keywords: Electrical conductivity, optimization, wastewater, adsorbent, composite Introduction
The discharge of industrial effluent usually poses threat to flora and fauna in the water. Commercial adsorbents used for the treatment of the effluents are usually effective but expensive; hence the need to develop adsorbents that are effective, inexpensive and locally available. A composite adsorbent prepared from groundnut shell char and commercial activated carbon has been investigated for the treatment of pharmaceutical wastewater. Groundnut shells were collected washed with water and sun-dried before carbonation and activation. A composite of the groundnut shell char and commercial activated carbon was prepared and was characterized in terms of functional groups, crystalline phase and structure, surface morphology and surface area. The adsorption experiment was designed and analyzed employing BoxBehnken design of response surface methodology. The effluent was treated with the prepared composite adsorbent by varying adsorbent dosage (0.2-1.8 g), contact time (10-110 min) and groundnut shell char fraction (0-1). The adsorbent showed the presence of amines, alkyne, alkene and amides while the XRD revealed a homogeneous and highly crystalline material. The surface morphology of the adsorbent revealed a highly developed irregular pore structure which is due to chemical activation in the activated carbon. The BET surface area, pore volume and pore size were found to be 305.11m 2 .g -1 , 0.27cm 3 .g -1 and 3.00 nm respectively. The physicochemical properties of the pharmaceutical wastewater before treatment revealed a pH, EC, TDS, salinity, COD and BOD values of 10.00, 755.50 µS/cm, 528.50 mg/l, 366.50 mg/l, 342.50 mg/l and 44.50 mg/l respectively. The maximum BOD removal efficiency of 97.45 % obtained by the composite adsorbent was achieved using a GSAC fraction of 1 with a mass of 0.20 g and at a contact time of 10.00 mins.