Filtration ineffective

Why is a Craig tube filtration ineffective for removing finely divided particles from a solution ... 

The fine precipitate may take several hours to settle. Filtration is often ineffective, but settling can be speeded up by centrifuging. 

Remove excess crosslinker by centrifugal dialysis or gel filtration using a molecular weight exclusion of 5,000. This procedure should be done quickly due to the labile nature of the maleimide group in aqueous solution, which will hydrolyze to a ring-open maleamic acid that is ineffective at coupling to thiols. 

Therefore, when operating in the filter cake mode, the axial velocity should be maintained at a level such that an adequate shear force exists along the filter media to prevent excessive caking of the catalyst that could cause a blockage in the down-comer circuit. For the separation of ultrafine catalyst particles from FT catalyst/wax slurry, the filter medium can easily become plugged using the dynamic membrane mode filtration. Also, small iron carbide particles (less than 3 nm) near the filter wall are easily taken into the pores of the medium due to their low mass and high surface area. Therefore, pure inertial filtration near the filter media surface is practically ineffective. 

Ruth et alS4-7) have made measurements on the flow in a filter cake and have concluded that the resistance is somewhat greater than that indicated by equation 7.1. It was assumed that part of the pore space is rendered ineffective for the flow of filtrate because of the adsorption of ions on the surface of the particles. This is not borne out by Grace18 or by Hoffing and Lockhart(9) who determined the relation between flowrate and pressure difference, both by means of permeability tests on a fixed bed and by filtration tests using suspensions of quartz and diatomaceous earth. 

Studies on conventional drinking-water treatment processes, such as filtration, coagulation and sedimentation, have shown that coagulation is largely ineffective in removing pharmaceuticals. Free chlorine is able to remove up to approximately 50% of the pharmaceuticals investigated, whereas chloramines have lower removal... 

Next several methods of filtering the pesticide contaminated wastewater were evaluated. Particle size filters were Ineffective since many of the particles are microcolloidal in size. Likewise coalescer type filters were generally Inadequate. After studying these filtration techniques, flocculation procedures were... 

Only about 10% of the Na-i- filtered by the glomerulus is reabsorbed by the distal convoluted tubule (DCT) and therefore the capacity of the thiazide group of diuretics to influence the elimination of Na-H in the urine is limited compared to the loop agents. Thiazides can prevent the reabsorption of up to 5% of the total filtered Na+, whereas the equivalent figure for loop diuretics is about 20%. Thiazides can still produce a moderate naturesis and diuresis compared to carbonic anhydrase inhibitors and the K+-sparing agents. Most thiazides are ineffective at low glomerular filtration rates. They also hinder the ability of the kidneys to produce a dilute urine. 

For aerobic fermentations, air needs to be supplied continuously. Typical aeration rates for aerobic fermentation are 0.5 - 1.0 vvm (air volume per liquid volume per minute). This requires an enormous amount of air. Therefore, not only the medium but also the air must be free of microbial contaminants. All of the sterilization techniques discussed for medium can also be employed for air. However, sterilization of air by means of heat is economically impractical and is also ineffective due to the low heat-transfer efficiency of air compared with those of liquids. The most effective technique for air sterilization is filtration using fibrous or membrane filters. 

Centrifugation is an alternative method when the filtration is ineffective, such as in the case of small particles. Centrifugation requires more expensive equipment than filtration and typically cannot be scaled to the same capacity as filtration equipment. 

Renal plasma flow and glomerular filtration rate are usually unaffected, but free water clearance may increase. Because most sodium is reabsorbed in the proximal renal tubules, spironolactone is relatively ineffective when administered alone. Concomitant administration of a diuretic which blocks re-absorption of sodium proximal to the distal portion of the nephron (such as a thiazide or loop diuretic) is required for maximum diuretic effects. When administered with other diuretics, spironolactone produces an additive or synergistic diuretic response and decreases potassium excretion caused by the other diuretic [65],... 

Nitrofurantoin works by inactivating bacterial ribosomal proteins and other large molecules and has a bactericidal effect. The drug is concentrated in the urine and relies on adequate renal function (glomerular filtration rate (GFR) >30 mL/min) to guarantee activity. Nitrofurantoin is ineffective for upper UTI because it does not achieve adequate concentrations in the blood. The use of nitrofurantoin in patients with moderate-to-severe renal failure (GFR <50 mL/min) is not recommended due to increased risk of peripheral neuropathy (Kucers et ah, 1997). 

As in giardiasis, measures to prevent transmission include proper disposal of feces, wastewater treatment, and a filtration step before chlorination in water treatment plants that draw from surface water sources. Cooking kills the oocysts in contaminated foods and boiling for at least one minute wiU make water safe for use. Heating to 160°F is known to kiU the oocysts. Chlorination is ineffective in killing... 

Dopamine. Dopamine is u.scd in the treatment of shock. It is ineffective orally, in large part because it is a substrate for both MAO and COMT. Thus, it is used intravenously. In contrast with the catecholamines NE and epinephrine, dopamine increases blood flow to the kidney in doses that have no chronotropic effect on the heart or that cause no increa.se in blood pressure, lire increased blood How to the kidneys enhances glomerular filtration rate, Na excretion, and. in turn, urinary output. The dilation of renal blood ve.s-.sels produced by dopamine is the result of its agonist action on the D -dopaminc receptor. 

Two wash techniques are used in plate-and-frame filter presses, illustrated in Fig. 18-125. In simple washing, the wash liquor follows the same path as the filtrate. If the cake is not extremely uniform and highly permeable, this type of washing is ineffective in a well-filled... 

Reverse osmosis This hyper-filtration method uses both pre-filters (such as activated carbon) and membranes with unbelievably small pores to trap contaminants. As such, it is effective for bacteria and viruses, arsenic, fluoride, nitrates, and most of the substances identified above. It is moderately effective on VOCs and hydrogen sulfide and ineffective on radon. 

Inhibitors are classified into reversible and irreversible types. Reversible inhibition implies that the activity of the enzyme is fiiUy restored when the inhibitor is removed from the system in which the enzyme acts by some physical separative process, such as dialysis, gel filtration, or chromatography. An irreversible inhibitor combines covalently with the enzyme so that physical methods are ineffective in separating the two. For example, organophosphorus compounds are... 

Subsoil passage is not efficient in removal of MTBE and other oxygenates, rendering riverbank filtration as treatment step in drinking water production ineffective. Therefore, natural attenuation cannot take care of the MTBE problem in respect to drinking water production. Eor remediation purposes where no drinking water resources are affected and the MTBE concentration is much higher, it may still be a viable option. 

---