From Plastic Waste to Recoverable Energy: Polymer-Dependent Pyrolysis Performance and Fuel Characteristics
Izunna Francis Okaro
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African University Of Science And Technology, Galadimawa, Abuja
Kamoru Adio Salam
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University Of Abuja
Fadimatu Nyako Dabai
—
University Of Abuja
Plastic pyrolysis offers a means of recovering useful energy from plastic waste, but differences in polymer structure can influence energy recovery and product characteristics. This study compared the energy recovery behaviour of low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS) during thermal pyrolysis in a semi-batch reactor. Total recoverable energy was determined from the energy contributions of the liquid and non-condensable gaseous products. PP recorded the highest total recoverable energy of 1.81 MJ, followed by LDPE at 1.68 MJ and PS at 1.59 MJ. Although PS produced a high liquid yield, it did not give the highest energy recovery, which shows that liquid yield alone may not adequately explain pyrolysis energy performance. The differences observed were linked to polymer molecular structure and the resulting degradation and product formation pathways. The recovered LDPE oil was further characterized using GC-MS and physicochemical tests. It contained mainly alkanes, alkenes and cyclic hydrocarbons within the diesel hydrocarbon range. The oil had a calorific value of 43.3 MJ/kg, flash point of 82.7 °C, pour point of − 23.3 °C, and cloud point of − 0.6 °C. However, its viscosity (18.0 mPa·s) and ash content (3.2%) indicate that further treatment would be required before direct use in diesel engines. The results show that polymer type influences product yield, total energy recovery and the practical fuel value of pyrolysis products.
Keywords
Plastic pyrolysis
Energy recovery
Polymer structure
Waste-to-energy
Fuel properties
Box-Behnken Optimization of Ciprofloxacin Adsorption onto Phosphorus-Doped Chrysophyllum albidum Biochar-CuO Nanocomposite for Sustainable Wastewater Treatment
Ismaila Ayinde Oba
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University Of Ilorin, Ilorin
Folahan Amoo Adekola
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Department Of Industrial Chemistry, University Of Ilorin, Ilorin, Nigeria
Friday Onyekwere Nwosu
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Department Of Industrial Chemistry, University Of Ilorin, Ilorin, Nigeria
Antibiotic residues in pharmaceutical effluents threaten water security and public health, demanding low-cost, sustainable remediation materials. A phosphorus-doped biochar-CuO nanocomposite (P-BC-CuO) was prepared from Chrysophyllum albidum seed biomass and applied to ciprofloxacin (CIP) removal from aqueous solution. The material was characterized by FTIR, SEM/EDX, TEM, XRD, XRF, TGA and BET analysis. Doping and CuO loading raised the BET surface area from 169.93 to 379.91 m²/g and pore volume from 0.16 to 0.35 cm³/g, with a 2.86 nm mean pore diameter indicating a mesoporous structure. The pHpzc was 6.6. A Box-Behnken design optimized initial CIP concentration, contact time, adsorbent dose and pH, yielding a highly significant quadratic model (p < 0.0001; adjusted R² = 0.9834; predicted R² = 0.9477) and a non-significant lack of fit (p = 0.5302); pH was the most influential factor. Optimum conditions (concentration 27.5 mg/L, dose 0.2 g, time 60 min, pH 8) gave an actual CIP removal of 94.8% against a predicted 95.1%. Equilibrium data fitted the Freundlich model best (R² = 0.9954), indicating heterogeneous multilayer adsorption, with a Langmuir capacity of 23.56 mg/g. Kinetics followed the pseudo-second-order model (R² = 0.9884), and a mean adsorption energy of 1.84 kJ/mol indicated physisorption. Thermodynamic analysis showed positive ΔH (16.76 kJ/mol) and ΔS (53.50 J/mol/K), indicating an endothermic process that became spontaneous (ΔG < 0) above about 313 K. These findings show that agro-waste-derived P-BC-CuO is a promising adsorbent for antibiotic-laden wastewater and supports circular-economy approaches to water treatment.
Keywords
Ciprofloxacin Phosphorus-doped biochar CuO nanocomposite
New Advances in Processing Bismutite Ore Varieties as Raw Materials for Photocatalytic Applications: A Comprehensive Review
Ajibola Blessing Nihinlola
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University Of Ilorin
Alafara Baba
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University Of Ilorin, Ilorin, Nigeria
The development of various industries has given rise to a significant surge in environmental pollution in our environments. Thus, a need for the development of safe chemical processes for the degradation of the environmental pollution especially for water remediation processes become important. Bismuth, industrially obtained from a named Bismutite ore is a green and inexpensive metal that is relatively less toxic, and it has shown significant potential as a safer alternative for toxic elements including lead, cadmium, antimony and mercury. In addition, photocatalysis, an innovative oxidation process has been extensively used for water remediation processes due to its ease of operation and efficiency. In comparison to other conventional methods, photocatalysis is a promising technology for breaking down of toxic/organic pollutants in the environment by reducing/oxidizing toxins to H2O and CO2; and solar energy conversion. Therefore, this study gave a detailed review on some indigenous Bismutite Ores for its possible applications as photocatalytic materials in water remediation processes.
Keywords
Bismuth
Bismutite Ore
Environmental Pollution
Photocatalytic Applications