STUDY ON THE EFFECT OF ADDED NPK FERTILIZER AND CITRIC ACID ON NICKEL CONCENTRATION IN PLANT DURING PHYTOMINING PROCESS USING PIPER BETLE

• Main Author: Maulana Yusuf, Iqbal
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67917
• Institution: Institut Teknologi Bandung

Nickel is one of the metals with a broad range of applications, from alloying elements to battery applications. There are two main sources of nickel: sulfide ores such as pyrrhotite, pentlandite, and chalcopyrite, and oxide ores such as lateritic ore. Around 80% of the nickel reserves in the world are in lateritic ores with low nickel concentrations. For lateritic ore, conventional concentration techniques are difficult to implement; therefore, an alternate method is necessary to extract nickel from this resource. Phytomining is one of the techniques that could be used to concentrate nickel from lateritic ore by planting, harvesting, and processing hyperaccumulator plants to produce bio-ore with a high nickel concentration. In phytomining, different treatments, such as the addition of fertilizer or chelating agents, are used to promote plant metal absorption. Green betel (Piper betle) is a plant that can be commonly found in Indonesia and has the ability to accumulate nickel. However, research on phytomining with these plants is limited. In light of this, the capacity of P. betle to accumulate nickel and the effect of additional NPK as fertilizer and citric acid as a chelating agent on nickel concentration in plants will be investigated further in this study. Hopefully, this research will provide new information regarding P. betle’s ability to accumulate metals and serve as a reference for future research. The experiment begins with ore preparation by crushing to obtain -2 mm ore and continues with characterization processes such as aqua regia digestion, extraction using diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA) solution, soil properties test, X-Ray Diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FTIR) analysis. Then, plants are transplanted onto the substrate that was previously prepared in a pot. For NPK treatment, three doses of 0 (N0), 0.1 (N1), and 0.2% (N2) (w/w) were applied on the first day after the plants were transplanted. Meanwhile, four weeks before harvest, citric acid was given at doses of 0 (C0), 10 (C1), and 20 (C2) mmol kg-1. Plants were allowed to grow for twelve weeks. Plants were harvested at the end of the twelfth week, and their nickel content was determined by digestion using a solution containing HNO3 65% and H2O2 30%. Aside from plant digestion, DTPA-TEA extraction and FTIR analyses were performed on the plant's growing substrate. Atomic Absorption Spectroscopy (AAS) was used to assess the metal contents of the digestion and DTPA-TEA solution. Based on the results of the experiment, it can be inferred that the addition of citric acid can reduce the plant's dry weight, whereas NPK addition has the opposite effect. However, when citric acid is combined with NPK, the lowered biomass seems to be lesser than when citric acid is used alone, where an increase in citric acid should be followed by an increase in NPK dose to counteract the reduced biomass effect. This effect can be attributed to plant toxicity symptoms such as chlorosis. As for total nickel concentration in plants, concentration values for N0-C0, N0-C1, N0-C2, N1-C0, N1-C1, N1-C2, N2-C0, N2-C1, and N2-C2 treatments are 67.51, 175.77, 178.57, 148.04, 156.25, 219.86, 172.05, 149.95, and 198.53 mg kg-1-dry weight with translocation factor of 0.24, 0.76, 1.5, 1.13, 0.66, 1.38, 0.18, 0.16, and 0.44 and bioconcentration factor of 94.61, 377.65, 398.1, 338.53, 318.77, 535.18, 355.35, 184.47, and 325.63.