The Effect of Oak Bark Bio-char Gradation on the Absorption of Various Textile Dyes under Discontinuous Conditions: Experimental Study

Dyes are organic materials with complex structure, often toxic, carcinogenic, mutagenic, and non-biodegradable. They are one of the most important textile industrial wastewater pollutants. This study was performed to investigate the effect of Oak Bark’s bio-char(OBB) gradation as an adsorbent for the removal of 2 anionic dyes that are acid red 206 (AR)and reactive red (RR)120 from synthetic waste water in a batch study. To make the OBB was placed in 400, 500, 600 and 700 °C oven for half to three hours and eventually the bio-char which was placed in 700 °C oven for 2 hours was used as adsorbent in this study. For studying the effect of adsorbent pulverize, 5 classification of mesh 100 to over 500 microns were made by standard sieves number 35, 40, 50, 100 &140 and showed that when mesh decreases, surface area exposed for adsorption of dye increases which enhanced the adsorption capacity of adsorbent. As a result, particles with 297-400 micron (passed from sieve 40 and remained on sieve 50) were chosen as the optimum size. Studied parameters were contact time, pH, initial dye concentration, and adsorbent dose. Tests showed a 90-minute equilibrium time and kinetic adsorptions test results were well fitted with a pseudo-second order model. Also, results showed that for both dyes, the absorption efficiency increases with decreasing pH and increasing adsorbent dose. Isotherm studies showed that Langmuir isotherm had the best fit to the experimental data with absorption of 21.59 mg/g for AR and 8.91 mg/g for AR. Generally, dye removal efficiency is obviously higher for AR than AR one, so it can conclude that OBB in compare with other bio - chars can act as an effective low cost adsorbent for acidic dye removal.

Keywords:

Textile dyes , Oak bark bio-char , Adsorption