Mohd Ali Hashim

Remediation technologies for heavy metal contaminated groundwater.

The contamination of groundwater by heavy metal, originating either from natural soil sources or from anthropogenic sources is a matter of utmost concern to the public health. Remediation of contaminated groundwater is of highest priority since billions of people all over the world use it for drinking purpose. In this paper, thirty five approaches for groundwater treatment have been reviewed and classified under three large categories viz chemical, biochemical/biological/biosorption and physico-chemical treatment processes. Comparison tables have been provided at the end of each process for a better understanding of each category. Selection of a suitable technology for contamination remediation at a particular site is one of the most challenging job due to extremely complex soil chemistry and aquifer characteristics and no thumb-rule can be suggested regarding this issue. In the past decade, iron based technologies, microbial remediation, biological sulphate reduction and various adsorbents played versatile and efficient remediation roles. Keeping the sustainability issues and environmental ethics in mind, the technologies encompassing natural chemistry, bioremediation and biosorption are recommended to be adopted in appropriate cases. In many places, two or more techniques can work synergistically for better results. Processes such as chelate extraction and chemical soil washings are advisable only for recovery of valuable metals in highly contaminated industrial sites depending on economical feasibility.

Superoxide Ion: Generation and Chemical Implications

Superoxide ion (O2(•-)) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2(•-) is rather scarce. In addition, numerous studies on O2(•-) were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2(•-) reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2(•-) so as to enable researchers to venture into future research. It comprises the main characteristics of O2(•-) followed by generation methods. The reaction types of O2(•-) are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2(•-) environmental chemistry is also discussed. The detection methods of O2(•-) are categorized and elaborated. Special attention is given to the feasibility of using ionic liquids as media for O2(•-), addressing the latest progress of generation and applications. The effect of electrodes on the O2(•-) electrochemical generation is reviewed. Finally, some remarks and future perspectives are concluded.

Are deep eutectic solvents benign or toxic

In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity effect was tested using the Artemia salina leach. It was found that there was no toxic effect for the tested DESs on all of the studied bacteria confirming their benign effects on these bacteria. Nevertheless, it was found that the cytotoxicity of DESs was much higher than their individual components (e.g. glycerine, ChCl) indicating that their toxicological behavior is different. For our best knowledge this is the first time that toxicity and cytotoxicity of DESs were studied. The toxicity and cytotoxicity of DESs varied depending on the structure of components. Careful usage of the terms non-toxicity and biodegradability must be considered. More investigation on this matter is required.

Spirulina cultivation in digested sago starch factory wastewater

Wastewater arising from the production of sago starchhas a high carbon to nitrogen ratio, which is improvedwith anaerobic fermentation in an upflow packed beddigester. The digested effluent with an average C: N:P ratio of 24: 0.14: 1 supported growth of Spirulina platensis (Arthrospira) with anaverage specific growth rate (μ) of 0.51day-1 compared with the average μ of 0.54day-1 in the inorganic Kosaric Medium in a highrate algal pond. Supplementation with 6 mM urea and2.1 mM K2HPO4 produced gross biomassproductivity of 14.4 g m-2 day-1. Aflow-rate of 24 cm s-1 increased the μ andgross biomass productivity (18 g m-2 day-1). The highest crude protein, carbohydrate and lipidcontents of the biomass were 68%, 23% and 11%,respectively. Percentage reductions in chemicaloxygen demand, ammoniacal-nitrogen and phosphatelevels of the digested effluent reached 98.0%, 99.9%and 99.4% respectively. The HRAP offers a goodtreatment system for sago starch factory wastewater.

Microbiological and biochemical changes during the composting of oil palm empty-fruit-bunches. Effect of nitrogen supplementation on the substrate

The composting of oil palm empty-fruit-bunches and of oil palm empty-fruit-bunches in supplementation with either goat dung, cow dung or chicken manure differed in the resulting C:N ratios. The initial C:N ratios (52:1, 35:1, 48:1, 47:1) for the four compost heaps were significantly reduced to 24:1, 14:1, 18:1 and 12:1, respectively, after 60 days of composting, resulting in the production of a stable humus that is suitable for crop production. A temperature of 70°C was maintained for 3 days at the onset of composting. Both mesophilic and thermophilic bacteria showed consistent activity throughout the process, whereas fungal activity was completely suppressed during the peak heating phase. The rate of utilization of cellulosic material showed a positive correlation with the increase in the nitrogen content of the compost.

Separation of Vitamin E (tocopherol, tocotrienol, and tocomonoenol) in Palm Oil

Previous reports showed that vitamin E in palm oil consists of various isomers of tocopherols and tocotrienols [α-tocopherol (α−T), α-tocotrienol, γ-tocopherol, γ-tocotrienol, and δ-tocotrienol), and this is normally analyzed using silica column HPLC with fluorescence detection. In this study, an HPLC-fluorescence method using a C30 silica stationary phase was developed to separate and analyze the vitamin E isomers present in palm oil. In addition, an α-tocomonoenol (α−T1) isomer was quantified and characterized by MS and NMR. α−T1 constitutes about 3–4% (40±5 ppm) of vitamin E in crude palm oil (CPO) and is found in the phytonutrient concentrate (350±10 ppm) from palm oil, whereas its concentration in palm fiber oil (PFO) is about 11% (430±6 ppm). The relative content of each individual vitamin E isomer before and after interesterification/transesterification of CPO to CPO methyl esters, followed by vacuum distillation of CPO methyl esters to yield the residue, remained the same except for α−T and γ−T3. Whereas α−T constitutes about 36% of the total vitamin E in CPO, it is present at a level of 10% in the phytonutrient concentrate. On the other hand, the composition of γ−T3 increases from 31% in CPO to 60% in the phytonutrient concentrate. Vitamin is present at 1160±43 ppm, and its concentrations in PFO and the phytonutrient concentrate are 4,040±41 and 13,780±65 ppm, respectively. The separation and quantification of α−T1 in palm oil will lead to more in-depth knowledge of the occurrence of vitamin E in palm oil.

Assessment of cytotoxicity and toxicity for phosphonium-based deep eutectic solvents.

In this work, the cytotoxicity and toxicity of phosphonium-based deep eutectic solvents (DESs) with three hydrogen bond donors, namely glycerine, ethylene glycol, and triethylene glycol were investigated. The cytotoxicity effect was tested using brine shrimp (Artemia salina). The toxicity was investigated using the two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity of tested DESs was much higher than that of their individual components, indicating their toxicological behavior was different. It was also found that there was toxic effect on the studied bacteria, indicating their potential application as anti-bacterial agents. To the best of our knowledge, this is the first time the cytotoxicity and toxicity of phosphonium-based DESs were studied.

Performance Evaluation of Organic Emulsion Liquid Membrane on Phenol Removal

The percentage removal of phenol from aqueous solution by emulsion liquid membrane and emulsion leakage was investigated experimentally for various parameters such as membrane:internal phase ratio, membrane:external phase ratio, emulsification speed, emulsification time, carrier concentration, surfactant concentration and internal agent concentration. These parameters strongly influence the percentage removal of phenol and emulsion leakage. Under optimum membrane properties, the percentage removal of phenol was as high as 98.33%, with emulsion leakage of 1.25%. It was also found that the necessity of carrier for enhancing phenol removal was strongly dependent on the internal agent concentration.

Application of supercritical fluid chromatography in the quantitative analysis of minor components (carotenes, vitamin E, sterols, and squalene) from palm oil

The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in palm oil were also isolated into their respective components, α-tocopherol, α-tocotrienol, γ-tocopherol, γ-tocotrienol, and δ-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was carried out and was found to be comparable to those analyzed by other established analytical methods.

A comparative study of experimental optimization and response surface optimization of Cr removal by emulsion ionic liquid membrane.

A comparative study on the optimization of process parameters of an emulsion ionic liquid membrane (EILM) by experimental work and response surface methodology (RSM) has been carried out. EILM was prepared by using kerosene as solvent, Span 80 as surfactant, NaOH as internal reagent, a hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM](+)[NTf(2)](-)) as a stabilizer and a second ionic liquid tri-n-octylmethylammonium chloride (TOMAC) as a carrier. The prepared EILM was used to separate and concentrate Cr from wastewaters. The comparison between the experimentally optimized and the RSM optimized values was accomplished by optimizing the following parameters: homogenization speed, carrier concentration, internal phase concentration, agitation speed, treat ratio, internal to membrane phase ratio, surfactant concentration and pH of the feed phase. The comparison showed that all the values were in good agreement except for the internal phase concentration and the treat ratio. It was observed that the stability provided by [BMIM](+)[NTf(2)](-) decreased as the extraction progressed due to its high density. Nevertheless, a good stability could be obtained by the combination of [BMIM](+)[NTf(2)](-) and Span 80 during extraction process.