Abbas F.M. Alkarkhi

Characterization of biopolymeric flocculant (pectin) and organic synthetic flocculant (PAM): A comparative study on treatment and optimization in kaolin suspension

Polyacrylamide (PAM), a commonly used organic synthetic flocculant, is known to have high reduction in turbidity treatment. However, PAM is not readily degradable. In this paper, pectin as a biopolymeric flocculant is used. The objectives are (i) to determine the characteristics of both flocculants (ii) to optimize the treatment processes of both flocculants in synthetic turbid waste water. The results obtained indicated that pectin has a lower average molecular weight at 1.63 x 10(5) and PAM at 6.00 x 10(7). However, the thermal degradation results showed that the onset temperature for pectin is at 165.58 degrees C, while the highest onset temperature obtained for PAM is at 235.39 degrees C. The optimum treatment conditions for the biopolymeric flocculant for flocculating activity was at pH 3, cation concentration at 0.55 mM, and pectin concentration at 3 mg/L. In contrast, PAM was at pH 4, cation concentration >0.05 mM and PAM concentration between 13 and 30 mg/L.

Comparing physicochemical properties of banana pulp and peel flours prepared from green and ripe fruits

Banana pulp and peel flour prepared from green and ripe Cavendish banana were assessed for physicochemical properties such as pH, total soluble solids (TSS), water holding capacity (WHC) and oil holding capacity (OHC) at 40, 60 and 80°C, colour values L∗, a∗ and b∗, back extrusion force (BEF) and viscosity. Data obtained were analysed by MANOVA, discriminant analysis and cluster analysis. All statistical analyses showed that physicochemical properties of flour prepared from pulp and peel, and green and ripe banana were different from each other. TSS, WHC40, WHC60 and BEF can be used to discriminate between peel and pulp flour, whilst TSS and viscosity can be used to discriminate between flour prepared from green and ripe banana.

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.

Photocatalytic decolorization of methylene blue by an immobilized TiO2 film under visible light irradiation: optimization using response surface methodology (RSM)

AbstractIn this study, response surface methodology, based on face-centered composite design was used to investigate the effect of operational parameters on the decolorization of methylene blue (MB) using an immobilized film of TiO2 onto glass plate under a 55-W household fluorescent lamp irradiation. Three operating variables, namely TiO2 loading (0.65–3.9 mg/cm2), pH (2–10), and irradiation time (15–90 min) with a total of 20 individual experiments conducted to optimize the combination effects of the variable. The significance of the model and regression coefficients was tested by the analysis of variance. Analysis of the data obtained showed there was a strong significant influence of the operational factors and their interactions on MB color removal (p < 0.0001) of the photocatalytic decolorization process. The results predicted by the models were found to be in good agreement with those obtained by performing experiment (R2 = 0.9706 and Adj-R2 = 0.9442). For MB color removal, the photocatalytic decol...

Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology

Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO2) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO2 sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO2-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO2 exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials.

Optimization of pectin extraction from durian rind (Durio zibethinus) using response surface methodology.

Response surface methodology (RSM) was carried out to study the effect of temperature, pH, and heating time as input variables on the yield and degree of esterification (DE) as the output (responses). The results showed that yield and DE of extracted pectin ranged from 2.27% to 9.35% (w/w, based on dry weight of durian rind) and 47.66% to 68.6%, respectively. The results also showed that a 2nd-order model adequately fitted the experimental data for the yield and DE. Optimum condition for maximum yield and DE was achieved at 85 degrees C, a time of either 4 or 1 h, and a pH of 2 or 2.5.

Effect of banana pulp and peel flour on physicochemical properties and in vitro starch digestibility of yellow alkaline noodles

The present study describes the utilization of banana—Cavendish (Musa acuminata L., cv cavendshii) and Dream (Musa acuminata colla. AAA, cv ‘Berangan’)—pulp and peel flours as functional ingredients in yellow alkaline noodles. Noodles were prepared by partial substitution of wheat flour with ripe banana pulp or peel flours. In most cases, the starch hydrolysis index, predicted glycaemic index (pGI) and physicochemical properties of cooked noodles were affected by banana flour addition. In general, the pGI values of cooked noodles were in the order; banana peel noodles < banana pulp noodles < control noodles. Since the peel flour was higher in total dietary fibre but lower in resistant starch contents than the pulp flour, the low pGI of banana peel noodles was mainly due to its high dietary fibre content. In conclusion, banana pulp and peel flour could be useful for controlling starch hydrolysis of yellow noodles, even though some physicochemical properties of the noodles were altered.

Optimization of nickel removal using liquid-liquid extraction and response surface methodology

Abstract The nickel extraction efficiency by means of liquid–liquid extraction (LLE) method was studied using response surface methodology; six parameters were identified as influential factors on nickel removal efficiency as the response. However, on screening experiments, only two factors were selected: pH and di-(2-ethylhexyl) phosphoric acid (D2EHPA) concentration. Face-centered composite design (FCCD) was applied in order to determine the optimum conditions for nickel removal by LLE. The results of FCCD showed that a second-order model described the relationship between the factors and nickel removal properly. Results showed that the optimum conditions are pH 1.1 and D2EHPA concentration 0.2 M, where 95.57% of nickel removal was achieved.

Effect of cooking on physical and sensory properties of fresh yellow alkaline noodles prepared by partial substitution of wheat flour with soy protein isolate and treated with cross-linking agents

Yellow alkaline noodles (YAN) prepared by partial substitution of wheat flour with soy protein isolate and treated with microbial transglutaminase (MTG) and ribose were investigated during cooking. Cooking caused an increase in lightness but a decrease in redness and yellowness, pH, tensile strength and elasticity values of noodles. The extents of these changes were influenced by formulation and cross-linking treatments. The pH and lightness for YAN-ribose were lowest but the yellowness and redness were the highest whilst the tensile strength and elasticity values remained moderate. For YAN-MTG, the color and pH values were moderate, but tensile strength and elasticity values were the highest. YAN prepared with both cross-linking agents had physical values between YAN-ribose and YAN-MTG. Although certain sensory parameters showed differences in score, the overall acceptability of all 10-min-cooked YAN was similar. It is possible to employ cross-linking agents to improve physical properties of cooked YAN.

Removal of Terasil Red R dye by using Fenton oxidation: a statistical analysis

AbstractThe Fenton oxidation is one of the advanced oxidation processes (AOPs) that produce hydroxyl radicals with the aid of ferrous ions as catalyst. This treatment method was used to study the treatment efficiency of 100 mg/L synthetic dye wastewater comprises of a disperse dye commercially named as Terasil Red R. The treatment efficiency was determined in terms of percentage chemical oxygen demand (COD) removal and percentage color removal. Statistical design of experiment was employed to obtain optimal operating parameters. The optimal parameters were pH 3.5 and H2O2/Fe(II) molar ratio of 4. With this optimal condition, the Fenton oxidation was capable to achieve 93% of COD removal and more than 99% of color removal. The process was optimized with 32 factorial design and the interaction (dependent) between pH and molar ratio were found to be significant from the analysis of variance (ANOVA).