Adsorption of reactive dyes from aqueous solution by silylated palygorskite

Surface modification of palygorskite is one of the important ways to enlarge its application field. This study adopts palygorskite modified by 3-aminopropyl triethoxysilane (APTES) as adsorbent of three reactive dyes. The surface modification of palygorskite was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. Batch studies were carried out to investigate various experimental parameters such as adsorbent dosage, contact time, initial dye concentration and initial pH. The kinetics of the adsorption followed the pseudo-second-order model. Adsorption equilibrium data were fitted by the Langmuir isotherm. The adsorption of the three dyes by palygorskite was low but was strongly increased by the silylated palygorskite. The maximum adsorption capacity calculated by the Langmuir model was 34, 38, 60 mg/g for Reactive Red 3BS, Reactive Blue KE-R and Reactive Black GR, respectively.