As a fast-developing country, the population, urbanization and industrialization have developed rapidly in Malaysia. The growth in population increases human activities, leading to a rise in the generation of waste. Municipal solid waste in Malaysia is currently estimated to rise from 23,000 tons/day in 2010 to 30,000 tons/day in 2020. Due to its simplicity and low costs, landfilling is the most common method in the country. However, there are various environmental drawbacks associated with landfills that have attracted social and environmental attention in recent decades. One of the key issues is the generation of leachate from the percolation of rainwater by waste disposal in a landfill. Landfill leachate contains many pollutants including ammonia-nitrogen (NH3-N) which is a particular concern due to its high concentration in leachate. High concentration of ammonia not only causes health and environmental problems but also affects the efficiency of leachate treatment. Therefore, a pre-treatment to remove ammonia is required before downstream treatment to prevent contamination to the surrounding ground and surface water. In general, leachate can be characterized by physico-chemical and biological parameters. Leachate characterization is essential to evaluate the leachate pollution potentials in the landfill site and to determine the treatment methods. Hence, the present review highlights the recent development of landfill leachate treatment methods and its potential for ammonia removal and recovery. Rather than releasing the extracted ammonia directly into the environment that causes air pollution, ammonia from the stripping process can be recovered and used to produce fertilizers. This review also contributes to the body of knowledge of the ammonia stripping treatment in terms of its efficiency and its application for leachate treatment.

To investigate the properties and structures of soot particles derived from candle combustion, two deposition routes were performed. In "Route-1," the aerosol (soot) particles were collected by direct exposure of a substrate in a chamber with controlled airflows. In "Route-2," deposited soot nanoparticles was transferred into suspension and subsequently, the deposition of particles on to the substrate was achieved by an electrospray. Raman spectral analysis has shown the difference of G-band intensity relative to D-band between hydrophobic and hydrophilic particle layers obtained from different collection regions of the candle flame. It also reveals the effect of airflows during the collection to the ratio of the D to G peak. Meanwhile, the Raman spectra of the particles seem invariant to the preparation methods of suspension and electrospray deposition process. From the curve gradient of spectroscopy (190-2500 nm) results, the electrospraydeposited particle layers (Route-2) show higher absorbance in the near-infrared region compared to direct-deposited particle layers (Route-1). This change in the spectrum may due to the change in morphology of nanoparticle layers formed by each route.

Electrospinning has been known for its’ ability in producing nanoporous fibres which uses electrical force to form a spinning jet out of a polymer solution. The electrospinning condition and polymer solution properties can influence the electrospinning jet formation as well as jet path. Polylactic acid (PLA) was dissolved in dimethylformamide (DMF) to produce a polymer solution. Bead is considered as a defect towards an electrospun fibres, yet previous study found that PLA/DMF produced beaded fibres for all concentrations. However, there is a limited study that explain the effect of concentration on the diameter of beads. Therefore, in this study we investigated the formation of electrospinning jet as well as the effect of PLA concentration of formation of beads, particularly the diameter of the beads. Polymer solution with different concentration was prepared. The concentration investigated in this study were 7.5, 10, 12.5, 15, 17.5, and 20 % w/v. Polymer solution was then subjected to the electrospinning process to evaluate the morphology of the electrospun produced via optical microscope. Simultaneously, the formation of electrospinning jet is observed with portable digital microscope. The morphology of the electrospun fibres, especially the fibre and bead diameter are analyzed using image analysis software, ImageJ. From this research, it is found that at voltage of 10 and 12.8 kV, a stable electrospinning jet can be formed which consists of ‘Taylor cone’, straight jet, and plume. Concentration from 7.5–20 % w/v were able to form electrospun fibres, yet only 12.5 and 15 % w/v PLA concentrations can produce an effective electrospun fibres with beads diameter of 3393 nm and 3642 nm, respectively. Also, the number of beads for both concentrations are 34 and 19, respectively. Since the main criteria in producing electrospun fibres is no beads or small and minimal beads at best, therefore 12.5 and 15 % w/v PLA concentration are considered as efficient electrospun fibres.

The increase of carbon dioxide (CO2) emission due to anthropogenic activities has become a threat to our environment. Hence there is an urgent need to control its emission via carbon capture and storage (CCS) strategy. However, the readily available method, which is liquid amine absorption, possesses some drawbacks including being energy intensive and may cause material corrosion. Dry CO2 adsorption using amine-functionalized silica has been studied to provide a simple and cost-effective alternative for CO2 capture. Recently emerged dendritic fibrous silica possesses excellent morphology and characteristics to be developed as an effective CO2 adsorbent. Herein, the CO2 adsorption performance using amine-modified fibrous silica nanoparticle, KCC-1 was studied. As-synthesized KCC-1 was modified with tetraethylenepentamine (TEPA) via impregnation method. Its characteristics were studied before it was subjected to the CO2 adsorption experiment. The Fourier Transform Infra-red (FTIR) results indicates that TEPA was successfully impregnated with peaks at 3383 cm−1, 2935 cm−1, 2837 cm−1, 1558 cm−1, 1479 cm−1 and 1309 cm−1, while X-ray diffraction (XRD) analysis showed that KCC-1 structure was preserved. KCC-1/TEPA recorded higher adsorption capacity of CO2 compared to the unmodified KCC-1, with maximum adsorption capacity of 189.86 mg/g. Equilibrium isotherm model fitting of the CO2 adsorption was also carried out, and the adsorption data of KCC-1/TEPA fitted well to Toth isotherm. Overall, it has been demonstrated that KCC-1/TEPA has excellent potential to be used for CO2 adsorption, and more studies need to be conducted for its development.

No abstract

No abstract

Incomplete combustion by fossil fuel has contributed to the increase in carbon dioxide (CO 2) emission as well as carbon soot production. Several methods have been done via carbon capture and storage (CCS) strategy to mitigate CO 2 emission such as via adsorption. However, a method to utilize the carbon soot production was still in question. Less discussion on utilizing soot as gas adsorbent up to this date. Therefore, this paper aimed to investigate the CO 2 adsorption performance from fresh candle soot (FS) and soot activated by potassium hydroxide (KOH) with mass ratio 2/1 KOH to soot (KOH-S1). The activation process was done by using muffle furnace at 700 °C for 1 h under vacuum condition. FTIR spectrum of the KOH-S1 appeared at 3500, 1639, 1048 and 1740 cm -1 due to KOH treatment before activation. The mean diameter for KOH-S1 particles was larger (22.328 μm) than FS (4.413 μm) due to agglomeration. The adsorption capacity obtained for KOH-S1 and FS were 24.4092 and 10.3052 mg/g respectively. It has been demonstrated that KOH-S1 has excellent potential to be used for CO2 adsorption and more studies need to conducted for its development.

Carbon dioxide, a type of greenhouse gases has drawn world wide’s attention as major contributors to global warming and climate change. Thus, several methods have been developed to mitigate this problem such as through adsorption. There are numerous types of adsorbents available, for instance is carbon-based adsorbent that can be synthesised from various type of biomass as reported in previous studies. However, there are very few studies used soil as an adsorbent for gases. Soils are porous medium developed in the uppermost layer of Earth’s crust which are available in several forms, abundance and cheap. In this study, three types of carbonised soils were used as carbon-based adsorbent to investigate its adsorption capacity for carbon dioxide. Influence of moisture content in this study is negligible as it is too low. Due to the nature of raw materials used, ash content for all sample was incredibly high which almost all exceeded 90%. Determination of densities by pycnometer showed that carbonised soil 2 has the lowest particle and bulk density of 2.4802 g/cm3 and 0.5248 g/cm3 respectively. Then the adsorption capacity of each sample was determined by sorption measuring instrument with magnetic suspension balance. Results showed that carbonised soil 2 with high surface area, pore volume, and small pore size has the highest adsorption capacity of 6.4 mg/g at 25 ˚C under atmospheric pressure. Therefore, soils exhibit prominent potential to be developed as carbon dioxide adsorbent with desirable properties.