3 research outputs found

    Sustainable conversion of agro-wastes into useful adsorbents

    Get PDF
    Preparation and characterization of raw andactivated carbon derived from three different selectedagricultural wastes: kola nut pod raw and activated (KNPRand KNPA), bean husk raw and activated (BHR and BHA)and coconut husk raw and activated (CHR and CHA) wereinvestigated, respectively. Influences of carbonization andacid activation on the activated carbon were investigatedusing SEM, FTIR, EDX, pHpzcand Boehm titration tech-niques, respectively. Carbonization was done at 350°C for2 h followed by activation with 0.3 M H3PO4(ortho-phosphoric acid). Results obtained from SEM, FTIR, andEDX revealed that, carbonization followed by acid acti-vation had a significant influence on morphology and ele-mental composition of the samples. SEM showed well-developed pores on the surface of the precursors after acidtreatment, FTIR spectra revealed reduction, broadening,disappearance or appearance of new peaks after acid acti-vation. EDX results showed highest percentage of carbonby atom respectively in the order BHA[KNPA[CHArespectively. The pHpzcwas found to be 5.32, 4.57 and 3.69for KNPA, BHA and CHA, respectively. Boehm titrationresult compliments that of pHpzc, indicating that the sur-faces of the prepared adsorbents are predominantly acidic.This study promotes a sustainable innovative use of agro-wastes in the production of cheap and readily availableactivated carbons, thereby ensuring more affordable waterand effluent treatment adsorbents

    Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

    No full text
    WOS: 000182039700036We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these data plus all available archival measurements to study the temporal behaviour of the pulsational amplitudes and frequencies of these stars for the first time. We demonstrate that both KUV 05134+2605 and PG 1654+160 pulsate in many modes, the amplitudes of which are variable in time; some frequency variability of PG 1654+160 is also indicated. Beating of multiple pulsation modes cannot explain our observations; the amplitude variability must therefore be intrinsic. We cannot find stable modes to be used for determinations of the evolutionary period changes of the stars. Some of the modes of PG 1654+160 appear at the same periods whenever detected. The mean spacing of these periods (approximate to40 s) suggests that they are probably caused by non-radial gravity-mode pulsations of spherical degree l = 1. If so, PG 1654+160 has a mass around 0.6 M.. The time-scales of the amplitude variability of both stars (down to two weeks) are consistent with theoretical predictions of resonant mode coupling, a conclusion which might however be affected by the temporal distribution of our data
    corecore