Sulfur hexafluoride (SF6) is the most potent greenhouse gas contributed by the power and semiconductor industries. The global emissions of gas in the past 10 years have increased tremendously due to lack of disposal routes. This was brought to 190 nations' attention in the Kyoto Protocol for the need of emission control measures to reduce its impacts of climate change and global warming. Various novel techniques have surfaced to tackle this issue, such as non-thermal plasma (NTP) which includes radio frequency plasma, microwave plasma, dielectric barrier discharge, and electron beam. The main by-products resulting from the decomposition of SF6 by these techniques are sulfur oxyfluorides, sulfur dioxide, hydrofluoric acid, and fluorine gas. This environmental and health effects as well as global emission of SF6 gas are considered a threat to humans and the climate, where modern disposal methods of contaminated SF6 gas and its by-products should replace the conventional approaches. Relevant government policies on the safety and disposal concern of SF6 gas are reviewed and challenges and further research directions for the disposal of SF6 gas are highlighted in this review article.
Liquid detergent has an increasing demand in North America, Western Europe, and Southeast Asia countries owing to its convenience to use and efficiency to clean. Alpha methyl ester sulfonates (α-MES), an anionic surfactant derived from palm oil based methyl ester, was reported to have lower manufacturing cost, good detergency with less dosage, excellent biodegradability, higher tolerance to hard water, and lower eco-toxicity as compared to linear alkylbenzene sulfonates (LABS). LABS was known as the workhorse of the detergent industry in the 20th century. Although palm-based α-MES was successfully used as the sole surfactant in powder detergent, there are still some unsettled technical issues related to phase stability and viscosity when using this anionic surfactant in heavy-duty laundry liquid detergent formulations. This paper will review not only the market overview of detergents, the application and performance of green surfactants in laundry detergents but also will highlight the technical issues related to the application of palm-based α-MES in laundry liquid detergent and some of the possible methods to overcome the formulation adversities.
Global demand for epoxidized vegetable oil has been steadily growing. Epoxidized vegetable oils are typically produced using a two-pot synthesis process in which the oxidation and epoxidation reactions are carried out sequentially. This two-pot synthesis method, however, has a major drawback in industrialscale production, particularly when it comes to operational and process safety issues. A laboratory-scale one-pot synthesis method was attempted in this study with the aim to safely synthesize epoxidized Moringa Oleifera oil (eMOo) by avoiding the occurrence of undesired exothermic runaway reaction. The oil extracted from Moringa Oleifera oil seed kernel (MOo) was used as a starting component due to its high degree of unsaturation and also because the Moringa Oleifera plant can be freely grown in any soil conditions. Two parallel oxidation and epoxidation reactions were carried out simultaneously in this one-pot synthesis method to produce eMOo. The effect of five different mole ratios of MOo, acetic acid and hydrogen peroxide (1:1:1, 1:1:2, 1:1.5:2, 1:1.75:2 and 1:2:2, respectively) on reaction mechanism was investigated at the controlled temperature range of 43 - 55°C and reaction time of 0 - 120 min. The physicochemical properties of MOo as well as the oxirane oxygen content (OOC) of the resulting eMOo were characterized. In addition, GC-MS and FTIR analysis were performed to verify the molecular composition of MOo and also to identify the epoxy group of the resulting eMOo respectively. Among the five different mole ratios studied, the 1:1.5:2 mole ratio has the highest unsaturation conversion of 79.57% and OOC of 4.12%.
Phosphate-free spray dried detergent powders (SDDP) comprising binary anionic surfactants of palm C16 methyl ester sulfonate (C16MES) and linear alkyl benzene sulfonic acid (LABSA) were produced using a 5 kg/h-capacity co-current pilot spray dryer (CSD). Six phosphate-free detergent (PFD) formulations comprising C16MES/LABSA in various ratios under pH 7-8 were studied. Three PFD formulations having C16MES/LABSA in respective ratios of 0:100 (control), 20:80 and 40:60 ratios were selected for further evaluation based on their optimum detergent slurry concentrations. The resulting SDDP from these formulations were analysed for its detergency stability (over nine months of storage period) and particle characteristics. C16MES/LABSA of 40:60 ratio was selected as the ideal PFD formulation since its resulting SDDP has consistent detergency stability (variation of 2.3% in detergency/active over nine months storage period), excellent bulk density (0.37 kg/L), fine particle size at 50% cumulative volume percentage (D50 of 60.48 μm), high coefficient of particle size uniformity (D60/D10 of 3.86) and large spread of equivalent particle diameters. In terms of surface morphology, the SDDP of the ideal formulation were found to have regular hollow particles with smooth spherical surfaces. Although SDDP of the ideal formulation have excellent characteristics, but in terms of flowability, these powders were classified as slightly less free flowing (Hausner ratio of 1.27 and Carr's index of 21.3).