Abstract
Pakistan, an agricultural country, raises 146.5 million commercial and domestic poultry birds, which generate around 544,831 tons of waste per year. This waste finds its final disposal in agricultural land as soil fertilizer or disposal site amendment. The usage of poultry litter for this purpose is uncontrolled, which results in environmental degradation such as emission of greenhouse gases, e.g., methane. However, alternative options such as thermochemical conversion of poultry litter can offer better solutions where this waste can be used as a low-cost carbon source for the synthesis of Multiwalled Carbon Nanotubes (MWCNTs). In this study, efforts were made to utilize this cheap and plentiful carbon source for the synthesis of CNTs in the presence of Ni/Mo/MgO as a catalyst, through pyrolysis. For a better yield of carbon product, the optimum ratio for the catalysts (Ni/Mo/MgO) was found to be 4:0.2:1. Furthermore, the process parameters were also optimized for better carbon yield. A good yield of CNTs resulted from a pyrolysis time of 12 min, a temperature of 825 °C, and a catalyst weight of 100 mg. The structure and morphology of the produced nanotubes were confirmed through X-ray Diffractometer (X-RD) and Scanning Electron Microscopy (SEM). The environmental application of the nanotubes was tested in a synthetic chromium solution in the lab using a batch experiment. Different experimental conditions (pH, adsorbent dosage, and contact time) were optimized to improve the adsorption of Cr (VI) by carbon nanotubes and a UV-Visible spectrophotometer was used at 540 nm to measure the absorbance of Cr (VI). The results showed that up to 81.83% of Cr (VI) removal was achieved by using 8 mg of CNTs at pH 3 with 400 rpm at 180 min of contact time. Thus, it was concluded that poultry litter can be a useful source for the synthesis of MWCNTs and thereby removal of Cr (VI) from industrial tanneries’ wastewater.
Highlights
In Pakistan, the poultry sector is one of the vibrant segments of the livestock division
Oxidation of Multiwalled Carbon Nanotubes (MWCNTs) was performed in a tube furnace at a temperature of 400 ◦C for a duration of 2 h, following the method explained by Vivekchand et al [28]
The prepared sample was first sonicated in ethanol for 5 min at room temperature, and a drop of dispersion was deposited on a Cu/Rh grid covered with a vinyl polymer, and the grid was dried overnight under vacuum [32]
Summary
In Pakistan, the poultry sector is one of the vibrant segments of the livestock division. Poultry litter has been used as a mulching material, since poultry litter has properties of conservation of soil moisture During summer when it is hot, it protects the surface, which feeds the roots [9]. Research on the direct growth of MWCNTs has been reported using in situ techniques in which a catalyst, i.e., transition metal alloy is taken and a carbon containing material is passed through it. Response Surface Methodology (RSM) was used to optimize the parameters (such as temperature, time, and weight of the catalyst) both for catalyst preparation and growth of MWCNTs. The second objective of this research was to analyze the adsorption behavior of CNTs for Cr (VI) adsorption. Effects of factors, such as system pH, adsorbent dosage, and adsorbent contact time were investigated. pH effects on the removal of Cr (VI) were investigated
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