Termite resistance of pine wood treated with nano metal fluorides

Abstract

Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF 2) and magnesium fluoride (MgF 2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF 2 and MgF 2 with an average mass loss less than 1% and visual rating of "1". These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect wood from termite attack.

Evaluation of Tung Oil (Vernicia fordii (Hemsl.)) for Controlling Termites

“…The alkaline copper quat (ACQ) [36] , boron-fluorine-chromium-arsenic (BFCA salts) [37] , copper azole (CA) [38] , copper chrome arsenate (CCA) [39] , chlorotalonil (CTL) [36] , copper-and zinc-salicylate [40] , quaternary ammonium compounds (QACs) [41] , siloxane [42] , sodium fluoride (NaF) [43][44][45] , and zinc borate [46] have been used to protect wood against termite damage. Besides these, nanoparticles from zinc oxide (ZnO) [47,48] , CuO and B 2 O 3 [49] , and magnesium fluoride (MgF 2 ) [50] have provided promising levels of protec-tion. Wood preservatives should ideally be environmentally friendly; thus, there is interest in safer alternative wood protection methods.…”

Improved Durability of Wood Treated with Nano Metal Fluorides against Brown-Rot and White-Rot Fungi

“…The resultant NMF treated wood was characterized by back-scattered electron images that showed aggregates of NMFs homogeneously distributed in the wood matrix. In addition, nano metal fluorides showed efficacy against brown-rot fungi, Coniophora puteana and termites, Coptotermes formosanus with mass losses below 3% [24]. However, the NMF treatment did not provide sufficient protection from Rhodonia placenta [23].…”

Nano metal fluorides: small particles with great properties

“…Previous papers reported that soluble fluorides can also be effective against termites [110][111][112]. Thus, nano MgF 2 and CaF 2 were tested against termites [113]. These studies showed that specimens treated with nano metal fluorides are less damaged than the severely attacked controls when exposed to termites.…”