Effect of PAO-based γ-Fe2O3 and surfactant concentration on viscosity characteristic

This is a preliminary study on the viscosity characteristics of polyalphaolefin (PAO)- based γ-Fe2O3 under zero magnetic fields. By varying the concentration of magnetic nanoparticles (MNPs), PAO-based γ-Fe2O3 with different concentrations were synthesized by co-precipitation method. The effect of this factor on the viscosity characteristic of γ-Fe2O3 (< 30 nm) was investigated on the basic of a series of rheological measurement. The use of oleic acid (OA) as a coating agent and surfactant was also investigated by varying its concentration. The results show the concentration of MNPs and the amount of OA has obvious effect on viscosity characteristics of PAO-based γ-Fe2O3. In the case of comparison between the concentrations of MNPs, higher concentration of MNPs increased the viscosity of the PAO-based γ-Fe2O3 and exhibit nearly Newtonian behavior. The large amount of OA also exhibits the increment on viscosity characteristic of MNPs. The experimental data were compared with the Bingham and Casson model and the results revealed that the rheology of the polyalphaolefin (PAO)-based γ-Fe2O3 fitted the Casson model better

Pilot scale extraction of crude bromelain from pineapple morris and md2 cultivar using hollow fiber nanofiltration membrane

Pineapple (Ananas comosus) is rich with nutrients, incredibly juicy and has been linked to many health benefits. Pineapples are not only taken fresh but they have been commercialized in the canning industry. However, in the canning industry only the flesh is utilized and the rest of the pineapple (50 wt %) such as the core, stem, peels and crown are discarded as waste. In the extraction of bromelain which is a vital proteolytic enzyme, the whole pineapple including its peels, core, stem and crown can be utilized. Bromelain is very valuable and different applications require different bromelain purity; therefore, the extraction and purification technique can be designed depending on the purpose of the bromelain. In this study, nanofiltration (NF) membrane process is used to extract bromelain of Morris and MD2 cultivar from the flesh, crown, stem, core and peel of pineapples. The different parts of the pineapple were crushed to extract the juice. The juice was then centrifuged and the supernatant was then passed through a hollow fiber NF. Finally, the retentate from the different pineapple parts which contain high amounts of bromelain were freeze-dried and quantified. Casein digestion unit method was used to determine the bromelain activity. The amount of bromelain activity increased after every process especially after freeze-drying. The bromelain content in retentate was also analysed using high performance liquid chromatography. Findings revealed that retention time peak of the bromelain appeared within 1 min and bromelain content was found to be highest in peel > flesh > stem > core for both pineapple species. The extracted bromelain solution was then freeze dried and maltodextrin was added so as to ensure encapsulation stability. The concentration of the maltodextrin added varied ranging from 2 – 10 % concentration (w/w %). Water was eliminated during freeze-drying, but unfortunately, bromelain powder with lower maltodextrin concentration (2 – 8 %) were found to be sticky compared to the highest concentration at 10 % which showed an amorphous glassy maltodextrin microstructure (i.e., “bromelain powder”). Upon crushing, the maltodextrin microstructure yielded a free-flowing powder with bromelain enzyme activity of 412.42 CDU/mg. As for the microbiological quality of the bromelain powder, it is safe to be consumed because pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella and Eshrerichia coli were absent in the core and flesh bromelain powder. Enterobacteria and other gram-negative bacteria were less than 10 MPN/ml whereas bacteria count and fungi count was 3.9 x 104 CFU/ml and 6.5 x 101 CFU/ml for core bromelain powder and 5.1 x 104 CFU/ml and 7.1 x 101 CFU/ml for flesh bromelain powder, respectively. 2,2′-diphenyl-1-picrylhydrazyl test results showed the presence of anti-oxidant activity of bromelain was 8.75 % and 11.23 %, respectively for core and flesh pineapple. Meanwhile the anti-inflammatory activity was also detected in the extracted bromelain from the core (50 %) and flesh (45 %) of pineapple. Profitability analysis of the crude bromelain powder plant estimates the rate of return is 34 % and the payback period for the company to start earning profit is 2.92 years. In terms of price, the lowest price in the market for 30 tablets in a bottle was RM 39.14. While the product from this process can be sold at the price of RM 35 for 30 capsules in a bottle, which is cheaper

Removal of cadmium using ferro magnetic gels

The removal of cadmium (Cd) from aqueous solution of cadmium chloride using ferromagnetic photocatalyst gel was investigated. The experiments were performed under sunlight and also away from sunlight. Recycling experiments were also performed to determine the durability of the ferromagnetic photocatalyst gel. The results revealed that removal of cadmium was higher in the presence of sunlight irradiation compared to without sunlight. Apparently the treatment process for Cd involved both adsorption and photocatalytic process. The removal rate of Cd was faster when it was exposed to sunlight where almost 100% of Cd was removed within 4 hours. The presence of pores was observed from FESEM images and such morphology was considered helpful for mass transfer of Cd(II) to the photocatalyst active sites embedded in the PVA-alginate magnetic beads. The PVA-alginate magnetic beads produced were reused after treating with 25 ppm of Cd(II) solutions without washing them. The performance of each cycle was about the same as the previous cycle until it reached the seventh cycle where the ferro photo gels start to lose its removal efficiency

Enhanced removal of Cu(II) by photocatalytic reduction using maghemite PVA-alginate separable beads: kinetic and equilibrium studies

The feasibility of Cu(II) removal by photoreduction using maghemite polyvinylalcohol-alginate beads was investigated. Photoreduction experiments were performed to investigate the influence of initial concentration and pH on the removal of copper(II) metallic ions. The fate of Cu(II) during the photoreduction process was investigated using the X-ray photoelectron spectroscopy. It was observed that the Cu(II) removal rate was faster under sunlight than without sunlight due to the reduction process of Cu(II) to Cu(I). The photoreduction results showed that the adsorption of Cu(II) ions followed a Langmuir Hinshelwood model with the photoreduction rate constant and adsorption coefficient values of 24.1 ppm/min and 0.0098 ppm-1, respectively

Photocatalytic magnetic separable beads for chromium (VI) reduction

Magnetically separable photocatalyst beads containing nano-sized iron oxide in alginate polymer were prepared. This magnetic photocatalyst beads are used in slurry-type reactors. The magnetism of the catalyst arises from the nanostructured particles ?-Fe2O3, by which the catalyst can be easily recovered by the application of an external magnetic field. These synthesized beads are sunlight-driven photocatalyst. In the system without magnetic photocatalyst beads, no chromium reduction was observed under sunlight irradiation due to the stability of the chromium (VI). Upon the addition of magnetic photocatalyst beads, the photo-reduction of Cr(VI) was completed in just after only 50 min under sunlight irradiation due to the photocatalytic activity of the beads. However when placed away from sunlight, the reduction rate of the chromium is just about 10%. These observations were explained in terms of absorption occurrence of chromium (VI) onto the catalyst surface which took place in this reaction. In addition, photo-reduction rate of chromium (VI) was more significant at lower pH. The results suggest that the use of magnetic separable photocatalyst beads is a feasible strategy for eliminating Cr(VI)

Synthesis of magnetic alginate beads based on maghemite nanoparticles for Pb(II) removal in aqueous solution

Magnetic alginate beads were successfully synthesized by incorporating ferrofluids based on maghemite nanoparticles (y-Fe 2O 3) and sodium alginate. The as-obtained dried sample characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the size of uncoated and citrate coated y-Fe 2O 3 to be 15nm and 9nm respectively. Fourier transform infrared (FTIR) was performed so as to ensure successful coating process. The specific saturation magnetization (Q s) value of coated particles was found to be lower than the uncoated particles. Zero coercivity of the magnetization curve indicated that the particles were superparamagnetic in nature. By using a ratio 1:10 of ferrofluids and alginate solution respectively, magnetic beads were prepared and the ability of magnetic beads to remove Pb(II) ion from aqueous solutions in batch media was investigated. Various physico-chemical parameters such as pH, initial metal ion concentration, and equilibrium contact time were also studied. The results revealed that 95.2% of the Pb(II) was removed within 2h at pH 7. The equilibrium amount of Pb(II) adsorbed onto the magnetic beads approached a constant value with increasing concentrations suggesting that the uptake of Pb(II) followed a Langmuir-type adsorption equation with q max of 50mg/g. Moreover, the presence of the magnetic particles in the beads allowed easy isolation of the beads from the aqueous solutions after the sorption process. In order to determine the reusability potential of the adsorbent, the isolated beads were used as a regenerated sorbent in repeated sorption-desorption cycles. Results revealed that the magnetic beads produced can be potentially used for the treatment of waste water contaminated with heavy metals and regenerated at least five times before losing their activity

Development of highly porous biodegradable gamma-Fe2O3/polyvinyl alcohol nanofiber mats using electrospinning process for biomedical application

The use of electrospinning process in fabricating tissue engineering scaffolds has received great attention in recent years due to its simplicity. The nanofibers produced via electrospinning possessed morphological characteristics similar to extracellular matrix of most tissue components. Porosity plays a vital role in developing tissue engineering scaffolds because it influences the biocompatibility performance of the scaffolds. In this study, maghemite (γ-Fe 2 O 3 ) was mixed with polyvinyl alcohol (PVA) and subsequently electrospun to produce nanofibers. Five factors; nanoparticles content, voltage, flow rate, spinning distance, and rotating speed were varied to produce the electrospun nanofibrous mats with high porosity value. Empirical model was developed using response surface methodology to analyze the effect of these factors to the porosity. The results revealed that the optimum porosity (90.85%) was obtained using 5% w/v nanoparticle content, 35 kV of voltage, 1.1 ml/h volume flow rate of solution, 8 cm spinning distance and 2455 rpm of rotating speed. The empirical model was verified successfully by performing confirmation experiments. The properties of optimum PVA/γ-Fe 2 O 3 nanofiber mats such as fiber diameter, mechanical properties, and contact angle were investigated. In addition, cytocompatibility test, in vitro degradation rate, and MTT assay were also performed. Results revealed that high porosity biodegradable γ-Fe 2 O 3 /polyvinyl alcohol nanofiber mats have low mechanical properties but good degradation rates and cytocompatibility properties. Thus, they are suitable for low load bearing biomedical application or soft tissue engineering scaffold