A novel approach to separation of waste printed circuit boards using dimethyl sulfoxide

Abstract

Waste printed circuit boards are complex heterogeneous mixture consisting of organic material, metal and glass fiber, therefore, it is quite difficult for the recovery of valuable materials from waste printed circuit boards. In this study, waste printed circuit boards without electronic components (known as bare boards) are submerged into dimethyl sulfoxide solvent at 170°C using refluxing process. Metallographic microscope shows that waste printed circuit boards produce the delamination after treated with dimethyl sulfoxide solvent for 15 min. When waste printed circuit boards are treated with dimethyl sulfoxide solvent for 30 min, the separation of waste printed circuit boards is complete to obtain metals and glass fibers. Moreover, the used dimethyl sulfoxide solvent is vaporized by the rotary decompression which obtains regenerative dimethyl sulfoxide and solid residues. Comparing two Fourier transform infrared spectroscopies, it is found that the regenerative dimethyl sulfoxide is the same as original dimethyl sulfoxide. Thermal analyses combined with Fourier transform infrared spectroscopy show that the solid residues are bromine epoxy resins. These findings suggest that this innovative technology offers an environmental friendly process with no pollution and high efficiency for separating valuable materials from waste printed circuit boards.

Characterization of waste printed circuit boards recycled using a dissolution approach and ultrasonic treatment at low temperatures

“…21 N-Methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and dimethyl formamide (DMF) are common solvents used in this separation approach due to their high boiling point, relatively high viscosity, and high thermal stability with an effective ability to dissolve numerous organic and inorganic chemicals without corroding metals. [22][23][24] However, the physical and chemical properties of NMP and DMSO were discouraging in view of commercial viability as well as in terms of public health, since DMSO is classied as a highly hygroscopic solvent with high specic heat, high viscosity, and an ability to penetrate human skin; furthermore, its vapors are heavier than air.…”

Delamination mechanism study of large size waste printed circuit boards by using dimethylacetamide

“…It results in the liberation and separation of metal clad of PCBs and hence the overall economy is also improved considerably (Zhu et al, 2013a). Among the various solvents, the organic solvent found most pronounced application because of their low cost, easy operation, regeneration and negligible effluent generation.…”

Phytotoxicity of dimethyl sulfoxide (DMSO) to rice seedlings

“…Due to the increasing reliance on these non-desirable chemicals and insufficient waste disposal, pollution derived from anthropogenic activities has imposed a serious risk on environmental and human health. Dimethyl sulfoxide (DMSO), an organosulfur compound having two C-S bonds in its molecular structure, has been widely used in a range of industrial processes since it easily dissolves many organic and inorganic substances (Simo 1998;Murakami et al 2002;Zhu et al 2013). Indeed, it has been estimated that the annual world production of DMSO was approximately 5.6 million tons (Murakami et al 2002;Hwang et al 2007).…”

“…It is known that DMSO can be easily accumulated in the water body without any indication of its presence due to its high polarity through anthropogenic inputs (Murakami et al 2002;Zhu et al 2013). Therefore, uptake of DMSO by plants may be a possible removal process during the treatment of DMSO-containing wastewater, which may subsequently cause variation of physiological and biochemical process and finally affects growth, nutrient absorption and yield of plants (Kumar et al 1976;Qiu et al 2013).…”