Acacia is well known to be susceptible to many fungal diseases. Heart rot, root rot, and Ceratocystis wilt disease are three major diseases of Acacia in the tropics that cause serious damages and significant economic impact. Loss of merchantable volume due to rotting of heart wood is a huge threat primarily to solid wood producers as it severely reduces the quality of wood, making it unsuitable for general utility. The damages on Acacia plantations associated with root rot and Ceratocystis wilt disease are far more serious than heart rot causing high mortality of trees. Furthermore, unavailability of effective control measures has urged the conversion of 600,000 ha of Acacia plantations to Eucalyptus in Indonesia. More importantly, Ceratocystis wilt disease infection can wipe out plantations as recorded in Peninsular Malaysia. Other diseases with the potential to cause serious destruction to A. mangium plantation programs are phyllode rust and the recent concern on Phytophthora root rot. To date, there are no control measures known to be effective against these diseases. This chapter presents the occurrence of Acacia diseases in nurseries and plantations as well as the status of Acacia as alien invasive species. Information provided in this chapter can be useful as guidelines for preventing and controlling the spread of diseases in both nurseries and plantations.
Brown root rot disease (BRRD), caused by Phellinus noxius, is an important tree disease in tropical/subtropical areas. To improve chemical control of BRRD and deter emergence of fungicide resistance in P. noxius, this study investigated control efficacies and systemic activities of fungicides with different modes of action. Fourteen fungicides with 11 different modes of action were tested for inhibitory effects in vitro on 39 P. noxius isolates from Taiwan, Hong Kong, Malaysia, Australia, and Pacific Islands. Cyproconazole, epoxiconazole, and tebuconazole (FRAC 3, target-site G1) inhibited colony growth of P. noxius by 99.9 to 100% at 10 ppm and 97.7 to 99.8% at 1 ppm. The other effective fungicide was cyprodinil + fludioxonil (FRAC 9 + 12, target-site D1 + E2), which showed growth inhibition of 96.9% at 10 ppm and 88.6% at 1 ppm. Acropetal translocation of six selected fungicides was evaluated in bishop wood (Bischofia javanica) seedlings by immersion of the root tips in 100 ppm of each fungicide, followed by liquid or gas chromatography tandem-mass spectrometry analyses of consecutive segments of root, stem, and leaf tissues at 7- and 21-days post-treatment. Bi-directional translocation of the fungicides was also evaluated by stem injection of fungicide solutions. Cyproconazole and tebuconazole were the most readily absorbed by roots and efficiently transported acropetally. Greenhouse experiments suggested that cyproconazole, tebuconazole, and epoxiconazole have a slightly higher potential for controlling BRRD than mepronil, prochloraz, and cyprodinil + fludioxonil. Because all tested fungicides lacked basipetal translocation, soil drenching should be considered instead of trunk injection for their use in BRRD control.
Acacia mangium is an important wood for commercial products especially pulp and medium-density fibreboard. However, it is susceptible to Ceratocystis fimbriata infection, leading to Ceratocystis wilt. Therefore, the present work aimed to (i) establish the diversity of endophytic fungi in different plant parts of A. mangium ,and (ii) evaluate the antifungal potentials of the isolated and identified endophytic fungi against C. fimbriata . Endophytic fungal identification was conducted by PCR amplification and sequencing of the internal transcribed spacer 1 (ITS1) and ITS4 regions of nuclear ribosomal DNA. A total of 66 endophytic fungi were successfully isolated from different parts of A. mangium ; leaf (21), stem (13), petiole (12), root (9), flower (6), and fruit (5). The endophytic fungal isolates belonged to Ascomycota (95.5%) and Zygomycota (4.5%). For Ascomycota 13 genera were identified: Trichoderma (28.6%), Nigrospora (28.6%), Pestalotiopsis (12.7%), Lasiodiplodia (9.5%), Aspergillus (6.3%), Sordariomycetes (3%), and Neopestalotiopsis , Pseudopestalotiopsis , Eutiarosporella , Curvularia , Fusarium , Penicillium , and Hypoxylon each with a single isolate. For Zygomycota, only Blakeslea sp. (5%) was isolated. Against C. fimbriata , Trichoderma koningiopsis (AC 1S) from stem, Nigrospora oryzae (AC 7L) from leaf, Nigrospora sphaerica (AC 3F) from the flower, Lasiodiplodia sp. (AC 2 U) from fruit, Nigrospora sphaerica (AC 4P) from petiole, and Trichoderma sp. (AC 9R) from root exhibited strong inhibition for C. fimbriata between 58.33 to 69.23%. Thus, it can be concluded that certain endophytic fungi of A. mangium have the potential to be harnessed as anti-Ceratocystis agent in future biotechnological applications.
To expand the genomic information of Hypericaceae, particularly on Cratoxylum, we characterized seven novel complete plastid genomes (plastomes) of five Cratoxylum and two of its allied taxa, including C. arborescens, C. formosum subsp. formosum, C. formosum subsp. pruniflorum, C. maingayi, C. sumatranum, Hypericum hookerianum, and Triadenum breviflorum. For Cratoxylum, the plastomes ranged from 156,962 to 157,792 bp in length. Genomic structure and gene contents were observed in the five plastomes, and were comprised of 128–129 genes, which includes 83–84 protein-coding (CDS), 37 tRNA, and eight rRNA genes. The plastomes of H. hookerianum and T. breviflorum were 138,260 bp and 167,693 bp, respectively. A total of 110 and 127 genes included 72 and 82 CDS, 34 and 37 tRNA, as well as four and eight rRNA genes. The reconstruction of the phylogenetic trees using maximum likelihood (ML) and Bayesian inference (BI) trees based on the concatenated CDS and internal transcribed spacer (ITS) sequences that were analyzed separately have revealed the same topology structure at genus level; Cratoxylum is monophyletic. However, C. formosum subsp. pruniflorum was not clustered together with its origin, raising doubt that it should be treated as a distinct species, C. pruniflorum based on molecular evidence that was supported by morphological descriptions.
Castor oil extracted from seeds of Ricinus Communis plant has an immense potential being used to yield valuable hydrocarbons with shorter chain length. Castor oil contains chemical structures of heavy hydrocarbons and long chains may undergo a cracking process which are similar to that as in petrochemical industries. However, cracking process requires extremely high temperature and energy input. This research came by with an attempt to reduce waste of energy using both microwave assisted method and modified metal catalyst, Zn/ZSM-5 to provide sufficient energy for cracking process to occur at comparatively low temperature. Wet impregnation method was used for Zn/ZSM-5 catalyst preparation and the experiments were carried out via microwave-assisted method. The microwave effect on the temperature and mass of condensate formed was investigated at three different output powers; 650, 700 and 750 W, under different Zn/ZSM-5 concentrations; 5, 8 and 10 wt% for 1 h. Results showed that cracking of castor oil is feasible at low temperature (<250 °C) using modified Zn/ZSM-5 via microwave assisted method. The highest yield of total mass of condensate (5.61%) was obtained from 750 W output power and 10 wt% Zn/ZSM-5 catalyst concentration. In addition, the highest cracking percentage (97.7%) was obtained from 750 W output power and 5 wt% Zn/ZSM-5 catalyst concentration. Valuable cracked compounds such as octane for fuel products and undecylenic acid for pharmaceutical uses were obtained.
Land conversion from natural forests to plantations (e.g., oil palm) in Southeast Asia is one of the most intensive land-use changes occurring worldwide. To clarify the effects of oil palm plantations on water quality, we conducted multipoint river and stream water sampling in peninsular Malaysia at the end of the rainy season over a 3-year period (2013–2015). We measured the major dissolved ions and stable isotope ratios of water (δ²H-H2O and δ¹⁸O-H2O) and nitrate (δ¹⁵N- NO3⁻ and δ¹⁸O-NO3⁻) in water from the upper streams in mountainous forests to the midstream areas of two major rivers in peninsular Malaysia. The electrical conductivity increased, and the d-excess value (as an index of the degree of evaporation) decreased with increasing distance from the headwaters, suggesting the effect of evaporative enrichment and the addition of pollutants. We separated the sampling points into four groups (G1–G4) through cluster analysis of the water quality data. From the land use/land cover (LULC) classification maps developed from satellite images and local information, we found that G1 and G2 mainly consisted of sampling points in forested areas, while G3 and G4 were located in oil-palm-affected areas. The concentrations of major ions were higher in the oil palm areas, indicating the effects of fertilizer and limestone (i.e., pH adjustment) applications. The dissolved inorganic nitrogen concentration did not differ among the groups, but the dissolved organic carbon, total dissolved nitrogen, and δ¹⁵N-NO3⁻ concentrations were higher in the oil palm area than in the forested area. Although the nitrogen concentration was low, even in the oil palm area, the significantly higher δ¹⁵N-NO3⁻ in the oil palm area indicated substantial denitrification. This implies that denitrification contributed to the lowering of the NO3⁻ concentration in rivers in the oil palm area, in addition to nutrient uptake by oil palm trees.
Nanocellulose is a versatile cellulosic nanomaterial that can be used in many application areas. Applying different preparation strategies leads to different types of nanocellulose. In this study, nanocrystalline cellulose (NCC) and nanofibrillated cellulose (NFC) were prepared from lesser known wood species, viz., Macaranga gigantea, using sulfuric acid hydrolysis and enzymatic pretreatment with ultrafine grinding approaches, respectively. The respective nanocellulose was characterized by means of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), atomic force microscopy (AFM). It was then converted into a thin film to assess its performance which includes tensile test, transparency, air permeance, water vapor transmission rate (WVTR), and water vapor permeability (WVP) properties. NCC and NFC produced from the raw material of Macaranga had average widths of 6.38 ± 3.92 nm and 13.17 ± 12.71 nm, respectively. Peaks in FTIR spectra showed the conversion of Macaranga wood to nanocellulose by the presence of cellulose fingerprint as well as absence of lignin and hemicellulose after alkaline treatment. The successful conversion was also supported by XRD analysis which displayed the increased crystallinity value from 54% to 70%. TGA decomposition pattern at 200–490 °C revealed the thermal stability of the samples. The thin film produced from nanocelluloses had WVTR values of 4.58 and 12.14 g/(day·m2) for NFC and NCC, respectively, comparable to those of films from polyester and oriented polypropylene. Nanocellulose-based thin film has the potential to be used as sustainable and biodegradable packaging.
Agarwood is a valuable aromatic resinous wood that is biosynthesised when a fungal attack injures the healthy wood tissue of the Aquilaria tree. The magnitude of infection related to sap flow (SF) is one of the most critical functional traits to evaluate the tree’s response to various adverse conditions. Therefore, the objective of this study was to investigate the reliability of sonic tomography (SoT) and sap flow meter (SFM) in studying the influence of inoculation fungi Pichia kudriavzevii Boidin, Pignal and Besson, and Paecilomyces niveus Stolk and Samson, on deteriorated wood (Dt) and SF rate in Aquilaria malaccensis Lam. A. malaccensis trees with small, medium, and large diameters were inoculated with each fungus separately at the bottom, middle, and top positions of the tree and the area of sapwood was measured after 6, 12, and 24 months to stimulate the agarwood formation. Furthermore, the SF rate was assessed using SFM in the position of the selected trees. There was a significant difference (p ≤ 0.05) in Dt% and SF rate between inoculated and uninoculated trees. The Dt percentage in trees inoculated with P. kudriavzevii, P. niveus, and control trees was 25.6%, 25.7%, and 15.0%, respectively. The SF rate was lower in P. kudriavzevii, with 207.7 cm3/h, than in the control trees, with 312.9 cm3/h in the small-diameter class. In summary, the results of this study emphasise the importance of inoculation duration (24 months) and the effects of water conductivity, especially tree diameter class (small), on the biosynthetic response of resinous substance.
This study aimed to assess antibacterial activity of Knema retusa wood extract (KRe) against antibiotic resistant staphylococci which are causative agents of bovine mastitis. From 75 cases of intramammary infections in dairy cows, 66 staphylococcal isolates were collected, including 11 Staphylococcus aureus isolates (17%) and 55 coagulase-negative staphylococci (83%). Sixty isolates (91%) formed strong biofilms. KRe had minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) against the isolates ranging 32–256 ug/mL and 64–512 ug/mL, respectively. Two-hour KRe exposures at 4×MIC, viabilities of S. aureus and S. haemolyticus decreased by 3 log10 compared to the control. Scanning EM (SEM) showed that KRe disrupted the bacterial cells of both species. KRe at 1/16×MIC significantly inhibited biofilm formation (P < 0.05) in both S. aureus and S. haemolyticus. At 1/2×MIC, S. aureus and S. haemolyticus biofilm inhibition ranged from 75 to 99%. Cells within established biofilms were disrupted 66–83% by KRe at 32×MIC. Moreover, 1/2×MIC KRe reduced bacterial adhesion to glass surfaces observed by SEM. According to GC-MS analysis, the major compound in KRe was endo-2-hydroxy-9,9-(ethylenedioxy)-1-carbethoxy bicyclo [3.3.1] nonane (E2N). Molecular docking analysis of E2N has a high affinity for staphylococcal accessory regulator A (SarA), binding free-energy − 6.40kcal/mol. The results suggested that KRe may have medicinal benefits by inhibiting the growth, biofilm, and adhesion of antibiotic resistant staphylococci isolated from bovine mastitis.
We investigated and compared the tree species composition and diversity of different forest types in Setiu Wetlands and on the three major islands of Terengganu. A total of 24 plots of 25 m × 25 m with four plots in each study site were established, viz. Melaleuca swamp forest in Kampung Fikri, freshwater swamp forest in Kampung Gong Batu, mangrove forest in UMT Setiu research station, and the islands, namely Pulau Bidong, Pulau Redang, and Pulau Perhentian. We calculated the basal area, stand density, Importance Value Index, species diversity, and above-ground biomass in the designated study areas. We assessed 139 tree species from 96 genera and 50 families based on a total of 2608 tree samples of 5 cm DBH and above. The freshwater swamp forest harbored the highest number of species with 20 species in Setiu Wetlands, and among the islands, Pulau Redang had the highest with 56 species. Melaleuca cajuputi was the most dominant species in the Melaleuca swamp forest, while Alstonia spatulata and Rhizophora apiculata are expected in the freshwater swamp and mangrove forest, respectively. Pulau Bidong, Pulau Redang, and Pulau Perhentian are mostly represented by Licania splendens, Shorea glauca, and Vatica sp., respectively. All the dominant species but Licania splendens contributed to the highest amount of above-ground bio-mass. Our current study indicated that different forest types vary in composition and structure, which may contribute to their unique ecological roles within their specific environment.
As one of the world's top megadiverse countries for tree species, Malaysia remains committed towards reducing tree population loss and species extinction. In order to ensure efficacy in the planning and implementation of conservation programmes, prioritisation of resources, and mainstreaming across the key drivers of biodiversity loss, it is essential to identify, document, and assess the extinction risk of families with high levels of endemism. In addition to being an integral component of ecosystems and their functions, from a socio‐ecological perspective, the rich biodiversity of Malaysia constitutes extraordinary natural capital that many people depend on for their livelihoods and well‐being. Malaysia is a megadiverse country for plant species. Knowledge of the diversity of Malaysian plant species is incomplete but has been significantly expanded by the Tree Flora of Sabah and Sarawak and Flora of Peninsular Malaysia projects. More than 400 new plant species, including at least 14 new genera, have been added since 1995. Between 1973 and 2015, Malaysia lost an estimated 29.4% natural forest cover; conserving plant species at immediate risk of extinction will help alleviate future loss of natural forests and biodiversity. With 9.2% of the world's tree species dwelling in Malaysia, of which 29.8% are endemic, species risk assessment is an important conservation planning tool for the Malaysian flora. Through the Global Tree Assessment project, Malaysia verified that approximately 24% of the tree diversity is exposed to a multitude of threats ranging from deforestation and forest degradation to poaching and incursion of invasive alien species. Here, we summarise the extent and types of extinction risk faced by several of our keystone tree families, namely, Dipterocarpaceae, and tree genera of Myristicaceae and Sapotaceae, whose timbers remain highly valued. We summarise the nature and aims of programmes that spur the country's conservation agenda for threatened plant species and describe some specific targets for Peninsular Malaysia, Sabah, and Sarawak. We focus on efforts that enhance in situ conservation and the understanding of population dynamics. Programmes that enable and support the main agenda, such as institutional capacity building and awareness of the importance of biodiversity, are also briefly explained. As one of the world's top megadiverse countries for tree species, Malaysia remains committed towards reducing tree population loss and species extinction. In order to ensure efficacy in the planning and implementation of conservation programmes, prioritisation of resources, and mainstreaming across the key drivers of biodiversity loss, it is essential to identify, document, and assess the extinction risk of families with high levels of endemism. In addition to being an integral component of ecosystems and their functions, from a socio‐ecological perspective, the rich biodiversity of Malaysia constitutes extraordinary natural capital that many people depend on for their livelihoods and well‐being.
The leaves of P. cauliflora were collected from Gambang, Pahang, in September 2018. The dried and powdered leaves (300 g) were ground and extracted exhaustively for 12 h by Soxhlet extraction with hexane and followed by dichloromethane (DCM). Extraction of alkaloids from crude DCM was carried out in the usual manner, which has been described in detail and gave crude alkaloid and non-alkaloid. As a result, three alkaloids, (+)-liriodenine (1) , (+)-predicentrine (2) , (+)-laurotetanine (3) ; four flavonoids, 5,7-dimethoxyflavone (4) , tectochrysin (5) , pinocembrin (6) , pinostrobin (7) ; together with β-sitosterol (8) , taraxerol (9) , and stigmasterol (10) , were successfully isolated.
Uropathogenic Escherichia coli has a propensity to build biofilms to resist host defense and antimicrobials. Recurrent urinary tract infection (UTI) caused by multidrug-resistant, biofilm-forming E. coli is a significant public health problem. Consequently, searching for alternative medications has become essential. This study was undertaken to investigate the antibacterial, synergistic, and antibiofilm activities of catechin isolated from Canarium patentinervium Miq. against three E. coli ATCC reference strains (ATCC 25922, ATCC 8739, and ATCC 43895) and fifteen clinical isolates collected from UTI patients in Baghdad, Iraq. In addition, the expression of the biofilm-related gene, acrA, was evaluated with and without catechin treatment. Molecular docking was performed to evaluate the binding mode between catechin and the target protein using Autodock Vina 1.2.0 software. Catechin demonstrated significant bactericidal activity with a minimum inhibitory concentration (MIC) range of 1–2 mg/mL and a minimum bactericidal concentration (MBC) range of 2–4 mg/mL and strong synergy when combined with tetracycline at the MBC value. In addition, catechin substantially reduced E. coli biofilm by downregulating the acrA gene with a reduction percent ≥ 60%. In silico analysis revealed that catechin bound with high affinity (∆G = −8.2 kcal/mol) to AcrB protein (PDB-ID: 5ENT), one of the key AcrAB-TolC efflux pump proteins suggesting that catechin might inhibit the acrA gene indirectly by docking at the active site of AcrB protein.
Asexual propagation techniques for producing good quality germplasm for breeding and dissemination purposes have proven difficult for acacia species comprised of mature planting material. The study was conducted to study the effect of rejuvenation on the rooting ability of mature cuttings. Shoots were induced from the lower branch by cutting a part of the mature branch of the crown and leaving it horizontally on the propagation bench under the misting system. Shoots were harvested and further used as stem cuttings to evaluate their rooting ability through the application of rooting hormone. The rooting ability of the cuttings is highly variable among species. The percentage of stem sections producing juvenile shoots was similar for Acacia mangium Willd. (88%) and Acacia auriculiformis A.Cunn. ex Benth. (90%). Only 52% of stem sections were able to produce shoots for Acacia crassicarpa A.Cunn. ex Benth., followed by Acacia aulococarpa A.Cunn. ex Benth. with only 31%. Overall, A. auriculiformis rooted better and recorded the highest mean value for all traits tested. Hormone treatment significantly enhances the rooting ability of A. auriculiformis and A. mangium. However, A. aulococarpa and A. crassicarpa did not respond well to the treatment. Rejuvenated stem cuttings were rooted better than mature cuttings, producing the highest mean value for all traits tested in all species, with or without hormone treatment. Results indicated that it is possible to rejuvenate mature cuttings through bud break in a controlled environment.
Aims The relationship between functional traits and growth conditions across tree species provides critical information for understanding resource acquisition strategy of each species. This study aims to elucidate the relationship between root tip morphology and growth conditions with considering the phylogenetic difference in a primary lowland dipterocarp forest. Methods We surveyed growth conditions for 13 target species of Macaranga and Shorea, i.e., light condition, soil physical properties, and soil nitrogen (N) dynamics, and root tip morphology, including specific root tip length (SRLt), root tip diameter (RDt), and root tip tissue density (RTDt) and analyzed their relationships considering the difference between genera. Results The differences in SRLt and RDt between two genera, Macaranga and Shorea, were validated by the difference in environmental factors, i.e., light intensity and soil ammonification rate. With considering the difference between genera, we detected an interspecific variation in SRLt, RDt, and RTDt across all 13 species in response to differences in environmental factors such as light intensity, soil physical properties, soil nitrification, and N mineralization rates. Among the same species, the SRLt decreased with increasing light intensity and increased with increasing nitrification rates, while the RDt exhibited an opposite trend. Conclusion We confirmed that the root tip morphology varies according to growth conditions in tropical tree species: shade-tolerant tree species and/or tree species grown in fertile condition had root tips with high efficiency of soil exploration or exploitation per a unit of root biomass. This variation pattern was different than that of temperate tree species.
Carpaine in papaya leaves has the potential to treat dengue fever and it also contains antioxidants which could prevent or inhibit oxidation processes in the human body. Studies were conducted on the effects of storage on carpaine retention and antioxidant properties of dried papaya leaves. Results showed that the Weibull model could predict well the degradation kinetics of carpaine in all samples (freeze drying and hot air drying at 60 °C and 70 °C) except for hot air dried samples at 80 °C and shade dried samples (first order model). Generally, freeze dried samples showed the highest half-life whereas total polyphenols content and antioxidant properties (ABTS and DPPH free radical scavenging activities) of all dried samples decreased with storage period. An increasing trend in total colour difference (Δ E * ) was observed in all samples possibly due to chlorophyll degradation. It is thus recommended to select freeze dried samples for storage purpose due to better stability as indicated by the lowest rate constant ( k = 0.0135 1/month) and the highest half-life ( t 1/2 = 51.2 months).
Trypanosoma brucei parasites are flagellated kinetoplastid protozoan which is responsible for Human African Trypanosomiasis (HAT). Current chemotherapy drugs have a number of side effects and drug resistance has emerged as a major issue in current treatment. Active bisindole alkaloid compound ochrolifuanine was previously isolated from the leaves of Dyera costulata. In vitro antitrypanosomal activity of ochrolifuanine against Trypanosoma brucei brucei strain BS221 showed strong activity with an IC50 value of 0.05 ± 0.01 µg/ml. We compared the effect of ochrolifuanine and reference compound staurosporine in T. b. brucei apoptosis. The apoptosis-inducing activity of ochrolifuanine was evaluated using TUNEL assay and cell cycle analysis. Trypanosoma brucei brucei was shown to undergo apoptotic cells death as demonstrated by the appearance of several conical hallmarks of apoptosis. Ochrolifuanine was found to induce apoptosis in parasites in a dose- and time-dependent manner. The cell cycle study revealed 0.025 and 0.05 µg/ml of ochrolifuanine arrested the growth of T. b. brucei at two different growth phases (G0/G1 and in S phases). While at concentration 0.10 µg/ml arrested at the G2/M phase. In conclusion, the results indicate that ochrolifuanine displayed an antitrypanosomal effect on T. b. brucei by inducing apoptosis cell death and causing the arrest of parasite cells at different growth phases. The results suggested that ochrolifuanine may be a promising lead compound for the development of new chemotherapies for African trypanosomiasis.
Ardisia whitmorei Julius & Utteridge, sp. nov. (Primulaceae-Myrsinoideae), a member of Ardisia subgenus Stylardisia on account of the style protruding from the closed petals prior to anthesis, is herein described and illustrated as a new species. This new species is easily distinguished by the combination of the inflorescences with a slender rachis branched to two orders, the corolla lobes are abaxially glabrous with usually up to only two gland-dots near the apex and the brochidrodromous secondary veins with double loops near the margin.
Exposure of unprotected wood to weathering can increase the wettability of the wood and the exposure period should be carefully monitored to preserve surface quality from severe deterioration. This study investigated the wettability of keruing ( Dipterocarpus spp.) wood after weathering exposure for 1–4 weeks. The keruing samples were first planed and coated at the edges prior to expose under tropical climate. Contact angle, crack formation and lignin content of the samples were recorded on weekly basis. The results showed that the wettability of weathered keruing wood increased tremendously (i.e., 32%) after 4 weeks of exposure compared to control samples. The increase in wettability can be associated with the increase in crackformation and reduction of lignin content after exposure. It is hereby recommended that keruing wood is not suitable to be exposed to weather for more than 3 weeks before finishing or coating is applied on its surface.
In this work, a chitosan (CHI) biopolymer was developed by loading different wt% of carbon-doped TiO2 (C–TiO2) with CHI to attain an efficient adsorbent of chitosan/carbon-doped TiO2 (CHI/C–TiO2). The fabricated materials were deployed for the removal of organic pollutants (methyl orange, MO; and reactive orange 16, RO16) and sulfur dioxide capture. The synthesized composites were characterized by BET, FTIR, XRD, TEM, SEM–EDX, pHpzc, and pH-potentiometric titrations. Statistical modeling represented by the Box–Behnken design (BBD) was utilized for optimization of the impacts of the various parameters; A: C–TiO2 particles loading (0–50%), B: dose (0.04–0.15 g), C: pH (4–10), and D: temperature (30–50 °C) on the adsorption of MO and RO16 dyes. The adsorption isotherms were obtained at equilibrium and under dynamic conditions, where the best fit to the isotherm results was shown by the Langmuir model and pseudo-first-order kinetic model, respectively. The maximum adsorption capacities of CHI/C–TiO2-50 (containing 50% of C–TiO2) was estimated at 196.6 mg/g and 270.5 mg/g for MO and RO16 dyes, respectively. This work revealed that the designed biomaterial (CHI/C–TiO2-50) could be realized as an effective adsorbent for environmental remediation that includes decontamination of wastewater and SO2 gas capture.
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