Removal of petroleum sulfonate from aqueous solution by hydroxide precipitates generated from leaching solution of white mud Lu Cheng a , Lanlan Ye a , Dejun Sun b , Tao Wu b,⇑ , Yujiang Li a,⇑ a Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Jinan 250100, PR China b Key Laboratory of Colloid & Interface Science of Education Ministry, Shandong University, Jinan 250100, PR China highlights  Freshly generated hydroxide precipitates.  Co-precipitation/adsorption process.  Electrostatic attraction and hydrogen bonding are the main adsorption mechanisms.  Adhesion and cohesion affect the adsorption of PS onto FGHP. article info Article history: Received 24 October 2014 Received in revised form 29 November 2014 Accepted 1 December 2014 Available online 8 December 2014 Keywords: Adsorption Petroleum sulfonate White mud Leaching solution abstract Freshly generated hydroxide precipitates (FGHPs), which was prepared by adding the leaching solution of white mud (LSWM) to highly alkaline solution, was used to remove petroleum sulfonate (PS) from aque- ous solution. The chemical composition of the white mud and petroleum sulfonate were determined by X-ray fluorescence spectrometry and gas chromatography–mass spectrometry. The surface properties of the FGHPs and PS-FGHPs were characterized by X-ray diffraction, transmission electron microscopy, Fou- rier transform infrared spectroscopy and zeta potential analyzer. The FGHPs displayed excellent treat- ment efficiency for PS at pH 12.0. The maximum equilibrium removal efficiency of PS was reached within 60 s. The maximum adsorption capacity of FGHPs for PS was 3798.06 mg/g at 303 K and pH 12.0. The Langmuir isotherm was the best choice to describe the adsorption behavior. The kinetic data fitted the pseudo-second-order kinetic model. Thermodynamic parameters suggested that the adsorption of PS onto FGHPs occurred via physisorption and was exothermic. Electrostatic attraction and hydrogen bonding were the main adsorption mechanisms. Moreover, adhesion and cohesion also strong affected the co-precipitation/adsorption process. Liquid bridges via hydrogen bonding, adhesive and cohesive forces linked up with MOH + /M(OH) 2 particles and the surfactant molecules to form a three-dimensional network structure and lead to deposition. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Surfactant wastewater is one of the major pollution sources of a receiving water body around the world [1]. In the surfactant waste- water produced by the households, surface active agents or surfac- tants invariably exist in significant amounts due to detergents used for all kinds of washings [1]. Surfactants have also been widely used in textiles, fibers, food, paints, cosmetics, pharmaceuticals, mining, oil recovery and pulp and paper industries [1,2]. The synthetic surfactants are of three major types: anionic, nonionic, and cationic. Anionic surfactants are the major class of surfactants and have been used widely in detergent formulations [3,4]. Petro- leum sulfonate (PS) surfactants differ from relatively homogeneous conventional surfactants in that they are mixtures of sulfonated alkyl–aryl petroleum products and free mineral oils [5]. Polymers and PS surfactants are used as effective ‘‘pusher fluids’’ to enhance oil recovery and the PS surfactants are therefore used to improve the flooding efficiency of crude oil and widely used in exploitation [6]. Some surfactants are toxic; others are not, depending on dose, chemistry, receptors, etc. They may cause foaming in rivers and reduce the quality of water [3]. Surfactants cause short and long- term changes in ecosystems [3]. PS surfactants removal from water http://dx.doi.org/10.1016/j.cej.2014.12.003 1385-8947/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. Tel./fax: +86 531 88365437 (T. Wu). Tel./fax: +86 531 8 8363358 (Y. Li). E-mail addresses: wutao@sdu.edu.cn (T. Wu), yujiang@sdu.edu.cn (Y. Li). Chemical Engineering Journal 264 (2015) 672–680 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej