Ruth N. WanjauEsther W. NthigaNg’ang’a, Ndung’u Samuel2022-03-222022-03-222021http://ir-library.ku.ac.ke/handle/123456789/23268A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Chemistry) in the School of Pure and Applied Sciences of Kenyatta University, November 2021Consumption of water contaminated with heavy metal ions compromise human and animal wellbeing even at permissible limits. Therefore, their removal from water is very important for the safety of consumers. Previously used conventional water treatment techniques were expensive and ineffective. Among them, adsorption has gained research interest because of its ease in design, environmentally friendly and availability of materials in large quantities, especially from agricultural wastes. Several chemical modification techniques are reported to have improved adsorbents removal capacity, including the use of modifying agents such as ethylene -1, 2- diamine. In this study, ethylene- 1, 2- diamine modified Jackfruit (Artocarpus heterophyllus Lam.) seeds were used. The raw adsorbent was chemically modified using thionyl chloride and ethylene -1, 2- diamine. Both raw and modified adsorbent were characterized using a Fourier transform infrared spectrophotometer (FT-IR) then employed in batch optimization, kinetic and thermodynamic adsorption experiments. The FT-IR results showed functional groups of hydroxyl (-OH), carbonyl (-C=O), carboxylate (-COO-) (raw adsorbent) and additional anchored amine (-NH2) groups (modified adsorbent) as important adsorption sites for metal ions removal. Batch results maximum adsorption capacity at optimal pH < 6.5; 20 minutes (raw) and 15 minutes (modified); optimal speed (150 rpm - 175 rpm), dosage (10 mg – 15 mg), temperature (310 K) and 30 mg/L. Adsorption of the three metal ions fitted Langmuir isotherm model (R2 > 0.98) with adsorption capacities in Pb2+ > Cu2+ > Cd2+ order. Kinetic data fitted pseudo-second-order (R2 > 0.91) which was more suitable in explaining the adsorption rate. Thermodynamic data showed that Gibb’s free energy (ΔG°) values for all metal ions were negative indicating feasibility and favorability of adsorption. Positive entropy change (ΔS°), enthalpy change (ΔH°) and activation energy (E𝑎) values which were > 40 kJ/mol and very low sticking probability (S*) values confirmed that chemisorption predominated adsorption of ions. The results showed good performance of modified Jackfruit seeds as a potential adsorbent for Cu2+, Pb2+ and Cd2+ ions removal from contaminated water. The study, therefore, recommends sachets of the modified adsorbent be made for water purification at the household level and also to scale up the applicability of the adsorbent to a pilot plant to cater for many communities considering its shelve life and regeneration.enKineticEquilibriumThermodynamic Adsorption StudiesSelected Heavy Metal IonsRawModified Jackfruit SeedsAqueous MediaThesis