Moisture Absorbents Research Articles

Sandwich-Structured Photothermal Wood for Durable Moisture Harvesting and Pumping.

Moisture capture coupled with photothermal regeneration provides an alternative and sustainable way to acquire fresh water. Composite moisture absorbents based on hygroscopic salts are environmentally friendly, economically feasible, and of high efficiency but suffer from the unavoidable desiccant leakage during absorption and evaporation-induced salt accumulation on material surfaces during desorption. In this study, we develop a superhydrophobic-hydrophilic-hydrophobic photothermal wood embedded with CaCl2 to promote the durability of the absorbents. The sandwich structure serves as a liquid/vapor gate allowing vapor transport but forbidding liquid permeation, enabling the condensation and evaporation within the wood. Beyond moisture harvesting, the sandwich-structured photothermal wood exhibits potential in indoor dehumidification by pumping the moisture through an absorption-desorption cycle.

New Bio-Based Furanic Materials Effectively Absorb Metals from Water and Exert Antimicrobial Activity.

Development of sustainable bio-based materials for removal of toxic contaminants from water is a high priority goal. Novel bio-based binary and ternary copolymers with enhanced ion-exchange, adsorption and antibacterial properties were obtained by using plant biomass-derived diallyl esters of furandicarboxylic acid (FDCA) as crosslinking agents and easily available vinyl monomers. The synthesized copolymer materials showed higher sorption capacities for NiII , CoII and CuII compared to the commercial ion-exchange resins, and they maintained their high metal adsorption capacities for over 10 cycles of regeneration. The synthesized copolymer gels containing 1-5 wt % of the crosslinker showed excellent water absorption capacities. The synthesized copolymers with 1 % crosslinker content showed swelling ratios high enough to also act as moisture absorbents. Synthesized copolymers with crosslinker content of 10 wt % performed as contact-active antibacterials by inhibiting the growth of Gram-positive (S. aureus) and Gram-negative bacteria (E. coli, K. pneumonia) in suspension tests.

EXPERIMENTAL CHECKING OF ABSORPTION OF MOISTURE ABSORBERS IN VARIOUS CLIMATE CONDITIONS

The article presents results of tests for moisture absorbers currently used and available on the market. Experimental investigations were carried out for two types of silica gels, the bentonite clay and two types of molecular sieves available on the market, as well as for the reused silica gel currently deployed in weapon systems. As part of the work, the maximum absorbency of moisture absorbers for various climatic conditions, the minimum relative humidity (RH) in the drying measuring chamber for various amounts of absorbent, and the durability of water binding at variable temperature conditions were determined. Analysis of results allowed both to compare advantages and disadvantages of various absorbents, and to assess a degree of the wear for moisture absorbents currently used in armament equipment.

Growth, Yield and Quality of Rabi Sunflower as Influenced by Moisture Absorbents, Organic and Inorganic Fertilizers

Growth, Yield and Quality of Rabi Sunflower as Influenced by Moisture Absorbents, Organic and Inorganic Fertilizers

Microgravimetric Thermodynamic Modeling for Optimization of Chemical Sensing Nanomaterials

On the basis of microgravimetric sensing data, an analytical modeling method is proposed for comprehensive evaluation and optimization of gas sensing or adsorbing related functional materials. Resonant microcantilever is loaded with the material to be evaluated for a gravimetric sensing experiment. With sensing isotherm curves obtained at different temperatures, key thermodynamic and kinetic parameters of the material, such as enthalpy ΔH°, Gibbs free energy, adsorption rate constant Ka, and coverage θ, etc., can be quantitatively extracted for optimal selection and design. On the basis of the gravimetric experiment, the modeling method is used on three sorts of trimethylamine sensing nanomaterials of mesoporous silica nanoparticles (MSNs). The COOH-functionalized material is clearly identified as the best sensing material among the three similar ones, thereby validating high accuracy of the proposed model. Broad applicability of the modeling method to other sensing materials and/or target gases is also experimentally confirmed, where sensing properties of a functionalized hyper-branched polymer to organophorous simulant of dimethyl methylphosphonate (DMMP) are still evaluated well. In addition to sensing materials, the gravimetric experiment-based modeling method can be expanded to other functional materials like moisture absorbents or detoxification agents. Water adsorbing experiment on KIT-5 mesoporous-silica is modeled, with the low -ΔH° value (i.e., low adsorption heat) result, indicating that the KIT-5 is a good adsorbent to humidity. Alternatively, the modeled high -ΔH° value (i.e., high reaction heat) shows promising usage of SBA-15 mesoporous-silica as detoxification material to hazardous organophorous chemicals. Therefore, the analytical modeling technology can be used for developing and evaluating new adsorbing materials for gas sensing, fixing, and detoxification applications.

Shelf-life enhancement of green bell pepper (Capsicum annuum L.) under active modified atmosphere storage

Abstract The effect of modified atmosphere packaging (MAP) along with moisture absorbent was assessed for maintaining quality attributes and extending shelf life of green bell pepper ( Capsicum annuum L.) in bulk packages. Under active packaging the quality of capsicum were based on MAP using permeable polymeric films and sachets of silica gel crystals as moisture absorbents. Pre-designed polypropylene film (38 μm) packages were used for storage study under MAP at 8 ± 1 °C temperature. The in-pack O 2 and CO 2 composition and respiration rate in the package headspace was monitored during storage in all the treatments. A modified atmosphere of 4.5% O 2 , 7.8% CO 2 and 4.7% O 2 , 7.5% CO 2 were achieved in the MA packages with and without moisture absorbent, respectively. The active packaging significantly reduced the respiration rate of fruit in the package. These packaged fruits were compared with non-packaged samples, which served as control stored at both ambient conditions (CS) and control at refrigerated temperature (CR). The quality of capsicums was assessed by physiological weight loss, color ( L *, h * and C *) values, firmness, ascorbic acid, decay and marketability. The shelf life of bell pepper was extended to 49 days in active packages, 42 days with MA packages, as compared to 21 days with CR packages and 7 days with CS. Above all, by placing silica crystals sachets in the head space with moisture absorbing ability, could further extend the shelf life of capsicum 7 days in addition to modified atmosphere packaging alone with 97% fruit marketability.

Enhancing the Thermotolerance of Entomopathogenic Isaria fumosorosea SFP-198 Conidial Powder by Controlling the Moisture Content Using Drying and Adjuvants

Entomopathogenic fungi are promising pest-control agents but their industrial applicability is limited by their thermosusceptibility. With an aim to increase the thermotolerance of Isaria fumosorosea SFP-198, moisture absorbents were added to dried conidial powder, and the relationship between its water potential and thermotolerance was investigated. Mycotized rice grains were dried at 10°C, 20°C, 30°C, and 40°C and the drying effect of each temperature for 24, 48, 96, and 140 hr was determined. Drying for 48 hr at 10°C and 20°C reduced the moisture content to < 5% without any significant loss of conidial thermotolerance, but drying at 30°C and 40°C reduced both moisture content and conidial thermotolerance. To maintain thermotolerance during storage, moisture absorbents, such as calcium chloride, silica gel, magnesium sulfate, white carbon, and sodium sulfate were individually added to previously dried-conidial powder at 10% (w/w). These mixtures was then stored at room temperature for 30 days and subjected to 50°C for 2 hr. The white carbon mixture had the highest conidial thermotolerance, followed by silica gel, magnesium sulfate, and then the other absorbents. A significant correlation between the water potential and conidial thermotolerance was observed in all conidia-absorbent mixtures tested in this study (r = −0.945). Conidial thermotolerance in wet conditions was evaluated by adding moisturized white carbon (0~20% H2O) to conidia to mimic wet conditions. Notably, the conidia still maintained their thermotolerance under these conditions. Thus, it is evident that conidial thermotolerance can be maintained by drying mycotized rice grains at low temperatures and adding a moisture absorbent, such as white carbon.

Metal oxide/polymer hybrid nanofiber as flexible moisture absorbent

In order to realize flexible organic light emitting diode (OLED), it is critically important to protect moisture and oxygen penetration into the flexible device through the polymer substrates because of intrinsically poor stability of organic materials of OLED to moisture. Since complete protection of the moisture penetration is almost impossible, moisture absorbents are used inside OLED. In this study, metal oxide/polymer hybrid nanofiber with mechanical flexibility and efficient moisture absorption capability was fabricated by electrospinning. Hydrophilic poly(vinyl pyrrolidone) (PVP) or hydrophobic poly(vinylidenefluoride) (PVDF) and calcium oxide (CaO) were used as the fiber forming polymers and as the moisture absorbing particle, respectively. Polymers were first dissolved in appropriate solvents and CaO was then dispersed in the prepared polymer solutions. The hybrid solution was then electrospun, producing the hybrid nanofiber web looking like paper with thickness of about 100 µm. It was observed that all CaO particles were uniformly held by the nanofiber. It was also observed that only a small portion of the surface of CaO particles was covered by fiber since the fiber diameter was much smaller than the CaO particle size. This implied effective moisture absorption through the free surface of CaO. The hybrid nanofiber absorbed moisture very efficiently upto about 70 % of the nanofiber mass. Once moisture was absorbed by the nanofiber, it was never released even at 150 °C in vacuum for 2 hours. It is, therefore, expected that the nanofiber may be applied as the flexible thin moisture absorbent to improve stability of the flexible OLED.

Importance of excipient wettability on tablet characteristics prepared by moisture activated dry granulation (MADG)

For moisture activated dry granulation (MADG), microcrystalline cellulose (MCC) or silicon dioxide is recommended for the moisture absorption stage. The aim of this study was to assess the suitability of alternative excipients as moisture absorbents with regard to the disintegration mechanism of resulting lactose based placebo formulations. Beside high and low moisture MCC grades, the additions of magnesium aluminometasilicate (MAMS), pregelatinized starch (S1500), crospovidone (Kollidon CL) and carmellose calcium (ECG 505) were evaluated. High shear granulation (HSG) was conducted as a reference process. The overall disintegration time of all tablets produced by MADG was significantly faster whereas hardness yield and mass-variability were equal or superior compared to the HSG process. Powder wettability of the different moisture absorbents was identified to be a key driver for rapid disintegration, whereas tablet porosity had only a minor influence on the target hardness of the tablets.

Synthesis of novel stimuli‐responsive polyglycerol‐based hydrogels

AbstractTemperature and pH‐responsive polyglycerol‐based hydrogels were successfully synthesized and characterized. An increase in polyglycerol molecular weight was achieved by cross‐linking polyglycerol using multifunctional electrophilic epoxide‐containing compounds. The chemical structure of polyglycerol‐based hydrogels was determined by FTIR spectroscopy. The temperature‐dependent swelling behavior of the hydrogels was studied at 293, 310, 333, and 353 K and a negative temperature‐sensitive system was observed. The hydrogels exhibited pH sensitivity at pH 4, 7, and 10. The hydrophilicity and biocompatibility of these hydrogels make them suitable for pharmaceutical, biomedical, and biotechnological applications. They could potentially serve as a replacement for fossil‐based poly(ethylene glycol) and poly(vinyl alcohol) hydrogels.Practical applications: Polyglycerol produced from glycerol consists of an inert polyether backbone with functional hydroxyl side groups which make it very suitable for the design of hydrogels. The structure of this biocompatible hydrogel resembles well‐known fossil‐based hydrogels poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVOH). Polyglycerol‐based hydrogel is suitable for applications in the pharmaceutical, biomedical, and biotechnological fields as drug delivery, tissue engineering, and hydrogel adhesives for wound dressing. Furthermore, since these hydrogels show relatively high swelling ratios, they can be used as moisture absorbents and solvent dryers.

Preparation and Characterization of Hydrogel Based on Poly(vinyl alcohol) Cross-Linked by Different Cross-Linkers Used to Dry Organic Solvents

Poly(vinyl alcohol) (PVA) hydrogels were chemically cross-linked with/without different cross-linkers such as glutaraldehyde and epichlorohydrin, in the presence of a catalyst, or activator (potassium hydroxide) to produce three types of hydrogels. The structures of PVA and the prepared gel types were determined by FTIR spectroscopy, the mechanical and thermal properties, of these hydrogels were examined. The effects of different pH values and temperatures on the swelling properties of the prepared gels were examined. From the obtained results, it was found that, the low concentration of the cross-linker produced hydrogel with moderate properties, but in absence of the cross-linker, the obtained hydrogel exhibited good properties and can be used as friendly environmentally moisture absorbents from the organic solvents. The insolubility and swelling properties of gels were tested in these solvents. The results indicated that these hydrogels can be used as moisture absorbents and solvent dryers.

A Novel Moisture-Absorbing Extracellular Polysaccharide from Rhodococcus rhodochrous SM-1.

An extracellular polysaccharide (EPS) prepared from SM-1, a mucoidal mutant of Rhodococcus rhodochrous ATCC 12674 was found to absorb and retain moisture in both dry and high-temperature environments. The EPS absorbed more than 120% and 17% of its weight in moisture under the conditions of 32% and 11% relative humidity, respectively, representing much higher absorption than that of known moisture absorbents such as silica gel, glycerol, and hyaluronic acid. The SM-1 EPS is an acidic polysaccharide containing D-galactose, D-glucose, L-fucose, and D-glucuronic acid at a molar ratio of 6: 3: 2: 4. In addition, 1.2% (W/W) stearic acid, 2.3% (W/W) palmitic acid, and 10.3% (W/W) pyruvic acid were also contained in the SM-1 EPS. These evidences indicate that the SM-1 EPS is a novel moisture-absorbing biopolymer.

PREDICTING RELATIVE HUMIDITY IN MODIFIED ATMOSPHERE PACKAGING SYSTEM CONTAINING BLUEBERRY AND MOISTURE ABSORBENT

A modified respiration-transpiration model was developed to predict the relative humidity in modified atmosphere packaging system containing fresh produce and moisture absorbent. The model is based on heat and mass balances accounting for the respiratory and transpiratory behavior of the fresh produce, the transport phenomena across the package, and the moisture sorption behavior of the absorbent. A set of experiments was conducted to obtain the parameter values that were necessary for generating model predictions. Another set of experiments was conducted using model packages containing blueberries and moisture absorbents Sanwet and xylitol to obtain experimental data under various conditions, including different weights of blueberries, types of absorbers, weights of absorbers, and temperatures. In general, the model predictions agree well with the experimental data, except the model sometimes exaggerates the effects of the absorbent in the initial period (<10 h).

APPLICATION OF MODIFIED ATMOSPHERE PACKAGING AND HUMIDITY CONTROL TO EXTEND THE STORAGE LIFE OF GRAPE VARIETIES GROWN IN EASTERN UNITED STATES - A COMPARATIVE STUDY

In 1987, 1988, and 1989, the behavior of four different table grape varieties including Alden, Concord, Himrod, and Vanessa were studied during storage at 0°C.The first objective of our study was to determine the behavior of table grapes in modified atmosphere packages in terms of general acceptance. After three years of experimenting with these three films we were able to obtain a modified atmosphere of about 3% O2 and 10-15% CO2 at 0°C using a 3 mil thickness LDPE.Our second objective was to use moisture absorbents as a means of reducing the relative humidity inside the void volume of a package by the inclusion of different desiccants in the package to establish a desirable relative humidity.Examining different storage characteristics, our data showed that `Himrod', `Vanessa', and `Concord' grape clusters stored in the presence of KNO3 and KCl had better quality compared to grape clusters stored in the presence of other sorption compounds or controls with no sorbants.

Investigations on the effect of sodium bentonite and other moisture absorbents on the production of effluent from grass silage

Sodium bentonite, a hydrolyzed starch-polyacrylonitrile graft co-polymer (SGP (R)) and alkali-treated straw were examined for their ability to stem the flow of effluent from silage made from low dry matter grass (105–172 g kg −1. Substantial reductions in effluent resulted from applications of these absorbents in excess of 10 g kg −1. Sodium bentonite was marginally more effective in this respect than SGP on an equi-weight basis whilst alkalitreated straw was the least effective.

The effectiveness of moisture absorbents in double-glazing units

The effectiveness of moisture absorbents in double-glazing units