Adsorptive properties investigation of natural sand as adsorbent for methylene blue removal from contaminated water

The aim of this study was to examine the adsorption of cationic dye methylene blue (MB) on two types of natural sand (Agdez, Assa). The raw sand was characterized using X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. To determine optimal conditions, batch adsorption experiments were conducted to study the effects of pH, sand quantity, contact time, solution temperature, and initial MB concentration on the removal process. It has been found that 1 g of our proposed adsorbents (Agdez sand/Assa sand) can achieve the maximum adsorption of MB after 5 min. The results also showed that the kinetics and equilibrium of the MB dye adsorption onto Agdez sand and Assa sand are well described by the pseudo-second-order kinetic and Langmuir models, respectively. The thermodynamic parameters indicate that the MB adsorption onto Agdez sand and Assa sand is governed by physisorption. Desorption studies were examined in six successive cycles using diluted NaOH solution and tap water on adsorbed dye.