Steam and KOH Activated Carbons from Peach Stones

Peach-stone-based activated carbons were prepared by using steam and KOH activation at 800 degrees C. The effects of solid/liquid phase KOH and steam activation, alkali and acidic pre-treatment, and also single-step activation on activated carbon properties were investigated comprehensively. The activated carbon produced by solid phase KOH impregnation showed the highest surface area of 835 m(2)/g and micropore volume of 0.412 cm(3)/g. Besides, single-step steam activation produced a highly microporous carbon having a relatively high surface area of 608 m(2)/g and micropore volume of 0.331 cm(3)/g. Peach-stone-based activated carbons with well-developed pore structure and functional properties were achieved, comparable to the commercial carbon, CPG-LF (Chemviron Carbon). The produced carbons were tested for Chromium (VI) removal from aqueous solution. Some of the activated carbons showed higher Chromium (VI) adsorption capacity than commercial activated carbon, CPG-LF (Chemviron Carbon)

Study of Cherry Stones as a Precursor in the Preparation of Low Cost Carbonaceous Adsorbent

A cherry stone-based activated carbon was electrochemically and chemically oxidized to enhance its adsorbent property for comparison with as-produced. The samples obtained were characterized by Boehm's titration, pH titration, zeta potential measurement, FT-IR, Brunauer-Emmet-Teller surface area, and pore size distribution. A significant increase in the concentration of surface functional groups was obtained from the oxidation of the samples due to the introduction of oxygen-containing functional groups, as confirmed by Boehm's titration, FT-IR, PZC, and IEP analyses. Activation methods significantly improved the amount of oxygen-containing surface functional groups that make the carbonaceous adsorbents more hydrophilic and acidic, decreasing the pH of their point of zero charge, and increasing their surface charge density. The activated carbon samples obtained were predominantly microporous, and their pore volumes decreased as a function of activation period and temperature. The surface chemistry development of carbons was correlated to increasing removal ability of heavy metals

An experimental design approach for modeling As(V) adsorption from aqueous solution by activated carbon

The present paper discusses response surface methodology as an efficient approach for predictive model building and optimization of As(V) adsorption on activated carbon derived from a food industry waste: peach stones. The objectives of the study are application of a three-factor 23 full factorial and central composite design technique for maximizing As(V) removal by produced activated carbon, and examination of the interactive effects of three independent variables (i.e., solution pH, temperature, and initial concentration) on As(V) adsorption capacity. Adsorption equilibrium was investigated by using Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. First-order and second-order kinetic equations were used for modeling of adsorption kinetics. Thermodynamic parameters (ΔG °, ΔH °, and ΔS °) were calculated and used to explain the As(V) adsorption mechanism. The negative value of ΔH (−7.778 kJ mol−1) supported the exothermic nature of the sorption process and the Gibbs free energy values (ΔG°) were found to be negative, which indicates that the As(V) adsorption is feasible and spontaneous.</jats:p

Evaluation of pertussis immunity status in schoolchildren immunized with whole-cell vaccine

SUMMARYIt has recently been reported that the worldwide increase in the number of pertussis cases is a result of the waning of whole-cell vaccine-induced immunity. Thus, in this study, we aimed to investigate the pertussis immunity status of primary and secondary school students in a district of Ankara, Turkey. A total of 997 healthy students, aged 9–17 years, who had been immunized with four doses of whole-cell pertussis vaccine were included in the study. The subjects were divided into two age groups: 9–14 and 15–17 years. To determine the immune status, serum levels of IgG anti-pertussis toxin (aPT) antibody were tested by in-house ELISA and arbitrarily evaluated as non-immune [&lt;10 ELISA units (EU)/ml], immune (10–100 EU/ml), and recent infection (&gt;100 EU/ml). Serum samples of 997 students (559 females, 438 males) aged between 9 and 17 years (mean 13·02±2·25, median 13 years) were tested. Non-immune, immune and recent infection levels of aPT were found in 27·3%, 59·3% and 13·4% of individuals, respectively. The immune group did not have statistically significant differences between males and females (P=0·68). In the 9–14 and 15–17 years age groups, serum aPT antibody levels ⩾10 EU/ml were 73·1% and 72·2%, respectively, which did not represent any statistical difference (P=0·81). Students aged 15–17 years had a higher immunity rate than the 9–14 years group, and the percentage of students with recent infection in the 9–14 years group was higher than the 15–17 years group (P&lt;0·001). The peak age of non-immunized subjects was 9 years (47·0%), and decreased to a minimum at age 12–13 years, and began to increase again from age 13–14 years. In contrast, the ratio of recent infection was least at age 9–10 years, began to increase, and reached a peak at 12 years, and then decreased. On the other hand, it was observed that household size and monthly income were not associated with the immunity status (P=0·65,P=0·37, respectively). The results of the present study show that levels of antibody against pertussis decreased in the younger age groups and, as a result, there is an increase in the number of pertussis cases. Thus, in order to decrease the incidence of pertussis and protect infants, we recommend the application of booster doses at regular intervals.</jats:p