Optimization of the Process Parameters for the Preparation of Activated Carbon from Low Cost Phoenix Dactylifera Using Response Surface Methodology

Research Article

Austin Chem Eng. 2015; 2(2): 1021.

Optimization of the Process Parameters for the Preparation of Activated Carbon from Low Cost Phoenix Dactylifera Using Response Surface Methodology

Devi AS, Kalavathy MH and Miranda LR*

Carbon Research and Engineering, Department of Chemical Engineering, A.C. Tech, Anna University, Chennai, India

*Corresponding author: Lima Rose Miranda, Carbon Research and Engineering, Department of Chemical Engineering, A.C. Tech, Anna University, Chennai, India

Received: November 23, 2015; Accepted: December 30, 2015; Published: December 31, 2015

Abstract

This work deals with the preparation of low-cost activated carbon from selected agricultural waste materials, by chemical activation with orthophosphoric acid. Activated carbon was prepared at various temperature, time and impregnation ratio. The effect of these preparation parameters on the yield and adsorption capacity of the prepared activated carbon was analyzed. The activation process was confirmed by the well-developed pore structure seen in SEM image and the FTIR analysis. The significant effect of three important process parameters were investigated systematically and optimized preparation condition was determined for the prepared ACDP to separate out different dyes of varying molecular weight range using Response Surface Methodology. This work showed that the effectiveness of an adsorbent lies in the way it is prepared and tuning the preparation condition directly has effect on the pore structure. The results reveal that ACDP can be recommended as a potential adsorbent for effective removal of pollutants from waste water and aqueous solutions.

Keywords: Activated carbon; Chemical activation; Characterization; Optimization; Response Surface Methodology

Abbreviations

AC Activated Carbon

ACDP Activated Carbon from date pits

CCD Central Composite Design

FTIR Fourier Transform Infrared Spectroscopy

IN Iodine Number

MB Methylene Blue

MR Methyl Red

MG Malachite green

MV Methyl Violet

MBN Methylene Blue Number

MRN Methyl Red Number

MGN Malachite green Number

MVN Methyl Violet Number

RSM Response Surface Methodology

SEM Scanning Electron microscope

TGA Thermo gravimetric analysis

Introduction

Among the various technologies available to remove toxic components such as anions, heavy metals, organic compounds and dyes from water sources, adsorption has been shown to be very effective for removal of dyes and other pollutants from aqueous solutions [1]. Activated carbon-based systems can remove a wide variety of toxic pollutants with very high removal efficiencies and has proved to be the least expensive treatment option, particularly in treating low concentrations of wastewater streams and in meeting stringent treatment levels. (Figure 1) shows the surface attraction of gases and chemicals onto activated carbon. This widely used adsorbent in industrial scale is commercially manufactured from various carbonaceous precursors like lignite and coal (42%), peat (10%), wood (33%) and coconut shell. However, the growing demand in adsorbing materials for polluted fluids treatment and increased cost of raw materials resulted in an increased research, concerning activated carbon preparation methods and sources.

In recent years, researchers have used low cost materials and waste agricultural material to reduce the cost of production. These include palm ash [2,3], chitosan/oil palm ash composite beads [4], pomelo (Citrus grandis) peel [5], salts treated beech sawdust [6], waste materials [7], natural Luffa cylindrica fibres [8], sunflower seed shells [9], algal biomass based materials [10], wheat bran [11], guava (Psidium guajava) leaf powder [12], almond shells [13], dehydrated peanut hull [14], rubber wood sawdust [15], Moringa oleifera wood [16], Agave sisalana fibre [17] and wheat shells [18]. But however, adsorption capacity and regeneration capacity for further cycle is limited. Thus, subverting the above mentioned disadvantages, porous activated carbon prepared from date pits (Phoenix dactylifera (Figure 2) by phosphoric acid activation method is being adopted in this study. Further, efficiency of the adsorption process depends on the type of precursor we use and how it is being prepared.

This work aims at reducing the heating time and chemical usage to determine the optimum preparation conditions for effectively removing a particular pollutant of particular molecular weight from an aqueous solution. The effects of the activation temperature, activation time and the impregnation ratio on the surface and chemical properties of activated carbon are studied to determine the optimum preparation conditions. Response Surface Methodology (RSM) was used to optimize preparation parameters of AC for separately removing four such dyes: Methyl red (molecular weight – 269.30), Methylene blue (molecular weight – 319.85), Malachite green (molecular weight – 36.91), Methyl violet (molecular weight – 407.98) and molecules less than 2 nm size from aqueous solution.