Water hyacinth (Eichhornia crassipes) is known as an aquatic weed that has rapid growth. However, the water hyacinth has the ability to remove metals from water as it acts as a natural

Composite built by patchouli biochar and metal oxide, Cr 2 O 3 , is a potential material for remediation of contaminated wasterwater. Oxidation of biochar using acid or salt oxidators can improve its surface polar functional groups. This treatment may be able to increase impregnation of metal cation (as salt) before calcination to form its oxide. In this research, 3 types of oxidators were used to oxidize the biochar before impregnation with purpose to study its influence toward physichochemistry and adsorption performance of the composite. Preparation of the composite included 3 steps, namely preparation of biochar by pyrolisis of patchouli biomass using

Synthesis of iron oxide FeOOH from FeCl 3 , followed by thermal transformation to form red hematite was conducted. The effect of pH and temperature calcinations was studied. The observed parameters were include crystal structure, grain size, color, particle size distribution, and morphology. The result showed that α-Fe 2 O 3 structure with relatively pure and good crystallinity were found at all designated synthesis condition. The highest degrees of redness and chroma, uniformity of morphology and particle size distribution were achieved at pH 6, while the lowest degrees was formed at pH 8. The pigment at pH 6 has spherical-like shape with an average size of 0.16±0.057 μm. Instead, at pH 8 has spherical-like and cubic-like shape with an average grain size of 0.17±0.051 μm. The highest degrees of brightness, redness, yellowness and the highest chroma as well as smallest grain size of 0.15±0.052 μm were achieved at 800 o C but at this temperature the crystal orientation of 006 was not appear and the presence of 2θ angle (63.99 o) were supposed as crystal defects and impurity.

This research studied to utilize the bagasse to be used as activated karbon in particular for the adsorption of Ca 2+ . The manufacture of activated carbon consists of carbonization dan activation process. Temperature variation for carbonization process in this research are 500°C, 550°C, 600°C, 650°C and 700°C then proceed with the activation process by carbon reflux with 6 M H2SO4 for 4 hours. Carbonization yield will decrease with increasing temperature carbonization. While the ash content, surface area, pore volume, and adsorption capacity of Ca 2+ will increase with increasing temperature of carbonization. Obtained activated carbon is best activated karbon made at a temperature of 700°C with an activation carbonization which has a surface area 100.62 m 2 /g, 22.3750 Å pore diameter, pore volume of 22.376 mL/g, can eliminate the Ca 2+ up to 13.26 %.

The presence of suspended and colloidal particles in water can cause turbidity. To reduce the turbidity, coagulation-flocculation process is commonly used. In this process, the colloidal particle is converted into flocs which is easily separated from water with the aid of coagulant. One of the natural coagulants that have been studied as water purifier is Moringa oleifera seeds. This research aims to reduce turbidity of kaolin synthetic wastewater through coagulation-flocculation process using Moringa oleifera seeds that have been extracted with NaCl 1 M. The variables used in this study were wastewater pH (3, 6, 10, and 12) and coagulant dosage (0, 1, 2, 3, 4, and 5 mL/L). Coagulation-flocculation was taken place in Jar Test with rapid stirring 150 rpm in 2 minutes, followed by slow stirring 30 rpm in 30 minutes, and sedimentation for 30 minutes. Then, the water was analyzed using Turbidimeter. The results showed that coagulant dosage and pH affected the effectiveness of coagulation in decreasing turbidity. The optimum dosage of extracted Moringa oleifera seeds coagulant in coagulation of kaolin synthetic wastewater at pH 3