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• Diamine (DMAPA) and glycine (GLY) mixtures have high CO 2 loading capacity. • Ethanol was used to convert liquid absorbent and CO 2 into carbamates. • At low GLY-DMAPA concentration (0.1 mol/L) no product was formed. • Carbamates were generated at high concentration of GLY-DMAPA (0.5–2.0 mol/L). 3-dimethylaminopropylamine (DMAPA) and glycine (GLY) mixture was studied as a potential absorbent for carbon dioxide (CO 2) capture and utilization. The solubility of CO 2 in aqueous GLY-DMAPA solutions within the range of 0.1–2.0 mol/L (M) were measured experimentally using pressure differential technique. Utilization of CO 2 was also studied by mixing the CO 2 -saturated absorbent with ethanol. The final products obtained were characterized by using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The solubility study revealed that the CO 2 loading capacity increased as pressure of CO 2 increased. In contrast, the loading capacity decreased when concentration of the absorbent and temperature in equilibrium cell increased. However, the total moles of CO 2 absorbed showed an opposite trend such that net CO 2 absorbed increased as concentration of absorbent increased. The chemical interactions between CO 2 and GLY-DMAPA molecules were studied by analyzing the changes of characteristic peaks observed form the FTIR spectra. For CO 2 utilization, the addition of ethanol as a reagent into 0.1 M CO 2 -saturated GLY-DMAPA solution did not produced any precipitate. Nonetheless, as the concentration of GLY-DMAPA increased from 0.5 M to 2.0 M, white precipitates were produced, indicated that the conversion of CO 2 into solid compounds occurred instantaneously after the CO 2 capture. The optimum concentration of GLY-DMAPA for CO 2 capture and utilization depends on the amount of solids generated and the CO 2 loading capacity of the absorbent. At 5 bar, the optimum concentration was found to be 1.0 M with 45 mg/g of solids recovered and CO 2 loading capacity of 1.6 mol CO 2 /mol absorbent. The final product was identified as carbamate salt based on the main characteristic peaks present on the FTIR and XPS spectra. [ABSTRACT FROM AUTHOR]

[Display omitted] • We looked into the potential applications of hydrate-based desalination (HBD) • HBD process treats produced water with a concentration 2.8 wt% • CO 2 as guest gas produced a water recovery of 45.55% • The desalination efficiency is strongly dependent on the ionic radii and strength of the ionic charge. This paper emphasizes sustainable development goal 6 and accepts that social progress and economic prosperity depend on the appropriate management of produced water. Produced water being the largest source of wastewater, several conventional desalination methods (thermal, membrane and freeze–thaw), are applied to obtain treated water. Nevertheless, the methods are highly energy intensive. Prospective utilization of hydrate-based desalination was proposed with a novel filter-based apparatus design to separate hydrate crystals from residual water and enhance the gas–liquid contact with all the unit operations (hydrate formation, and dissociation) occurring inside a single reactor. Experimentations were implemented to obtain the optimum conditions for CO 2 hydrate formation and compared with pure water. CO 2 hydrate formation kinetics revealed induction time, moles consumed, water-to-hydrate conversion, and water recovery were 57 mins, 1.28 mol, 27.72 %, and 50.65 % at optimum conditions of 500 ml, 3.0 MPa, 450 rpm, and 275.15 K for purification of produced water. A desalination efficiency of 62–80 % is achieved with each of the metal ions in the sequence K+>Na+>Mg2+>Ca2+, and anions SO 4 2- > Cl- without any pre and post-treatment. Also, demonstrated that the ionic charge and size have a significant impact on the ion rejection mechanism. The findings disclosed that with an upsurge in the temperature to 277.15 K the desalination efficiency enhanced nevertheless the volume of formed hydrate is less resulting in less driving force. The total dissolved solids and electrical conductivity results indicate that the treated water meets Malaysia's water quality standards for irrigation purposes. This showcases the execution of the hydrate-based desalination process, investigating salt rejection and yield with our custom reactor design. The proposed reactor design may be utilized for the effective separation of hydrate and effectively desalinating waters of higher salinities. Hydrate-based desalination integrated with membrane reactors could lead to a sustainable source of clean water by treating produced water. [ABSTRACT FROM AUTHOR]