Search

A microstructured mixer, equipped with double-tube, swirl, and contraction flow channels, is proposed for the stable and continuous solvothermal synthesis of metal-organic framework (MOF) particles. The synthesis of Cu-BTC nanoparticles from copper nitrate and benzene 1,3,5-tricarboxylic acid ethanol solutions was conducted across temperatures ranging from 283 to 523 K. This study investigated the effects of temperature, flow rate, and mixing sequence on product yield and particle diameter. Comparative analysis of the results helped in highlighting the advantages of this mixer in preventing preheating of the starting solution and subsequent clogging.

A microstructured cover flow mixer equipped with two cyclone structures was used for stable continuous hydrothermal synthesis of ZnO nanoparticles from Zn(NO3)2 and NaOH aqueous solutions in supercritical water. The effects of the NaOH/Zn(NO3)2 ratio, Zn(NO3)2 molality, and flow rate on Zn conversion, crystal structure, particle size, particle morphology, and mixer clogging were examined. The advantages of this mixer were identified by comparing with the results obtained using the same chemical conditions with tee-type, cross-type, and central collision-type mixers.

To prevent and cure clay clogging in grouting pipelines of coal mine water control, experiments and practices on softening clay clogging in grouting pipelines of coal mining were studied. The clogging characteristics of clay grouting pipelines had been analyzed. A group of disintegration tests under different clay softeners as well as the mechanisms had been studied. The results show that chemical reaction of strong oxidizer is the most intense, acidic softener the second, and alkaline softener is the weakest. The 0.1 mol/L amino sulfonic acid solution or 0.25 mol/L acetic acid solution is best softener. Coal mine practice has effectively prevented clay grouting pipeline clogging by applying epoxy resin, monitoring the pressure of key parts and putting softener into the clogging parts.

• Study of a continuous precipitation reaction in an ultrasonic micro-reactor. • Obtained particle size distribution is controlled by the ultrasound parameters. • Pulsed ultrasound is able to prevent clogging and provides temperature control. • An effective ultrasound treatment time of 12.5% is identified for optimum operation. Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C. [ABSTRACT FROM AUTHOR]

Abstract: The availability of freshwater to meet different water needs has raised serious concerns in the last decades all around the world. Water scarcity, deterioration of quality and increasing demand have led to the development and use of alternative sources of water. Reclamation and recycling are now considered as key components of water and wastewater management policies around the world. In this context, the adoption of soft wastewater treatments with a minimum use of chemical agents and having minimum environmental impact is widely encouraged. An experimental campaign was carried out on a pilot plant which consisted of a two-stage disinfection system for a secondary biological effluent. Disinfection consisting of a chemical step (mild chlorination) followed by a natural one (filtration through a horizontal subsurface flow (HSF) bed) was tested in order to evaluate the possibility of producing a final effluent adequate for agricultural reuse. The investigation has shown that this combined system, with low doses of NaClO (2 mg L−1 of disinfectant and a retention time of 30 min, corresponding to an applied dose of 2 × 30 = 60 mg L−1 min−1) and a well designed final subsurface flow system (at least 1 m2 EI−1) is able to obtain an effluent complying with reuse quality limits, in particular for microbiological parameters. For HSF design parameters, neither filling material, aspect ratio nor vegetation type (Phragmites australis and turf) caused significant differences in the average levels of COD, suspended solids, NH4, total phosphorus and Escherichia coli concentrations in the effluent. Finally in order to protect HSF bed fromsubstrate clogging and to prolong its working life, a rapid sand filter was placed before the bed and its impact analyzed. It was demonstrated that the filter was able to retain occasional but unavoidable activated sludge carry-overs fromthe secondary clarifier which otherwise would rapidly accumulate in the front region of the bed resulting in poor performance (overflows and medium clogging) in quite short time. [Copyright &y& Elsevier]