Development of microporous activated Aloji clay for adsorption of lead (II) ions from aqueous solution.

Aloji clay was activated with HCl at optimal conditions variables (acid concentration, activation temperature and time) using central composite design with yield (%) and Pb2+ uptake as responses targeted. The obtained optimum conditions for high yield (%) and Pb2+ uptake were at 0.5 M, 100 °C and 120 min. At these conditions, BET surface area of 214.80 m2/g of the microporous activated adsorbent gave a maximum monolayer of 333.33 mg/g for Pb2+. The effects of equilibrium time, initial Pb2+ concentration, temperature and adsorbent dosage were examined. Pseudo-second-order kinetic and Freundlich models best described Pb2+ adsorption onto Aloji activated clay as compared to the other isotherms and kinetics models investigated. The adsorption process was spontaneous, exothermic and physical as revealed by the nature of the thermodynamic studies. The study shows that the discharge of harmful substances posed by industrials into water bodies can be salvage by effective and efficient use of activated Aloji clay.

A thermogravimetric analysis of the combustion kinetics of karanja (Pongamia pinnata) fruit hulls char.

The combustion characteristics of Karanj fruit hulls char (KFH-char) was investigated with thermogravimetry analysis (TGA). The TGA outlined the char combustion thermographs at a different heating rate and isoconversional methods expressed the combustion kinetics. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods authenticated the char average activation energy at 62.13 and 68.53kJ/mol respectively, enough to derive the char to burnout. However, the Coats-Redfern method verified the char combustion via complex multi-step mechanism; the second stage mechanism has 135kJ/mol average activation energy. The TGA thermographs and kinetic parameters revealed the adequacy of the KFH-char as fuel substrate than its precursor, Karanj fruit hulls (KFH).

Coalesced chitosan activated carbon composite for batch and fixed-bed adsorption of cationic and anionic dyes.

A renewable waste tea activated carbon (WTAC) was coalesced with chitosan to form composite adsorbent used for waste water treatment. Adsorptive capacities of crosslinked chitosan beads (CCB) and its composite (WTAC-CCB) for Methylene blue dye (MB) and Acid blue 29 (AB29) were evaluated through batch and fixed-bed studies. Langmuir, Freundlich and Temkin adsorption isotherms were tested for the adsorption process and the experimental data were best fitted by Langmuir model and least by Freundlich model; the suitability of fitness was adjudged by the Chi-square (χ(2)) and Marquadt's percent standard deviation error functions. Judging by the values of χ(2), pseudo-second-order reaction model best described the adsorption process than pseudo-first-order kinetic model for MB/AB29 on both adsorbents. After five cycles of adsorbents desorption test, more than 50% WTAC-CCB adsorption efficiency was retained while CCB had <20% adsorption efficiency. The results of this study revealed that WTAC-CCB composite is a promising adsorbent for treatment of anionic and cationic dyes in effluent wastewaters.