Determination of Lead(II) in Liver Corpse of a Slaughtered Cattle with Preconcentration on a Chelating Sorbent
The copolymer of the maleic anhydride-styrene is modified at the presence of 4-amino-2-thiouracil and formaldehyde and the new polymeric sorbate with spatial structure is received. The received sorbate is identified by the IR-spectroscopy method. The complete static sorption capacitance was studied (CSSC+K= 7.8 mmol/g) and the ionization constants of ionic groups in a sorbate link was defined by electrometric method. Ionization constants were determined by potentiometric titration of the sorbent (). Sorption and desorption of the received sorbent with a lead ion (II) are investigated and optimum concentration conditions are defined: рНopt. = 5, ionic force μ = 0.8 pier/l, full sorption balance 4 hours, optimum eluent 5 ml of 0.5 M HCl.
THERMOGRAVIMETRIC STUDY OF SORBENT BASED ON COVALENTLY IMMOBILIZED ZINC DITHIOCARBAMATE ON A POLYESTER MATRIX.
: This article investigates the thermogravimetric characteristics of a sorbent based on covalently immobilized zinc dithiocarbamate on a polyester matrix. Based on the results of the obtained experimental data, it was shown that the sorbent is stable up to a temperature of 140 ᵒС. The resulting sorbent is recommended for use in the sorption of copper and zinc ions from solutions of higher temperatures.
Increasing pulp yield in kraft cooking of softwoods by high initial effective alkali concentration (HIEAC) during impregnation leading to decreasing secondary peeling of cellulose
Abstract Pulp yield can be improved by a more homogeneous delignification of the chips, achieved by improved impregnation prior to the cooking stage. Complete and efficient impregnation is obtained by increasing the diffusion rate by means of an impregnation liquor with a high initial effective alkali concentration (HIEAC). In the present study, the effect of HIEAC in the impregnation was evaluated and compared to a reference impregnation procedure and a prolonged impregnation. After the various impregnation scenarios, the alkali concentration was always adjusted to the same level in the beginning of the cooking stage. Impregnation with a HIEAC resulted in yield improvements by 1–1.5% units, due to a higher cellulose yield and possibly also to higher yield of glucomannan. The HIEAC with an even alkali distribution within the chips prior to the cooking stage resulted in a more uniform delignification carbohydrate degradation. Yield increase obtained by uniform delignification is due to both decreased shives content as well as less secondary peeling.