Insight into the Sorption and Activation Energy Phenomenon of Kenaf Shive Sorbents in Crude Oil/Water Mixture

The secondary effect discovery of synthetic sorbents opened another research direction for many field of studies. However, the sorption parameters of lignocellulosic sorbents are rarely reported most importantly, kenaf shive. This paper centered at the sorption behavior of optimized kenaf shive sorbents using Response Surface Methodology (RSM) via surface deposit technique. Five-level Central Composite Design (CCD) experimental matrix was used to analyze the effect of particle sizes (125-1000 µm), stirring time (5-30min) and methyltrimethoxysilane (MTMS) concentration (5-20% v/v) as individual and combined variables process in the developed sorbents. The unmodified shive was compared with the modified, and it reveals a positive shift in the sorption capability. Instrumental analysis such as FTIR (Fourier Transform Infra-Red), DT-TGA (Differential Thermal-Thermogravimetric analysis) and BET (Brunaure-Emmett-Teller) were carried out on the optimized sorbent and the results were in conformity with the sorption results. The sorption behavior deployed fits the pseudo-first-order and Langmuir isotherm with regression coefficient R2=0.9496 and R2=0.9400. The sorption property was found to be spontaneous and exothermic, however, the activation energy studies shows physic-sorption phenomenon with 25.3 kJmol-1 and R2=0.9360.

Strength and dimensional stability of cement-bonded wood waste-sand bricks

Conservation of trees which belong to renewable natural resources in developing countries through judicious utilization in building industry has been seriously left unattended to over the years. The utilization of this unprocessed wealth materials which could serve as one of the alternative constituents in construction materials is now a global concern. Therefore, the needs to investigate the strength and water sorption property of wood waste as a partial replacing material in brick production for building construction arise. Sawdust, sand and cement were mixed together at three different mixing ratios of 1 : 1 : 1, 1 : 1 : 2 and 1 : 1 : 3. The brick samples were replicated three times and subjected to water absorption, density and compressive strength tests. The results show that the effect of the equal volume of sand and sawdust with a subsequent increase in the cement portion at each mixing ratio level gave compact bricks without sudden fracture, reduced unit weight of bricks and subsequent lower water sorption properties of the bricks. The bricks show potentials to be used for wall partitioning. The introduction of sawdust also serves as partial sand replacement in concrete brick making.

Characterization and Sodium Cations Sorption Capacity of Chemically Modified Biochars Produced from Agricultural and Forestry Wastes

Excessive amounts of sodium cations (Na+) in water is an important limiting factor to reuse poor quality water in agriculture or industry, and recently, much attention has been paid to developing cost-effective and easily available water desalination technology that is not limited to natural resources. Biochar seems to be a promising solution for reducing high loads of inorganic contaminant from water and soil solution, and due to the high availability of biomass in agriculture and forestry, its production for these purposes may become beneficial. In the present research, wheat straw, sunflower husk, and pine-chip biochars produced at 250, 450 and 550 °C under simple torrefaction/pyrolysis conditions were chemically modified with ethanol or HCl to determine the effect of these activations on Na sorption capacity from aqueous solution. Biochar sorption property measurements, such as specific surface area, cation exchange capacity, content of base cations in exchangeable forms, and structural changes of biochar surface, were performed by FTIR and EPR spectrometry to study the effect of material chemical activation. The sorption capacity of biochars and activated carbons was investigated by performing batch sorption experiments, and adsorption isotherms were tested with Langmuir’s and Freundlich’s models. The results showed that biochar activation had significant effects on the sorption characteristics of Na+, increasing its capacity (even 10-folds) and inducing the mechanism of ion exchange between biochar and saline solution, especially when ethanol activation was applied. The findings of this study show that biochar produced through torrefaction with ethanol activation requires lower energy demand and carbon footprint and, therefore, is a promising method for studying material applications for environmental and industrial purposes.

Avaliação da influência do polimento químico na sorpção, solubilidade e microdureza de uma resina acrílica de termopolimerização

The purpose of this study was to evaluate the influence of the chemical polishing, when compared to the mechanical polish, in the sorption, solubility and microhardness of a heat-polymerizable acrylic resin. The heatactivated acrylic resin used was Clássico (Art. Odontológicos Clássico Ltda., S.P.). The properties of sorption and the solubility were tested in accordance with International Organization for Standartization (ISO) specification n. 1567, making 20 samples in the format of disks, divided aleatory in two groups, where the first group received lhe mechanical polish with abrasive pastes, and the second, the chemical polish during IOS, in the chemical polisher PQ 9000 (série 4868-2, Termotron do Brasil Ltda., Piracicaba, SP). The samples were maintained in a desiccator with silica gel, at 37 DC, until the moment they reached constant mass (M1), obtained in a scale with resolution of 0,0001g. The samples were submerged in distilled water, at 37 Uc, for 7 days, when it was Obtained new mass value (M2). The difference between M1 and M2 divided by the volume Of each sample resulted in the sorption. The samples were desiccated again until they reach constant mass (M3). The difference between M1 and M3 divided by the volume of each sample resulted in the solubility Of the same ones. For the Knoop microhardness measurement, were made 20 specimens of acrylic resin, of which 10 samples received the mechanical polish and the others, the chemical polish. The Knoop microhardness test was made with a NU Research Microscope (VEB Carl Zeiss JENAGermany). The results indicated that the technique of the chemical polish is acceptable when considered the sorption property, even so unviable with the solubility property, in accordance with the specification n.1567 of ISO. The chemical polish also reduced significantly the superficial microhardness of the acrylic resin, which consequences can interfere in the clinical performance of the material.

Análise da movimentação de dentes de próteses totais polimerizadas com energia de microondas em função da sorção de água: influência da pressão e temperatura

The processing of denture base resins may originate dimensional changes that can alter the occlusal position of artificial teeth of the concluded prosthesis. The polymerization method and the water sorption property of the acrylic resin may cause these changes. Pressure, temperature, and time of water sorption may also have influence on the previous alterations. The aim of this research was to verify the alteration of buccal cusps position of first molars on marillary dentures, polymerized by water bath (9 hours at 76ºC) and microwave energy (3 min at 500W), regarding water sorption under different conditions of time, pressure, and temperature of water storage. Sixty dentures were waxed onto metal die simulating an edentulous maxilla and divided into 4 groups (GI, GII, GIII, and GIV) of 15 samples each. Four different treatments, as follows, were applied to these samples: processing by water bath and stored in water under environmental pressure for 30 days at 37±2ºC (control -GI); processing by water bath and stored in water under 40 pounds for 1 hour at 60±2ºC (Gll): processing br microrwawe energy and stored in water under environmental pressure for 30 days at 37±2ºC(GIII): and processing by microware enerrgy and stored in water under 40 pounds for 1 hour at 60±2ºC (GIV). The degree diferences obtained between the pre and post water sorption were 0.65 for GI; 0.55 for GII; 0.83 for GIII, and -0.57 for GIV (p>0.05). There was significant alteration in the positioning of the artificial firth maxillary molars among the control and the treated storage groups, when cured by microwave energy or water bath.

Water Sorption and Solubility of Vanillin-Incorporated Self-Curing Orthodontic Polymethylmethacrylate Resin

Polymethylmethacrylate (PMMA) resin is one of the most commonly used materials for fabricating the base of removable orthodontic appliances. It is known that PMMA resin can promote the adhesion of microbes due to its surface porosity and from long-term use. Vanillin-incorporated PMMA resin has been reported to have antimicrobial effects against Candida albicans. However, the influence of vanillin incorporation on the water sorption and solubility of self-curing orthodontic PMMA resin has not been studied. Objective: To determine the water sorption and solubility of self-curing orthodontic PMMA resin incorporated with different concentrations of vanillin. Materials and methods: Three groups of self-curing orthodontic PMMA resin incorporated with 0.1% and 0.5% vanillin as well as PMMA without vanillin as a control were prepared with ten specimens per group. Water sorption and solubility tests were performed according to ISO 20795-2:2013 specifications. One-way ANOVA and Tukey’s multiple comparison tests at a p<0.05 significance level were used to analyse the data. Results: All three groups met ISO standard requirements. The means of water sorption values showed insignificant differences among the three groups even though the value of the 0.5% vanillin group tended to decrease. Water solubility of the 0.1% vanillin-incorporated group was not significantly different when compared with the control group whereas that of the 0.5% vanillin-incorporated group exhibited a significant lower value when compared with both control and 0.1% vanillin-incorporated groups. This suggests that increasing concentrations of vanillin would decrease the water solubility of PMMA resin. Conclusion: The incorporation of 0.5% vanillin into self-curing orthodontic PMMA resin could significantly reduce its water solubility and showed a trend of less water sorption property. Even with different vanillin concentrations, the water sorption and water solubility properties of PMMA resin were within the ISO standards. Nevertheless, further studies are recommended to determine the amount of residual monomer present in different concentrations of vanillin-incorporated PMMA resin.

Sr2+ sorption property of seaweed-like sodium titanate mats: effects of crystallographic properties

Seaweed-like sodium titanate mats (SSTs) have excellent sorption capacity of Sr2+ compared to sodium trititanate monodispersed nanofibers due to the sodium dititanate structure and its unique nano/micro-scale morphologies.

Physicochemical Characterization of Grewia ferruginea Hochst. ex A. Rich Mucilage for Potential Use as a Pharmaceutical Excipient

Gum and mucilages from natural sources are in recent times increasingly investigated for pharmaceutical applications. Different studies have shown that the gum and mucilage fraction of various species of the genus Grewia were found to be effective viscosity enhancers, stabilizers, disintegrants, suspending agents, gelling agents, bioadhesives, film coating agents, and binders. However, no study has been conducted on the potential use of Grewia ferruginea mucilage (GFM) as a pharmaceutical excipient. Therefore, this study was aimed at characterizing the Grewia ferruginea bark mucilage for its potential use as a pharmaceutical excipient. The mucilage was extracted from the Grewia ferruginea inner stem bark through aqueous extraction, precipitated with 96% ethanol, dried, and powdered. The powdered mucilage was characterized for different physicochemical properties such as powder property, loss on drying, solubility and swelling index, ash value, pH, viscosity, moisture sorption property, microbial load, and acute oral toxicity. According to the results, the percentage yield of the final dried and powdered GFM was found to be 11.96% (w/w). The density and density-related properties of the mucilage showed good powder flow property. The GFM exhibited pseudoplastic flow behavior. Moisture sorption property of GFM revealed its hygroscopic nature, and its solubility and swelling property was increased with temperature. The pH of GFM was near neutral. Microbial load of the mucilage was within the pharmacopoeial limit, and the oral acute toxicity test revealed that the mucilage is safe up to 2000 mg/kg. From the investigations of this study, it can be concluded that Grewia ferruginea bark mucilage has the potential to be utilized as an excipient in pharmaceutical formulations.