The rapid increase in the world population and the development of industry has been caused the land and aquatic environmental pollution. Organic pollutants include a wide range of contaminants that most of them are persistent in the environment and adversely affect the ecosystems. Among these organic contaminants, the furfural (C 5 H 4 O 2 ) that is present in the wastewater from the manufacture of rubber and plastics industries, petroleum and oil refinery, and the production of furfural, causes the detrimental environmental and health effects. The purpose of this study was the biosorption of furfural from aqueous solutions using the biomass of green algae Scendesmus quadricauda . To prepare the adsorbent, the algae was cultivated in the containers of 250 liters, harvested after two months and air dried. Batch and column adsorption experiments were conducted using Taguchi design. Factors affecting adsorption including pH, temperature, the initial concentration of furfural, the amount of adsorbent and the contact time were studied. Some of physico-chemical properties of adsorbent were determined by the infrared spectroscopy with Fourier transform techniques (FTIR), the scanning electron microscopy (SEM), the atomic force microscopy (AFM), the BET and the particle size analyzer. The FTIR indicated the involvement of carboxylic, carbonyl amides, esters, amines and hydrocarbon functional groups on the adsorbent. The SEM images showed that the surface depressions and pores were reduced after the adsorption. The AFM analysis of adsorbent indicated that the majority of adsorbent particles were in the nanometer scale and had the high surface roughness coefficient and pores. The specific surface area of adsorbent determined by BET method was 40 m 2 /g. The results of Taguchi tests showed that the optimum conditions for furfural adsorption were at pH 6, the optimal temperature of 25 ° C, the furfural initial concentration of 100 mg/L , the adsorbent dosage of 10 g/L and the contact time of 60 minutes. The isotherm models of the Langmuir, Redlich-Patterson, Koble-corrigon and Temkin showed better fitness than Freundlich model. The maximum adsorption of furfural was obtained 38.81 mg/g at 25°C according to the Langmuir equation. The kinetics data were better fitted by the Pseudo-first-order and Elovich. The column adsorption experiments showed that the adsorption efficiency is approximately 31%. The results of regeneration of the adsorbent with distilled water and 50% ethanol showed 79% efficiency. Based on the thermodynamics data, the adsorption was exothermic, randomly and spontaneous. Overall, it was concluded that the biomass of algae S. quadricauda is an effective adsorbent for the adsorption of furfural from aqueous solutions. Keywords: Furfural, Biosorption, Algae, Scenedesmus quadricauda , Aqueous solutions
