Norli Ismail

Extraction of Cu(II) from aqueous solutions by vegetable oil-based organic solvents

Various types of vegetable oil-based organic solvents (VOS), i.e. vegetable oils (corn, canola, sunflower and soybean oils) with and without extractants (di-2-ethylhexylphosphoric acid (D2EHPA) and tributylphosphate (TBP)), were investigated into their potentiality as greener substitutes for the conventional petroleum-based organic solvents to extract Cu(II) from aqueous solutions. The pH-extraction isotherms of Cu(II) using various vegetable oils loaded with both D2EHPA and TBP were investigated and the percentage extraction (%E) of Cu(II) achieved by different types of VOS was determined. Vegetable oils without extractants and those loaded with TBP alone showed a poor extractability for Cu(II). Vegetable oils loaded with both D2EHPA and TBP were found to be the most effective VOS for Cu(II) extraction and, thus, are potential greener substitutes for the conventional petroleum-based organic solvents.

Analysis of heavy metal concentrations in sediments of selected estuaries of Malaysia—a statistical assessment

Statistical analysis of heavy metal concentrations in sediment was studied to understand the interrelationship between different parameters and also to identify probable source component in order to explain the pollution status of selected estuaries. Concentrations of heavy metals (Cu, Zn, Cd, Fe, Pb, Cr, Hg and Mn) were analyzed in sediments from Juru and Jejawi Estuaries in Malaysia with ten sampling points of each estuary. The results of multivariate statistical techniques showed that the two regions have different characteristics in terms of heavy metals selected and indicates that each region receives pollution from different sources. The results also showed that Fe, Mn, Cd, Hg, and Cu are responsible for large spatial variations explaining 51.15% of the total variance, whilst Zn and Pb explain only 18.93 of the total variance. This study illustrates the usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets to get better information about the heavy metal concentrations and design of monitoring network.

Screening of factors influencing Cu(II) extraction by soybean oil-based organic solvents using fractional factorial design.

This study aimed to identify the significant factors that give large effects on the efficiency of Cu(II) extraction from aqueous solutions by soybean oil-based organic solvents using fractional factorial design. Six factors (mixing time (t), di-2-ethylhexylphosphoric acid concentration ([D2EHPA]), organic to aqueous phase ratio (O:A), sodium sulfate concentration ([Na(2)SO(4)]), equilibrium pH (pH(eq)) and tributylphosphate concentration ([TBP])) affecting the percentage extraction (%E) of Cu(II) were investigated. A 2(6-1) fractional factorial design was applied and the results were analyzed statistically. The results show that only [D2EHPA], pH(eq) and their second-order interaction ([D2EHPA] × pH(eq)) influenced the %E significantly. Regression models for %E were developed and the adequacy of the reduced model was examined. The results of this study indicate that fractional factorial design is a useful tool for screening a large number of variables and reducing the number of experiments.

Treatment of Terasil Red R Dye Wastewater using H2O2/pyridine/Cu(II) System

The H(2)O(2)/pyridine/Cu(II) advanced oxidation system was used to assess the efficiency of the treatment of a 1 g L(-1) Terasil Red R dye solution. This system was found to be capable in reducing the concentration of chemical oxygen demand (COD) of the dye solution up to 90%, and achieving 99% in decolorization at the optimal concentration of 5.5mM H(2)O(2), 38 mM pyridine and 1.68 mM Cu(II). The final concentration of COD was recorded at 117 mg L(-1) and color point at 320 PtCo. Full 2(4) factorial design and the response surface methodology using central composite design (CCD) were utilized in the screening and optimization of this study. Treatment efficiency was found to be pH independent. The amount of sludge generation was in the range of 100-175 mg L(-1) and the sludge produced at the optimal concentration was 170 mg L(-1).

Zeolite Y encapsulated with Fe-TiO2 for ultrasound-assisted degradation of amaranth dye in water

A new heterogeneous catalyst for sonocatalytic degradation of amaranth dye in water was synthesized by introducing titania into the pores of zeolite (NaY) through ion exchange method while Fe (III) was immobilized on the encapsulated titanium via impregnation method. XRD results could not detect any peaks for titanium oxide or Fe(2)O(3) due to its low loading. The UV-vis analysis proved a blue shift toward shorter wavelength after the loading of Ti into NaY while a red shift was detected after the loading of Fe into the encapsulated titanium. Different reaction variables such as TiO(2) content, amount of Fe, pH values, amount of hydrogen peroxide, catalyst loading and the initial dye concentration were studied to estimate their effect on the decolorization efficiency of amaranth. The maximum decolorization efficiency achieved was 97.5% at a solution pH of 2.5, catalyst dosage of 2 g/L, 20 mmol/100 mL of H(2)O(2) and initial dye concentration of 10 mg/L. The new heterogeneous catalyst Fe/Ti-NaY was a promising catalyst for this reaction and showed minimum Fe leaching at the end of the reaction.

Isolation, identification, characterization, and evaluation of cadmium removal capacity of Enterobacter species

This study focused on the isolation and characterization of high cadmium‐resistant bacterial strains, possible exploitation of its cadmium‐accumulation and cadmium‐induced proteins. Cadmium‐resistant bacterial strains designated as RZ1 and RZ2 were isolated from industrial wastewater of Penang, Malaysia. These isolates were identified as Enterobacter mori and Enterobacter sp. WS12 on the basis of phenotypic, biochemical and 16S rDNA sequence based molecular phylogenetic characteristics. Both isolates were Gram negative, cocci, and growing well in Lauria–Bertani broth medium at 35 °C temperature and pH 7.0. Results also indicated that Enterobacter mori and Enterobacter sp. WS12are capable to remove 87.75 and 85.11% of the cadmium from 100 µg ml−1 concentration, respectively. This study indicates that these strains can be useful as an inexpensive and efficient bioremediation technology to remove and recover the cadmium from wastewater.

Nickel ion coupled counter complexation and decomplexation through a modified supported liquid membrane system

A modified supported liquid membrane reactor was designed and used for nickel removal from aqueous solutions using a polyacrylonitrile hydrophobic fluoropore membrane impregnated by di-2-ethylhexyl phosphoric acid (D2EHPA) as carrier in kerosene. A screening experiment using factorial design was carried out to find the effect of selected variables (factors) on nickel removal efficiency, followed by face centered composite design (FCCD) to obtain the optimum operating conditions, using response surface methodology (RSM). The factors considered in the design were feed phase pH, carrier concentration, shaking time, stirring time, stripping agent concentration, stirring speed, inert salt concentration and phase modifier concentration. It was found that feed phase pH, carrier concentration, interaction between feed phase pH and carrier concentration, stripping agent concentration and stirring time have a significant effect on nickel removal. Optimum conditions were feed phase pH 4.8, [D2EHPA]: 0.156 M, stirring time: 450 minutes and stripping phase agent of 1.5 M of H2SO4 which resulted in 95.38% of nickel removal. Stoichiometric coefficients of complexation and decomplexation reactions were obtained by Job’s continuous variation method, loading capacity and loading test and the results confirmed that one nickel ion is extracted to the organic phase by two dimeric D2EHPA molecules. The mass transfer coefficient (k) for the optimum conditions was 2.3 × 10−6 m s−1.

Isolation, Identification, and Characterization of Cadmium Resistant Pseudomonas sp. M3 from Industrial Wastewater

The present study deals with the isolation, identification, and characterization of the cadmium resistant bacteria from wastewater collected from industrial area of Penang, Malaysia. The isolate was selected based on high level of the cadmium and antibiotic resistances. On the basis of morphological, biochemical characteristics, 16S rDNA gene sequencing and phylogeny analysis revealed that the strain RZCd1 was authentically identified as Pseudomonas sp. M3. The industrial isolate showed more than 70% of the cadmium removal in log phase. The cadmium removal capacity of strain RZCd1 was affected by temperature and pH. At pH 7.0 and 35°C, strain RZCd1 showed maximum cadmium removal capacity. The minimal inhibitory concentration of strain RZCd1 against the cadmium was 550 µg/mL. The resistance against the cadmium was associated with resistance to multiple antibiotics: amoxicillin, penicillin, cephalexin, erythromycin, and streptomycin. The strain RZCd1 also gave thick bands of proteins in front of 25 kDa in cadmium stress condition after 3 h of incubation. So the identified cadmium resistant bacteria may be useful for the bioremediation of cadmium contaminated industrial wastewater.

Optimization of COD, apparent color, and turbidity reductions of landfill leachate by Fenton reagent

ABSTRACTThe efficiency of Fenton reagent (Fe2+ + H2O2 + H+) for the leachate generated from Pulau Burung sanitary landfill site, located in Malaysia, was evaluated with the objectives of chemical oxygen demand (COD), apparent color, and turbidity reductions. Response surface methodology was used to study the effect of hydrogen peroxide (as oxidant) and ferrous sulfate (as catalyst) on COD, apparent colour, and turbidity reductions of sanitary landfill leachate. A central composite design in two factors [hydrogen peroxide dosage (mg/L) and ferrous sulfate dosage (g/L)] was employed to build a model as well as to perform optimization of the Fenton process. The optimum results for COD, apparent color, and turbidity reductions were 68, 81, and 86%, respectively, setting [H2O2] at 747.8 mg/L and [FeSO4] at 12.8 g/L.

Reuse of Fruit Waste as Biopolymeric Flocculant and Optimizing Turbidity Reduction: Comparison Study with Industrial Flocculant

The performance of two flocculants on turbidity reduction was studied. The two flocculants were: a biopolymeric flocculant which was extracted from fruit waste and a commercial industrial flocculant. The effect of the flocculants’ average molecular weight on turbidity treatment, the treatment efficiency of both flocculants and the flocculants’ degradability were investigated. Response surface methodology was carried out using Box Behnken design to find the optimal pH, cation concentration, and flocculant dosage to maximize the turbidity reduction. The results showed that the maximum turbidity reduction by industrial flocculant occurs between pH 7.5 and pH 8.2, cation concentration between 0.02 and 0.06 mM, and industrial flocculant dosage between 6.5 and 8.0 mg/L. While with biopolymeric flocculant, maximum turbidity reduction occurred between pH 4.6 and pH 7.5, cation concentration between 0.60 and 0.95 mM, and biopolymeric flocculant dosage between 4 and 6 mg/L.