Inorganic Preservatives Research Articles

Dicationic imidazole ionic liquid stationary phase for preservative detection and its application under mixed mode of HILIC/RPLC/IEC

BackgroundFood safety has always been a great concern, and the detection of additives is vital to ensuring food safety. Therefore, there is a necessity to develop a method that can quickly and efficiently separate and detect additives in food. High performance liquid chromatography is widely used in the analysis and testing of food additives. Ionic liquids have attracted wide attention in the preparation of high performance liquid chromatography stationary phases owing to their high stability, low vapor pressure and adjustable structure. ResultsWe developed a novel dicationic imidazole ionic liquid stationary phase for the simultaneous determination of organic preservatives (sodium benzoate, potassium sorbate) and inorganic preservatives (nitrate and nitrite) in foodstuffs under mixed-mode chromatography. The method had the advantages of easy operation, high reproducibility, good linearity and precision. In the detection of these four preservatives, the limit of detection ≤0.4740 mg⋅L−1 and the limit of quantification ≤1.5800 mg⋅L−1. The intra-day and inter-day precision were less than 4.02%, and the recovery rate was 95.90∼100.19 %. At the same time, we also characterized the stationary phase, explored the mechanism and evaluated the chromatographic performance. The stationary phase was able to operate under the mixed mode of reversed phase/hydrophilic interaction/ion exchange chromatography, and it was capable of separating hydrophilic substances, hydrophobic substances, acids, and inorganic anionic substances with good separation efficiency and had high column efficiency. SignificanceIn summary, the stationary phase has a promising application in the routine analysis of organic and inorganic preservatives in food. In addition, the stationary phase has good separation ability for hydrophilic, hydrophobic, ionic substances and complex samples, making it a prospective material for chromatographic separation.

Effect of Primary Spruce Lamella Aging on the Bending Characteristics of Glulam Beams

Glued laminated (glulam) beams are used in the roofs, ceilings and walls of buildings as well as in bridges and towers. At present, with the limitation of tree harvesting, the production of glulam beams from recycled wood sources is implemented with the proviso that their mechanical properties and resistance to pests, fire and weathering will not be aggravated. This work deals with the primary effect of aging Norway spruce wood (Picea abies Karst. L.) lamellas on the moduli of rupture (MOR) and elasticity (MOE) in bending of three-layer glulam beams composed of sound and aged lamellas and polyurethane (PUR) glue. Three methods of lamella aging were used: (A) natural, lasting 60 years in the form of roof trusses with a greater or lesser degree of bio-attack by woodworm (Anobium punctatum De Geer); (B) artificial, caused by increased temperatures from 160 to 220 °C for 4 h; (C) artificial, caused by 2% water solutions of inorganic preservatives, namely, CuSO4 × 5H2O, ZnCl2, H3BO3 or (NH4)2SO4, for 28 days. The lowest MOR values were determined for glulam beams in which all three lamellas or two surface lamellas had a greater degree of bio-attack (60.5 MPa, a decrease of 25.9%) or were exposed to primary aging at 220 °C (62.6 MPa, a decrease of 23.3%). On the contrary, the exposure of lamellas to 160 or 180 °C did not significantly influence the MOR of beams (76.0–82.7 MPa, an average decrease of 1.6%). The MOE of glulam beams ranged from 7540 to 10,432 MPa without an obvious influence of the method of lamella aging or their location in the beams. Linear correlations between the MOR or MOE of glulam beams and the shear strength (σ) of glued joints, if both composite types consisted of similarly aged lamellas, were only slightly significant or insignificant.

The Effect of Inorganic Preservatives in the Norway Spruce Wood on Its Wettability and Adhesion with PUR Glue

Recycled recovered wood, for example, from historic buildings, containing biocides, fire retardants or anti-weather paints is an attractive material for manufacturing composite wood panels which can be used for decoration as well as load-bearing walls with a typical patina. This paper investigates the effect of four inorganic wood preservatives—CuSO4·5H2O, ZnCl2, H3BO3 and (NH4)2SO4—commonly used in the past, with the focus on their effect on the quality of wood bonding. The milled surfaces of Norway spruce (Picea abies Karst L.) wood were treated with 0.5, 1 and 2% aqueous solutions of these preservatives. The effect of preservatives in spruce wood was evaluated: (1) by its wettability with the drops of redistilled water, measuring the contact angles; (2) by the shear strength of the “spruce wood—polyurethane (PUR) Kestopur 1030 glue” interphases according to the standard EN 205; (3) by microscopic analysis of the “wood—PUR” interphases. The wettability of spruce wood worsened when using ZnCl2, by a maximum of 28.2%, but on the contrary, it improved due to other preservatives mainly by using (NH4)2SO4, at a maximum of 22.9%. In general, the shear strength of glued joints “wood—PUR” continually decreased with higher concentrations of all the preservatives. The most significant decrease of adhesion “wood—PUR”, by 19.8% from 10.66 MPa to 8.55 MPa, was caused by 2% ZnCl2 used for the treatment of both spruce wood specimens in interphase with the PUR glue. On the contrary, the less significant decrease of adhesion “wood—PUR”, by 2.5%, was caused by 0.5% (NH4)2SO4 applied only on one surface of the two inter-bonded spruce wood specimens. The effects of preservatives on the wood wettability and its adhesion with PUR glue were partly confirmed by microscopic analysis.

Preparation, Test, and Analysis of a Novel Aluminosilicate-Based Antimildew Agent Applied on the Microporous Structure of Wood.

Fungi play a considerable role in the deterioration of lignocellulose materials, as their activities either affect the esthetic properties or lead to decay of the host materials. The new generation of organic–inorganic preservatives, which are copper-based but chrome- and arsenic-free, is a subject of many research works. Mildew fungus prevention, treatment of affected materials, and their successive conservation are essential to the woodworkers. To prevent degradation and prolong the service life of wood, a sol–gel organic–inorganic procedure was employed in this study. Aluminum sulfate (Al2(SO4)3), copper sulfate (CuSO4·5H2O), and boric acid (H3BO3) were introduced into phosphoric acid (H3PO4) and water glass as an antimildew agent, with different treatment concentrations (0.7, 1.4, and 2%). Wood was inoculated with Aspergillus niger and Trichoderma viride after new treatment based on the inorganic preservative. The changes in wood surface, structural chemistry, and the crystalline structure of the treated wood were examined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD), respectively. The growth of the two mildew fungi showed distribution, and evidence of mildew covering only the untreated wood surfaces and an increase in the crystallinity of wood was observed after the process. The study suggests that the two mildew fungi investigated herein could be prevented by sol–gel coating with a Si–Al–Cu–P antimildew agent.

Shelf Life and Sensory Evaluation of Hill Lemon (Citrus pseudolimon Tan.) Juice using Organic and Inorganic Preservatives

Hill lemon (Citrus pseudolimonTan.) is a hardy plant and grown well in low and mid hills of Himachal Pradesh. Its juice is preserved and being used as souring agent in many food preparations, pickles and chutneys. The shelf life of Hill lemon juice was assessed by using organic and inorganic preservatives. Boiling of juice till the end of formation of foam/leather and adding organic source of preservative (Salt @ 20gm/L of juice + top dressing of mustard oil @ 20ml/L of juice) was found best and received highest rating on various sensory attributes especially colour and flavour under nine point hedonic scale. This treatment not only enhanced the shelf life of the juice up to 10 months but also retained original flavour and colour of juice. Under inorganic preservatives, Potassium meta bisulphite @0.7 gm/L of juice and Sodium benzoate @ 0.5gm/L of juice, six and five months shelf life was observed respectively. Hence use of organic method for preserving the juice can be a better substitute of inorganic preservatives in many food processing industries.

Treatment of coconut palm wood using inorganic preservatives

Freshly felled coconut wood is very much susceptible to wood boring insects, moulds and stain fungi as it has high levels of sugar, starch and moisture content throughout the trunk. The objective of this study was to develop appropriate preservative methods to protect sawn coconut palm wood from insects and other pathogens under the prevailing eco-climatic conditions in Kerala and to evaluate the effect of different preservative factors on the treatability of coconut wood. Wood samples were treated with inorganic chemicals like Copper Chrome Boron - CCB and Borax Boric Acid – BBA by diffusion and pressure treatment, of which pressure treatment performed better. Diffusion treatment of inorganic preservatives in high and medium density wood showed no significant difference in retention whereas significant difference was observed for penetration percentage. For pressure treatment, retention and penetration were significant in high density wood whereas medium density wood showed only significant retention. Solution concentrations and overall retention and penetration percentage were found to be significantly related. The study found that sawn coconut wood samples could be effectively treated with preservatives complying with the prescribed retention and penetration percentages as per the different standards and therefore, could be used as a potential substitute for conventional timbers and the insect damage was negligible. No incidence of insects, particularly termites and pin hole borers was observed during the graveyard studies.

Salt efflorescence in historic wooden buildings

Efflorescence and subflorescence are frequent phenomena occurring in buildings of porous inorganic materials such as bricks, stone, and concrete. Since the above phenomena have detrimental effects, they were the subject of detailed physicochemical investigations. Efflorescence on wooden material was commonly observed on collection artefacts treated with preservatives such as inorganic salts or organic pesticides. Occurrence of efflorescence in historical wooden buildings was less studied although it could cause serious conservation concerns. This paper describes an examination of chemical and mineralogical composition of salt efflorescence in wooden buildings. In situ analysis by X-ray fluorescence spectrometry was followed by investigation of plain efflorescence by infrared spectrometry, X-ray diffraction, electron microscopy, and electron probe microanalysis. Quantitative analysis of purified efflorescence was performed by plasma atomic emission spectrometry, ion chromatography and absorption spectrophotometry. In addition, depth-profiling of characteristic ions in wood was performed. The objects of study were a series of log houses of the Sverresborg Trondelag Folk Museum in Trondheim, Norway. It was found that the efflorescence in these buildings includes a series of metal ions, the most abundant being Al3+, Mg2+, Zn2+, K+, Na+, and Fe2+. In addition the ammonium ion is present in a large amount. The single detected anion is sulfate. Actually, the efflorescence consists of a mixture of simple and double sulfate salts of alum and Tutton’s compound types. Identified Tutton’s compounds are mohrite ((NH4)2Fe(SO4)2·6H2O), ammonium zinc sulfate hexahydrate ((NH4)2Zn(SO4)2·6H2O)), and boussingaultite ((NH4)2Mg(SO4)2·6H2O)). Among the alums, both tschermigite (NH4Al(SO4)2·12H2O), and potassium alum (KAl(SO4)2·12H2O)) were detected. The composition of efflorescence suggests that the wooden material was treated with a blend of sulfate salts ((NH4)2SO4, Al2(SO4)3·18H2O, MgSO4·7H2O, FeSO4·7H2O, ZnSO4·7H2O, and Na2SO4·10H2O)) for protection against fire and biological degradation. The efflorescence appeared as a consequence of water leakage through the roof that led to the dissolution of the salts contained in the wood, followed by evaporation and salt crystallization at the surface in the form of double sulfate salts. Although the occurrence of efflorescence in this case was accidental, a natural and more frequent cause of efflorescence could be the deliquescence of inorganic preservatives impregnated in the wood.

Variation of arsenic concentration on surfaces of in-service CCA-treated wood planks in a park and its influencing field factors.

Wood preservatives can protect wood from dry rot, fungi, mould and insect damage, and chromated copper arsenate (CCA) has been used as an inorganic preservative for many years. However, wood treated with CCA has been restricted from residential uses in the EU from June 30, 2004, due to its potential toxicity. Such a regulation is not in place in China yet, and CCA-treated wood is widely used in public parks. A portable XRF analyser was used to investigate arsenic (As) concentration on surfaces of in-service CCA-treated wood planks in a popular park as well as the influencing field factors of age in-service, immersion and human footfall. With a total of 1207 readings, the observed As concentrations varied from below the detection limit (<10 mg/kg) to 15,746 mg/kg with a median of 1160 mg/kg. Strong variation of As concentrations were observed in different wood planks of the same age, on the surface of the same piece of wood, inside the same piece of wood, and different surfaces of walkway planks, hand rails and poles in the field. The oldest planks exhibited high As concentrations, which was related to its original treatment with high retention of CCA preservative. The effect of immersion in the field for about 4 months was insignificant for As concentration on the surfaces. However, a significant reduction of As was observed for immersion combined with human footfall (wiping by shoes). Human traffic in general caused slightly reduced and more evenly distributed As concentrations on the wood surfaces. The strong variation, slow aging and relatively weak immersion effects found in this study demonstrate that the in-service CCA-treated wood poses potential health risks to the park users, due to easy dermal contact especially when the wood is wet after rainfall. It is suggested that further comprehensive investigations and risk assessments of CCA-treated wood in residential areas in China are needed, and precautionary measures should be considered to reduce the potential risks to residents and visitors, especially children.

Effects of preservative-chemicals on the bonding strength of urea–formaldehyde adhesive in Bambusa vulgaris Schrad. ex J. C. Wendl. var. vulgaris hort. laminates

Timber over-exploitation has threatened traditional commercial species such that alternatives including bamboos are being sought especially in the wood composite industry. However, bamboo has short service-life, as it is bio-degradable. For its laminated boards to substitute those of timber, the strips would need preservative-treatment. The effect of conventional preservative (i.e., CCA) and extracts from an organic source (e.g., Erythrophleum suaveolens bark) on the bonding (i.e., shear) strength of urea–formaldehyde (UF) resin in hot-pressed Bambusa vulgaris (green bamboo) laminates was examined. Sixty treated strips (200 mm long × 20 mm wide × 4.5 mm thick) were glued at their inner culm surfaces (i.e., 160 mm-glued and 40 mm-unglued portions). Untreated strips served as controls. Strips were paired at their glue-lines and hot-pressed at 85 °C and 15 Mb for 20 min. Bonding strengths at the glue-lines of the laminates were assessed using shear test (EN 13354: 2008). Bonding strengths of UF-resin laminates were weakened by the preservative chemicals, especially the inorganic type. Control laminates recorded greater mean shear strength (3.828 MPa) than those impregnated with E. suaveolens extract (2.751 MPa) and CCA (1.452 MPa). Thus, when chemical treatment is the only option to increase the service-lives of laminates against bio-deterioration, inorganic preservatives (e.g., CCA) should be the less favourable choice due to their weaker bonding strengths than extracts from organic sources.

Leachability and efficacy of CCA, creosote and two durable hardwood extracts in Ceiba pentandra (L.) Gaertn.-treated stakes against termite attack

Leaching affects chemical potency of treated wood in service and has generated environmental and health concerns. Attempts to supplant inorganic preservatives with those from organic sources are achievable but their leaching potential is worth-ascertaining. Leaching resistance of two notable conventional preservatives (i.e., CCA and creosote) was compared with that of extracts from two durable hardwoods (i.e., Erythrophleum suaveolens bark and Azadirachta indica seed extracts) in pressure-treated Ceiba pentandra stakes (500 × 50 × 25 mm). Seventy treated stakes each were subjected to leaching in distilled water in the laboratory. Ten replicates were removed every 48 h and the water changed until 336 h. Decay resistance of the leached stakes was then assessed after 5 years of field exposure using visual durability ratings, mass and hardness losses. Ten non-leached treated stakes served as controls. Chemical retention was greater for stakes treated with water-borne preservatives (i.e., the extracts and CCA) than with creosote. Resistance of extract-treated stakes to bio-deterioration for all the durability parameters decreased as leaching periods lengthened. Inorganic preservative components leached and showed less mass losses in a more consistent fashion than their extract-treated counterparts, especially A. indica. This study shows that chemical discharge from treated stakes should not be overlooked by the wood treatment industry. Larger treated woods for outdoor construction would leak fewer chemicals than stakes under laboratory conditions, field exposure of the stakes simulates their service performance.

Maybe Absolutely Green - with Chinese Traditional Medicine as Wood Preservative

An important way of conservation and protection of forest resources is wood preservative treatment. Currently, chemical preservatives are always used in the wood preservative treatment. Therefore, preservatives security has become an important environmental issue. This study focuses on national wood preservation, which workers are committed on. Many studies have been directed to look for new preservatives that are harmless to humans, animals and environment. Chinese herbal medicine as a wood preservative is selected for the environmental pollution problems of inorganic preservatives. In this paper, according to the application of traditional Chinese medicine, the nature of wood preservative and a preliminary study by the relevant trial, the theory of Chinese herbal medicine wood preservative is proposed. The results showed that Chinese herbal medicine can be used as wood preservatives. Finally, the paper puts forward the potential abilities of Chinese herbal medicine as wood preservatives.

Accelerated Field Durability Assessment Of Two Non-Durable Timbers (Ceiba Pentandra (L.) Gaertn. And Celtis Milbraedii Engl.) Impregnated With Natural And Inorganic Preserva-tives

Some timbers have natural resistance against decay. Others are made durable through treatment with preservatives several of which are noxious (e.g. CCA), destroy delicate body organs and are banned in many countries. Eco-friendly but efficient alternatives from organic sources including heartwood extracts of naturally durable plants are being sought. This study compares the effec-tiveness of extracts from two durable timbers (i.e. Tectona grandis L. f. (teak) and Erythro-phleum suaveolens (Guill. & Perr.) Brenan (potrodom) with three notable inorganic preserva-tives (i.e. CCA, Pyrinex 48EC and Creosote) on the field performance of two non-durable tim-bers (i.e. Ceiba pentandra (L.) Gaertn. and Celtis milbraedii Engl.). Mini-stakes (20x2x1cm) were impregnated [at 1.2bars, 123ºC for 3hrs] with 0.5% water-soluble bark extracts of T. gran-dis and E. suaveolens, CCA (0.5%), Pyrinex 48EC (0.5%) and creosote (at manufacturer’s speci-fication), and their retention in each stake determined. The stakes were then buried in the top-soil for 20 weeks. Preservative retention is less for the more viscous creosote than its water-borne counterparts. For all the durability parameters studied (i.e. visual ratings, hardness and mass losses), no significant differences (p

Investigation of synergistic effects of extracts from Erythrophleum suaveolens, Azadirachta indica, and Chromolaena odorata on the durability of Antiaris toxicaria

The service life of non-durable wood can be extended with inorganic preservatives, but several are harmful to the environment and non-target organisms. Recently, eco-friendly types from organic sources including plants have been used. The influence of bark extracts from Erythrophleum suaveolens and Azadirachta indica, and leaf extract from Chromolaena odorata, singly and in combinations (all at 1.5%) was investigated in field performance tests with non-durable Antiaris toxicaria wood. Treated and control stakes (500 × 50 × 25 mm) were exposed for 5 years. Data included extract retention, visual durability ratings, and mass and hardness losses. Retention was greatest for mixed E. suaveolens and C. odorata extract and least for single E. suaveolens extract. For durability parameters, non-treated stakes performed worse than treated ones. E. suaveolens bark-treated stakes were most durable; those treated with mixtures containing E. suaveolens also performed well, while stakes treated with other mixtures performed similarly to the controls, except for hardness. The mixed extracts exhibited various effects. For retention, synergism exists between E. suaveolens and C. odorata, there was antagonism between A. indica and C. odorata, while E. suaveolens extract reduced the retention of A. indica. Regarding durability, no synergism existed between effects of the mixed components. However, E. suaveolens bark extract enhanced A. indica, and C. odorata ingredients, while the effect of E. suaveolens extract was suppressed when it was mixed with the others. These extracts are potential alternatives for inorganic preservatives, especially E. suaveolens and its mixed extracts, as its effects enhanced the others.