Abstract:
Water pollution remains a major problem in developing countries. Textile industries
contribute to this problem by producing large amounts of wastewater during dyeing and
finishing processes. The dye that remains in the wastewater is a disturbance to the
ecological system besides being a health hazard. Therefore, the main objective of this
project was to develop an adsorbent material from a blend of sugarcane bagasse and water
hyacinth for removal of reactive red 198 dye, commonly used on cellulosic fibers, from
textile effluent. The specific objectives of the study were to develop adsorbent materials
from sugarcane bagasse and water hyacinth through chemical modification, to blend
modified sugarcane bagasse and water hyacinth at different ratios and analyze their dye
adsorption at varied conditions (dye concentrations, particle sizes) and to optimize dye
adsorption of the blend by varying adsorbent dosage, blend ratio and initial dye
concentration. Sugarcane bagasse treated with 0.1M hydrochloric acid and water hyacinth
treated with 0.1M sodium hydroxide were blended together and used to treat wastewater
containing reactive red 198 dyes. Batch experiments were carried out varying the initial
dye concentration from 5 mg/l to 50 mg/l, adsorbent particle sizes from 280 um to 2000
um and blend ratios of 0:100, 25:75, 50:50 and 100:0. The absorbance of the samples was
measured using UV Vis spectrophotometer and percentage dye removal determined.
Minitab statistical tool was used in experimental optimization based on the rotatable
central composite design. A full quadratic regression equation that related the variables and
the response was developed. A two-way interaction of the regression model was
investigated. From the regression model, initial dye concentration and blend ratio had
significant effect on adsorption since P-value was less than 0.005. Adsorption of reactive
red 198 dye was optimal at initial dye concentration of 50.23 mg/l, particle size of 745.87
um and at a blend ratio of 100:0. At these optimum conditions, the dye removal percentage was found to be 89%, with the chemical oxygen demand (COD) reduction of 95%. From
the current result, it was concluded that chemically modified sugarcane bagasse could
serve as adsorbent materials for removing reactive red 198 dyes from textile wastewater.
Treatment of the adsorbents enhances their dye adsorption compared to non-modified
adsorbents. Adsorption process may therefore be employed as a clean technology in
wastewater treatment.
However, the two adsorbents should be used separately to obtain better results unless an
optimal blend is established.