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The adsorption potential of iron acetate coated activated alumina (IACAA) for removal of arsenic [As (III)] as arsenite by batch sorption technique is described. IACAA was characterized by XRD, FTIR, EDAX and SEM instruments. Percentage adsorption on IACAA was determined as a function of pH, contact time and adsorbent dose. The study revealed that the removal of As (III) was best achieved at pH =7.4. The initial As (III) concentration (0.45 mg/L) came down to less than 0.01 mg/L at contact time 90 min with adsorbent dose of 1 g/100 mL. The sorption was reasonably explained with Langmuir and Freundlich isotherms. The thermodynamic parameters such as ΔG 0 , ΔH 0 , ΔS 0 and E a were calculated in order to understand the nature of sorption process. The sorption process was found to be controlled by pseudo-second order and intraparticle diffusion models.

Water hyacinth ash is found to be an efficient and reusable catalyst for the synthesis of β-amino carbonyl/nitrile compounds by aza-Michael reaction of amines with α,β-unsaturated compounds at room temperature under solvent free condition. Due to low cost of the catalyst, good activity, ease of handling and easy recovery with high yields of the products in short reaction time, easy workup procedure, mild reaction condition, the protocol is highly applicable in synthetic organic chemistry.

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Background: Dhokora khar (solid alkali), derived from water hyacinth (Eichhornia crassipes) is used by the people of Assam as a traditional food additive and as an antacid. It is usually prepared from the aqueous extract of water hyacinth ash. It is very popular in lower Assam particularly in the district of Barpeta and nearby areas. Apart from its use as a food additive in preparing palatable dishes, it is also used for the cure of ailments arising from stomach acidity and indigestion. In rural Assam, this khar finds applications as a natural fertilizer as well as a cleansing agent. Methods: Standard chemical and spectral procedures have been used to confirm the presence of acid and basic radicals. SEM-EDX, Atomic Absorption Spectrometry and Flame Photometry were used for information on chemical constituents. Results: Standard chemical and spectral procedures have been used to confirm the presence of acid and basic radicals. SEM-EDX, Atomic Absorption Spectrometry and Flame Photometry were used for information on chemical constituents. Conclusion: The investigation suggests that dokhora khar consists of a mixture of carbonates, chlorides, sulfates and phosphates of various metals such as K, Mg, Ca, Na, Fe, Mn, Zn, Cu, etc. Some of these metals such as Fe, Co, Mn, Ni, Cu, Zn, Cr, etc., are essential nutrients. Hence the results establish that the consumption of this traditional food additive by the natives of Assam provides health benefits.

The catalytic activity of water hyacinth ash (WHA) has been evaluated for the transesterification reaction of soybean oil with methanol. The reaction was carried out under ambient temperature as well as reflux conditions. The yields of the corresponding fatty acid methyl esters were 95% under both experimental conditions. The catalyst loading was 20% by weight of the oil and the reaction time varied from 30 minutes under reflux condition to 2.5hours at ambient temperature. The catalyst is recyclable and could be reused for up-to 4 runs with marginal loss in catalytic activity.

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