Printed circuit board waste as a source for high purity porous silica

• Printed circuit board waste has been used for the first time for silica production.
• Concentrated sulfuric acid is not as effective as nitric or hydrochloric acid treatment.
• The as-prepared silica is porous with specific surface areas exceeding 300 m2/g.
• The purity of the obtained silica can be higher than 99%.
• If the treatment temperature is too high the surface area will diminish due to agglomeration.

The electronic waste stream is one of the fastest growing streams of waste in the world. Printed circuit boards which are found in all electronic equipment are composed of a mixture of various metallic and non-metallic constituents. In this manuscript, the nonmetallics have been treated with acids followed by thermal treatment aiming at the production of high purity porous silica. The results show the possibility of obtaining SiO2 with a specific surface area (BET) as high as 300 m2/g and purity higher than 99% (X-ray fluorescence, molar%). The as-prepared silica is comparable to industrially sold samples. The study has successfully demonstrated the possibility of using these unwanted electronic wastes for the synthesis of materials with higher value and utility.

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