The chemical modification of maritime pine sapwood (Pinus pinaster) with alkoxysilanes was studied according to three different pathways: carbamoylation with 3isocyanatopropyltriethoxysilane, etherification with 3glycidoxypropyltrimethoxysilane and alcoholysis of n-propyltrimethoxysilane. Grafting was confirmed by weight percent gain calculations (WPG), infrared spectroscopy (FTIR) as well as 13 C and 29 Si NMR CP MAS analysis. Signals of the grafted groups in the different spectra were assigned and the reactivity of the trialkoxysilane moieties towards wood was discussed. Experiments with model wood blocks showed that the reactions investigated occurred within the wood cell walls. Grafted chemicals were found to be relatively stable with regard to water leaching but only slight dimensional stabilisation was noted after treatment.

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In order to understand the chemical reactivity and the relative susceptibility of I  and I β cellulose allomorphs of some tropical hardwoods with coupling agents bearing succinic moiety, their cellulose fibers were isolated and esterified by succinic anhydride molecule heated at 120 °C for 4 h in dimethylformamide(DMF)/pyridine(Py) used as swelling solvent. The morphological structure of Testulea gabonensis (T. gabonensis), Julbernardia pellegriniana (J. pellegriniana), Aucoumea klaineana (A. klaineana) and Tieghemella africana (T. africana) fibers were characterized by the MORFI® apparatus. The fibers were the longest for T. africana (769 m), J. pellegriniana (717 m) and T. gabonensis (700 m) while those from A. klaineana were the shortest (624 m). No difference was found between T. gabonensis, A. klaineana and T. africana fibers width which varied from 24.0 to 24.2 m while J. pellegriniana cellulose exhibited the smallest width (18.6 m). The cellulose fibers of T. gabonensis, T. africana and J. pellegriniana displayed the better reactivity as revealed by their respective weigh per cent gains: 16.57  1.11%, 14.16  0.67% and 12.96  0.77% compared with A. klaineana (11.85  0.62%). The latter exhibited the lowest decrease of crystallinity among those cellulose esters. Nevertheless, solid state 13 C NMR showed a strong reactivity of amorphous cellulose and chains exposed on crystal surfaces than interior crystallite chains. Any evidence of I  and I  allomorphs esterification was found in those cellulose fibers with the exception of T. africana which displayed a decrease of I  and I  allomorphs without a preferential reactivity of I  cellulose. The trend of heterogeneous phase esterification of cellulose fibers with succinic anhydride in DMF/Py at 120 °C for 4 hours to be merely controlled by amorphous phase and chains exposed on crystal surface was discussed.

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The aim of this study was to investigate the anatomical structure of the trunk wood and the roots of A. nitida and R. racemosa, two mangrove trees from Gabon. The anatomical differences between the trunks and the roots were used to understand their bio-remediating differences through heavy metals. It was found that the roots of A. nitida were less abundant in cells number/mm 2 than its trunk which exhibited the largest cells diameter. The roots and the trunk of R. racemosa didn't exhibit significant difference between their cells number. Nevertheless, the trunk of that mangrove tree displayed the largest cells diameter and somewhat traumatic channels. Any interspecies variability was found between their trunk vessels diameter. However, a significant difference was found regarding their vessels number/mm 2 , the trunk of A. nitida was richer in vessels compared to R. racemosa one. The roots of the latter were more abundant in vessels and they displayed the largest cells diameter than A. nitida. Broad parenchyma bands and sclerous cells lacked within R. racemosa while they were richer in A. nitida roots and trunk. The occurrence of those anatomical structures which storage substances was thought to act in the highest heavy metals bio-remediation of Avicenniaceae than Rhizophoraceae.

This work investigates for the first time the different reactivity exhibited by sapwood and heartwood wastes under two conditions: They were pretreated with catalyzed ethanol organosolv in the presence of sulfuric acid and their pulps underwent enzymatic hydrolysis by Trichoderma reesei which causes them to release neutral sugars for the production of cellulosic ethanol. Aucoumea klaineana Pierre (Okoumé) wood wastes were used for the experiment. Organosolv pretreatment was performed to investigate how to harness the benefits of fermentable sugars and lignin, which were reacted at varying defined severity levels as follows: 160°C≤T≤210°C and 0%≤[H 2 SO 4 ]≤2% (w/w). The highest ethanol organosolv lignin content was obtained at T=160°C and [H 2 SO 4 ]=1% for sapwood (18.10%) and heartwood (19.46%) (w/w). Enzymatic hydrolysis of the pretreated wood samples displayed that sapwood and heartwood pulps released their highest sugars content under free acid pretreatment conditions. The maximum neutral sugar released by heartwood pulps pretreated at T=160°C and [H 2 SO 4 ]=0% was 0.126 g/L while that from sapwood pretreated at T=185°C and [H 2 SO 4 ]=0% was 0.125 g/L. It is noteworthy that, the neutral sugars from sapwood and heartwood do not have the same sensitivity to temperature increase. When pretreated at T=160°C and [H 2 SO 4 ]=0%, sapwood pulps yielded the following neutral sugars: Xyl< AraGal < Man < Glu, while heartwood was: Ara < Gal < Xyl < Man < Glu. However, with increased temperature (T=185°C and [H 2 SO 4 ]=0%), sapwood yielded the following neutral sugars: Ara < Gal < Xyl < Man < Glu, while heartwood yielded the following: Xyl < AraGal < Man < Glu. Similar trend was observed in both sapwood and heartwood pulps when sulfuric acid concentration was increased.