An alternative chemical method for regeneration of activated carbon at room temperature consisting in the in situ combination of a diluted acid and two oxidants with a catalyst for the desorption and oxidation of pollutants previously adsorbed on carbon material. This so called CARBOX technology is less expensive than state-of-the art thermal regeneration of activated carbon since no energy input is required.
The feasibility and economics of the adsorption technology at industrial scale largely depends on the reactivation and reuse of the spent activated carbon. The ideal activated carbon regeneration process involves desorption of the pollutants adsorbed on the carbon material with minimal modification of its initial properties. Spent activated carbons can be regenerated using thermal, physicochemical or biological processes, but the thermal processes dominate the current industrial practice. In thermal regeneration of activated carbon about 30% of carbon is lost by combustion, producing CO2 and other volatile pollutants that contribute to climate change and to social and environmental concerns. This process is complex, costly and has high energy demand. It requires temperatures between 600-1000 °C, and oxidizing or inert gases. A less expensive and environmental friendly technology is thus required to recycle/recover this key material of growing use in our modern society.
CARBOX is a clean industrial technology that offers a solution to these problems while protecting man and environment. Therefore, it is considered a green technology. Chemical desorption and complete oxidation of carbon adsorbed pollutants is carried out under mild conditions at a cost well below that of state-of-the-art thermal regeneration. Basically it consists in contacting the carbon material to be regenerated and detoxified with a cleansing solution for a short period of time in a single step. This technology can be used, among others, in the following industrial sectors: pharmaceutical, waste recycling, wastewater treatment and drinking water.
Allows regeneration of activated carbon in the same place where it is being used (in-situ regeneration), avoiding removal, replacement and transport of activated carbon (a costly and laborious process).
It is easy to control. The treatment can be stopped in seconds, controlling the regeneration process at different time scales.
It works at room temperature and atmospheric pressure.
The energy consumption is negligible.
The equipment used is simple and provides an overall economical process.
The regeneration efficiency is high (see example below).
A real industrial sample of spent granulated activated carbon (GAC) from a drinking water treatment plant in California, which iodine number was 327, was treated in our laboratory with CARBOX technology in a single trial of less than 1 hour. No optimization effort was undertaken. The Iodine number of the regenerated GAC sample was 566, showing an improvement of 239. In the USA, the standard is for iodine number to be >500.
In summary, CARBOX technology enhances performance in many aspects of conventional technology (thermal regeneration). It is characterized by a high efficiency and sustainability at low cost. This regeneration method is an alternative technology with unique features: It can be conveniently operated in situ at room temperature and pressure, with low energy consumption and with short time requirements. It is therefore a real alternative that offers a great business opportunity in the growing market of activated carbon regeneration.
Current development status
Further research required
Optimization of the process to finnish the technology at bench scale.
Scale up to a pilot working prototype.
Partners for future research
Our group is looking for companies interested in CARBOX process for technology transfer agreement and/or R&D cooperation.