Cardanol-based adhesive with reduced formaldehyde emission to produce particleboards with waste from bean crops

Free formaldehyde is a carcinogen whose emission reduction in particleboard has been studied recently to mitigate this environmental and human health problem. One alternative to reduce the emission of formaldehyde in particleboards is by using adhesives produced from natural sources. Cardanol-formaldehyde is an environmentally friendly adhesive made with cashew nut liquid, a byproduct from the cashew chain. This work aimed to produce particleboard using cardanol-formaldehyde in place of urea. In addition, different proportions of bean straw wastes were used to replace pine wood. The combination of eco-friendly adhesive and lignocellulosic waste particles could result in a product that meets market demands while being environmentally nonaggressive. Cardanol-formaldehyde promoted a higher modulus of elasticity (MOE) (1172 MPa) and modulus of rupture (MOR) (4.39 MPa) about panels glued with urea-formaldehyde, which presented a MOE of 764 MPa and MOR of 2.45 MPa. Furthermore, the cardanol-formaldehyde adhesive promoted a 93% reduction in formaldehyde emission, with a reduction from 16.76 to 1.09 mg/100 g oven-dry board for particleboards produced with cardanol-formaldehyde, indicating potential as an adhesive in the particleboard industry.

The mechanisms and prediction of non-structural carbohydrates accretion and depletion after mechanical wounding in slash pine (Pinus elliottii) using near-infrared reflectance spectroscopy

BACKGROUND

The allocation of non-structural carbohydrates (NSCs) plays a critical role in the physiology and metabolism of tree growth and survival defense. However, little is known about the allocation of NSC after continuous mechanical wounding of pine by resin tapping during tree growth.

RESULTS

Here, we examine the NSC allocation in plant tissues after 3 year lasting resin tapping, and also investigate the use of near-infrared reflectance (NIR) spectroscopy to quantify the NSC, starch and free sugar (e.g., sucrose, glucose, and fructose) concentrations in different plant tissues of slash pine. Spectral measurements on pine needle, branch, trunk phloem, and root were obtained before starch and free sugar concentrations were measured in the laboratory. The variation of NSC, starch and free sugars in different plant tissues after resin tapping was analyzed. Partial least squares regression was applied to calibrate prediction models, models were simulated 100 times for model performance and error estimation. More NSC, starch and free sugars were stored in winter than summer both in tapped and control trees. The position of resin tapping significantly influenced the NSCs allocation in plant tissues: more NSCs were transformed into free sugars for defensive resin synthesis close to the tapping wound rather than induced distal systemic responses. Models for predicting NSC and free sugars of plant tissues showed promising results for the whole tree for fructose (R²_CV = 0.72), glucose (R²_CV = 0.67), NSCs (R²_CV = 0.66) and starch (R²_CV = 0.58) estimates based on NIR models. Models for individual plant tissues also showed reasonable predictive ability: the best model for NSCs and starch prediction was found in root. The significance multivariate correlation algorithm for variable selection significantly reduced the number of variables. Important variables were identified, including features at 1021-1290 nm, 1480, 1748, 1941, 2020, 2123 and 2355 nm, which are highly related to NSC, starch, fructose, glucose and sucrose.

CONCLUSIONS

NIR spectroscopy provided a rapid and cost-effective method to monitor NSC, starch and free sugar concentrations after continuous resin tapping. It can be used for studying the trade-off between growth and production of defensive metabolites.

Substitution of urea-formaldehyde by renewable phenolic compound for environmentally appropriate production of particleboards

In recent years, research has been conducted in search of alternative adhesives that are less harmful to human health and the environment. Cardanol derived from cashew nut shell liquid (CNSL) has attracted considerable attention due to its chemical and specific characteristics (antioxidant activity, flame resistance, and hydrophobicity). In this sense, this study aimed to evaluate the quality of particleboards using cardanol instead of urea-formaldehyde (UF) adhesive. Different percentages of cardanol were used (0, 20, 40, 60 and 80%) in which its physicochemical properties were evaluated. The panels were produced with particles of Pinus oocarpa and nominal density of 0.75 g/cm³, their physical and mechanical properties were evaluated, wood-adhesive interface evaluation with scanning electron microscopy (SEM), and the combustibility test. It is concluded that the maximum replacement of UF by cardanol is 5%, since, in this situation, the mentioned properties reach the established norms for the commercialization of the boards.

Pelletizing of lignocellulosic wastes as an environmentally friendly solution for the energy supply: insights on the properties of pellets from Brazilian biomasses

In the context of the circular bioeconomy and cleaner production, the incorporation of the by-products of plant biomass production in the bioenergy chain is fundamental. However, lignocellulosic wastes have properties that hinder their use for the production of biofuels. This study aims to evaluate how blends of lignocellulosic wastes improve the physical, chemical, and mechanical quality of pellets destined to the industrial sector, and to identify the challenges associated with the use of agroforestry biomass as raw material for pelletizing. Pellets were produced from blends of soybean wastes, sorghum wastes, pine needles, rice powder, Eucalyptus sawdust, and charcoal fines. Additionally, pure pellets composed of soybean wastes, sugarcane bagasse, and pine wood were evaluated. The effect of biomass type on the energy density, ash content, net heating value, and ultimate analysis was significant. The pellets produced with soybean wastes presented high contents of N (3.5-4.9%) and ashes (16.4-26.7%), besides low mechanical durability (≤ 96%), hindering its commercialization for industrial purposes. Pellets with sugarcane bagasse presented N (1.5%), S (0.03%), ashes (5.6%), mechanical durability (96.6%), and net heating value (15.1 MJ kg^-1), suitable for industrial energy use in accordance with ISO 17225-6. The high N and ash contents and the low mechanical durability are the greatest challenges for the energy use of pellets produced from Brazilian agroforestry wastes.

Sustainable valorization of recycled low-density polyethylene and cocoa biomass for composite production

The development of products from wastes such as plastic and lignocellulosic materials brings great advantages from the economic and sustainable point of view. The use of waste, previously destined for disposal, enables the changes in production patterns, and prevents major environmental problems. This research investigated the inclusion of different contents of cocoa almond husk on the properties of composites with recycled low-density polyethylene (LDPE) matrix. The composites were produced by extrusion process with proportions: 0%, 10%, 20%, 30%, and 40% of cocoa waste reinforcement in the polymer matrix. The density of the composites decreased (from 0.81 to 0.61 g/cm3) with the addition of the lignocellulosic waste in the matrix. The hygroscopicity was increased, however, at considerably low levels (0.17 to 2.68 %). There was a decrease in composite strength and elongation, becoming the material more rigid. The use of the cocoa waste for composites production is feasible to use since it can be adapted to the required application and still incorporate additives requested for specific purposes. This research demonstrated that is possible the combination of recycled low-density polyethylene and lignocellulosic wastes for the production of materials with high added value.

Potential destination of Brazilian cocoa agro-industrial wastes for production of materials with high added value

This research proposed to investigate a possible destination for the cocoa waste as component in the core layer of Medium Density Particleboards (MDPs) and to evaluate the effect of the waste insertion on the physical-mechanical properties of the panel. The core layers of the MDPs were composed by different percentages of cocoa wastes (0, 25, 50, 75 and 100%) in combination with pine wood. The targeted density of the panels was pre-established in 0.7 g cm^-3, bonded with urea-formaldehyde. The cocoa waste showed higher extractives content (34.8%) when compared with the pine wood (4.0%). The inclusion of the waste did not cause a significant difference in the moisture and bulk density of the panels; however, there was an increase in water absorption 24 h (71-105%) and thickness swelling 24 h (13-35%). Despite the values of the mechanical properties decreased in general, in low percentages, the cocoa waste does not prevent the use of the MDPs as furniture for internal environments. The results show that the cocoa waste has potential for being applied as raw material in the core layer of the MDP, in percentages up to 21%. The lignocellulosic wastes are promising alternatives for the achievement of the required current context of the sustainability and should be highlighted with research focused on their management for the development of added value materials.

Babassu nut residues: potential for bioenergy use in the North and Northeast of Brazil

Babassu is considered the largest native oil resource worldwide and occurs naturally in Brazil. The purpose of this study was to evaluate the potential of babassu nut residues (epicarp, mesocarp and endocarp) for bioenergy use, especially for direct combustion and charcoal production. The material was collected in the rural area of the municipality of Sítio Novo do Tocantins, in the state of Tocantins, Brazil. Analyses were performed considering jointly the three layers that make up the babassu nut shell. The following chemical characterizations were performed: molecular (lignin, total extractives and holocellulose), elemental (C, H, N, S and O), immediate (fixed carbon, volatiles and ash), energy (higher heating value and lower heating value), physical (basic density and energy density) and thermal (thermogravimetry and differential thermal analysis), besides the morphological characterization by scanning electron microscopy. Babassu nut residues showed a high bioenergy potential, mainly due to their high energy density. The use of this biomass as a bioenergy source can be highly feasible, given their chemical and thermal characteristics, combined with a low ash content. Babassu nut shell showed a high basic density and a suitable lignin content for the sustainable production of bioenergy and charcoal, capable of replacing coke in Brazilian steel plants.