Removal of Phosphate from Waste Waters by Adsorption

In this study, the adsorption of phosphate on gas concrete from aqueous solutions has been studied as functions of temperature, mixing rates and suspension pH. Over 99% of phosphate removal was found. The chemical composition of the gas concrete has been defined by X-ray analysis. Experimental data was fitted to the Langmuir equation in order to Langmuir coefficients. After calculating Langmuir coefficients, adsorption free energy (Δ G ⁰ _ads.) has been determined. In order to gather information about adsorption mechanism, electrophoretic mobilites of particles were measured at various pHs by using Zeta meter 3.0+. It has been found that the adsorption is driven by the interactions between the ionizations of CaO and Al₂O₃ and the formation of AlPO₄. According to the BET (N₂) measurements, the specific surface area of gas concrete was found as 22 m²g^-1. The surface area after adsorption has been found as 17 m²g^-1. The surface area covered by adsorbate has been found as 5.23 m²g^-1 by usinga_s = n^s _m. a_m. N_A. These two areas determined by BET and Langmuir model were close to each other (BET: 22 m²g^-1–17 m²g^-1).     

Mortality and F1 production of Rhyzopertha dominica (F.) on wheat treated with diatomaceous earth: impact of biological and environmental parameters on efficacy

A series of experiments were conducted in which label rate (0.3 g per kg of wheat) with diatomaceous earth (DE) formulation Protect-It. Exposure studies were carried out at two levels of relative humiditiy (40% and 55%), two levels of insect density (10 or 20 adults per vial), and three levels of exposure periods. Test insects were placed in vials containing 40 g of soft white winter wheat mixed with either 0 or 0.3 g Protect-It per kg of wheat. After relating exposure periods for both insect density and relative humidity levels, highest mortality was only 16%. Mortality, regardless of the dose rate applied (0 and 0.3 g) were not significantly increased as the exposure period increased. Regardless of relative humidity (r.h.) (40% and 55%r.h.), mortality in control were not significantly increased as the exposure period increased for the same insect density. However, significant differences among the three exposure periods in 10 adults’ density in 0.3 g DE application. Mortality was significantly increased in 10 adults’ density. In this case mortality of R. dominica adults increased with the increasing of the exposure intervals. As for 20 adults’ density, mortality in 0.3 g DE application was not significantly changed along with the exposure intervals. After insects were exposed for 1, 2, or 3 week, dead and live insects were removed, and the wheat in the vial were returned to relating humidity box and kept for 8 week until F₁ adults emerged. Then, the number of F₁ adult was counted. The mean numbers of F₁ adults on untreated wheat at all density and r.h. combinations, regardless of exposure periods were significantly higher than that of 0.3 g DE- treated wheat (Fig. 3). At each density and treatment, the mean number of F₁ adults at 55% r.h. were higher that that of 40%r.h. The comparison between adult densities at each r.h. and treatment showed that adult densities influenced the F₁ production of R. dominica and F₁ adults were always higher at 20 adults’ density. The mean number of F₁ adults at each density, regardless of treatment progressively increased as the exposure period increased. Fewer progeny were produced at 10 adults’ density compared to 20 adults’ density for same exposure periods. The highest reproduction occurred in 3 week of exposure period for both insect densities. Regardless of adult densities, the mean number of F₁ adults was significantly increased as the exposure period increased (Fig. 5) for both control and 0.3 g DE treatment. Reduction of F₁ adults at 0.3 g DE application compared to control were found to be 76.88, 74.78 and 67.63% for 1, 2 and 3 week of exposure period, respectively.