The air dried exudate of native Acacia nilotica, referred as natural gum or NG in this article, has been purified and characterized for using it as a local, bio-based flocculant for kaolin suspension. Results show that NG is a carbohydrate of nearly 25% purity out of which 7% is the reducing sugar and the rest 75% is natural silica present as contaminant. The macromolecule contains COOH units. This along with OH units impart polyelectrolytic character for which the molecules interact with SiOH units of kaolin and settles the suspension. The settling data shows that 25 ppm is the best flocculant dose in respect of fastest settling and lowest residual turbidity for settling a 3 wt% suspension. Investigation on pH shows that 1.6-2.6 is the best working range, however, in the high stability zone (low acidity to strong basicity), the results are satisfactory. Due to high average floc size and low effective density of the flocs obtained at high acidic condition, the amount of fresh water lost inside the sediment is higher as compared to neutral and basic conditions. © 2014 Elsevier B.V. All rights reserved.

ABHIJIT BANDYOPADHYAY

Polymer Science and Technology

T NASIM

A PAL

A GIRI

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Separation and Purification Technology

Acacia nilotica gum (NG) was blended with high hydrolyzed grade biodegradable poly (vinyl alcohol) (Mn¯ 14,000) in different mass proportions to produce a green and efficient flocculant for separartion of a low concentration of kaolin particles (3 mass%) from its suspension. Flocculation efficacy (settling time and turbidity number) was optimized with respect to flocculant dose, PVA-NG blend composition and pH of the medium. Results showed that PVA-NG73 (70% PVA and 30% NG) was the best performing flocculant at 25 ppm dose when the pH of the medium was maintained at 2.6. Zeta potential (both before and after addition of flocculant), hydrodynamic size, isoelectric point and reduced viscosity number were measured to explain the sedimentation rate and turbidity numbers. The floc size was measured and was found to be comparative to the rate of sedimentation. The amount of water absorbed and lost during operation was found to be proportional with the floc size. Impact of inorganic salts on sedimentation was investigated at a neutral pH which showed a faster settling potential of both bivalent and trivalent salts at an optimized concentration (0.3 M), at the best flocculant dose (25 ppm). © 2017 Elsevier B.V.

Applied Clay Science

Flocculation of aqueous kaolin suspension using a biodegradable flocculant system of poly (vinyl alcohol)-Acacia nilotica gum blends

This paper introduced a green technology for the synthesis of a shape controlled silver nanoparticles (AgNPs) through a mutual interaction of indigenous polysaccharides, Acacia nilotica or natural gum (NG) and tamarind kernel powder or TKP under a specified condition. The resultant particles were characterized using spectroscopy, microscopy and light scattering techniques which demonstrated the generation of a spherical nanoparticles with an average hydrodynamic size ranging between 10 nm to 78 nm (from light scattering experiment). The AgNPs were fairly stable. On in vitro application into different organ specific cancer cell lines e.g. cervical cancer or hela, lung cancer or A549 and mice macrophage or Raw 264.7, it elucidated a dose responsive antitumor cum antioxidant activity with high selectivity which might be an indication for its potential use in anticancer therapy. © 2017 Elsevier B.V.

Journal of Molecular Liquids

In-vitro anti-cancer activity of shape controlled silver nanoparticles (AgNPs) in various organ specific cell lines

Noble copolymers from xanthan gum (XG) and poly(acrylic acid) (PAA) were synthesised through surfactant mediated graft copolymerization. The copolymers were applied as a biosorbent for inorganic Hg(II) at higher concentration level (300 ppm). The copolymers were characterized using different analytical techniques which showed, the grafting principally occurred across the amorphous region of XG. Measurement of zeta potential and hydrodynamic size indicated, the copolymers were strong polyanion and possessed greater hydrodynamic size (almost in all cases) than XG, despite a strong molecular degradation that took place simultaneously during grafting. In the dispersed form, all grades of the copolymer displayed higher adsorption capability than XG, however, the grade with maximum grafting produced the highest efficiency (68.03%). Manipulation produced further improvement in efficiency to 72.17% with the same copolymer after 75 min at a pH of 5.0. The allowable biosorbent dose, however, was 1000 ppm as determined from the experimental evidences. © 2016

Carbohydrate Polymers

Surfactant mediated synthesis of poly(acrylic acid) grafted xanthan gum and its efficient role in adsorption of soluble inorganic mercury from water

This is probably the first report on kaolin flocculation done with aqueous guar gum (GG) at various pH. Dynamic light scattering and reduced viscosity proved the polyelectrolytic feature (zeta potential) of aqueous GG which changed on changing pH. Interestingly, the molecular size of GG did not always increased with rising zeta potential due to strong intermolecular repulsion leading to macromolecular recoiling. Best pH range for settling was 4.0-5.0 which included isoelectric point (IEP) of kaolin. Post-settling turbidity was also acceptable at that range. Optimized GG was further blended with oligomeric poly (vinyl alcohol) (PVA) (Mn 14,000) to prepare a new set of flocculant. Oligomeric PVA was previously optimized at similar pH as excellent kaolin flocculant in our earlier investigation. All GG-PVA blends including neat GG exhibited faster settling than neat PVA. However, settling times of all blend compositions were slightly greater than that of neat GG except for few cases where the post settling turbidity was found significantly lower than all our previous investigations. © 2013.

International Journal of Biological Macromolecules

Guar gum and guar gum-oligomeric poly(vinyl alcohol) blends as novel flocculants for kaolinated waste water

High hydrolyzed grade, different poly (vinyl alcohol)s (PVA) are introduced as new eco-friendly flocculants for aqueous kaolin suspension. Sedimentation efficiency is investigated as a function of PVA molecular weight, pH and presence of different surfactants in the suspension media. Results are interesting. Low molecular weight PVA (M n 14,000) at pH 4 excels over other high molecular weight polymers (M n 30,000 and 115,000) by producing fastest sedimentation followed by low residual turbidity and minimum fresh water removal from the medium. Presence of surfactants has largely delayed sedimentation and has produced exceedingly high residual turbidity except cetyltrimethyl ammonium bromide, CTAB which shows turbidity slightly less than the low molecular weight PVA at its best working pH (pH 4). © 2011 Elsevier B.V. All rights reserved.

Journal	Data powered by TypesetSeparation and Purification Technology
Publisher	Data powered by TypesetElsevier
ISSN	1383-5866
Open Access	No