Publications by authors named "Pedro Nakasu"

Growing environmental concerns have driven the search for sustainable wastewater treatment solutions, particularly for the removal of persistent synthetic dyes. This study explores hydrogels made from squid pen protein (SPP) and chitosan, biodegradable polymers, for anionic dye adsorption-reactive blue 4 (RB4) and methyl orange (MO). A 50%/50% SPP/chitosan hydrogel was optimal for RB4 adsorption while minimizing chitosan use.

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This study explores the use of squid pen protein to enhance the chemical stability and heavy metal ion (Cu and Zn) affinity of β-chitosan. Hydrogel beads with enhanced porosity and scalability were prepared using 1-butyl-3-methylimidazolium acetate, ([BMIM][OAc]), which simultaneously functionalized β-chitosan by decreasing its crystallinity and enhancing binding site access, as indicated by Fourier transform infrared (FT-IR) spectroscopy, which revealed intensification of functional group expression. Notably, this functionalization compensated for the effects of glutaraldehyde crosslinking.

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This study investigates the utilization of squid pen waste through a biocompatible ionic liquid approach, focusing on choline acetate, [Ch][OAc]. This ionic liquid effectively extracts over 80 wt % of protein from squid pen waste. To optimize the extraction process, a factorial design of experiments was employed to achieve a protein recovery of 75% at an estimated purity of 86%, along with highly acetylated, crystalline β-chitin with a purity of up to 95%.

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This study establishes a foundation for the ionic liquid (IL) pretreatment of duckweed biomass. An optimized IL-based process was designed to exploit the unique properties of duckweed including efficient metal removal, potential starch accumulation, and protein accumulation. Two ILs, namely, dimethylethanolammonium formate ([DMEtA][HCOO]) and -dimethylbutylammonium hydrogen sulfate ([DMBA][HSO]), were investigated for the pretreatment of two duckweed species ( and ).

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In this paper, we investigated the effect of cation structure and water content on proton dissociation in alkylammonium [HSO] protic ionic liquids (ILs) doped with 20 wt % water and correlated this with experimental Hammett acidities. For pure systems, increased cation substitution resulted in a reduction in the number of direct anion-anion neighbors leading to larger numbers of small aggregates, which is further enhanced with addition of water. We also observed spontaneous proton dissociation from [HSO] to water only for primary amine-based protic ILs, preceded by the formation of an anion trimer motif.

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The impact of pretreatment severity in the acidic protic ionic liquid (IL) ,-dimethylbutylammonium hydrogen sulfate, [DMBA][HSO] using pine softwood was investigated using a modified severity factor that considers the IL solution acidity based on Hammett acidity. A Box-Behnken experimental design was employed to evaluate pretreatment severity with temperature, pretreatment time, and IL concentration as factors and degree of delignification as the response variable. The optimal pretreatment conditions were found to be at 170 °C, 30 min, and 80 wt % IL, which yielded nearly 90% of delignification and 95% of glucose yield in enzymatic saccharification.

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Biorefineries integrate processes for the sustainable conversion of biomass into chemicals, materials, and bioenergy so that resources are optimized and effluents are minimized. Despite the vast potential of lignocellulosic biorefineries, their success depends heavily on effective, economically viable, and sustainable biomass fractionation. Although efficient, organosolv pretreatment still faces challenges that must be overcome for its widespread utilization, mainly related to solvent type and recycling, robustness regarding biomass type and integration of hemicellulose recovery and use.

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