<p>Cardanol is a natural phenol obtained from anacardic acid, the main element of cashew nut shell oil. The oil is highly effective against metal corrosion and is used in many industries. Cashew nuts are one of Vietnam’s important industrial crops. Vietnam raw cashew output averages well above 300,000 tonnes over the years. However, after harvesting and processing of cashew nuts, the shells have usually been thrown away. Scientists believe that if the shells can be properly treated, the waste will turn into ‘gold’ and bring high profits.It is estimated that one ton of dried cashew can produce 700-750 kilos of shells from which 154 kilos of cashew nut shell oil is created. Cashew nut shell oil can be used as industrial fuel which is 60 percent less costly than FO.</p> <p>It is estimated that one ton of dried cashew can produce 700-750 kilos of shells from which 154 kilos of cashew nut shell oil is created. The oil can also be used as material to make adhesives, anti-corrosive metal, insulating materials, electronic products boards, forest product preservatives, and structural wood treatment liquid.In 1999, Vietnam began exporting cashew nut shell oil. At that time, the export volume was modest, 1,000 tons only. The figure rose to 80,000 tons in 2011. Vietnamese enterprises export 600,000 tons of the oil to China, South Korea, Indonesia and Spain. A representative of F.T.E Technology Development said cashew nut shell oil brings $7 million a year to the company with the profitability rate of 20 percent. He said that Vietnam has great advantages to become a world’s cashew nut shell oil production base.</p> <p>However, most Vietnamese enterprises export cashew nut shell oil as fuel or raw material. They could even earn bigger money if they developed more valuable products from cashew nut shell oil, such as Carnadol. In countries with hot weather and high humidity like Vietnam, the demand for substances which can protect construction works, machines and equipment from corrosion is especially high. Carnadol is a good solution.</p> <p>A group of scientists from the Youth Scientific and Technological Promotion Center (TST) headed by Pham Quoc Nghiep recently conducted research on using carnadol to make a green corrosion inhibitor to protect metallic materials from corrosion. The researchers used the cardanol extraction method from cashew nut shell with supercritical CO2 technology. The carnadol content obtained was 23 percent with a purity of 68.6 percent. The product can protect metal at a high rate of 84 percent.</p>