Colloids and Surfaces B: Biointerfaces 88 (2011) 521–526 Contents lists available at ScienceDirect Colloids and Surfaces B: Biointerfaces jou rn al h om epage: www.elsevier.com/locate/colsurfb Biosorption of Acid Blue 25 by unmodified and CPC-modified biomass of Penicillium YW01: Kinetic study, equilibrium isotherm and FTIR analysis Yuyi Yang, Danfeng Jin, Guan Wang, Danfeng Liu, Xiaoming Jia ∗ , Yuhua Zhao ∗ College of Life Sciences, Zhejiang University, Hangzhou, 310058, PR China a r t i c l e i n f o Article history: Received 1 March 2011 Received in revised form 8 July 2011 Accepted 19 July 2011 Available online 26 July 2011 Keywords: Acid Blue 25 Cetylpyridinium chloride Biosorption isotherms Penicillium YW 01 a b s t r a c t The main objective of this work was to investigate the biosorption performance of unmodified and Cetylpyridinium chloride (CPC)-modified biomass of Penicillium YW 01 for Acid Blue 25 (AB 25). Maximum biosorption capacity of AB 25 onto CPC-modified biosorbent was 118.48 mg g -1 under phosphoric–phosphate buffer with initial dye concentration of 200 mg L -1 at 30 ◦ C. The biosorption pat- tern of AB 25 onto unmodified biosorbent in aqueous solution and phosphoric–phosphate buffer was well fitted with both Langmuir and Freundlich isotherm models. While the equilibrium data of CPC- modified biosorbent in aqueous solution and phosphoric–phosphate buffer failed to fit the Freundlich isotherm model, indicating the monolayer biosorption formed onto CPC-modified biosorbent. The values of initial biosorption rate of biosorbent in phosphoric–phosphate buffer were found to be higher than that of corresponding values in aqueous solution, indicating phosphoric–phosphate buffer enhanced the initial biosorption rate of biosorption process. Weber–Morris model analysis indicated that the bound- ary layer effect had more influence on the biosorption process in phosphoric–phosphate buffer. The BET surface area of CPC-modified biosorbent (0.5761 m 2 g -1 ) was larger than that of unmodified biomass (0.3081 m 2 g -1 ). Possible dye–biosorbent interactions were confirmed by Fourier transform infrared spectroscopy. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Pigments and dyes which have complex aromatic structures are widely used in leather, textile, paper, printing, cosmetic, plastic, food, and pharmaceutical industries [1,2]. More than 7 × 10 5 tonnes of synthetic dyes were reported to be produced per year around the world for various industrial processes [3]. Discharge of these dyes into water bodies can consume the dissolved oxygen required by aquatic life and some of them have direct toxicity and/or carcino- genic to mammals [4]. Hence, effluents containing dye molecules must be treated to minimize the threat to the environment. Many processes are investigated for dye removal, such as bio- logical, chemical and physical methods. The main disadvantage of physical methods is that they simply transfer the dye molecule to another phase rather than destroying them [5]. Chemical methods are not widely used because of high cost and disposal problems [6,7]. The efficiency of biological degradation processes are prone to be influenced by the components and physiochemical conditions of dye effluents [8]. Adsorption has been found to be one of the prominent techniques for dye wastewater treatment in terms of ∗ Corresponding authors. Tel.: +86 571 88206995; fax: +86 571 88206995. E-mail addresses: jiaxiaoming@21cn.com (X. Jia), yhzhao225@zju.edu.cn (Y. Zhao). cost and operation [9]. Moreover, adsorption does not result in the formation of harmful substance during the process and can pro- duce high-quality effluent [10]. The biomass or activated carbon derived from fungi have been widely used as prominent adsorbents for dye removal, such as Aspergillus niger [11], Rhizopus oryzae [12], Trametes versicolor [13], Cunninghamella elegans [14] and so on. Penicillium is one of the most widespread fungi in the terres- trial environment. Findings in our previous study demonstrated that Penicillium YW 01 could be used as a biosorbent material for the removal of Congo red and acid black 172 [15]. In this work, the biomass prepared from Penicillium YW 01 was modi- fied with a cationic surfactant (cetylpyridinium chloride) through a simple method in order to obtain an effective and alternative material for dye removal. Most of the adsorption experiments in published literatures were carried out in deionized water, but a part of studies have used phosphate buffer in experiments [16–18]. Therefore, it was meaningful to investigate the biosorption behav- ior of unmodified and modified biosorbents under the conditions of deionized water, citrate–phosphate and phosphoric–phosphate buffer. Kinetic and isotherm analysis of the biosorption processes was analyzed in terms of the pseudo-second-order, Weber–Morris models, Langmuir and Freundlich isotherm models. The char- acterization of the unmodified and modified biosorbents and possible dye–biosorbent interaction were evaluated by Fourier transform infrared spectroscopy and BET-surface area analysis. The 0927-7765/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfb.2011.07.047