Adsorption of 4-Nitrophenol Using Pilli Nut Shell ActiveCarbon

An economically feasible technology for the removal of pollutants from wastewater is adsorption.Active carbon was prepared bysingle stage method via chemical impregnation of pili Nut-Shell(PNS)with orthophosphoric acid and activation at a temperature of 450oC using precursor-acidratio of 1:4 for a period of 2 h. The effects of initial concentration, contact time, adsorbent doseand pH on the uptake of 4-nitrophenol/ para-nitrophenol(PNP) usingpili nut-based active carbon(PAC) were determined. The PAC maximum adsorption capacity value (190.39 mg/g) wasobtained at an initial concentration of 1000 mg/L and was found to be greater than that of acommercial granular active carbon(CGAC)(166.97 mg/g) at an initial concentration of 800 mg/L.The BET surface area and total pore volume of PAC (960 m2/g, 0.422 cm3/g) respectively werealso greater than that of CGAC (426.3 m2/g, 0.208 cm3/g). The pore size distribution of the PAC(2.842 nm) classifies it to be within range of super-microporous and as such could be used fortoxic gas removal as well as small liquid molecules. The Langmuir isotherm best described theadsorption of PNPonto PAC, while pseudo second order kinetics fitted best. The adsorptionprocess was exothermic and spontaneous. Thus,active carbon produced fromPNScan be used toadsorb PNP.