Removal of Malachite Green Dye From Aqueous Solution Using Multi-Walled Carbon Nanotubes: An Application of Experimental Design

Abstract

An experimental design methodology was performed in the optimization of removal of malachite green dye by multi-walled carbon nanotubes. A Central Composite Design (2 5 ) was chosen to develop a mathematical model and determine the optimum condition for adsorption of malachite green by carbon nanotubes. Five experimental factors, namely initial dye concentration, mass of adsorbent, pH, contact time and agitation speed were studied. Maximum adsorption of malachite green was achieved at the suggested optimum conditions: initial dye concentration (20 ppm), weight of adsorbent (0.03 g), pH solution (7) contact time (17 min) and agitation speed (150 strokes per min). The experimental value of adsorption by multi-walled carbon nanotubes were found to be in good agreement with the predicted value (R 2 = 0.922).The experimental equilibrium data were best fitted to isotherm model (Langmuir) and kinetic model (pseudo second-order) respectively. Maximum adsorption by carbon nanotubes at monolayer for malachite green was obtained at 112.36 mg/g while kinetic rate constant was calculated to be 0.0017 g mg -1 min -1 .Keywords: carbon nanotubes, adsorption, malachite green, experimental design Abstrak Metodologi reka bentuk eksperimen telah dijalankan dalam pengoptimuman penyingkiran pewarna malakit hijau oleh karbon tiub nano multi-dinding. Reka bentuk komposit berpusat (2 5 ) telah dipilih untuk membentuk satu model matematik dan menentukan kondisi yang optima untuk penjerapan malakit hijau oleh karbon tiub nano. Lima faktor eksperimen yang terdiri daripada kepekatan awal pewarna, berat bahan penjerap, pH larutan, masa sentuhan dan kelajuan goncangan telah dikaji. Malakit hijau telah mencapai penjerapan yang optima oleh karbon tiub nano pada kondisi: kepekatan awal pewarna (20 ppm), berat bahan penjerap (0.03 g), pH larutan (7), masa sentuhan (17 minit) dan kelajuan goncangan (150 strok/minit). Nilai eksperimen untuk penjerapan oleh karbon tiub nano multi-dinding telah mencapai persetujuan yang baik pada nilai jangkaan (R 2 = 0.922). Data eksprimen keseimbangan menunjukkan kesesuaian pada model Langmuir dan model pseudo tertib kedua. Penjerapan maksimum oleh karbon tiub nano pada monolapisan untuk malakit hijau ialah 112.36 mg/g manakala pemalar kadar kinetik ialah 0.0017 g mg -1 min -1 .Kata kunci: karbon tiub nano, penjerapan, malakit hijau, reka bentuk eksperimen

Adsorption of malachite green in a fixed-bed columns by Thiourea modified poly(acrylonitrile-co-acrylic acid)

“…The pH of the dye solution has a significant influence on the adsorption process. It affects the interaction of the adsorbent's surface with dye molecules [47,48]. The influence of pH on breakthrough curves at three distinct pH values are shown in Figure 4a.…”