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This study reports on the unique water vapor adsorption properties of biomass-derived starch particles (SPs). SPs offer an alternative desiccant for air-to-air energy exchangers in heating, ventilation, and air conditioning systems because of their remarkable adsorption–desorption performance. SP 15 has a particle diameter ( d p ) of 15 μm with a surface area (SA) of 2.89 m 2 /g and a pore width ( P w ) of 80 Å. Microporous starch particles (SP 15 ) were compared with high amylose starch (HAS 15 ; SA = 0.56 m 2 /g, d p = 15 μm, P w = 46 Å) and silica gel (SG 13 ; SA = 478 m 2 /g, d p = 13 μm, P w = 62 Å). Transient water vapor tests were performed using a customized small-scale energy exchanger coated with SP 15 , HAS 15 , and SG 13 . The water swelling (%) for SP 15 was ca. 2 orders of magnitude greater with markedly higher (ca. three- and six-fold) water vapor uptake compared to HAS 15 and SG 13 , respectively. At similar desiccant coating levels on the energy exchanger, the latent effectiveness of the SP 15 system was much improved (4–31%) over the HAS 15 and SG 13 systems at controlled operating conditions. SP 15 is a unique desiccant material with high affinity for water vapor and superior adsorption properties where ca. 98% regeneration was achieved under mild conditions. Therefore, SPs display unique adsorption–desorption properties, herein referred to as the “Goldilocks effect”. This contribution reports on the utility of SPs as promising desiccant coatings in air-to-air energy exchangers for ventilation systems or as advanced materials for potential water/energy harvesting applications.

The sorption of water vapor on high amylose starch was investigated as an alternative desiccant for air-to-air energy exchangers used in ventilation units. Sorption performance of micron-sized mesoporous high amylose starch (HAS15, d p = 15 μm, P w = 46 Å) and two mesoporous silica gel samples (SG13, d p = 13 μm, P w = 62 Å; P w = 62 Å; SG55, d p = 55 μm, P w = 77 Å) were studied and compared. Transient water vapor sorption tests were performed using small-scale energy exchangers coated with HAS15 and silica gel. Although N2 gas adsorption tests showed lower sorption capacity for HAS15 compared to the silica gel samples, higher sorption rates and uptake capacity were shown for HAS15 when measured by water vapor transient sorption results. In addition, the latent effectiveness, an indicator of moisture recovery efficiency for exchangers, was calculated for each exchanger. With the same amount of desiccant coated on the energy exchanger channels, the latent effectiveness of the HAS-coated material was 2%–13% greater than that of the silica gel materials, depending on the operating conditions.

Cellulose (CE) was cross-linked with epichlorohydrin (EPI) at variable compositions, and the fractionation properties were investigated in binary water−ethanol (W−E) solutions, including the pure solvent systems. The relative uptake of each solvent was measured using quantitative 1 H nuclear magnetic resonance (qNMR) spectroscopy. This study highlights the utility of qNMR as a rapid screening method for estimation of solvent selective fractionation in binary mixtures. The uptake properties of CE−EPI cross-linked polymers with ethanol and water were well-described using the Sips isotherm model. Modeling shows that the monolayer surface coverage (Q m ) of ethanol and water onto the polymer materials covers a range (1.13−2.44 g/g) of values with heterogeneous adsorption behavior, in agreement with the Sips exponential fitting parameter (n s ≠ 1). The CE−EPI adsorbents display unique fractionation with water and ethanol from binary solutions, as evidenced by the relative selectivity (R selectivity ) value in binary W−E solvent systems. The R selectivity [Q m (W)/Q m (E)] values at saturative conditions varied (from 1.10 to 2.03) and further illustrate that CE materials display molecular selective solvent fractionation in binary W−E solutions. This study provides a greater molecular level understanding for the adsorptive uptake properties of CE that are relevant to developing CE-based adsorbent technology for the fractionation of biofuels and related chemical separations.

Oxidation is a chemical reaction that occurs in lubricants upon exposure to an oxidizing agent such as oxygen and can be catalyzed by copper and iron. Antioxidants are a group of chemicals that can be used in the formulation of lubricants to stop or reduce the rate of oxidation. Based on the mechanism of action, antioxidants are categorized as primary antioxidants (radical scavengers), secondary antioxidants (Peroxide decomposers), and metal deactivators (complex-forming or chelating agents). Selection of the antioxidants in a formulation is a critical decision that depends on the base oil, application and other ingredients in the formulations. Presence of some other ingredients in the product with antagonistic behavior may suppress the role of antioxidants; however, optimal application of antioxidants with synergistic behavior would increase the stabilization impact of the ingredients on the base oil.

This Research Article describes a systematic study on the structure and sorption properties of Carnation-based starch-particles (SPs) by various techniques. Structural characterization of the SPs utilized spectroscopy (1H NMR and FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The sorption properties of the SPs were characterized by solvent swelling and uptake isotherms with cationic adsorbates at equilibrium and kinetic conditions. The surface area (SA; ∼3–588 m2/g) of the SPs was estimated using nitrogen gas and dye adsorption isotherm methods, where the range in SA was related to solvent swelling effects on the textural properties. The SPs contain lipid constituents according to results obtained by 1H NMR spectroscopy, DSC, and confocal laser microscopy (CLM) with iodine staining. The unique solvent swelling properties of the SPs reveal greater swelling in water over ethanol. SPs display preferential equilibrium uptake of methylene blue (MB; Q m ≈ 716 mg/g) over cetylpyridinium bromide (CPB; Q m ≈ 292 mg/g). The uptake of MB was reduced by an order of magnitude (Q m ≈ 67 mg/g) when the SPs were doped with CPB, further revealing the role of competitive adsorption and similar binding modes for MB and CPB. The doping of SPs with CPB provide a facile approach for alteration of the surface functional properties such as the hydrophile–lipophile character, surface charge, and hydration properties of the SPs. Evidence of monolayer and multilayer adsorption of CPB onto SPs lead to switchable adsorption properties where such amphiphile surface patterning can be harnessed to yield materials with unique controlled-release properties for diverse chemical systems according to tunable surface charge using self-assembly.

Various structural forms of poly(aniline) (PANI) were synthesized in aqueous solution with different acids and/or a chitosan template support to afford nanoparticle PANI (NP; synthesized in water), bulk-PANI (aqueous acetic acid (HAc), hydrochloric acid (HCl) and sulfuric acid (SA) and a chitosan-PANI composite (CH) material. The polymer materials were characterized using spectroscopy ( 1 H NMR, FT-IR, UV-vis), TGA and P-XRD. The polymer materials were structurally diverse according to their unique morphology related to the ratio between quinoid and benzenoid monomer units of PANI. The sorption and kinetic uptake properties of PANI materials with methylene blue (MB) in aqueous solution were studied where variable sorption capacity was observed, as follows: NP > HAc > HCl > SA > CH. The Sips isotherm model describes the adsorptive equilibrium uptake while the pseudo-second order kinetic model describes the time dependent uptake of MB. The monolayer sorption capacities (Q m ) reported herein are among the highest (ca. 6-fold greater) relative to other Q m values reported for PANI materials in the literature.

Molecular selective adsorption processes at the solid surface of biopolymers in mixed solvent systems are poorly understood due to manifold interactions. However, the ability to achieve adsorptive fractionation of liquid mixtures is posited to relate to the role of specific solid–liquid interactions at the adsorbent interface. The hydration of solid biopolymers (amylose, amylopectin, cellulose) in binary aqueous systems is partly governed by the relative solvent binding affinities with the biopolymer surface sites, in accordance with the role of textural and surface chemical properties. While molecular models that account for the surface area and solvent effects provide reliable estimates of hydration energy and binding affinity parameters, spectroscopic and thermal methods offer a facile alternative experimental approach to account for detailed aspects of solvation phenomena at biopolymer interfaces that involve solid−liquid adsorption. In this report, thermal and spectroscopic methods were used to understand the interaction of starch- and cellulose-based materials in water–ethanol (W–E) binary mixtures. Batch adsorption studies in binary W–E mixtures reveal the selective solvent uptake properties by the biomaterials, in agreement with their solvent swelling in pure water or ethanol. The nature, stability of the bound water, and the thermodynamic properties of the biopolymers in variable hydration states were probed via differential scanning calorimetry and Raman spectroscopy. The trends in biopolymer–solvent interactions are corroborated by dye adsorption and scanning electron microscopy, indicating that biopolymer adsorption properties in W–E mixtures strongly depend on the surface area, pore structure, and accessibility of the polar surface groups of the biopolymer systems, in agreement with the solvent-selective uptake results reported herein.