Mechanical Properties and Durability of Composite Cement Pastes Containing Phase-Change Materials and Nanosilica.

Escalating global surface temperatures are highlighting the urgent need for energy-saving solutions. Phase-change materials (PCMs) have emerged as a promising avenue for enhancing thermal comfort in the construction sector. This study assessed the impact of incorporating PCMs ranging from 1% to 10% by mass into composite Portland cement partially replaced by fly ash (FA) and nanosilica particles (NS). Mechanical and electrochemical techniques were utilized to evaluate composite cements. The results indicate that the presence of PCMs delayed cement hydration, acting as a filler without chemically interacting within the composite. The combination of FA and PCMs reduced compressive strength at early ages, while thermal conductivity decreased after 90 days due to the melting point and the latent heat of PCMs. Samples with FA and NS showed a significant reduction in the CO2 penetration, attributed to their pozzolanic and microfiller effects, as well as reduced water absorption due to the non-absorptive nature of PCMs. Nitrogen physisorption confirmed structural changes in the cement matrix. Additionally, electrical resistivity and thermal behavior assessments revealed that PCM-containing samples could reduce temperatures by an average of 4 °C. This suggested that PCMs could be a viable alternative for materials with thermal insulation capacity, thereby contributing to energy efficiency in the construction sector.

Experimental data on the production and characterization of biochars derived from coconut-shell wastes obtained from the Colombian Pacific Coast at low temperature pyrolysis.

Biochars are emerging eco-friendly products showing outstanding properties in areas such as carbon sequestration, soil amendment, bioremediation, biocomposites, and bioenergy. These interesting materials can be synthesized from a wide variety of waste-derived sources, including lignocellulosic biomass wastes, manure and sewage sludge. In this work, abundant data on biochars produced from coconut-shell wastes obtained from the Colombian Pacific Coast are presented. Biochar synthesis was performed varying the temperature (in the range: 280 °C-420 °C) and O2 feeding (in the range: 0-5% v/v) in the pyrolysis reaction. Production yields and some biochar properties such as particle size, Zeta Potential, elemental content (C, N, Al, B, Ca, Cu, Fe, K, Li, Mg, Mn, Na, P, S, Ti, Zn), BET surface area, FT-IR spectrum, XRD spectrum, and SEM morphology are presented. This data set is a comprehensive resource to gain a further understanding of biochars, and is a valuable tool for addressing the strategic exploitation of the multiple benefits they have.

Enzymatic hydrolysis of cellulose nanoplatelets as a source of sugars with the concomitant production of cellulose nanofibrils.

Cellulose, the most abundant biopolymer on earth, is produced at different ratios by all land plants. Since the morphology and crystallinity of cellulose are key factors involved in its enzymatic hydrolysis, in the present work, we tackled the study of the effects of such variables on the nanocellulose conversion into glucose. Cellulase from Trichoderma sp at 37 °C was used to produce glucose, the best results were found for the cellulose nanoplatelets (S-CNP) after 60 h of hydrolysis, which afforded a conversion of 47% to glucose, in contrast to 15% for the non-purified sample (W-CP) and 22% for microcrystalline cellulose (MCC20) used as control. The X-ray diffractogram recorded on the samples showed an initial crystallinity index of 45%, 54% and 72% for W-CNP, S-CNP and MCC20, respectively. Also, we showed that after 24 h of hydrolysis, long cellulose nanofibrils (∅ ≈ 30 nm) were found as a residue.