Research Progress in Determination Methods of Formaldehyde Content in Indoor Air

The detection methods of formaldehyde content in indoor air, including traditional laboratory detection methods (AHMT spectrophotometry, phenol reagent spectrophotometry, acetyl acetone spectrophotometry and gas chromatography) and rapid detection methods (electrochemical sensor method, photoelectric spectrophotometry, etc.), were introduced and described. This paper systematically analyzes and compares the detection principle, applicable environment medium, detection flux and the advantages and disadvantages of each detection method. The future detection methods of formaldehyde content in indoor air were prospected.

Effect of salting time on formaldehyde content of dried salted Indo-Pacific mackerel

This paper reports an analysis of formaldehyde in dried salted short mackerel (Rastrelliger brachysoma) which was intentionally added with formaldehyde compared to those that was not. The purpose was to see whether salting could cover up the illegal use of formaldehyde. Mackerel was obtained from one day fishing landed at Karangantu Fishing Port, Serang-West Java. The fish was transported in ice by road (3 hours) to the laboratory in Jakarta, and divided into two groups upon arrival. One group was soaked in 3% (w/v) formaldehyde solution for 30 minutes, while another group was not (control treatment). They were then salted in saturated brine for 12 and 24 hours at ambient temperature and sun dried subsequently to 40% moisture content or less. The formaldehyde content of raw materials was in the range of 1.4-1.7 ppm, indicating that natural formaldehyde was present in the fish. Soaking in 3% formaldehyde solution for 30 minutes significantly increased fish formaldehyde content from 1.4-1.7 to 154-157 ppm, and decreased to 42.3-58.1 after 24 and 12h salting which then dropped to 25.0-35.9 ppm after drying, respectively. Those of control showed a slight decrease after salting and increase after drying, i.e. 2.7-3.4% in the final products. This results indicate that salting could not disguise the illegal use of formaldehyde to preserve raw materials, however small amount of formaldehyde in dried salted fish could be regarded natural formaldehyde of the fish.

Preparation and assistant-dyeing of formaldehyde-free amphoteric acrylic retanning agent

With the enhancement of environmental protection consciousness, concerns have been raised about non-toxic and biodegradable leather retanning agents. According to the European standard 2002/231/EC, the free formaldehyde content of leather products should be less than 150 mg/kg. As one of the retanning agents in the market, the content of free formaldehyde in the Multifunctional retanning agent (MTA) is 372.22 mg/kg and higher than the limit value. In this work, glutaraldehyde as an alternative of formaldehyde was used to modify acrylic polymer and an amphoteric acrylic retanning agent was prepared. Then it was used in retanning process, and its retanning and assistant-dyeing properties were investigated. The results showed that the free formaldehyde content of amphoteric acrylic retanning agent modified with glutaraldehyde was only 4.17 mg/kg. Meanwhile, the presence of amino groups in the amphoteric acrylic retanning agent improved the dyeing properties of leather by electrostatic attraction. Compared with the leather treated with anionic acrylic retanning agent, the residual dye concentration of the dyeing effluent of the retanned leather with amphoteric acrylic retanning agent decreased from 17.4 mg/L to 10.0 mg/L, and the dyed leather had better resistances to friction and water-washing. In addition, the BOD5/COD value of the wastewater after Mannich base polymer retanning was only 0.32, indicating that the retanning agent was biodegradable. Moreover, the leather retanned with amphoteric acrylic retanning agent had good thermal stability, fullness and physical and mechanical properties. Graphical abstract

Properties of Eco-Friendly Particleboards Bonded with Lignosulfonate-Urea-Formaldehyde Adhesives and pMDI as a Crosslinker

The purpose of this study was to evaluate the feasibility of using magnesium and sodium lignosulfonates (LS) in the production of particleboards, used pure and in mixtures with urea-formaldehyde (UF) resin. Polymeric 4,4′-diphenylmethane diisocyanate (pMDI) was used as a crosslinker. In order to evaluate the effect of gradual replacement of UF by magnesium lignosulfonate (MgLS) or sodium lignosulfonate (NaLS) on the physical and mechanical properties, boards were manufactured in the laboratory with LS content varying from 0% to 100%. The effect of LS on the pH of lignosulfonate-urea-formaldehyde (LS-UF) adhesive compositions was also investigated. It was found that LS can be effectively used to adjust the pH of uncured and cured LS-UF formulations. Particleboards bonded with LS-UF adhesive formulations, comprising up to 30% LS, exhibited similar properties when compared to boards bonded with UF adhesive. The replacement of UF by both LS types substantially deteriorated the water absorption and thickness swelling of boards. In general, NaLS-UF-bonded boards had a lower formaldehyde content (FC) than MgLS-UF and UF-bonded boards as control. It was observed that in the process of manufacturing boards using LS adhesives, increasing the proportion of pMDI in the adhesive composition can significantly improve the mechanical properties of the boards. Overall, the boards fabricated using pure UF adhesives exhibited much better mechanical properties than boards bonded with LS adhesives. Markedly, the boards based on LS adhesives were characterised by a much lower FC than the UF-bonded boards. In the LS-bonded boards, the FC is lower by 91.1% and 56.9%, respectively, compared to the UF-bonded boards. The boards bonded with LS and pMDI had a close-to-zero FC and reached the super E0 emission class (≤1.5 mg/100 g) that allows for defining the laboratory-manufactured particleboards as eco-friendly composites.

Repeated thermo-hydrolytic disintegration of medium density fibreboards (MDF) for the production of new MDF

Medium density fibreboards (MDF) are currently not recycled after service life, but various publications report on recycling by the disintegration of MDF using various techniques and the properties of obtained recovered fibres (RF). In this study, the main aim was to put back RF into the MDF manufacturing process as closed-loop recycling using repeated thermo-hydrolytic disintegration. Compared to previous studies, the focus was on the recycling of MDF with a relatively low F:U molar ratio (1.11). Urea–formaldehyde-bonded MDF with a target density of 700 kg m−3 was subjected to thermo-hydrolytic disintegration in an autoclave using only water at 95 °C for 20–30 min. Afterwards, the properties of RF and virgin fibres (VF), of MDF produced thereof and the composition of the disintegration water (DW) were determined. The nitrogen content (NC) revealed that RF contained about 30% of the initially applied UF. The pH of the DW hardly changed during recycling and it contained considerable amounts of reducing sugars. Using RF did not result in higher formaldehyde emissions than VF. Compared to earlier studies using a higher formaldehyde content (higher F:U ratio), MDF bonded with modern UF resins can be disintegrated under clearly milder disintegration conditions with respect to temperature and time. The properties of recycled MDF were similar to those of reference MDF; up to 100% RF could be used without severely deteriorating the strength and increasing formaldehyde emissions from these panels.

Analysis of formaldehyde content in salted fish at Ciroyom market, Bandung City, Indonesia

Salted fish is one of the processed fish products that are in great demand by the people of Indonesia. This type of preparation has good durability with natural processes. However, there are some cases that use chemicals as preservatives, such as formaldehyde. This study aims to determine the formaldehyde content in salted fish that is traded in the market in Indonesia. This research is descriptive and the sample is taken from Ciroyom Market, Bandung City, Indonesia, randomly. Samples were analyzed qualitatively to observe the physical characteristics of salted fish. In addition, quantitative analysis was also carried out to determine the level of formaldehyde present in salted fish using a UV-Vis spectrophotometer at a wavelength of 520 nm. The results of the analysis showed that 4 of the 15 samples tested contained formaldehyde with a concentration of 0.033 – 0.482 ppm. The characteristics of these samples physically also have similarities with the characteristics of fish containing formaldehyde, namely bright white and hard textured.

Eco-Friendly Fiberboard Panels from Recycled Fibers Bonded with Calcium Lignosulfonate

The potential of using residual softwood fibers from the pulp and paper industry for producing eco-friendly, zero-formaldehyde fiberboard panels, bonded with calcium lignosulfonate (CLS) as a lignin-based, formaldehyde free adhesive, was investigated in this work. Fiberboard panels were manufactured in the laboratory by applying CLS addition content ranging from 8% to 14% (on the dry fibers). The physical and mechanical properties of the developed composites, i.e., water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), bending strength (MOR), as well as the free formaldehyde emission, were evaluated according to the European norms. In general, only the composites, developed with 14% CLS content, exhibited MOE and MOR values, comparable with the standard requirements for medium-density fiberboards (MDF) for use in dry conditions. All laboratory-produced composites demonstrated significantly deteriorated moisture-related properties, i.e., WA (24 h) and TS (24 h), which is a major drawback. Noticeably, the fiberboards produced had a close-to-zero formaldehyde content, reaching the super E0 class (≤1.5 mg/100 g), with values, ranging from 0.8 mg/100 g to 1.1 mg/100 g, i.e., equivalent to formaldehyde emission of natural wood. The amount of CLS adhesive had no significant effect on formaldehyde content.