Studies on complex formation between curcumin and Hg(II) ion by spectrophotometric method: A new approach to overcome peak overlap

Complex formation between curcumin and Hg(II) ion MeOH/H₂O (1: 1 v/v) was investigated and monitored by the spectrophotometric method. The absorption peak of unreacted curcumin which was close and overlapped with that of the complex, was removed by calculation using Microsoft Excel, thereby, allowing determination of the stoichiometry of the complex by the mole-ratio and the Job’s continuous variation methods. Both methods indicated that a 1:1 complex of curcumin and Hg(II) was formed in solution. The formation constant of the 1:1 Hg(II) complex was obtained from two methods, the equilibrium concentration calculation and the linear plot of Benesi-Hildebrand equation, as log K = 4.44 ± 0.16 and 4.83 ± 0.02, respectively. The structure is proposed as a tetrahedral complex of Hg(II) with one curcumin and two chloride ions as ligands. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users.     

Selective synthesis of zeolitic phillipsite and hibschite hydrogarnet from lignite ash employing calcium hydroxide under mild conditions

A selective synthesis of zeolitic material, phillipsite, employing calcium hydroxide under mild chemical conditions is reported. This is to provide a potential method in reducing the amount of the waste from lignite power plant and the addition of economical value to the material. The fly ash was first activated by calcination at high temperature, and then fused with calcium hydroxide. The water was then added to the solid mixture before curing under saturated water vapour at low temperature. The treatment of as-received fly ash with either calcium hydroxide or a mixture of calcium and sodium hydroxide following as-described preparative procedure of phillipsite, but without prior calcination was also conducted, and led to the formation of Hibschite hydrogarnet, which was also evidentially selective. The following parameters, i.e. type and amount of alkali reagent, the amount of added water, fusion temperature and reaction time were investigated. Powder X-ray diffraction was used to identify type of crystalline solid products, and scanning electron microscope was employed to follow the alteration of solid morphologies. X-ray fluorescence (XRF) was used to trace the chemical composition of the solids. The heavy metal cation removal abilities toward lead ion of the prepared phillipsites were also investigated.     

Characterization of biologically active compounds from different herbs: Influence of drying and extraction methods

The hot air (HA) method is the most widely implemented drying method for plants (herbs, vegetables, and fruits). This method has a few drawbacks that include long drying time, limited heat transfer, and limited thermal conductivity. This study investigated the effects of HA and infra-red (IR) heating method on biologically active compounds from different herbs (Khaffir lime, Lemongrass, Prai, Tamarind, and Turmeric). The efficiency of the drying methods was evaluated by considering (a) moisture ratio (MR), (b) specific energy consumption (SEC, MJ/kg.H₂O), (c) moisture diffusivity (D_eff), and (d) activation energy (E_a, kJ/mol). The active compounds were extracted from HA and IR dried herbs using different solvents (hexane, water, and ethanol) through Solid-Liquid Extraction (SLE) and Soxhlet Solvent Extraction (SSE) methods. The moisture removal in the IR drying process increased 10–11% for the herb samples. Specific energy consumption (SEC) increase during the IR drying process is attributed to the rapid evaporation of water at shorter time intervals than HA. Activation energy (E_a) values decreased by 1.66, 1.48, 2.24, 3.13, and 2.07 fold times for IR dried prai, turmeric, lemongrass, tamarind, and kaffir lime, respectively. The higher yields of herbal extracts and the abundance of bioactive terpene derivatives in hexane extracts were obtained from HA herbs compared to IR samples. Therefore, it is concluded that the IR method and SSE process using hexane was suitable to dry and retain the bioactive active compounds within herbs. Further, the IR method over the HA method was considered based on energy consumption, processing time, yield, and active compounds.