1 23 Environmental Science and Pollution Research ISSN 0944-1344 Volume 20 Number 2 Environ Sci Pollut Res (2013) 20:1106-1116 DOI 10.1007/s11356-012-0947-4 Treatment of industrial wastewater containing Congo Red and Naphthol Green B using low-cost adsorbent M. F. Attallah, I. M. Ahmed & Mostafa M. Hamed