Amine functionalized and Fe 3 O 4 incorporated activated carbon for bisphenol-A separation Drishti Bhatia, Sakshi Batra and Dipaloy Datta ABSTRACT Activated carbon (AC) is the most commonly used adsorbent for water purification, although the dispersive nature of AC in aqueous solution poses a serious problem. To overcome this limitation, AC was magnetized with iron oxide using iron salts as precursor. Further to enhance its effectiveness, it was impregnated with Aliquat 336. Different characterization techniques (Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), along with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD)) were used to analyze the adsorbent. Furthermore, the value of the pH at which the overall charge on the surface of the adsorbent is neutral was found by pH drift method. The modified form of the activated carbon was used to treat the aqueous solution of bisphenol-A in the batch as well as in the continuous mode of operation. In batch mode, the data were validated using equilibrium and kinetic models, and in continuous mode, data were fitted with the Thomas, Adams-Bohart, and bed depth service time (BDST) fixed bed adsorption models. Also, the changes in Gibb’s free energy, enthalpy, and entropy were estimated from the temperature study. The design of an adsorption column is proposed to treat 10,000 L/day of an industrial effluent containing BPA. Drishti Bhatia Sakshi Batra Dipaloy Datta (corresponding author) Department of Chemical Engineering, Malaviya National Institute of Technology Jaipur, Jaipur, Rajasthan 302017, India E-mail: dipaloy@gmail.com Key words | adsorption, Aliquat 336, batch, bisphenol-A, column, magnetic activated carbon INTRODUCTION Endocrine disrupting compounds (EDCs) are defined as ‘an exogenous agent that interferes with synthesis, secretion, transport, metabolism, binding action, or elimination of natural blood-borne hormones that are present in the body and are responsible for homeostasis, reproduction, and developmental process’ by the US Environmental Protec- tion Agency (Diamanti-Kandarakis et al. ). EDCs enter the human body either through ingestion or inhala- tion. The interference mechanism of EDCs in living organisms is carried out in three different ways: (i) they imi- tate the naturally working hormones in living beings such as androgen, estrogen and thyroid hormones, (ii) they can be attached to cell receptors, preventing the binding of endogenous hormones, and (iii) they alter the production of various hormones by different organs. EDCs include a diverse range of products; these may be naturally occurring or human-made. These include pharmaceuticals, DDT and pesticides, polychlorinated biphenyls, dioxin, and dioxin- like compounds, and plasticizers like bisphenol-A (BPA). 2,2-(4,4 0 -Dihydroxydiphenyl) or BPA is an organic compound with phenolic groups. It is in a solid state at room temperature with less volatility, low vapor pressure, and moderate water solubility (Maffini et al. ). BPA finds its application as a monomer in the manufacture of polycarbonate (used in plastic toys, infant feeding bottles, food storing containers, etc.), and high performance trans- parent rigid plastic. These containers and toys provide a source of BPA for the environment. Store receipts, dental sealants, linings of canned foods, plastic wrap, and toilet paper are also sources of BPA in nature. BPA travels in some amount into food and beverages that are stored in such containers. The maximum use of BPA (95%) is in the production of epoxy resins and polycarbonates. The remain- ing 5% is used in phenolic resin, phenoplast resins, antioxidants, and PVC manufacturing. The presence of BPA in the environment can also be endorsed to anthropo- genic activities. The adverse effect of exposure to BPA can be seen in the reproduction of wildlife. In males, BPA can lead to a decrease in sperm count, DNA damage, and mobi- lity. There are increased chances of prostate cancer. In 1755 © IWA Publishing 2019 Water Science & Technology | 79.9 | 2019 doi: 10.2166/wst.2019.175 Downloaded from http://iwaponline.com/wst/article-pdf/79/9/1755/619477/wst079091755.pdf by guest on 12 July 2022