsorption on both sand particle and kaolinite.

Development and potential applications of gelatine, honey, and cellulose electrospun nanofibres as a green polymer

Nanofibres have emerged as a brilliant technology to be applied in various areas due to their excellent properties that include having a great flexibility, prominent specific surface area and structural strength. Electrospinning is one of the most effective and favourable methods to fabricate nanofibres mainly because electrospun nanofibres have been demonstrated to possess small pore sizes, large specific surface area, and can be produced with different functions to fill the need of various applications in industries. Due to their remarkable properties, electrospun nanofibres have been proven to be suitable for applications in food packaging, medical, pharmaceutical and even in tissue engineering. Currently, there have been numerous research utilising both electrospun synthetic and natural polymers. Natural or green polymers are considered more favourable due to their biodegradable properties and potential biocompatibility. Therefore, there has been a shift to include more research regarding these green polymers. Green polymers can source from both plant polysaccharides and animal protein. Considering the different characteristics of synthetic polymers, the processing and fabrication methods may differ and must be adjusted accordingly. To well summarise the development of these green polymer nanofibres, we review fabrication methods of gelatine, honey and cellulose-based nanofibre and their potential applications in industries. There are indeed numerous promising areas for the usage of these green polymers which are based on their splendid individual properties especially when combined to form nanofibres via electrospinning. We hope this will promote continuous research and development for the applications in various industries including but not limited to tissue engineering, biomedical, food and pharmaceutical industries.