Biorefinery of the green seaweed Ulva lactuca to produce animal feed, chemicals and biofuels.

The growing world population demands an increase in animal protein production. Seaweed may be a valuable source of protein for animal feed. However, a biorefinery approach aimed at cascading valorisation of both protein and non-protein seaweed constituents is required to realise an economically feasible value chain. In this study, such a biorefinery approach is presented for the green seaweed Ulva lactuca containing 225 g protein (N × 4.6) kg-1 dry matter (DM). The sugars in the biomass were solubilised by hot water treatment followed by enzymatic hydrolysis and centrifugation resulting in a sugar-rich hydrolysate (38.8 g L-1 sugars) containing glucose, rhamnose and xylose, and a protein-enriched (343 g kg-1 in DM) extracted fraction. This extracted fraction was characterised for use in animal feed, as compared to U. lactuca biomass. Based on the content of essential amino acids and the in vitro N (85 %) and organic matter (90 %) digestibility, the extracted fraction seems a promising protein source in diets for monogastric animals with improved characteristics as compared to the intact U. lactuca. The gas production test indicated a moderate rumen fermentation of U. lactuca and the extracted fraction, about similar to that of alfalfa. Reduction of the high content of minerals and trace elements may be required to allow a high inclusion level of U. lactuca products in animal diets. The hydrolysate was used successfully for the production of acetone, butanol, ethanol and 1,2-propanediol by clostridial fermentation, and the rhamnose fermentation pattern was studied.

Opportunities and challenges for seaweed in the biobased economy.

The unique chemical composition of seaweeds and their fast growth rates offer many opportunities for biorefining. In this article we argue that cascading biorefinery valorization concepts are viable alternatives to only using seaweeds as carbohydrate sources for the fermentative production of biofuels. However, many challenges remain with respect to use of seaweeds for chemical production, such as the large seasonal variation in the chemical composition of seaweeds.

Solution Dynamics of Thallium-Metal Carbonyl Compounds Using (205)Tl NMR Spectroscopy.

A (205)Tl NMR study to probe the solution structure and dynamics of a series of thallium-containing metal complexes has been conducted. The following compounds were examined: Tl{Co(CO)(4)}(3) (Ia), [BnMe(3)N](3)[Tl{Fe(CO)(4)}(3)] ([BnMe(3)N](3)[Ib]), Tl{M(CO)(3)Cp}(3) (Ic, M = Cr; Id, M = Mo; Ie, M = W), TlFp(3) (If; Fp = CpFe(CO)(2)), [PPN](2)[Tl(2)Fe(6)(CO)(24)] ([PPN](2)[II]), [Et(4)N](2)[Tl(2)Fe(4)(CO)(16)] ([Et(4)N](2)[III]), [Et(4)N][L(2)Tl{Fe(CO)(4)}(2)] ([Et(4)N][IV]: [IVa](-), L(2) = bipy; [IVb](-), L(2) = en; [IVc](-), L(2) = phen; [IVd](-), L(2) = tmeda; [IVe](-), L(2) = dien), [Et(4)N](4)[Tl(4)Fe(8)(CO)(30)] ([Et(4)N](4)[V]), and TlCo(CO)(4) (VI). The (205)Tl NMR technique was used to probe the dynamic behavior of the Tl-metal cluster complexes [II](2-), [III](2-), and [V](4-) in solution and the formation of Lewis base adducts of [III](-), as well as the possibility of formation of carbonylate anion adducts of Ia, Ic, Id, and If. [IVb](-) reacted with acetone and formed, after fortuitous oxidation, [{(CO)(4)FeL(2)'Tl}(2)Fe(CO)(4)] (L(2)' = Me(2)C=NCH(2)CH(2)N=CMe(2)) (VII). The initially formed complex [L(2)'Tl{Fe(CO)(4)}(2)](-) ([Et(4)N][IVf]) was spectroscopically characterized. Additionally, the two known but structurally uncharacterized complexes Ia and If as well as the new complexes [BnMe(3)N](3)[Ib] and VII were characterized by single-crystal X-ray diffraction. Compound Ia crystallizes in the monoclinic space group P2(1)/n with a = 16.855(3) Å, b = 6.7790(10) Å, c = 19.049(4) Å, beta = 113.84(3) degrees, V = 1990.8(6) Å(3), Z = 4, R(1)(F) = 0.0221, and wR(2)(F(2)) = 0.0542 [I > 2sigma(I)]. Compound If was synthesized from K[Fp] and TlCl(3).4H(2)O and crystallizes in the triclinic space group P&onemacr; with a = 10.789(2) Å, b = 14.239(3) Å, c = 16.703(3) Å, alpha = 69.39(3) degrees, beta = 89.50(3) degrees, gamma = 69.07(3) degrees, V = 2223.1(7) Å(3), Z = 4, R(1)(F) = 0.0350, and wR(2)(F(2)) = 0.0877 [I > 2sigma(I)]. Compound [BnMe(3)N](3)[Ib] was synthesized from Na(2)Fe(CO)(4).(3)/(2)diox and Tl(OAc)(3) in MeCN and crystallizes in the hexagonal space group P6(3)/m with a = 18.290(3) Å, c = 8.479(2) Å, V = 2456.4(8) Å(3), Z = 2, R(1)(F) = 0.0235, and wR(2)(F(2)) = 0.0494 [I > 2sigma(I)]. Compound VII crystallizes in the triclinic space group P&onemacr; with a = 13.597(3) Å, b = 15.040(3) Å, c = 10.536(2) Å, alpha = 92.75(3) degrees, beta = 95.07(3) degrees, gamma = 114.40(3) degrees, V = 1946.0(7) Å(3), Z = 2, R(1)(F) = 0.0461, and wR(2)(F(2)) = 0.1295 [I > 2sigma(I)].