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Phenolic substances are harmful to humans and other living things, even at low concentrations. Therefore, phenol must be removed from water with the proper process. One of the most effective processes for degrading phenol is heterogeneous catalytic oxidation. Three carbon materials as supports were used to prepare manganese-oxide based catalyst (2.5% MnOx/ACP and 2.5% MnOx/ACN), and graphene oxide (2.5% MnOx/GO). These catalysts were tested for the degradation of phenol in aqueous solution using peroxymonosulfate as a source of sulfate radical. The physio-chemical catalysts were characterised by several characterisation techniques such as powder X-ray diffraction, N2-sorption (BET), scanning electron microscopy (SEM) equipped with Dispersive Energy X-ray Spectroscopy (EDS). In comparison to other catalysts, heterogeneous activation of peroxymonosulfate was more effectively done by 2.5% MnOx/ACP, resulting in a higher production rate of sulfate radicals. In the presence of a catalyst at 0.2 g and 1 g peroxymonosulfate in 500 mL solution at 25 °C, 90% total organic carbon (TOC) removal and phenol decomposition of 100% was achieved in 90 min with phenol concentration of 75 mg/L. First-order kinetics were followed by phenol decomposition with the energy of activation on 2.5% MnOx/ACP of 15.0 kJ/mol.

Geopolymer hybrid is a combination of geopolymer and Ordinary Portland Cement (OPC) or other binders to produce an alternative binder. This type of binder could be used to transform low-quality fly ash into multi-purpose concrete. Ordinary Portland Cement (OPC) concrete subjected to an acidic organic environment such as peatland, is more prone to deterioration in long-term than concrete using the supplementary cementitious material. In this research, the geopolymer was made by activating low-quality fly ash (contains more than 5% carbon) with the alkaline activator. The inclusion of OPC and Portland Cement Composite (PCC) as a fly ash replacement material is intended to promote curing at ambient temperature and immobilization of heavy metals in fly ash. The specimens were cast and cured at ambient temperature up to 28 days. OPC was used as a control mix. Subsequently, the concrete was immersed in fresh peat water in the laboratory up to 28 days. Characteristics of the geopolymer hybrid such as compressive strength, porosity, and leaching were determined. Microstructure analysis, such as SEM-EDX and FTIR, were conducted. Results show that the geopolymer hybrid has a good strength development at early days. At 28 days, there was a reduction of strength and increase of porosity, probably due to the attack of calcium from the OPC concrete. There was a transformation of aluminosilicate gel into C/N-A-S-H that is advantageous for the strength development at the early days. However, a weaker material has formed in the long term that cannot resist further acid attack. It can be concluded that the geopolymer hybrid is a promising binder, but it is essential to design the material appropriately to have better strength, durability and environmental properties in the long term.

The canal blocking system is commonly applied in to control water table in peatland recovery during prolonged dry weather in tropical peatland. The canal blocking is an effective strategy in preventing peat fire in many areas in Riau Province. Various local material such as earth, timber, sand, stone, rock, and concrete have been used in canal blocks. The concrete canal blocks are usually built at the river downstream and need to be stronger, durable and stable than other materials. Tropical peatland is a highly organic and highly acidic environment that could damage and reduce concrete structures service life in the long term. In this research, strength properties and porosity were evaluated to indicate the effectiveness of using pozzolanic material to increase resistance to the acid attack in concrete canal blocks. The concrete was produced by incorporating 10% Palm Oil Fuel Ash (OPC POFA) as a pozzolanic material from biomass to replace the Ordinary Portland Cement (OPC) cement content. The locally available commercial Portland Composite Cement (PCC) that contains pozzolanic material was also studied. The OPC concrete was used as a control mix with a target strength of 35 MPa. Specimens were cast and cured for 28 days in a laboratory water pond before subsequently placed in peat water canal nearby Rimbo Panjang Regency in Riau Province. The reduction rate in compressive strength, tensile strength, Young's Modulus of Elasticity, and porosity of concrete at 28, 91, 120 and 150 days were determined. Results show that the inclusion of pozzolanic material in concrete has increased the compressive strength, tensile strength, Young's Modulus of Elasticity and reduced the porosity. PCC and OPC POFA had better performance than the OPC concrete after immersed in the canal up to 150 days. Hence, it can be concluded that the pozzolanic material is effective in improving properties and acid resistance of concrete canal blocks in tropical peatland.

Porous hydroxyapatite have been attracting considerable attention for bone surgery. Relatively low mechanical strength of porous hydroxyapatite hampers its application for permanent bone implant. The aim of this work was to study the effect of chitosan concentration and time of coating on the physical, chemical and mechanical properties of porous hydroxyapatite/chitosan composites prepared using dip coating technique. Firstly, chitosan powder was dissolved into acetic acid with a concentration of 0.50 %, 0.75 % and 1.00 % (w/v). Subsequently the porous hydroxyapatite bodies were coated with chitosan using dip-coating method at dip time during 30, 45, 60 min. The composites bodies were dried in room temperature for 24 h. The hydroxyapatite/chitosan bodies with compressive strength in the range of 1.52 - 4.05 MPa, porosity of 75 - 78 %, pore size of 22.8 - 26.61 um, and density of 0.71 - 0.78 g/cm3 were obtained. The increase of chitosan concentration from 0.50 % to 0.75 % can decrease the porosity from 78 % to 76 % and pore size from 28.25 um become 22.88 um. The compressive strength of the composites increased with the coating time.

An eight-stage centrifugal pump that was used in the oil and gas industry had plastic deformation on the shaft because of the torque load. Thus, this study was aimed at analyzing the shear stress that occurred on the shaft by an exact and finite element method. The shaft, with a length of 1.5 m and diameter of 0.05 m, was made of SUS 304 material. From the exact and finite element analysis results, the shear stress that occurred on the shaft was higher than the shear stress of the shaft material. Therefore, the pump shaft became plastically deformed and twisted. The results of the finite element analysis showed that the torque, shear stress, and strain were increased when the twist angle on the pump shaft was increased.

The waste from industrial textile waste is one of the environmental problems, it is required effective and efficient processing. In this study spent bleaching earth was used as absorbent. It was found that the absorbent was effective to remove methylene blue from aqueous solution with removal efficiency 99.97 % in 120 min. Several parameters such as pH, amount of absorbent loading, stirring speed are found as key factor influencing removal of methylene blue. The mechanism of adsorption was also studied, and it was found that Langmuir isotherm fitted to data of experiment with adsorption capacity 0.5 mg/g.

Palm Oil Mill Fly Ash (POMFA) the solid waste of palm oil industry was used as a raw material for synthetic amorphous silica and carbon zeolite composite synthesis in order to minimize the wastes of palm oil industry. The alkaline extraction combine with the sol-gel precipitation and mechanical fragmentation was applied to produce synthetic amorphous silica. The byproduct, extracted POMFA was rich in carbon and silica content in a significant amount. The microwave heated hydrothermal process used to synthesize carbon zeolite composite from the byproduct. The obtained silica had chemical composition, specific surface area and the micrograph similar to commercial precipitated silica for rubber filler. The microwave heated hydrothermal process has a great potential for synthesizing carbon zeolite composite. The process only needs one-step and shorter time compare to conventional hydrothermal process.

In this work, geopolymer was prepared from rice husk ash (RHA) made into sodium silicate then synthesized by reacting metakaolin, NaOH, and water. The catalyst was characterized using Scanning Electron Microscopy (SEM), Energy-dispersive X-Ray analysis (EDX), Brunaeur Emmet Teller (BET), and basic strength. Then, the catalyst used for transesterification of Calophyllum inophyllum seed oil in order to produce biodiesel. The variation of process variables conducted to assess the effect on the yield of biodiesel. The highest yield obtained 87.68% biodiesel with alkyl ester content 99.29%, density 866 kg/m3, viscosity 4.13 mm2/s, the acid number of 0.42 mg-KOH/g biodiesel and the flash point 140 degC. Generally, variations of %w/w catalyst provides a dominant influence on the yield response of biodiesel. The physicochemical properties of the produced biodiesel comply with ASTM standard specifications.

Theincreasing of demand of pulp and paper products, will following with the growing the pulp and paper industryand generate significant mill waste. The total waste reached 1/3 of the amount raw materials used and ash boiler is the waste with the largest percentage of 52%. For that it takes effort to manage the existing waste. The boiler ash contained the chemical elements, it can be utilized such as fertilizer, because it also contains transition metals in form of heavy metal such as Cadmium (Cd), Cobalt (Co), Chrome (Cr), Cupprum (Cu), Ferrum (Fe), Nickel (Ni), and Zinc (Zn), the use of boiler ash must follow the threshold specified by the Government. Several studies have been undertaken to reduce and extract heavy metals from ash and sand of the boiler by using carbon dioxide as its ligand. Eelectrochemical method was used to remove and recovery of heavy metals from the incenerator. This study focused on removal of heavy metals using Lauryl Amine as collector and three solvents namely Dichloromethane, Ethanol and n-Hexane. The treatmentswas able to extract the heavy metal and generally reduce the heavy metal content of ash boiler pulp and paper mill waste. The combination treatment used toreduce the heavy metal content of 5 gram Lauryl Amine collector in Dichloromethane solvent for 4 hours process time.

A palm fly ash supported calcium oxide (CaO) catalyst was prepared and used in transesterification from off-grade palm oil for biodiesel production. The catalyst synthesized by loading CaO of calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) into fly ash through impregnation method. The optimum catalyst preparation conditions were determined by influence of calcination temperature and weight ratio of Ca(NO3)2.4H2O and fly ash. Catalyst with highest catalytic activity was achieved when calcined at 800 degC and proportion of Ca(NO3)2.4H2O to fly ash is 80:20. Under the conditions of oil : methanol ratio of 1:6, catalyst dosage of 6 wt% and temperature of 70 degC for 2 h, the biodiesel yield reaches to 71.77%. CaO, SiO2, Ca(OH)2 and Ca2SiO4 were found in the catalyst through X-ray diffraction (XRD) while the basic strength of the catalyst H_ in the range 9.3 - 11. Surface area of the developed catalyst is 24.342 m2/g through Brunauer-Emmett-Teller (BET). Characteristics of biodiesel such as density, kinematic viscosity, acid value, flash point has been matched with standard for biodiesel specification of Indonesia.

Contact area and stress distribution of the polyethylene liner (PE liner) have a major influence on the wear process. The main factor that affects the contact area and stress on the PE liner is thickness. The International Standards Organization (ISO) recommends a minimum PE liner thickness of 6 mm. However, the thickness of PE liner in a bipolar hip prosthesis has a limited range of motion compared to the unipolar one due to the addition of the outer liner component. Therefore, the study of the effect of PE liner thickness on the contact area and stress distribution in the bipolar model is interesting. Theaim of this research is to investigate the effect of the PE liner thickness to the contact area and stress distribution on the surface of contact between head and PE liner and the contact between outer liner and cup in the bipolar model. This research was carried out by finite element analysis. The results showed that the highest contact stress on the liner occurred at the lowest liner thickness. The maximum contact radius on the liner surface took place at the highest liner thickness. The bipolar model with the liner thickness of 4.5 mm in this research provided the lowest contact stress.