Surface modification of nano-TiO2 with lanthanide-acetylacetonate complexes

The surface modification of nano-TiO2 was carried out with lanthanide-acetylacetonate complexes by adsorption method. The effects of lanthanide complexes content, lanthanide element type, adsorption temperature, solvent dosage, adsorption time and other conditions on the photodegradation activity of methyl orange by the modified catalyst were studied, and suitable modification conditions were obtained. The results show that the photocatalytic activity of the modified nano-TiO2 is much higher than that of the unmodified pure TiO2, and the lanthanide-acetylacetonate complexes is an excellent surface modifier.

The Adsorption Performance of Polyaniline/ZnO Synthesized through a Two-Step Method

Polyaniline/Zinc oxide (PANI/ZnO) were prepared using a two-step method, and the morphology and the structure of PANI/ZnO composites were characterized through a scanning electron microscope (SEM) and X-ray diffraction (XRD). Factors such as the content of ZnO, the adsorption time and the mass of the adsorbent, and the kinetic equation of PANI/ZnO as adsorbents for the adsorption of methyl orange solution were studied. The results showed that the adsorption efficiency of methyl orange by polyaniline with the increase of adsorbent mass firstly increased and then decreased. Among the composites with the same quality, PANI composites with 8% ZnO have a better adsorption effect for methyl orange, and the maximum adsorption ratio can reach 69% with the increase of adsorption time at 0.033 g; With the increase of adsorbent mass, the adsorption efficiency of PANI composites with 8% ZnO increased continuously. When the mass increased from 0.033 g to 0.132 g, the adsorption rate increased from 69% to 93%, and the adsorption of the methyl orange solution by PANI/ZnO composites was more in line with the quasi-second-order kinetic equation.

Bleaching optimization of tuna (Thunnus sp.) oil using response surface methodology

The quality of crude tuna (Thunnus sp.) oil aimed for food-sector-purpose can be improved by performing purification. The present study was aimed to optimize the bleaching step during the purification process and determine the optimum variable conditions using response surface methodology (RSM) in obtaining the lowest oxidation parameters value to meet the International Fish Oil Standard (IFOS) standard. A total of five responses including free fatty acids (FFA) value, acid value (AV), peroxide value (PV), anisidine value (AnV) and total oxidation (Totox) value were studied using central composite design (CCD), a full factorial design with all combinations of the factors at two levels (high, +1, and low, −1 level), repeated thrice; applied for two variable factors (adsorbent concentration [A];% and adsorption time [B]; mins). The optimum model suggested by the program was a quadratic model for FFA and AnV, and a linear model for AV, PV and Totox value. The optimum response was reached by the combination of 5% adsorbent concentration [A] with adsorption time [B] of 20 mins. This formula reduced the FFA value, AV, PV, AnV, and Totox Value up to 56.57%, 55.36%, 88.86%, 69.69% and 77.03%, respectively. The purified tuna oil has a clear yellow colour appearance with a rising percentage of pure fish oil for EPA and DHA of 10.71% and 11.50% from crude tuna fish oil.

Removal of Nickel Ions from Aqueous Solutions by 2-Hydroxyethyl Acrylate/Itaconic Acid Hydrogels Optimized with Response Surface Methodology

The adsorption of Ni2+ ions from water solutions by using hydrogels based on 2-hydroxyethyl acrylate (HEA) and itaconic acid (IA) was studied. Hydrogel synthesis was optimized with response surface methodology (RSM). The hydrogel with the best adsorption capacity towards Ni2+ ions was chosen for further experiments. The hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis before and after the adsorption of Ni2+ ions. Batch equilibrium experiments were conducted to investigate the influence of solution pH, hydrogel weight, ionic strength, adsorption time, temperature and initial concentration of nickel ions on the adsorption. Time-dependent adsorption fitted the best to the pseudo-second-order kinetic model. A thermodynamic study revealed that the adsorption was an exothermic and non-spontaneous process. Five isotherm models were studied, and the best fit was obtained with the Redlich–Peterson model. Consecutive adsorption/desorption studies indicated that the HEA/IA hydrogel can be efficiently used as a sorbent for the removal of Ni2+ ions from the water solution. This study develops a potential adsorbent for the effective removal of trace nickel ions.

Bacteria Cell Hydrophobicity and Interfacial Properties Relationships: A New MEOR Approach

For microbial enhanced oil recovery (MEOR), different mechanisms have been introduced. In some of these papers, the phenomena and mechanisms related to biosurfactants produced by certain microorganisms were discussed, while others studied the direct impacts of the properties of microorganisms on the related mechanisms. However, there are only very few papers dealing with the direct impacts of microorganisms on interfacial properties. In the present work, the interfacial properties of three bacteria MJ02 (Bacillus Subtilis type), MJ03 (Pseudomonas Aeruginosa type), and RAG1 (Acinetobacter Calcoaceticus type) with the hydrophobicity factors 2, 34, and 79% were studied, along with their direct impact on the water/heptane interfacial tension (IFT), dilational interfacial visco-elasticity, and emulsion stability. A relationship between the adsorption dynamics and IFT reduction with the hydrophobicity of the bacteria cells is found. The cells with highest hydrophobicity (79%) exhibit a very fast dynamic of adsorption and lead to relatively large interfacial elasticity values at short adsorption time. The maximum elasticity values (at the studied frequencies) are observed for bacteria cells with the intermediate hydrophobicity factor (34%); however, at longer adsorption times. The emulsification studies show that among the three bacteria, just RAG1 provides a good capability to stabilize crude oil in brine emulsions, which correlates with the observed fast dynamics of adsorption and high elasticity values at short times. The salinity of the aqueous phase is also discussed as an important factor for the emulsion formation and stabilization.

Characterization of vB_Sau_S90, and vB_Sau_S165, a Broad Host Range Phages, and Multiple Phage Doses as a Potential Therapeutic Strategy to Eliminate Transient Phage Resistant Mutants in Staphylococcus Aureus

Methicillin-Resistant Staphylococcus aureus is a human pathogen. MRSA has acquired resistance to major antibiotics; thus, phage therapy has become a potential alternative treatment. In this work, two broad host range Staphylococcus phages were characterized for lifecycle, physio-chemical parameters and bacterial killing kinetics, and the in vitro behavior of phage insensitive bacterial cells to alternative serial passage and multiple phage doses were assessed by reduction in the bacterial turbidity and spot assay. Phage vB_Sau_S90 showed an absorption efficiency of 91 ± 0.6% with an adsorption time of 17 ± 1 min and vB_Sau_S165 of 95 ± 0.5% adsorption efficiency and 15 ± 2 min adsorption time. Both the phages were stable over a wide range of temperature (20 to 50 ℃) and pH (3 to 11). vB_Sau_S90 phage belonging to the family Siphoviridae [order Caudovirals] showed killing efficiency against 88% (181/205) of S. aureus isolates, and vB_Sau_S165 belonging to family Podoviridae [order Caudovirals] showed killing efficiency against 94% (192/205) of S. aureus isolates. The sensitive and transient phage-resistant cells that remained uninfected during the single dose of phage treatment were eliminated upon a minimum of five alternative serial passage and multiple phage doses. This study concludes that both the phages showed promising activity against methicillin-resistant Staphylococcus aureus. Our study revealed that despite phage auto-dosing and high therapeutic efficiency, both phages did not produce a complete bacterial clearance at a single phage dose; hence indicated that multiple phage doses were required to attain a successful and complete bacterial eradication.

Efficient Removal of Pb(II) from Aqueous Medium Using Chemically Modified Silica Monolith

The adsorptive removal of lead (II) from aqueous medium was carried out by chemically modified silica monolith particles. Porous silica monolith particles were prepared by the sol-gel method and their surface modification was carried out using trimethoxy silyl propyl urea (TSPU) to prepare inorganic–organic hybrid adsorbent. The resultant adsorbent was evaluated for the removal of lead (Pb) from aqueous medium. The effect of pH, adsorbent dose, metal ion concentration and adsorption time was determined. It was found that the optimum conditions for adsorption of lead (Pb) were pH 5, adsorbent dose of 0.4 g/L, Pb(II) ions concentration of 500 mg/L and adsorption time of 1 h. The adsorbent chemically modified SM was characterized by scanning electron microscopy (SEM), BET/BJH and thermo gravimetric analysis (TGA). The percent adsorption of Pb(II) onto chemically modified silica monolith particles was 98%. An isotherm study showed that the adsorption data of Pb(II) onto chemically modified SM was fully fitted with the Freundlich and Langmuir isotherm models. It was found from kinetic study that the adsorption of Pb(II) followed a pseudo second-order model. Moreover, thermodynamic study suggests that the adsorption of Pb(II) is spontaneous and exothermic. The adsorption capacity of chemically modified SM for Pb(II) ions was 792 mg/g which is quite high as compared to the traditional adsorbents. The adsorbent chemically modified SM was regenerated, used again three times for the adsorption of Pb(II) ions and it was found that the adsorption capacity of the regenerated adsorbent was only dropped by 7%. Due to high adsorption capacity chemically modified silica monolith particles could be used as an effective adsorbent for the removal of heavy metals from wastewater.

Modelling and optimization of free fatty acid reduction in bulk palm cooking oil

Bulk cooking oil from palm oil processing is one of the biodiesel materials which is available in large quantities. The pre-treatment process can be done by adding 100 mesh activated zeolite adsorbent as a substitute for the esterification process to reduce free fatty acid (FFA). The purpose of this research was to model and optimize the zeolite concentration and adsorption time to reduce free fatty acids in bulk palm cooking oil. This study used a response surface method with a central composite design (CCD), resulting in 13 experimental combinations of two factorial treatments, i.e. the concentration of zeolite adsorbent and adsorption time. The zeolite concentration and the adsorption time with an upper limit of 30% and 120 minutes and a lower limit of 10% and 60 minutes had a significant effect on the FFA reduction. The best model was a quadratic model. The testing of validation data used the recommended optimum combination, i.e. the zeolite concentration of 10.59% and the adsorption time of 101.57 minutes resulting in a deviation of 5.37% between the predicted data and the actual data.

Study on synthesis and adsorption property of porous carbon/Ni nanoparticle composites

The porous carbon/Ni nanoparticle composite was prepared by a freeze-drying method using NaCl as the template. It was applied in the effect of the concentration, adsorption time, and temperature of adsorption on the adsorption behavior. The kinetic model and the adsorption isothermic fitting results show that the adsorption behavior fits with the pseudo-secondary dynamics and the Langmuir isothermal model, indicating that the adsorption process is monolayer adsorption. Thermodynamic results indicate that the adsorption process is spontaneous physicochemical adsorption. The fitting showed that the porous carbon/Ni nanoparticle composites reach 217.17 mg·g-1, at 313 K indicates good adsorption for Congo red.

Removal of Congo Red and Procion Red Using Zn/Fe Pillared Bentonite

The process of pillarization of metal oxide Zn/Fe compounds in bentonite has been carried out. The study of adsorbent weight, pH, adsorption time, and initial concentration were investigated to get the optimum reduction of Congo red and Procion red concentration. In addition, the pseudo kinetic also determined to investigate the rate and type of adsorption. From the experiment, the optimum conditions for removal of Congo red for the adsorbent weight, pH, and adsorption time were 0.02 g, 2, 20 minutes, respectively, while for the removal of Procion red was 0.04 g, 2, 20 minutes, respectively and both of adsorbent followed the pseudo-second-order model kinetics with chemisorption mechanism. Although the optimum conditions for removal of the two dyes were similar, in fact the percentage removal of the Congo red dye was greater. In conclusion, the Zn/Fe pillared bentonite was more suitable for the removal of the Congo red than Procion red.