Insights into Sorption–Mineralization Mechanism for Sustainable Granular Composite of MgO-CaO-Al2O3-SiO2-CO2 Based on Nanosized Adsorption Centers and Its Effect on Aqueous Cu(II) Removal

Although copper is needed for living organisms at low concentrations, it is one of the pollutants that should be monitored along with other heavy metals. A novel and sustainable composite mineralizing sorbent based on MgO-CaO-Al2O3-SiO2-CO2 with nanosized adsorption centers was synthesized using natural calcium–magnesium carbonates and clay aluminosilicates for copper sorption. An organometallic modifier was added as a temporary binder and a source of inovalent ions participating in the reactions of defect formation and activated sintering. The sorbent-mineralizer samples of specified composition and properties showed irreversible sorption of Cu2+ ions by the ion exchange reactions Ca2+ ↔ Cu2+ and Mg2+ ↔ Cu2+. The topochemical reactions of the ion exchange 2OH− → CO32−, 2OH− → SO42− and CO32− → SO42− occurred at the surface with formation of the mixed calcium–copper carbonates and sulfates structurally connected with aluminosilicate matrix. The reverse migration of ions to the environment is blocked by the subsequent mineralization of the newly formed interconnected aluminosilicate and carbonate structures.

Pemanfaatan Bekas Adukan Mortar pada Pratikum Batu (Masonry) untuk Paving Block

Stone Construction Laboratory is one of the existing courses in the Department of Civil Engineering Polytechnic State of Padang. Students are required to practice firsthand the theories about stone construction that have been studied. Stone work or often called masonry is wall or brick installation work for floor, wall, or fence. In practicum stone, the material used is artificial stone like brick and can also natural stone by using an adhesive substance usually known by the name of spesi or mortar.Mortar or spesi is one of the building materials that serves to glue the pairs of bricks, brick, stucco and so on. Mortars consist of sand, cement and water. In a stone work practicum where the work is not permanent (unloading pairs) then the cement material is replaced by lime which is a temporary binder. So far, the rest of the mortar use for the stone practicum is just thrown away because it cannot be used anymore, therefore it takes alternative utilization of the former mortar, for that the author tries to research by using it to make paving blocks. Paving blocks or concrete bricks for floors are a component of building material made from a mixture of hydraulic cement or the like, aggregates and water with or without other additives which do not reduce the quality of the paving blockThe study used comparison between paving block with mixed composition of mortar, cement and water mixture and paving block with standard mixture composition ie cement, sand and water. Paving is made by pressing using hydraulic press machine with a compressive strength of 25 kg and compressive strength testing with Universal Testing Machine.Based on the results of the research, it was found that the paving block from the utilization of mortar has a compressive strength higher than the standard paving block. At the age of 14 days, the compressive strength of the paving block from the utilization of mortar used has a compressive strength of 76.14 kg

Studies on Diamond Brazing Process (Part one)

Through scientific experiments, we studied the binder, diamond, solder, uniform distribution and heating curves in brazing. We selected DH temporary binder, compared two kinds of diamond, selected the diamond with fine thermal stability. The experiments adopted diamond with uniform templates, experimenting 13 kinds of solder of which 9 were mixed with diamond for comparison of brazing effects and thermal damage. We optimized solder and brazing process and comprehensive analyzed experimental results. The analysis showed a small amount of DH temporary binder residue in brazing, fine effect in case of low alloy solder brazing temperature, better adhesion of solder and diamond achieved by elements formed by Cr and other strong carbides, sufficient volatilization of temporary binder and other impurities achieved by insulation before 500°C, heating rate of 1°C/min when the temperature it is higher than 20°C-50°C, the solder melting point, and that cooling should be carried out under high vacuum, brazing diamond should have fine thermal stability.

Studies on Diamond Brazing Process

Through scientific experiments, we studied the binder, diamond, solder, uniform distribution and heating curves in brazing. We selected DH temporary binder, compared two kinds of diamond, selected the diamond with fine thermal stability. The experiments adopted diamond with uniform templates, experimenting 13 kinds of solder of which 9 were mixed with diamond for comparison of brazing effects and thermal damage. We optimized solder and brazing process and comprehensive analyzed experimental results. The analysis showed a small amount of DH temporary binder residue in brazing, fine effect in case of low alloy solder brazing temperature, better adhesion of solder and diamond achieved by elements formed by Cr and other strong carbides, sufficient volatilization of temporary binder and other impurities achieved by insulation before 500°C, heating rate of 1°C/min when the temperature it is higher than 20°C-50°C, the solder melting point, and that cooling should be carried out under high vacuum, brazing diamond should have fine thermal stability.