The use of chromium waste sludge for the adsorption of colour from dye effluent streams

Adsorption studies show that chromium hydroxide precipitates can be used for the removal of methylene blue, reactive blue, congo red and disperse orange dyes from aqueous media. Three different mechanisms are involved: attraction of positive surface charges on the precipitate at low pH for dye anions (reactive blue and congo red); attraction of negative surface charges on hydroxide at high pH for dye cations (methylene blue), and dye particle entrapment for the neutral disperse orange. The point of zero charge of the chromium hydroxide precipitate based on the dye adsorption studies is pH 10.5. The changes in the surface charge of such precipitates with pH can be used to achieve the removal of any charged dye species. © 2002 Society of Chemical Industry     

Effect of emulsion temperature on physical properties of palm oil-based margarine

Margarines made from refined, bleached, and deodorized palm oil at different emulsion temperatures showed no significant difference in their consistency, polymorphic behavior, and solid fat content (SFC) during storage, although differences were observed during processing. The emulsion temperatures studied were 40, 45, and 50°C, with other parameters such as emulsion flow rates, tube cooler temperature, and pin rotor speed kept constant. The SFC developed during processing and storage at 28°C was measured to evaluate the quality of margarine. The emulsion contained no SFC at any emulsion temperature studied. However, the amount of SFC in the perfector or tube cooler unit increased to 15.9, 13.9, and 15.6% in margarine produced at emulsion temperatures of 40, 45, and 50°C, respectively. At 40°C, the lowest SFC was developed during storage even though this margarine had the highest consistency. The softening point of this sample was moderately high and closely related to the type of crystal developed, which was a mixture of β′ and β crystals. Emulsion at 45°C gave the most stable margarine consistency and SFC with crystal in the β′ form even after the fourth week. At 50°C, moderately soft product was produced, which might be undesirable for some applications, although the crystals were in the β′ form.     

Effect of scraped-surface tube cooler temperatures on the physical properties of palm oil margarine

The effects of scraped-surface tube cooler temperatures on the isothermal solid fat content (SFC) of palm oil margarine during processing and on margarine consistency (yield value, g/cm²), SFC, and polymorphic changes in storage were studied. SFC was measured in the mixing tank after leaving the tube cooler and the pin worker. The SFC at the tube cooler exit was proportional to the amount of cooling; a higher SFC was produced by more extreme cooling treatment. The SFC of all margarines were reduced in the pin worker, and the reduction was related to the initial SFC profile of palm oil. Margarine samples were stored at 28°C for 28 d and tested daily. Margarine processed at 25°C in the tube cooler had the highest consistency and the least change in SFC, but by the second week crystals had transformed into the β form. Uniform product consistency and SFC were observed in margarines processed at 20 and 15°C. These margarines retained the β′ crystal form for 3 and 4 wk, respectively. The best palm oil margarine was obtained with a tube cooler temperature of 15°C and a residence time of 1.8 min.     

Formulation and Evaluation of an Automatic Dishwashing Detergent Containing T1 Lipase

The use of enzymes in detergent formulations is becoming popular due to the concerns about the environment. T1 lipase (E.C. 3.1.1.3) was evaluated for its stability and performance in dishwashing along with other common components of an automatic dishwashing detergent. Therefore, the process of formulating the detergent would depend on the stability of T1 lipase, which may also reflect the performance during the washing. T1 lipase was mostly stable in nonionic surfactants, especially those that were made of polyhydric alcohols. T1 lipase was also stable in a mixture of sodium carbonate and glycine. However, sodium carbonate alone destabilized T1 lipase possibly due to the interaction between carbonates and Ca²⁺. These results indicated that polyhydric alcohols and glycine had stabilizing effects on T1 lipase. The dishwashing performance was evaluated in term of percent soil removed. The dishwashing performance of the formulated detergent was positively affected by the increase in temperature but negatively affected by the presence of hard water, specifically Ca²⁺ and Mg²⁺. However, T1 lipase was not negatively affected by the presence of hard water, and this enzyme was enhanced by the presence of polyacrylates. The presence of Ca²⁺ improved the structural integrity of T1 lipase. It is generally known that most enzymes that depend on Ca²⁺ for their structural integrity would be greatly destabilized in the presence of metal chelators; thus, stabilizing strategies such as adding glycine would be essential to maintain enzyme activity during the wash.     

Acetanilide-loaded injectable hydrogels with enhanced bioactivity and biocompatibility for potential treatment of periodontitis

Chronic periodontitis poses long-term challenges in dentistry, requiring the development of innovative dental composites with biocompatibility, bone regeneration, and antibacterial properties. This study focuses on synthesis of novel injectable thermoresponsive hydrogels composed of chitosan, sodium bicarbonate, bioactive glass (20 and 40% w/w), and acetanilide drug (0.3 and 0.6% w/w). These hydrogels exhibit a sol–gel transition at 37°C, addressing periodontal challenges with reduced gelation time. The smooth flow characteristic was evaluated through 17-22 gauge syringe needles at low temperature. Rheological studies demonstrated pseudoplastic behavior, with viscosity decreasing as shear rate increases. Fourier transform infrared and x-ray diffraction analysis confirmed the bioactivity of hydrogels, forming a bone-like apatite layer in simulated body fluid. The drug-loaded hydrogels demonstrated promising in vitro antibacterial properties against dental pathogens, specifically Staphylococcus aureus and Pseudomonas aeruginosa. Drug dissolution analysis revealed relatively high release rate at 37°C, highlighting its role in rapidly eliminating bacterial colonies at the target site, while the subsequent sustained release contributes to the prevention of infection recurrence. Finally, biocompatibility was assessed with fibroblast, where the cells were observed anchoring into the polymeric chains of hydrogel through extended filopodia.     

Effect of rolling deformation on the structures and properties of multi‐walled carbon nanotube filled isotactic polypropylene

Isotactic polypropylene filled with various contents of multi‐walled carbon nanotubes (MWCNTs) were fabricated by the injection molding technique and then rolled at room temperature. The unrolled samples (URS) and rolled samples (RS) were characterized by X‐ray diffraction studies, scanning electron microscopy, mechanical and micromechanical tests and differential thermal analyses. Although the URS exhibit the lamellar α‐crystal with a*‐axis orientation, the RS show the same crystals with both a*‐ and c‐axis orientation, which is explained by interlamellar and intralamellar slips and lamellar destruction. Scanning electron micrographs display distinct surface morphological features for both URS and RS. While the tensile strength of RS is higher than that of URS, the Young's modulus (Y) is found to be lower than that of URS. Anisotropy in microharness (H) parallel and perpendicular to the rolled direction has been detected, although H for both samples increases with increasing MWCNT contents. The average relationship H/Y ≈ 0.18 as estimated for URS is closer to the predicted value of 0.10 for polymers than the H/Y ≈ 0.22 obtained for RS. The lamellar thickness for URS increases with increase of MWCNT content and that for RS decreases, as evaluated from both differential thermal analyses and X‐ray diffraction data. Copyright © 2011 Society of Chemical Industry     

The effect of carotene extraction system on crude palm oil quality, carotene composition, and carotene stability during storage

Palm carotene was successfully concentrated from crude palm oil (CPO) by an adsorption process using a synthetic adsorbent followed by solvent extraction. Evaluation of feed CPO and CPO which underwent the carotene extraction process was conducted. The quality of CPO after the extraction process was slightly deteriorated in terms of free fatty acid, moisture content, impurities, peroxide value, anisidine value, discriminant function, and deterioration of bleachability index. However, the CPO still can be refined to produce refined, bleached, deodorized palm oil that meets the Palm Oil Refiners Association of Malaysia specifications. No extra cost was incurred by refining this CPO as the dosage of bleaching earth used was very similar to the refining of standard CPO. The triglyceride carbon number and fatty acid composition of CPO after going through the carotene extraction process were almost the same as CPO data. The major components of the carotene fraction were similar to CPO, which contains mainly α- and β-carotene. The carotene could be stored for at least 3 mon.     

Synthesis and structural characterization of an alternating double aquo-bridged and single cyano-bridged polymeric barium–iron complex: {[Ba2(phen)4(H2O)6Fe(CN)6]·Cl·2(phen)·3H2O}n

A new alternating double aquo-bridged and single cyano-bridged polymeric complex {[Ba₂(phen)₄(H₂O)₆Fe(CN)₆]·Cl·2(phen)·3H₂O}_n (1) (phen = 1,10-phenanthroline) has been synthesized and structurally characterized. In the crystal structure the two centrosymmetric [Ba₂(phen)₄(H₂O)₆] units are bridged through two trans CN groups of [Fe(CN)₆]³⁻ ion, which results in the formation of a zig-zag polymeric chain. In each [Ba₂(phen)₄(H₂O)₆] unit, the two Ba centers are joined by double aquo bridges. Both the Ba atoms are 9-coordinated with distorted mono-capped square antiprismatic geometry. An elaborate hydrogen bonding system holds the parallel polymeric chains together.     

Effects of partial replacement of commercial fillers by recycled poly(ethylene terephthalate) powder on the properties of natural rubber composites

Commercial fillers, including carbon black (N550), halloysite nanotubes (HNTs), and precipitated silica, were replaced by recycled poly(ethylene terephthalate) powder (R‐PET) in natural rubber (NR) composites. Five different compositions of NR/N550/R‐PET, NR/HNTs/R‐PET, and NR/silica/R‐PET compounds, i.e., 100/20/0, 100/15/5, 100/10/10, 100/5/15, and 100/0/20 parts per hundred rubber (phr), were prepared on a two‐roll mill. The curing behavior, tensile properties, and morphological characteristics of the natural rubber composites were investigated. The results indicated that the replacement of carbon black, HNTs, and silica by R‐PET decreased the tensile strength and tensile modulus, such that NR/silica/R‐PET composites showed the lowest effect, followed by NR/HNTs/R‐PET and NR/N550/R‐PET composites. The negative effect on these properties can be explained by the decrease of crosslink density. The curing results revealed that with the replacement of carbon black by R‐PET, the scorch time and cure time decreased, but that the NR/HNTs/R‐PET and NR/silica/R‐PET composites exhibited the opposite trend. Scanning electron microscopy investigation of tensile fracture surfaces confirmed that the co‐incorporation of N550/R‐PET improved the dispersion of R‐PET and enhanced the interaction between the fillers and NR matrix more than R‐PET and silica/R‐PET hybrid fillers. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Thermal and mechanical behavior of natural rubber latex‐silica aerogel film

A major problem in most natural rubber latex (NRL) commonly encountered like other polymer is susceptibility to mechanical properties and thermal degradation; particularly in thin film due to the presence of double bonds in the main chain. Therefore, it is desirable to seek for ways of improving these properties. Silica aerogel is a material with extraordinary properties was believed to have potential enhance properties in NRL films because of its high specific surface area. Therefore, based on the unique character of silica aerogel, NRL‐silica aerogel film was developed by latex compounding and dry coagulant dipping to form thin film where silica aerogel acts as filler. Silica aerogel, synthesized from rice husk was dispersed in a ball‐mill using distilled water for NRL compounding. Results indicate that increasing silica aerogel loading enhances the mechanical properties of the NRL‐silica aerogel film. Effects of postvulcanization processes were also investigated, whereby the best reinforcing effect was obtained at 4 phr silica aerogel loading with leaching postvulcanization condition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012