Faculty of Science, Engineering and Technology (FSET)

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Browsing Faculty of Science, Engineering and Technology (FSET) by Subject "Adsorption"

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    Determination of Physico-Chemical Parameters and Removal of Bis(2-Ethylhexyl) Phthalate from Wastewater Using Prosopis juliflora Biochar/Carbon Nanotubes Composite Adsorbent
    (Chuka University, 2024) Mutua John Mutinda
    Phthalates, such as BEHP, are endocrine-disrupting compounds commonly used as plasticizers. Their presence in wastewater, often from industrial and household effluents, poses health risks including congenital anomalies, cancer, and chronic toxicity. The high cancer prevalence in Meru County has been linked to toxicants in effluent released into Kathita River, used for domestic purposes and irrigation. This is attributed to the inefficiency of the lagoon wastewater treatment technology in removing chemicals like BEHP. This study evaluates the physico-chemical properties and BEHP levels in wastewater from Meru Sewage Treatment Plant and explores the adsorption of BEHP using a Prosopis juliflora biochar/carbon nanotubes composite adsorbent. The temperature, pH, conductivity, turbidity, TDS, TSS, BOD and COD of the wastewater were determined using the standard APHA methods for wastewater, the concentrations of heavy metals using AAS while those of BEHP using HPLC. The following mean values were reported after data analysis: BEHP 0.055mg/L, Cu ND, Pb 0.042mg/L, Cd 0.0019 mg/L, COD 65.99 mg/L, TSS 29.3mg/L, TDS 639.17mg/L, turbidity 117.9FTU, conductivity 1079.9µS, pH 7.3, temperature 26oC and BOD5 65.9 mg/L; for dry season. Only pH and COD exceeded WHO limits for wastewater discharge into environment. The wet season parameter mean values were: COD 359.7mg/L, TSS 198.3mg/L, TDS 2094.2mg/L, turbidity 105FTU, conductivity 1244µS, pH 8, temperature 26 , BEHP 0.0429mg/L, Cu 0.47mg/L, Pb 0.037mg/L, Cd 0.056mg/L and BOD5 71.2mg/L. The temperature, TDS, BOD, Cu and Pb met WHO limit while conductivity, turbidity, TSS, COD and Cd exceeded. The composite adsorbent was characterized using FTIR and powder XRD. The dominant functional groups of the composite were C=O, CO2, OH-, Si-OH, C=N, MgO, CaCO3, and SiO2. The composite adsorbent was very efficient in the adsorption of BEHP with up to 96% removal in the samples at determined optimum adsorption parameters of; pH 5, temperature 24 , 15 minutes contact time and an adsorbent dose of 200 mg. The isotherm studies showed that the adsorption process was in agreement with the Freundlich isotherms with R2 value of 0.90469 while the kinetic studies revealed that BEHP adsorption followed pseudo second order model with R2 of 0.994. It was concluded that the application of biochar/CNTs composite adsorbent for the removal of BEHP from the wastewater is relatively cheaper and eco-friendly and should be applied for treatment of wastewater for irrigation and domestic use to improve water quality and minimize health risks associated with BEHP.
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    Determination of physicochemical parameters and estriol levels in nyeri waste water treatment plant and the adsorption of estriol using sugarcane bagassemultiwalled carbon nanotube composite
    (Chuka University, 2024) Njue Jediel Mwenda
    Persistent organic pollutants and endocrine disrupting substances have been found to be highly resistant to degradation. Exposure to these chemicals interferes with normal functioning of endocrine system by causing adverse effects such as cancer and impaired neurodevelopment. Waste water treatment plant mostly concentrate on removal of microorganisms leaving behind micro contaminants such as Estriol. The objective of the study was determination of physicochemical parameters and Estriol levels in Nyeri sewage treatment plant and the removal of Estriol using carbon nanotubes-sugarcane bagasse composite adsorbate. The composite was synthesized by oxidizing Multiwalled carbon nanotube in a ratio 3:1 nitric (V) acid to sulphuric (VI) acid mixture. Multiwalled carbon nanotube were then washed with deionized water and then added to a suspension of sugarcane bagasse powder in a ratio of 100:1 ,100:0.5 and 100:0.1. The characterization of the composites was done using Fourier transform infrared spectroscopy and X-ray diffraction techniques. The results showed that turbidity was higher in the dry season at 103.954 NTU compared to 46.5647 NTU in the wet season. Cd was recorded at 0.0168 mg/L during the wet season, which is significantly higher than the 0.0015 mg/L observed in dry season. Copper exhibited a concentration of 0.0833 mg/L in the wet season, which increased substantially to 1.0172 mg/L in the dry season. For Lead, the wet season value was 0.0159 mg/L, while the dry season value of 0.0050 mg/L. Dissolved Oxygen decreased markedly from 7.0617 mg/L in the wet season to 2.2396 mg/L in dry season. These differences in Pb, Cu, and DO levels were confirmed to be statistically significant p < 0.05 based on the Fisher’s LSD test with Bonferroni correction for p-value adjustment. Electrical Conductivity increased from 695.782 µS/cm in the wet season to 1056.104 µS/cm in the dry season. A t-test was conducted to compare Estriol concentrations between the wet and dry seasons at the Nyeri Water Treatment Plant. The mean Estriol concentration during the dry season was 1.444 ±0.671 Mg/L while in the wet season it was 0.982 ±0.870 Mg/L. The mean difference between the two seasons was 0.463, with a weighted standard deviation of 0.777. The optimum conditions obtained from the adsorption of Estriol were; equilibrium time 10 minutes, pH 4, maximum adsorbate concentration adsorbed at 0.1 g of composite 2 was 8 ppm. The composite that gave the best results was composite 2 (100:0.5) with 76.7% adsorption efficiency. The kinetic analysis of estriol best fitted the pseudo first order model with the rate constant for reaction as k1=−0.1−1, with an R2 value of 1.0. The analysis of adsorption isotherms for Estriol indicated that the Langmuir model provided a good model for fitting adsorption data than the Freundlich model, with a higher R² value of 0.5280 compared to 0.439 in Freundlich model. The enthalpy change (ΔH) for the process was calculated to be 26,165.44 J/mol, indicating that the adsorption is endothermic, meaning it absorbs heat from its surroundings. The entropy change (ΔS) was positive 68.85 J/mol-K suggesting an increase in disorder at the solid-liquid interface during adsorption. The Gibbs free energy change (ΔG) was negative at all the tested temperatures showing that the process naturally progresses without the need for external energy input.The findings demonstrated that sugarcane bagasse-carbon nanotube composite is a good low cost and environmentally friendly adsorbent for removal of Estriol from waste water.