Direct contact membrane distillation DCMD

Direct contact membrane distillation (DCMD), in which the membrane is in direct contact with the liquid phase on both sides... 

Membrane distillation - photocatalysis To solve the problem of membrane fouling observed in the pressure-driven membrane photoreactor, Mozia et al. [90] studied a new type of PMR in which photocatalysis was combined with a direct contact membrane distillation (DCMD). MD can be used for the preparation of ultrapure water or for the separation and concentration of organic matter, acids and salt solutions. In the M D the feed volatile components are separated by means of a porous hydrophobic membrane thanks to a vapor-pressure difference that acts as driving force and then they are condensed in cold distillate (distilled water), whereas the nonvolatile compounds were retained on the feed side. 

Direct contact membrane distillation (DCMD) is an effective process applied for the concentration of dissolved matter in water solutions. The process can be considered a feasible method for liquid radioactive waste treatment and, in some cases, it can effectively serve in reducing the hazard connected with its toxicity. 

The most common configurations of PMRs with suspended photocatalyst are those utilizing pressure driven membrane processes, such as microfiltration (MF), ultraflltration (UF) and NF. In other types of PMRs, photocatalysis is combined with dialysis, pervaporation (PV) or direct contact membrane distillation (DCMD, MD) (Mozia, 2010). 

For water purification, not only the separation of photocatalyst particles is required but also the exclusion of some degradation products. A new type of photocatalytic membrane reactor (PMR), combining photocatalysis with direct contact membrane distillation (DCMD), was constructed in the laboratory and tested by using carbon-coated Ti02 [300-305]. It is schematically illustrated in Figure 3.44. 

An aqueous solution colder than the feed solution is maintained in direct contact with the permeate side of the membrane, giving rise to the configuration known as direct-contact membrane distillation (DCMD). Both the feed and permeate aqueous solutions are circulated tangentially to the membrane surfaces by means of circulating pumps or are stirred inside the membrane cell by means of a magnetic stirrer. In this case the transmembrane temperature difference induces a vapor pressure... 

AGMD air gap membrane distillation DCMD direct contact membrane distillation... 

Figure 6.12 Common configurations used for membrane distillation (a) DCMD.direct contact membrane distillation (b)AGMD, air-gap membrane distillation (c) SGMD,sweep gas membrane distillation and (d)VMD, vacuum membrane distillation (Caputo etal.,2007).

DCMD Direct contact membrane distillation system... 

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