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The present invention relates to a continuous process for the production of sodium bicarbonate crystals from the carbon dioxide of a gas stream comprising an absorption step of the carbon dioxide from a gas stream into an aqueous solution comprising a sodium carbonate salt to produce an aqueous solution of sodium bicarbonate, then a crystallization step of the sodium bicarbonate salt obtained at the first step. The invention also relates to a system for the production of sodium bicarbonate crystals from carbon dioxide of a gas stream comprising a control unit 10, an absorption unit 20 and a crystallization unit 30.

This study evaluates the performance of commercial reverse osmosis (RO) and nanofiltration (NF) membranes for the removal of metal ions from synthetic water and surface water carried from the north‐west of Lake Tanganyika in the city of Uvira, in the east of the Democratic Republic of Congo. Metal ion analyses were performed by the standardized ICP‐MS and ICP‐OES methods. The RO membrane showed higher metal ion rejection in high‐concentration solutions (synthetic samples) prepared in the laboratory as well as in low‐concentration samples from real raw water collected near Lake Tanganyika. Rejection levels were higher than 98% for Cr3+, Pb2+, Cd2+, As3+, Ni2+, and Sb+3 ions in the synthetic solutions, and 99.2, 98.8, 98.6, 99.2, 98.4, and 98.8%, respectively, in the real samples. The concentrations of metals in the permeate varied depending on the feed concentration and were 0.15 to 1.02 mg/L, 0.33 to 22 mg/L, and 0.11 to 22 mg/L in RO, NF90, and NF270 membranes, respectively. Regarding the NF membranes, the rejection of Cr, Ni, and Cd ions was interesting: 98.2, 97.8, and 92.3%, respectively. However, it was lower for Pb, As, and Sb ions: 76.9, 52.5 and 64.1%, respectively. The flux of NF was 329 to 375 L/m2.h, much higher than for RO membranes, which had a flux of 98 to 132 L/m2.h. The studied membranes are thus a feasible solution to remove the studied metals from real water sources at low concentrations since they meet the standards of the World Health Organization on specific values assigned to chemicals from industrial sources and human habitation areas where these ions are present in drinking water.

Climate change is clearly an urgent challenge nowadays. The constant accumulation of greenhouse gases and their drastic consequences have led to intensified research aiming to reduce the impact of human activities on the environment. As carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities, numerous projects focus on the reduction of CO2 emissions. Carbon capture and storage are considered, but this strategy considers carbon dioxide as a waste. Carbon capture and utilization, on the other hand, gives a sustainable answer by giving value to the carbon by transforming it into another reusable product. Several revalorization routes are being explored, and mineralization (crystallization) seems to be an efficient methodology as it is thermodynamically favorable. Several carbonate compounds can be produced and marketed. Sodium bicarbonate (NaHCO3) is an interesting candidate as it can be used for numerous applications in the chemical, food, pharmaceutical, and textile industries. Such a carbon capture and revalorization process is currently under development in our group in UCLouvain. The process makes use of membrane technologies to capture and convert carbon dioxide into sodium bicarbonate as a final product. The process is divided into two steps: first, the CO2 is captured in a membrane base absorption process using a solvent promoted by enzymes or amino acids. Then, the resulting solution is concentrated up to crystallization in a membrane contactor. The different promoted solvents and routes for crystallization are being optimized. [1-4] The results are the following: In the first step (absorption), the CO2 absorption efficiency was evaluated, observing the enhancement of the mass transfer when enzymes or amino acid salts were used. In the second step (crystallization), we were able to obtain crystals with high purity. The morphology of the crystals is shown in Figure 1. Ongoing research is focusing on the study of the presence of other

Carbon dioxide (CO2) capture and sequestration/reutilization has become one of the most urgent technological demands in order to reduce CO2 emissions in a global context. Conventional technology is typically based on absorption using selective solvents, such as monoethanolamines, and a posterior desorption process using heat to release pure CO2 and reuse the amines. However, this process presents strong limitations [1]: i) amine production is very energy intensive, which involves non-negligible CO2 emissions; and ii) the desorption process requires energy, and again, we can expect CO2 emissions associated to the production of the required energy. This means that even though CO2 is capture in the site, it is also emitted somewhere else, decreasing significantly the overall CO2 captured/CO2 emitted. In this context, membrane technology appears as a promising technique to capture CO2 and convert it into a valuable product. In this work, a novel process based on a first step of absorption followed by a second step using membrane crystallization is presented [2]. A liquid phase containing a mass transfer promoter (i.e., enzymes or amino acids) is used to capture CO2. After absorption, the (bi)carbonate solution is sent to the membrane crystallization unit so that the (bi)carbonate salts are produced. The mass transfer efficiency will be evaluated considering different membrane crystallization methods (i.e., osmotic membrane crystallization, direct contact membrane crystallization and vacuum membrane crystallization) and varying the operation conditions, such as feed velocity, temperature and vacuum. The effect of the presence of impurities will be also discussed. This process presents an alternative to conventional CO2 absorption-sequestration methods in order to valorize the CO2 while closing the carbon cycle.

Inverse omosis elimination rate is high compared to nanofiltration. The concentration of certain metals in the the permeates of domestic wastewater are lower to the WHO standard, while in the industrial water permeates, it remains above the WHO standard, hence the need to prepare a low cost membrane to remove these metals in the permeate according to the WHO standard.