Issue 39, 2013

Fuel intermediates, agricultural nutrients and pure water from Kappaphycus alvarezii seaweed

Abstract

The present work reports a standalone integrated scheme for the production of 5-hydroxymethyl furfural (HMF) and potassium sulphate (K2SO4) from granular biomass rich in the sulphated polysaccharide, κ-carrageenan. Fresh Kappaphycus alvarezii seaweed was crushed to expel the juice rich in KCl (0.7 m3 t−1 of fresh seaweed) and granular biomass (0.04 t dry weight per t of fresh seaweed). The latter yielded κ-carrageenan through seawater extraction. HMF was derived from this phycocolloid through reaction with Mg(HSO4)2 acid catalyst and isolated in pure form. Galactose was a co-product which remained in the aqueous phase. The aqueous phase was recycled up to 10 times by maintaining a constant acid strength, and utilized thereafter for the recovery of K2SO4. Selective crystallization of K2SO4 was guided by the phase diagram and use was made of a part of the seaweed juice in this process. The spent aqueous phase rich in galactose was subjected to further reaction with HCl obtainable through bipolar electro-dialysis (ED) of seaweed juice. The reaction yielded levulinic acid (LA) and formic acid (FA) in nearly equal proportions. The processing of 1 t of granular biomass was computed to require 30.15 GJ of energy and would yield 0.18 t HMF, 0.056 t LA, 0.020 t FA, 0.27 t K2SO4, and 5.77 m3 pure water. The process energy requirement for the scheme can be met from additional supplies of granule (3.35 t). Combustion/gasification of this biomass would yield additionally 0.74 t glaserite fertilizer and the required amount of H2SO4 for Mg(HSO4)2 preparation.

Graphical abstract: Fuel intermediates, agricultural nutrients and pure water from Kappaphycus alvarezii seaweed

Supplementary files

Article information

Article type
Paper
Submitted
12 Jun 2013
Accepted
29 Jul 2013
First published
31 Jul 2013

RSC Adv., 2013,3, 17989-17997

Fuel intermediates, agricultural nutrients and pure water from Kappaphycus alvarezii seaweed

D. Mondal, M. Sharma, P. Maiti, K. Prasad, R. Meena, A. K. Siddhanta, P. Bhatt, S. Ijardar, V. P. Mohandas, A. Ghosh, K. Eswaran, B. G. Shah and P. K. Ghosh, RSC Adv., 2013, 3, 17989 DOI: 10.1039/C3RA42919A

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