Nitrate removal from groundwater by adsorption onto coconut husk granular activated carbon | |
| Author | Mensah, Huno Solomon Kofi |
| Call Number | AIT Thesis no.ET-SUD-18-01 |
| Subject(s) | Groundwater Purification Nitrate removal Nitrates |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management with specialization in Environmental Technology for Sustainable Development jointly offered by the Asian Institute of Technology, Thailand and UNESCO - IHE, The Netherlands |
| Publisher | Asian Institute of Technology |
| Abstract | Nitrate contamination of groundwater is a global problem and a threat to human health. Research to improve adsorptive removal of nitrate from groundwater is important for promoting low cost and effective groundwater nitrate treatment. Highly porous granular activated carbon was produced from coconut husk by chemical activation with K2CO3 at impregnation ratio of 1:1 (weight ratio) and carbonization temperature of 800 ̊C. Fourier transform infra-red spectra (FTIR), thermogravimetric analysis (TGA/DTA), scanning electron microscopy and BET surface area analyses were used to characterize the coconut husk granular activated carbon. Nitrate removal from groundwater by adsorption onto K2CO3 activated carbon was investigated using series of adsorption batch experiments. Nitrate adsorption onto the coconut husk granular activated carbon was evaluated as a function of the initial nitrate concentration of groundwater (10 to 150 mg/L), adsorbent dose(0.1 g/50 mL) and contact time (0.5 to 15 h) at neutral pH and ambient temperature. The kinetics of adsorption was studied using pseudo-first order, pseudo-second order kinetic models and the intra-particle diffusion equation. Langmuir and Freundlich isotherm models were fitted to the batch experiment data. Response surface methodology and Box-Behnken design of experiment was used to optimize and evaluate the effect of each process parameter and their interaction effects on nitrate removal from groundwater. Activated carbon yield of 35.1% and a very porous surface texture was observed. Brunauer-Emmett-Teller (BET) surface area and micropore volume of the coconut husk granular activated carbon observed was 1120 m2/g. Results from the kinetic study suggest pseudo-second order model was followed and intra-particle diffusion was rate limiting for higher initial nitrate concentrations (> 10 mg/L). The data were best represented by the Langmuir mono-layer adsorption isotherm with maximum adsorption capacity of 6.01 ±1.3 mg/g for initial nitrate concentration of 150 mg/L,0.1 g/ 50 mL adsorbent and equilibrium time of 6 h. A predictive quadratic model was generated for the nitrate removal efficiency. Nitrate removal from groundwater was found to be influenced significantly by adsorbent dose (46.5%) and initial nitrate concentration (20.5%.) About 92% nitrate removal from groundwater was achieved at optimal conditions of 150 mg/L initial nitrate concentration, with 0.5 g/100 mL adsorbent dose and contact time of 6.25 h. The results of the study suggest that, activated carbon with high quality adsorptive properties for groundwater nitrate treatment can be made from coconut husk. |
| Year | 2018 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Annachhatre, Ajit P.;Rene, Eldon R.; |
| Examination Committee(s) | Thammarat Koottatep;Shipin, Oleg V.; |
| Scholarship Donor(s) | Netherlands Fellowship Programmes (NFP);UNESCO-IHE;Asian Institute of Technology; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology - UNESCO-IHE, 2018 |