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PublicationPoly-ferric sulphate as superior coagulant: a review on preparation methods and properties(De Gruyter Brill, 2023-09)Iron-based coagulants are widely used in wastewater treatment due to their high positively charged ion that effectively destabilise colloidal suspension, and thus contribute to the formation of insoluble flocs. Ferric chloride, ferrous sulphate, and poly-ferric sulphate (PFS) are examples of iron-based coagulants that are highly available, and are beneficial in producing denser flocs, thereby improving settling characteristics. This work aims to review the preparation methods of PFS and critically discuss the influence of these methods on the PFS properties and performance as a chemical coagulant for water and wastewater treatment. In polymeric form, PFS is one of the pre-hydrolysing metallic salts with the chemical formula [Fe2(OH) n (SO4)3-n/2] m (where, n < 2, m > 10) and has a dark brownish red colour as well as is more viscous and less corrosive. PFS has an amorphous structure with small traces of crystallinity, containing both hydroxyl and sulphate functional groups. It has been applied in many industries including water or wastewater treatment which is also discussed in this study. It has the ability to remove pollutants contained in water or wastewater, such as turbidity, colour, chemical and biological oxygen demand, phosphorus, and others. This study also provides a review on the combination of PFS with other chemical coagulants or flocculants in the coagulation/flocculation process, and also flocs formed after a more stable treatment process.
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PublicationStable release of enhanced organic solvent tolerant amylase from bacillus amyloliquefaciens AMY02 under sub-merged fermentation(CSIR-National Institute of Science Communication and Policy Research (CSIR-NIScPR), 2020-10)This study has been performed to isolate a potential strain able to release the prolific amylase under non-aqueous conditions to meet the current demand in industries to substitute the amylase produced in aqueous media. A bacterial strain that produces organic solvent-stable amylase in the media containing 15% benzene was isolated from the soil. The recovered strain was identified to be Bacillus amyloliquefaciens AMY02by 16S rRNA sequencing. Under sub-merged fermentation, the optimized amylase release by this strain was found with the condition having starch (carbon source), pH 7.0, the temperature at 30°C for 48 h (incubation time). This optimized condition promoted the amylase production to be 2.04-fold higher than the culture was kept under standard condition with the basic media composition. Further, the stability of the enzyme in the presence of 20% organic solvents was assessed by incubating for 2 weeks. The enzyme was found to be active and stable in the presence of benzene, chloroform, o-xylene, and toluene. The higher organic solvent stability of this amylase production by B. amyloliquefaciens under sub-merged fermentation can be an alternative catalyst in non-aqueous media for industrial applications.
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PublicationEffect of LST parameter on surface morphology of modified copper substrates(Malaysian Tribology Society, 2020-09-02)This study aimed to investigate the effect of laser surface texturing (LST) parameter on the surface morphology of copper substrate. The results of different loop number (L1 to L5) on the resolidified material of micro-dimpled surface modified copper substrate were examined. The micro-dimple with a diameter of 100 µm was produced via LST process by varying the dimple distance at 100 µm and 180 µm. The resolidified material that was formed after the surface texturing process was analysed using 3D measuring laser microscope. Based on the data collected, the dimple was successfully engraved on the copper substrate. The increasing number of loop increase the quantity of the melted material which lead to higher amount of resolidified material and surface roughness.
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PublicationMicrostructural analysis of Sn-3.0Ag-0.5Cu-TiO₂ composite solder alloy after selective electrochemical etching(IOP Publishing, 2020-01)This work aims to provide deep morphological observation on the incorporated TiO₂ nanoparticles within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry were used to investigate the selective etching performances. The removal of β-Sn matrix was conducted at a fixed potential of-350 mV. Average performances of 2.19 and 2.30 mA were attained from the chronoamperometry. The efficiency of β-Sn removal was approved according to the reduction of the intensities on the phase analysis. Successful observation of the TiO₂ near the Cu6Sn5 layer was attained for an optimum duration of 120 s. Clusters of TiO₂ nanoparticles were entrapped by Cu6Sn5 and Ag3Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO₂ nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 IMC layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of the shape and size of the Cu6Sn5 and Ag3Sn. It was found that TiO₂ content facilitates the β-Sn removal, which allows better observation of the IMC phases as well as the TiO₂ reinforcement particles.
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PublicationAlumina recovery from industrial waste: study on the thermal, tensile and wear properties of Polypropylene/Alumina nanocomposites(Springer, 2019-07)The investigation on the influences of alumina (Al₂O₃) particles in nano-sized retrieved from Aluminium (Al) dross was conducted on the tensile, thermal and wear properties of polypropylene (PP) composites. The thermal decomposition method was used to synthesise the micro α-Al₂O₃ particles from Al-dross, was followed by the wet-milling method to produce the nano α-Al₂O₃. The PP composites (nano and micro α-Al₂O₃ particles) were prepared via melt compounding followed by compression molding. The coupling agent was also added to facilitate the particle dispersion. The tensile tests showed the maximum tensile strength and Young’s modulus of both composites to be corresponding to the samples containing 5 wt% of α-Al₂O₃. The superiority of nano α-Al₂O₃ on improving the property of PP had also been evident in the abrasive wear performance. A small amount of α-Al₂O₃ had been adequate in enhancing the thermal stability of PP than that of neat PP. The study on tensile and worn surface with SEM had revealed better adhesion and interaction between the filler and matrix in composites that were treated with coupling agent. The recovery of nano α-Al₂O₃ particles from Al-dross potentially decreases the quantity of harmful solid waste and can be an effective alternative filler for thermoplastics.