การศึกษาตัวดูดซับราคาถูกจากเส้นใยธรรมชาติเหลือทิ้งเพื่อกำจัดสีคริสตัลไวโอเลต

Abstract

Nowadays, the water pollution derived from dyeing industry affects environment and human life. Crystal violet (CV) is a dye widely used in dyeing industry. The release of CV to environment causes health risk to human and animals. In this work, Moringa oliefera pod husk (MOPH), an agricultural waste, was studied for using as adsorbent for removal of CV. The objective of this research is to prepare low cost adsorbent for CV removal. The MOPH adsorbent was firstly prepared and studied its properties. It was found that, the pariticle size of MOPH adsorbent was 28.35 ± 21.77 μm. Fourier transform infrared spectra (FTIR) and Thermogravimetric analysis (TGA) confirmed the presence of cellulose, hemicelluloses, and lignin. The point of zero charge of MOPH of 5.1 indicated that the surface of adsorbent was negative charges providing its capability to bind with CV. The effects of contact time, initial CV concen- tration, pH, adsorbent dose, and adsorption temperature on the adsorption capacity were studied. The results indicated that the optimum conditions were the contact time of 2 h, initial concentration of CV 50 mg/L, dose of 0.6 g/L, pH 6 and temperature of 25 °C. The effect of initial CV concentration was evaluated and the results corresponded to Langmuir isotherm which indicated the monolayer of 156.25 mg/g at pH 6, and temperature of 25 °C. A study of kinetics adsorption responded to the pseudo-second order and suggested that the removal of CV from the solution was due to physicochemical interaction between MOPH and CV. Under thermodynamic study, the negative value of Gibb's free energy of -4.55 kJ/mol indicated a spontaneous adsorption process and the enthalpy change of -20.24 kJ/mol implying an exothermal adsorption process. Moreover, the percentage of desorbed CV solution was 57.91% by using 1 M of CH3COOH solution. The results indicated that MOPH is an alternative low cost adsorbent and may be useful for wastewater treatment application.