Thermal, Physical and Mechanical Performance of Orange Peel Boards: A New Recycled Material for Building Application

Abstract

More than 124 million tons of oranges are consumed in the world annually. Transformation of orange fruit generates a huge quantity of waste, largely composed of peels. Some attempts to reuse by-products derived from citrus waste have been proposed for energy production, nutrient source or pharmaceutical, food and cosmetic industries. However, their use in the building sector had not been researched. In this study, orange peels, in five different ratios, from 100% of wet peels to 75% and from 0% of dry peels to 25%, were submitted to a thermo-compression procedure. They were evaluated according to their physical (bulk density, water absorption, thickness swelling, surface soundness and thermal conductivity) and mechanical properties (bending strength and modulus of elasticity). The results showed that orange peels can be used as thermal insulation material. The addition of dried peels makes the structure of the board heterogeneous and thus increases its porosity and causes the loss of strength. Hence, the board with the sole use of wet peel, whose thermal conductivity is 0.065 W/mK while flexural strength is 0.09 MPa, is recommended.

The citrus economy in Sicily in the early bioeconomy era: a case study for bioeconomy practitioners

“…Selected achievements include the discovery of microwave-assisted 41 and hydrodynamic cavitation-assisted 42 (HC-assisted) extraction processes carried out in water alone to obtain pectin, cellulose, biophenols and EOs; the optimization of biogas production from WOP, 36 and from industrial wastewater; 37 the use of WOP as source of cellulose (extracted with hydrogen peroxide under basic conditions) to make textile fibers; 43 the use of WOP as soil biofertilizer, 44 and to produce thermal insulating panels for the construction industry. 45 Clearly, in a island with high solar irradiation levels like Sicily, there is room for the utilization of value-adding conversion technologies applied to WOP using solar energy such as that developed by Chemat, Mandi, and co-workers, again employing water as the only extraction medium. 46 With regard to the practical feasibility of bioproductions based on citrus processing waste, research papers often omit to consider the highly perishable nature of this biowaste, which contains plentiful sugars, water, and residual air that are quickly used by acetic acid bacteria and yeasts to produce acetic acid and ethanol.…”

“…This dynamic situation has also been reflected in the bioeconomic research carried out in Sicily in the last decade (2012–2022) by researchers at universities and research institutes based in Sicily, on the valorization of citrus processing waste. Selected achievements include the discovery of microwave‐assisted 41 and hydrodynamic cavitation‐assisted 42 (HC‐assisted) extraction processes carried out in water alone to obtain pectin, cellulose, biophenols and EOs; the optimization of biogas production from WOP, 36 and from industrial wastewater; 37 the use of WOP as source of cellulose (extracted with hydrogen peroxide under basic conditions) to make textile fibers; 43 the use of WOP as soil biofertilizer, 44 and to produce thermal insulating panels for the construction industry 45 …”

The Browning Properties, Antioxidant Activity, and α-Glucosidase Inhibitory Improvement of Aged Oranges (Citrus sinensis)

“…Scanning electron microscope is commonly used to examine the microstructure and alterations of samples for use as a point of reference in product development and improvement [37]. Figure 2 shows the microstructure of black oranges.…”

“…Figure 2 shows the microstructure of black oranges. We examined how various pre-treatments affect the structure of black orange peel by comparing its internal and surface features to regular orange peel [37]. After six weeks of aging, the NB group developed wrinkles compared to the F group due to water loss.…”