Hongyan Zhai

There is a rising concern about the safety risk that trihalomethanes (THMs) in drinking water pose. In this work, to adsorb THMs such as chloroform (TCM), dibromochloromethane (DBCM), bromodichloromethane (BDCM), and bromoform (TBM), we coated chitosan (CS) on coconut shell activated carbon (CAC). The adsorbents were characterized using BET, XRD, FTIR, and SEM techniques. The impact of various variables was examined, including contact time, quantity of adsorbent, initial pH, and initial THM concentrations. Under the same conditions, TCM was adsorbed most efficiently, followed by BDCM, DBCM, and TBM. When the pH was between 4 and 8, the adsorption of THMs onto the coconut shell activated carbon supported chitosan (CS/CAC) varied relatively little; however, when the pH increased above 8, the adsorption of THMs decreased. For THMs, CS/CAC adsorption was a chemical reaction and monolayer adsorption that fit better with the pseudo-second-order kinetic model and the Langmuir isotherm model. According to the thermodynamic study, THMs were adsorbed endothermically and spontaneously on CS/CAC. For column experiments, the adsorption of THMs was influenced by bed height and flow rate. After up to four cycles of adsorption and desorption, it was found that the adsorbent was reusable. The maximum adsorption capacities for Langmuir were 187.27, 114.29, 93.28, and 89.61 µg/g for TCM, BDCM, DBCM, and TBM, respectively. CS/CAC has a high adsorption capacity, especially for TCM, which is responsible for a major portion of THMs in drinking water. This indicates that CS/CAC has a lot of potential uses when it comes to removing THMs from water.