Effect of Red Mud and Rice Husk Ash-Based Geopolymer Composites on the Adsorption of Methylene Blue Dye in Aqueous Solution for Wastewater Treatment oleh Khoa Dang Nguyen, Trang Tran Thu, Anh Thi Hoang Tran, Oanh Thi Kim Le, Suresh Sagadevan, Noor Haida Mohd Kaus