Precipitated calcium carbonate

One of the main trends in developing bio-based materials is to improve their mechanical and physical properties using MFC derived from sustainable natural sources and compatible low-cost chemicals. The strength of anionic MFC based materials can be increased with addition of multivalent cations.

5p vihermione 06-01-2023 6 2   Download

Bê tông là một vật liệu không thể thiếu trên thế giới, theo thời gian sử dụng, bê tông xuất hiện các vết nứt và các lỗ nhỏ trên bề mặt, nguyên nhân là do tác động từ điều kiện tự nhiên, do phải chịu trọng tải lượng lớn, do kết cấu bê tông thiếu khả năng chịu lực hoặc do sụt lút nền móng. Từ đó, các nhà khoa học đã nghĩ đến việc nghiên cứu ra một loại bê tông tự liền nhờ khả năng tạo tủa Calcite do vi sinh vật gây ra (MICCP: Microbially induced calcium carbonate precipitation) như một loại xi măng sinh học.

7p vizenvo 30-11-2022 9 2   Download

The visual observation and water permeability tests showed that bacterial mortar could repair the cracks and prevent the invasion of liquids and gases compared with the negative control. Besides, SEM and XRD analytical results indicated that the different carbonate polymorphs were formed inside the cracks. Additionally, the plate count method revealed that there were vegetative S. pasteurii cells in cracks even after 28 days, which means the bacterial mortar may have a long-lasting effect on the cement.

11p linyanjun_2408 23-04-2022 13 1   Download

In the present study, the properties of calcium carbonate mineralization and urease and carbonic anhydrase activities of Bacillus amyloliquefaciens U17 isolated from calcareous soil of Denizli (Turkey) were analyzed. CaCO3 was produced in all growth phases. Strain U17 showed 0.615 ± 0.092 µmol/min/mg urease enzyme activity in calcium mineralization medium and 1.315 ± 0.021 µmol/min/mg urease enzyme activity in Luria-Bertani medium supplemented with urea, whereas it showed 36.03 ± 5.48 nmol/min/ mg carbonic anhydrase enzyme activity in CaCO3 precipitation medium and 28.82 ± 3.

11p thiencuuchu 27-11-2021 18 1   Download

Inducing calcium carbonate precipitation is another important function of urease in nature. The process takes advantage of the supply of carbonate ions derived from urea hydrolysis and of an increase in pH generated by the reaction, effects that in the presence of Ca2+ ions lead to the precipitation of CaCO3.

9p trinhthamhodang1 14-11-2019 15 0   Download

Microbially induced calcium carbonate precipitation is a biomineralization process that has various applications in remediation and restoration. In the present study, calcifying bacteria, Bacillus subtilis and Bacillus megaterium isolated from soil (Viet Nam) and were investigated for sand stiffening using syringe set-up with daily nutrient addition at 7, 14 and 28 days.

7p vidonut2711 08-11-2019 9 0   Download

There have been some problems reported associated with the use of alkyl ketene dimer (AKD) in alkali papermaking. Excessive use of size emulsion, poor size performance when filler used, problems with back water contamination, poor retention, and formation of pitch deposits on machinery are some of the problems experienced during papermaking operations.

8p aquaman27 15-01-2019 22 1   Download

In this study, the calcite precipitation bacteria were investigated. Bacterial strains were isolated from cement samples and were tested for urease activities, potential to form endospore and calcite precipitation. The results showed that four candidates were isolated with high urease activities and calcite precipitation.

9p tieuthi3006 16-03-2018 29 1   Download

We used mill-level production and pollution data to estimate (1) the effect of China’s system of pollution control levies on three environmental effluents, and then (2) examined further the effect of this system of levies on the technical efficiency of mill-level production. Our results show that the pollution levies worked for those larger establishments that were the main targets of reform policies in this period.

28p loixinloi 08-05-2013 49 4   Download

Canxi cacbonat kết tủa (Precipitated Calcium Carbonate - viết tắt là PCC), có tên thương phẩm là bột nhẹ, là hoá chất phổ biến, được sử dụng làm chất độn trong công nghiệp sản xuất giấy, cao su, chất dẻo, kem đánh răng, dược phẩm, mỹ phẩm,…Chất lượng sản phẩm PCC được đánh giá qua thành phần hoá học (hàm lượng các tạp chất, độ kiềm dư) và các tính chất vật lý (kích thước hạt, độ xốp, độ trắng), trong đó bề mặt riêng, kích thước hạt và độ kiềm dư là những chỉ tiêu kĩ thuật quan trong nhất [1]. Đặc biệt với...

7p tuanloc_muido 11-12-2012 103 9   Download