Evaluating the Feasibility of Forward Osmosis in Diluting RO Concentrate Using Pretreatment Backwash Water

Forward osmosis (FO) is an excellent membrane process to dilute seawater (SW) reverse osmosis (RO) concentrate for either to increase the water recovery or for safe disposal. However, the low fluxes through FO membranes as well the biofouling/scaling of FO membranes are bottlenecks of this process requiring larger membrane area and membranes with anti-fouling properties. This study evaluates the performance of hollow fibre and flat sheet membranes with respect to flux and biofouling. Ferric hydroxide sludge was used as impaired water mimicking the backwash water of a filter that is generally employed as pretreatment in a SWRO plant and RO concentrate was used as draw solution for the studies. Synthetic salts are also used as draw solutions to compare the flux produced. The study found that cellulose triacetate (CTA) flat sheet FO membrane produced higher flux (3-6 L m-2 h-1) compared to that produced by polyamide (PA) hollow fibre FO membrane (less than 2.5 L m-2 h-1) under the same experimental conditions. Therefore, long-term studies conducted on the flat sheet FO membranes showed that fouling due to ferric hydroxide sludge did not allow the water flux to increase more than 3.15 L m-2 h-1

Determination of the optimal pre-processing technique for spectral data of oil palm leaves with respect to nutrient

Precision agriculture with regard to crop science was introduced to apply only the required and optimal amount of fertiliser, which inspired the present study of nutrient prediction for oil palm using spectroradiometer with wavelengths ranging from 350 to 2500 nm. Partial least square (PLS) method was used to develop a statistical model to interpret spectral data for nutrient deficiency of nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca) and boron (B) of oil palm. Prior to the development of the PLS model, pre-processing was conducted to ensure only the smooth and best signals were studied, which includes the multiplicative scatter correction (MSC), first and second derivatives and standard normal variate (SNV), Gaussian filter and Savitzky-Golay smoothing. The MSC technique was the optimal overall pre-treatment method for nutrients in this study, with highest prediction R2 of 0.91 for N and lowest RMSEP value of 0.00 for P

Plasticization Phenomena and Fire Retardancy in pvc

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Thermodynamics of flow and vaporization processes in long-chain liquids

The flow and vaporization behaviors of long-chain esters of varying molecular weights (300-900) ana branching (linear, Y-shaped, and +-shaped molecules) have been studied. The flow behavior is found to depend on the structure as well as the molecular weight. Below a molecular weight of 600, the molecules flow wholly but above this, segmental motion occurs, and the flow becomes independent of the molecular weight which is explained from the blob model. The blob concept demonstrates that the hole of a size of about 11 angstrom is needed for the flow to occur and it is much less than the size of the molecule. The blob size is observed to slightly decrease along the series linear and Y- and +-branched esters. The heat of vaporization is found to be independent of the molecular structure since the molecules acquire a coiled spherical shape during vaporization and hence depends only on the molecular weight. A significant structural effect is observed for the esters on their glass transition temperature (T(g)). The T(g) vs molecular weight plot displays contrasting trend for linear and +-branched esters, with Y esters showing an intermediate behavior. It is explained from their molecular packing and entanglement as visualized by the blob model

Entropy catastrophe and configurational entropies in supercooled and superheated regimes

Utilizing the well known Kauzmann’s entropy catastrophe paradox, we have developed simple thermodynamic expressions for calculating the Kauzmann’s temperatures in the supercooled liquid $(T_{k1})$ and superheated solid $(T_{k2})$ regions besides obtaining new Kauzmann’s temperature in the superheated liquid $(T_{k3})$ regime. $T_{k3}$ is actually the critical temperature of liquids. The configurational entropies in respective regimes can also be obtained from this thermodynamic treatment that leads us to a new “characteristic entropy constant which also seems to be indicative of configurational entropy. Comparison has also been made for the configurational entropies of supercooled and superheated liquid states. The generality of the above thermodynamic treatment has been successfully tested for alkali metals and $Na_2K$ alloy and polymers

Structural Expressions of Long-chain Esters on Their Plasticizing Behavior in Poly(vinyl chloride)

This is the first comprehensive report on the influence of structure and molecular weight of long-chain esters on their plasticization behavior with PVC. Below a molecular weight of 550, there is a decrease in $T_g$, with molecular weight in linear, three-branched and four-branched neat esters, which is explained by the dilution effect of carbonyl groups with an increase in chain length. In the high molecular weight esters above 550, $T_g$, continuously decreases in linear esters, but in three-branched and four-branched esters it increases with the molecular weight, which is explained from the blob model. The dilution effect in the linear esters decreases the PVC-plasticizer interaction and consequently $T_g$, increases with molecular weight both in the low and the high molecular weight esters. In the three-branched and four-branched esters the dilution effect is overtaken by structural effects. The carbonyl groups are shielded and less exposed to PVC in the beginning, but as the arms grow with molecular weight, they become more flexible which facilitates their interaction with PVC. This continuously decreases the $T_g$ with molecular weight in three-branched and four-branched esters upto a molecular weight of 550, beyond which entanglement suppresses the flexibility and, as a result, $T_g$ increases with molecular weight