Preparation, Characterisation And Evaluation Of Five Agriculture By-Products’ Activated Carbons Using Heavy Metals And Dye
Access to safe drinking water is the most concern in developing countries. Surface water is a common source of usable water. Heavy metal toxicity has become a great threat to the environment due to industrial wastewater. Lead, nickel, copper, and cadmium are the most toxic heavy metals in polluted w...
Saved in:
| Summary: | Access to safe drinking water is the most concern in developing countries. Surface water is a common source of usable water. Heavy metal toxicity has become a great threat to the environment due to industrial wastewater. Lead, nickel, copper, and cadmium are the most toxic heavy metals in polluted water. It has harmful effects such as lung cancer, kidney damage, mental and nerve disorder. Conventional methods for removing toxic metals and dyes from wastewater such as the use of commercial activated carbon are very expensive for third-world countries. The main objective of this study was to evaluate the ability of activated carbon produced from agricultural waste-products (rice husk, coconut coir, corn cobs, neem bark and Moringa oleifera bark) to remove heavy metals (copper (II), cadmium (II), lead (II) and nickel (II)), and dye (methylene blue). The activated carbons were produced using carbonized method in an inert state with chemical activation in varieties ratio at different temperatures. Desorption process were conducted using 0.1M acid (hydrochloric acid and sulphuric acid) and basic (sodium carbonate) solutions. Hydrochloric acid was the best solvent to desorb loaded contaminants from the adsorbents. The lead was absolutely removed from spiked aqueous solution in 5 mg/L using five types of activated carbon. In the batch adsorption process, copper (97.00 %, 97.52 %, 64.49 %, 36.60 %, 98.24 %), cadmium (56.72 %, 54.16 %, 69.40 %, 41.48 % 56.00 %) and nickel (92.22 %, 81.79 %, 83.35 %, 88.10 %, 82.30 %) were removed from spiked aqueous solution in 5 mg/L by activated carbon of rice husk, coconut coir, corn cobs, neem bark, and Moringa oleifera bark, respectively at pH 6 using lower dosage (0.025 g/100 mL) at room temperature (25 ± 1 °C). The maximum quantity of lead uptake at equilibrium time was (46.51, 43.08, 47.16, 51.57, 53.73 mg/g) using five activated carbons of rice husk, coconut coir, corn cobs, neem bark, Moringa oleifera bark, respectively. The highest adsorption capacity of adsorbents was Moringa oleifera bark. Activated carbon of Moringa oleifera bark was produced with carbonization temperature at 700 °C and impregnation ratio of ZnCl2 with H2SO4 to charcoal at ratio 5:1. The produced well adsorbents were characterized using Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier-Transform Infrared (FTIR) and proximate analysis. Moringa oleifera bark showed the best adsorption results due to well surface area (439.23 m²/g) and pore volume (0.189 cm³/g). Freundlich isotherm was well fitted with coefficient regression (R2 ≈ 1) for experimental data than the Langmuir and D-R model. The second order model also was closely fitted (R2≈ 1) with experimental data. From FTIR data, most of the activated carbon contained hydroxyl, carboxyl and methoxy groups to adsorb heavy metals and dye. A further experiment showed that methylene blue was greatly removed from spiked water using all activated carbons. The maximum quantity of methylene blue (qmax) uptake were 108.94 mg/g, 107.71 mg/g, 107.71 mg/g, 109.34 mg/g, and 108.12 mg/g using rice husk, coconut coir, corn cobs, neem bark and Moringa oleifera bark, respectively. |
|---|