Boron Leaching Research Articles

Effect of Amine Functionalization and Ageing on Copper and Boron Leaching from Wood Preservatives Grafted to Siloxane Networks

The study evaluated copper, boron, and silicon release from wood samples treated with sol-gel formulations based on tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) functionalized with copper (II) chloride and boric acid, respectively. The adopted leaching procedure was Japanese protocol JIS K 1571 (2004). Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Electron Spray Ionization Mass Spectrometry (ESI-MS) were employed for analyzing the leached solutions. The obtained results highlighted the important role of the amine function that was derived from the APTES precursor, in anchoring both copper and boron through coordinative and ionic interactions, respectively. In fact, copper formulations with TEOS alone (without APTES) showed higher copper leaching. In contrast, the silicon leaching was decreased due to better siloxane reticulation performed by TEOS alone. In addition, ageing (two months) of the samples treated with APTES containing formulation TEOS/APTES/Cu 10:1:0.2 resulted in a reduction of copper leaching (from 27% in the fresh samples to 7% in the aged ones), which was attributable to increased efficiency of inorganic sol-gel polymerization. The TEOS/APTES/B 1:1:0.2 formulation gave a leaching value of 20%, which was lower in comparison with the values reported in previous literature.

Tannin-caprolactam and Tannin-PEG formulations as outdoor wood preservatives: biological properties

Key MessageThis article presents the enhancement in boron fixation as well as the improved biological resistance against fungi and termites for wood samples treated with tannin-caprolactam and tannin-PEG formulations.ContextAlthough the recently developed tannin-boron wood preservatives have shown high biological protection, they presented also average resistance against weathering. The tannin-caprolactam formulations have shown improved weathering resistances and dimensional stability.AimsFor this reason, more detailed biological tests were performed to evaluate the influence of the caprolactam and PEG on the biological resistance.MethodsIn this paper, the boron leaching of the tannin-caprolactam and tannin-PEG impregnated Scots pine specimens was observed and the biocidal effect against fungi (Antrodia spp. and Coniophora puteana) and insects (Reticulitermes flavipes and Hylotrupes bajulus) were determined according to the guidelines of EN 113, EN 117, and EN 47.ResultsThe advanced formulations containing PEG have shown interesting resistance against fungal decay, but very low penetration and weak resistance against larvae while the tannin-caprolactam preservatives have shown overall improved biological performances and higher boron fixations.ConclusionThe biocidal activity of the caprolactam-added formulations was overall enhanced and therefore these formulations are confirmed to be an interesting alternative for the wood preservation in outdoor environment.

Water leaching of boron from soda-ash-activated ludwigite ore

Water leaching of boron from ludwigite ore activated by soda ash under reductive, natural and oxidative atmospheres was investigated by evaluating the effects of roasting parameters (roasting atmosphere, temperature and time) and leaching parameters (leaching temperature, leaching time, liquid-to-solid mass ratio and feed particle size) on boron leaching. The presence of CO during soda-ash activation promoted boron leaching because of the reduction of iron-bearing minerals in the ore, whereby iron species within magnetite (Fe3O4) and ludwigite ((Mg,Fe)4Fe2[B2O6]O4) transformed to metallic iron. This facilitated the reaction between B2O3 and soda ash, giving rise to the formation of water-soluble sodium metaborate. The boron of 92.7% could be extracted from the ore roasted in the presence of soda ash (25wt.%) under the 100% CO atmosphere at optimized roasting and leaching conditions.

Influence of microwave irradiation on boron concentrate activation with an emphasis on surface properties

In this study, we employed microwave irradiation for activating boron concentrate, an abundant but low-grade boron mineral resource in China. The boron concentrate was pretreated by microwave irradiation based on TG-DTG-DSC analysis, and the influence of each parameter on processing efficiency was characterized using chemical analysis, XRD, SEM, FTIR and particle distribution analysis. Subsequently, the surface properties of boron concentrate and the mechanism of microwave irradiation was analyzed. Our results indicate that microwave irradiation decreased the processing temperature and shortened the roasting time by accelerating dehydroxylation and oxidation reactions in the boron concentrate, reducing the particle diameter and damaging the microstructure of the minerals, and it increased the B2O3 activity of boron from 64.68% to 86.73%, greater than the optimal conventional treatment. Compared with the simple thermal field, microwave roasting obviously increased ability of the boron concentrate to absorb OH− in the leachant and promoted boron leaching by expanding the contact area of the mineral exposed to leachant, boosting the amount of Mg2+ and Fe3+ on mineral surfaces, and increasing the hydrophilicity of the boron concentrate respectively. It enhanced the γSVLW and γSV− of boron concentrate from 29.15mJ/m2 and 5.07mJ/m2 to 37.07mJ/m2 and 12.41mJ/m2.

Post-Synthesis Conversion of Borosilicate Zeolite Beta to an Aluminosilicate with Isolated Acid Sites: A Quantitative Distance Analysis by Solid-State NMR

Isolated acid sites were selectively generated by postsynthesis modification of a borosilicate zeolite beta. To this end, samples were prepared with pairs of adjacent boron sites balanced by Ca2+ ions, whereas isolated boron in the zeolite framework was balanced by NH4+ ions. To avoid undesired boron leaching, these ion exchange reactions were carried out in methanol solution rather than in water. Trigonal boron forms near the NH4+ ions by decomposing the latter into NH3 (and a proton), and selective extraction of the trigonal boron is achieved by water treatment, whereas the tetrahedral boron near Ca2+ ions remains in the zeolite framework. The vacancies were refilled with aluminum by treatment with an aqueous Al(NO3)3 solution. Two Bronsted acid sites with 1H chemical shifts of 4.0 and 5.0 ppm exist in the dehydrated samples. 1H–27Al REAPDOR solid-state NMR measurements yield quantitative information on the local H–Al distances of isolated H–Al two-spin and H–Al–Al three-spin systems. The nearest H–Al d...

Pillared Sn‐MWW Prepared by a Solid‐State‐Exchange Method and its Use as a Lewis Acid Catalyst

AbstractPillared Sn‐MWW (Sn‐MWW(SP)‐SSE) was prepared through a solid‐state‐exchange (SSE) route. The pillared structure was inherited from pillared B‐MWW, and Sn was inserted in the framework by boron leaching and solid‐state‐exchange with tin tetrachloride pentahydrate. The Sn‐MWW(SP)‐SSE with framework Sn sites exhibits Lewis acidity and good catalytic performance for the Baeyer–Villiger oxidation, and mono‐ and disaccharide isomerizations.

Boron Leaching Decreases withIncreases on Soil pH

Management of boron fertilization depends on the magnitude of B leaching in the soil profile, which varies proportionally with the concentration of B in the soil solution, which, in turn, decreases as the soil pH increases due to the higher sorption of B on soil solid surfaces. The objective of this study was to quantify the effect of liming and rates of B applied to the soil on B leaching. The experiment was carried out in the laboratory in 2012, and treatments consisted of a factorial combination of two rates of liming (without and with lime to raise the soil pH to 6.0) and five rates of B (0, 10, 20, 50 and 100 mg kg-1, as boric acid). A Typic Rhodudalf was used, containing 790 g kg-1 clay and 23 g kg-1 organic matter; the pH(H2O) was 4.6. Experimental units were composed of PVC leaching columns (0.10 m in diameter) containing 1.42 kg of soil (dry base). Boron was manually mixed with the top 0.15 m of the soil. After that, every seven days for 15 weeks, 300 mL of distilled water were added to the top of each column. In the percolated solution, both the volume and concentration of B were measured. Leaching of B decreased with increased soil pH and, averaged across the B rates applied, was 58 % higher from unlimed (pH 4.6) than from limed (pH 6.6) samples as a result of the increase in B sorption with higher soil pH. In spite of its high vertical mobility, the residual effect of B was high in this oxisol, mainly in the limed samples where 80 % of B applied at the two highest rates remained in the soil, even after 15 water percolations. Total recovery of applied B, including leached B plus B extracted from the soil after all percolations, was less than 50 %, showing that not all sorbed B was quantified by the hot water extraction method.

Development of new wood treatments combining boron impregnation and thermo modification: effect of additives on boron leachability

Environmental pressures in France and in most European countries during the last decade have led to the development of more environmentally acceptable preservation methods. In this context, wood heat treatment is one of the most investigated alternative methods. Important chemical modifications resulting from thermo-degradation reactions confer new properties to wood, like increased decay resistance or higher dimensional stability, while mechanical properties like tensile strength decrease after treatment. However, the improved durability of heat treated wood is not sufficient to allow its utilization in ground contact, where it is subjected to insect and fungi attacks. Impregnation with borax before thermal treatment could be an interesting method to improve the properties of thermally modified wood. Boron is a relatively harmless biocide that improves resistance to fungi and insects like termites. Additionally, borax can also improve wood fire resistance due to its fire retardant effect. To reduce boron leachability, two additives previously developed in the laboratory corresponding to water soluble polymerizable polyglycerol derivatives were added to the borax solution, taking advantage of thermal treatment to fix the latter through polymerization within the wood structure limiting boron leachability.

Hydrogels obtained from an original catanionic system for efficient formulation of boron wood-preservatives

A new catanionic system associating amphiphilic carnosine (βAlaHisC8) and lauric acid forms supramolecular hydrogel at a very low concentration. This gel was investigated and we checked the validity of the concept of hydrogel utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) fosters improvement in the resistance of Scots pine sapwood subjected to water leaching toward the brown-rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood.

A Laboratory Test of the Leachability and Decay Resistance of Some Synthesized Borate Compounds

Abstract Quaternary ammonium tetraphenylborates (TPBs) and quaternary ammonium tetrafluoroborates were synthesized for the manufacture of leaching-resistant boron wood preservatives. The leachability of these boron compounds and the termite and decay resistance of wood treated with these compounds were evaluated. The boron leaching rate of wood treated with quaternary ammonium TPB formulations ranged from 2.1 to 6.7 percent, while that of quaternary ammonium tetrafluoroborate formulations ranged from 23.3 to 59.0 percent. Quaternary ammonium tetrafluoroborates performed better than quaternary ammonium TPBs in termite resistance and inhibition zone tests. Quaternary ammonium tetrafluoroborates could inhibit Gloeophyllum trabeum and Phanerochaete chrysosporium at all concentrations used in the laboratory inhibition zone test. Weight loss of masson pine (Pinus massoniana) sapwood treated with quaternary ammonium tetrafluoroborate solutions was 1.4 to 2.6 percent (G. trabeum) and 2.5 to 3.8 percent (by Coriolus versicolor) at preservative retentions around 7.0 kg/m3.

Leaching of boron from wood impregnated with preservative solutions based on boric acid and liquefied wood

Reducing boron leaching from impregnated wood has been one of the most challenging tasks for at least 50 years. In order to slow down the leaching of boron, aqueous solutions of boric acid were combined with liquefied spruce wood. The results clearly showed that leaching of boron from spruce wood impregnated with preservative solutions based on boric acid and liquefied wood was significantly reduced.

The combined effects of boron and oil heat treatment on beech and Scots pine wood properties. Part 1: Boron leaching, thermogravimetric analysis, and chemical composition

The aim of the study was to screen any possible synergistic effect available with combination of plant oils and boron compounds to decrease boron leaching and improve thermal degradation of wood by means of dual treatment. In order to reduce the leachability of boron compounds, sapwood of beech and Scots pine samples were treated with oils to create a hydrophobic layer on the wood cells that may prevent water uptake. Increase (%) of boron retained in double-treated samples after leaching was approximately 20% compared to boron-treated samples without oil. The most promising results on boron leaching obtained in the case of using waste and sunflower oil. Thermogravimetric residues were increased by the higher loading of boron compounds in double-treated samples. Spectra of FTIR-Photoacoustic spectrometer showed some deformation of lignin and cellulose followed by degradation of hemicelluloses of treated wood samples due to heat effect at 160 °C.

Effects of polyvinyl alcohol on leachability and efficacy of boron wood preservatives against fungal decay and termite attack

In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigated. Two levels of PVA (2.5 and 4%) were evaluated with disodium octaborate tetrahydrate (DOT) at three concentrations (1, 2 and 4% boric acid equivalent (BAE)) using a double vacuum impregnation process on Scots pine sapwood specimens. Leaching was performed according to a laboratory leaching procedure. Boron analysis using atomic absorption spectrometer showed a significant reduction in boron leachability for the samples treated with both concentrations of PVA when compared to the stand-alone boron treatment leading to boron retentions capable of preventing wood biological degradations. Decay resistance of the leached specimens was evaluated using the brown rot fungus Poria placenta. Even if complete protection was not fully achieved, an improvement in decay resistance was observed for the samples treated with DOT in presence of PVA. This leak of efficacy was attributed to a decrease in the biological activity of the complexed boron against fungi. Durability of treated wood against termite attack, evaluated using Reticulitermes santonensis, indicated a significant enhancement for the samples treated in presence of the fixative agent compared to the pure boron treatment.

Effects of monoglycerides on leachability and efficacy of boron wood preservatives against decay and termites

Borates are well known for their ability to protect wood against fungal and insects attacks. However, their use in outdoor applications is limited due to their high leachability from treated wood. In this study, monoglycerides were investigated as fixative agents to reduce boron depletion from Scots pine using a double vacuum impregnation process involving impregnation with disodium octaborate tetrahydrate (DOT) followed by a second impregnation with the fixative agent. Significant reduction in boron leachability in samples treated with monoglycerides was observed compared to the standalone boron treated specimens. Evaluation of decay resistance of treated blocks using the brown rot fungus Poria placenta indicated a slight increase of durability, while resistance to termites attacks was strongly improved as demonstrated by the low weight losses and the high termites mortality levels observed. Monoglycerides could therefore be valuable additives to reduce boron depletion for outdoor applications in which wood is exposed to natural leaching conditions.

Boron isotopes geochemistry of the Changjiang basin rivers

We report analyses of B isotopic compositions in water and suspended particulate matter collected in the Changjiang and its main tributaries. We showed that four sources control the dissolved boron budget; namely atmospheric deposition, evaporite dissolution, anthropogenic inputs and silicate weathering. The contribution of silicate weathering to the dissolved B load ranges from 40% to 50% for the Changjiang main channel and from 45% to 88% for the main tributaries. The isotopic composition of dissolved boron derived from silicate weathering range from −3‰ up to +9‰ suggesting that isotopic fractionation occurs during silicate weathering. The boron isotopic composition of suspended particulate matter range from −11.4‰ to −6‰. Boron derived from silicate weathering is preferentially carried out by the dissolved load which accounts for 30–96% of the total boron. We show that the isotopic compositions of both the dissolved load and suspended particulate matter are controlled by the competition between boron leaching and boron uptake into secondary phases. The first process is characterized by a loss of boron relative to the bedrock without apparent isotopic fractionation whereas the last one is associated to a large isotopic fractionation which enriches the dissolved boron in heavy isotope.

Modification of wood with Si compounds to limit boron leaching from treated wood and to increase termite and decay resistance

In this study, we tested tetraethoxysilane and methyltriethoxysilane as modifying silicon-based compounds for their potential to limit boron leachability from modified wood and to increase biological durability of the wood against fungi and termites. Both the silane compounds were used in silane state where acidified ethanol was added and stirred at ambient temperature for 30 min. We used two different processes for preservative treatments: double treatment and single treatment. In double treatment, the specimens from sugi wood were first treated with boric acid at 1% concentration and subsequently treated with the silanes. In single treatment, boric acid was mixed with the silane compounds in the silane state yielding 1% boric acid concentration. Subsequent to the treatments, wood specimens were subjected to laboratory leaching tests, and leachates were analyzed for boron content with an inductively coupled plasma (ICP) spectrometry. ICP analyses showed that silane treatments were able to limit boron leaching from treated wood by about 40% in all cases for each silane compound. Wood specimens were then subjected to laboratory termite and decay resistance tests using the subterranean termites, Coptotermes formosanus, and the wood decaying fungi, Fomitopsis palustris and Trametes versicolor. Termite and fungal decay resistance tests revealed that resistance of modified wood with the silane and boron compounds increased when compared to untreated and boron-only treated wood specimens. More in-depth studies on the mechanisms of interactions between the silicon compounds, boron elements and wood components are in progress.

Heavy metal leaching from aerobic and anaerobic landfill bioreactors of co-disposed municipal solid waste incineration bottom ash and shredded low-organic residues

In this study, heavy metal leaching from aerobic and anaerobic landfill bioreactor test cells for co-disposed municipal solid waste incineration (MSWI) bottom ash and shredded low-organic residues has been investigated. Test cells were operated for 1 year. Heavy metals which were comparatively higher in leachate of aerobic cell were copper (Cu), lead (Pb), boron (B), zinc (Zn), manganese (Mn) and iron (Fe), and those apparently lower were aluminum (Al), arsenic (As), molybdenum (Mo), and vanadium (V). However, no significant release of heavy metals under aerobic conditions was observed compared to anaerobic and control cells. Furthermore, there was no meaningful correlation between oxidation–reduction potential (ORP) and heavy metal concentrations in the leachates although some researchers speculate that aeration may result in excessive heavy metal leaching. No meaningful correlation between dissolved organic carbon (DOC) and leaching of Cu and Pb was another interesting observation. The only heavy metal that exceeded the state discharge limits (10 mg/l, to be enforced after April 2005) in the aerobic cell leachate samples was boron and there was no correlation between boron leaching and ORP. Higher B levels in aerobic cell should be due to comparatively lower pH values in this cell. However, it is anticipated that this slightly increased concentrations of B (maximum 25 mg/l) will not create a risk for bioreactor operation; rather it should be beneficial for long-term stability of the landfill through faster washout. It was concluded that aerobization of landfills of heavy metal rich MSWI bottom ash and shredded residues is possible with no dramatic increase in heavy metals in the leachate.

Effects of Evaporation and Different Flow Regimes on Solute Distribution in Soil

Water evaporation and solute transport processes were studied in large soil columns filled with a sandy clay loam (SCL) and a clay loam (CL) soils. To create different water flow velocity through the soil column, the 3 cm (Treatment I) and 6 cm (Treatment II) depths of water were ponded at the soil surface during leaching. After leaching, soils were left for evaporation for 10 days. Some salinity parameters were monitored during three leaching and evaporation periods. To achieve the same degree of leaching more water was needed in Treatment II than in Treatment I for both soils. The electrical conductivity (EC) at the soil surface after evaporation increased, to 41–46% of the pre-drying level for the SCL and 28–31% for the CL. Although very low concentrations of Cl− were detected at the soil surface after the first leaching in both soils, high increase was monitored after the evaporation period, due to the high mobility of this anion. The fluctuation of exchangeable sodium percentage (ESP) during the leaching and evaporation periods was attributed to the different transportation rates of Na+, Ca2+ and Mg2+. The boron leaching in Treatment I was more effective than that in Treatment II for both soils.

Effects of N?-N-(1, 8-Naphthalyl) hydroxylamine (NHA-Na) and hydroxynaphthalimide (NHA-H) on boron leachability and biological degradation of wood

Although boron wood preservatives have many advantages, boron itself does not adequately protect wood in ground contact and exterior applications because its susceptibility to leaching. As a result of previous studies to limit or decrease boron leaching, several fixation systems have been developed. In this study, we evaluated the effects of N′-N-(1, 8-Naphthalyl) hydroxylamine (NHA-Na) and hydroxynaphthalimide (NHA-H) on boron leaching and decay and termite resistance via possible boron precipitation in wood after NHA treatments at varying concentrations. Results showed that treatment of wood blocks with disodium octaborate tetrahydrate (DOT), boric acid (BA), or calcium tetraborate (CaB) incorporation with 1.0% NHA-Na solutions in sequential processes appears to somewhat reduce the susceptibility of boron to leaching. Blocks treated sequentially with boron compounds and then 1.0% NHA-Na solutions showed about 30% less boron leaching compared to boron only treated blocks. In addition, the existence of boron and NHA-Na in wood together showed a synergistic effect against brown-rot fungus, Fomitopsis palustris. We conclude that the relationship between boron and NHA-Na concentration in wood as regards precipitation possibilities appears to be predictive for reducing boron leachability.

Decay and termite resistance of boron-treated and chemically modified wood by in situ co-polymerization of allyl glycidyl ether (AGE) with methyl methacrylate (MMA)

Chemical modification was carried out on disodium octoborate tetrahydrate (DOT)-treated wood using allyl glycidyl ether (AGE) in combination with methyl methacrylate (MMA) to limit boron leaching. Co-polymerization of the monomers in DOT-treated sugi ( Cryptomeria japonica D. Don) wood was completed by catalyst heat treatment. Besides boron leachability, the dimensional stability and decay, and termite resistance of chemically modified wood were also determined. Dimensional stability in terms of anti-swelling efficiency and water absorption was found to improve in chemically modified wood specimens. Co-polymerization of AGE with MMA in DOT-treated wood resulted in less boron leaching compared with DOT-only-treated wood. Chemically modified wood containing boron proved to be more resistant to the brown-rot fungus Fomitopsis palustris (Berkeley et Curtis) Murrill (FFPRI 0507) and the white-rot fungus Trametes versicolor (L. ex Fr.) Quel. (FFPRI 1030) in laboratory decay resistance tests after severe leaching for 10 days. Termite resistance tests also showed that wood specimens treated with DOT and MMA plus AGE monomers were effective against subterranean termites Coptotermes formosanus Shiraki even after severe leaching cycles.