Removal of 4-chloro-2-methyl phenoxy acetic acid pesticide using coffee wastes from aqueous solution

The objective of this study is to investigate the use of coffee waste (CW) to remove the 4-chloro-2-methyl phenoxy acetic acid (MCPA) from aqueous solutions. To prepare CW, it was first washed and boiled to remove color and impurities then it was air dried at room temperature for 48 h. Afterward the particle size distribution and zeta potential of the CW ground were determined. The porous texture of coffee was proved by scanning and transition electron microscopy. Batch adsorption tests were performed at 298 K. The effects of contact time, MCPA concentration, and pH were investigated. It was observed that the adsorption of MCPA by using CW is independent of the solution pH level. The Langmuir isotherm provided the best correlation for MCPA adsorption onto CW, showing that the adsorption was favorable. The Langmuir adsorption capacity was found to be 0.34 g/g. The second-order model provided the best description of MCPA adsorption onto CW when compared with the first order model. Infrared spectral studies revealed that acidic groups carboxyl and hydroxyl, are predominant contributors to MPCA adsorption by coffee.