Ammonia removal from aqueous solution using modified oil palm empty fruit bunches based adsorbent

Highly ammonia-nitrogen concentration in water will destroy the marine ecology and contribute to bad odor. In this study, oil palm empty fruit bunches fibers (EFB), an abundant agricultural by-product/waste in Malaysia are selected for the ammonia-nitrogen removal from urban drainage water . The main aim is to study the effectiveness of EFB on ammonia-nitrogen removal from synthetic ammonia-nitrogen aqueous solutions under various experimental parameter conditions. The recovery of ammonia-nitrogen was studied with different soil media and submerged modified fresh EFB by planting the Cymbopogon citrus. In modification of the oil palm EFB, the sodium hydroxide (NaOH) and sulphuric acid (H2SO4) are used in the pretreatment of oil palm EFB under various parameters such as soaking time and concentration. The results showed that the modification of oil palm EFB using NaOH petreatment gives a better adsorption of ammonia nitrogen. The ammonia-nitrogen adsorption experiment was done in 180 minutes with the effect of different temperature (15, 20, 25, 30, 35, 40 oC) for sorption isotherm, kinetic modeling and thermodynamics studies. After that, these submerged EFB fibers are further tested with Cymbopogon citrus plant growth resulted best condition media of 50 % soils and submerged EFB fibers. The preliminary study shown that the optimized ammonia-nitrogen adsorption capacity was 0.828 mg/g under the NaOH treatment onto the EFB fibers which is better than H2SO4 modification with the adsorption capacity of 0.561 mg/g. The ammonia nitrogen removal by using partly decomposed EFB give adsorption capacity of 0.821 mg/g. The adsorption isotherm (Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich (DB-R)) data analysis were used for mathematical description of the adsorption equilibrium of ammonia nitrogen for unmodified (fresh) and modified EFB fibers. The Tempkin isotherm model fitted the biosorption experimental data with the best correlation for fresh EFB (R2 = 1) and modified EFB (R2 = 0.9999). Adsorption of ammonia nitrogen kinetics modeling data showed that the pseudo-second-order model fits the experimental data very well for fresh EFB (R2 = 0.9900) and modified (R2 = 0.9997) at 298 K predicting a chemisorption process for both fresh and modified EFB fibers. Thermodynamic parameter ( , and ) studies showed that the biosorption ammonia nitrogen onto modified EFB was predicted to be spontaneous and endothermic in nature. These modified fresh EFB were applied into urban drainage at Kampung Sembulan Lama, Kota Kinabalu for 7 days and the recovery of ammonia nitrogen recovered by Cymbopogon citrus plant growth. After 90 days, the optimum total weight for this plant was determined to be 93.33 grams in the media soil condition of 50 % soil and 50 % submerged EFB fibers. It can be concluded that the ammonia nitrogen from the water can be recovered by applying the empty fruit bunches fibers