Reduction of chemical oxygen demand of vinasse using sugar cane bagasse ash geopolymer

摘要

The aim of this study was to determine the use of sugar cane bagasse ash geopolymer (SCBAG) as an adsorbent fororganic compounds to reduce the chemical oxygen demand (COD) of vinasse. The effects of solid loading, time andtemperature on batch adsorption were investigated, while the effects of bed height and flow rate were investigatedthrough column studies. The adsorption of organic compounds onto SCBAG could be modelled well using theLangmuir isotherm and pseudo-second-order kinetics. The maximum batch adsorption capacity was 738 mg/g at298.15 K after 5 h of adsorption. The column studies showed that the highest COD reduction of 81% could beachieved using a flow rate of 2.5 ml/min and a bed height of 13 cm. These conditions gave a dynamic uptake of107 458 g and a breakthrough time of 600 min. The column adsorption could be best described using theBohart–Adams model, giving a correlation coefficient of 0.98, a Bohart–Adams rate constant of 3.05 × 10~(?8) l/(mg min)and a saturation concentration of 6.93 × 10~7 g/l. The SCBAG could be regenerated and be used as an adsorbent inthree cycles without significant loss in adsorption capacity.