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This paper aims to investigate the potential use of cempedak durian peel (CDP) from Negara Brunei Darussalam, which is low-cost, locally available, eco-friendly and highly efficient to remove methyl violet (MV) dye from aqueous solutions. The time required for equilibrium to be reached is 2.0 h with no adjustment of pH necessary. FTIR analysis was indicative of the involvement of -COOH and C=O functional groups in adsorption process. The Langmuir model provided the best fit with maximum adsorption capacity of 0.606 mmol g -1 . Thermodynamics data indicate that the adsorption is spontaneous, feasible and endothermic in nature. Best regeneration of CDP's adsorption ability is achieved by base solution, showing about 95% removal efficiency of MV even after 5 cycles, indicating that CDP can be regenerated and reused. This, together with its high adsorption capacity, makes CDP a potential adsorbent for the removal of MV in wastewater.

Pistia stratiotes L. (water lettuce or WL) was investigated for its potential as an effective low-cost biosorbent for the removal of methyl violet 2B (MV). Equilibrium isotherm for the adsorption of MV, fitted using six different isotherm models followed by error analyses, indicates that the maximum biosorption capacity (qmax) is 0.68 mmol g−1 (267.6 mg g−1) and that both the Langmuir and Sips isotherm models lead to good correlation with experimental data. Investigation on effects of pH, ionic strengths, and pre-treatment of the biosorbent on the extent of biosorption indicates the effect of these parameters on MV–biosorbent interaction. Kinetics of the interaction of MV and the biosorbent is fast with more than 50% dye being removed and follows the pseudo-second-order model.

This study investigates the adsorption characteristics of methylene blue (MB) on core of breadnut, Artocarpus camansi Blanco. Oven-dried Artocarpus camansi core (ACC), with point of zero charge at pH 4.1, was found to be very effective in removing MB when compared to most literature reported fruit biomasses. Six isotherm models coupled with error analyses were used to investigate possible models of adsorption. Both the Langmuir and Sips models were found to give the best fit with maximum adsorption capacity, measured as mg of MB per g of adsorbent, of 369 and 328 mg g−1, respectively. Thermodynamics studies showed that the adsorption process was both spontaneous and exothermic. Fast kinetics, with 50% MB being removed within 5 min when 50 mg L−1 dye solution was used, showed pseudo-second-order. Fourier transform infrared, X-ray fluorescence, and scanning electron microscopic investigation of ACC before and after MB adsorption conclusively demonstrated that oven-dried breadnut core has great poten...

Peat, a natural adsorbent, has been successfully used for the removal of the hazardous water-soluble cationic dye, brilliant green (BG). Characterization of peat was carried out by determining its physical and chemical compositions such as moisture, ash, carbon%, hydrogen%, nitrogen%, and sulphur% (CHNS), crude protein and crude fat. X-ray fluorescence (XRF) was used for the determination of the percentage of elements present in peat. Functional groups present in peat were analyzed using Fourier transform infra-red (FTIR). Changes in the surface morphology of peat before and after treatment with BG were studied using Scanning Electron Microscopy (SEM). The optimization time required for establishment of an adsorption equilibrium is determined to be 2.0 h. The ambient pH of BG was used throughout the study. Adsorption isotherm models such as Langmuir, Freundlich, Halsey, Temkin, Redlich–Peterson (R–P) and Sips were simulated to fit with the experimental equilibrium data. Based on linear regression, simulated isotherm models and error analyses, the R–P isotherm fitted well for the adsorption of BG by peat. Adsorption kinetics was found to follow the pseudo second order model, with a rate constant of 0.39 g mmol−1 min−1. BG-loaded peat was successfully regenerated using 0.01 M sodium hydroxide (NaOH) solution for up to 5 consecutive cycles, while maintaining high adsorption ability of 98% even after the 5th cycle.

Breadnut skin, in both its unmodified (KS) and base-modified (BM-KS) forms, was investigated for its potential use as a low-cost adsorbent for the removal of toxic dye, malachite green (MG). Characterization of the adsorbents was carried out using scanning electron microscope, X-ray fluorescence and Fourier transform infra-red spectroscopy. Batch adsorption experiments, carried out under optimized conditions, for the adsorption of MG were fitted using five isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin and Sips) and six error functions to determine the best-fit model. The adsorption capacity was greatly enhanced when breadnut skin was chemically modified with NaOH, leading to an adsorption capacity of 353.0 mg g(-1), that was far superior to most reported adsorbents for the removal of MG. Thermodynamics studies indicated that the adsorption of MG was spontaneous on KS and BM-KS, and the reactions were endothermic and exothermic, respectively. Kinetics studies showed that both followed the pseudo-second order. Regeneration experiments on BM-KS indicated that its adsorption capacity was still maintained at90% even after five cycles. It can be concluded that NaOH-modified breadfruit skin has great potential to be utilized in real-life application as a low-cost adsorbent for the removal of MG in wastewater treatment.

Solid and dissolved organic matter (DOM) compositions were investigated in a pristine and a deforested tropical peat forest in Brunei Darussalam. A combination of elemental (%C, %N, C/N), isotopic (δ 15 N, δ 13 C, Δ 14 C), molecular (lignin phenol biomarkers) and optical (Specific UV Absorbance at 280 nm (SUVA 280 ), fluorescence index (FI)) analyses were performed to characterize DOM in porewater and river water. The DOM composition was compared to vegetation and peat to assess DOM origin and transformations in the ecosystem. Significant relationships were observed between optical properties (SUVA 280 , FI) and bulk (Δ 14 C) and molecular (ratio of cinnamyl to vanillyl phenols, C/V) composition of DOM. The radiocarbon content of DOM shows that it is modern at both sites for both surface and deep (to 4.5 m) samples (Δ 14 C = 74.58 ± 8.53‰ at the pristine site and Δ 14 C = 87.84 ± 4.5‰ at the deforested site for the first 2 meters), indicating transport of young DOM to deeper layers. Stable carbon-13 content of vegetation, peat and DOM showed only slight fractionation and ranged from −32.2‰ to −28.3‰. Nitrogen showed a greater shift between ecosystem pools. Nitrogen-15 content was higher in the solid peat (δ 15 N = −0.92 ± 0.49‰ in the pristine site, δ 15 N = −1.22 ± 1.37‰ in the deforested site) than in DOM (δ 15 N = −4.2 ± 2.5‰ in the pristine site, δ 15 N = −4.1 ± 2.3‰ in the deforested site). This difference in δ 15 N is significantly correlated with the C/N values of peat and DOM and attributable to higher microbial degradation in the peat compared to DOM. Porewater DOM contains less lignin (λ8 = 1.10 ± 0.27 mg 100 mg dw −1 in the pristine site and λ8 = 1.38 ± 0.46 mg 100 mg dw −1 in the deforested site) than does the solid peat (λ8 = 5.66 ± 2.14 mg 100 mg dw −1 in the pristine site and λ8 = 10.29 ± 4.69 mg 100 mg dw −1 in the deforested site). All indicators of lignin degradation (P/(V + S), 3,5Bd/V, (Ad/Al)V, (Ad/Al)S) are significantly higher in DOM than in the solid peat. This shows that lignin can be processed rapidly in the porewater of upper layers of tropical peatlands. Logging activity affected the composition of organic matter at the deforested site. Higher lignin content (λ8) was observed in the solid peat, and the composition of DOM differed greatly in the deforested site: Δ 14 C, FI, 3,5Bd/V, (Ad/Al)V are significantly different from the pristine site. Thus it appears that the composition of DOM is more sensitive than the solid phase to the effects of land use change on organic matter dynamic in tropical peatlands.

This study focuses on the adsorption behavior of using Lemna minor (Duckweed) as a potential low-cost biosorbent for the removal of methyl violet 2B (MV). The effects of parameters such as contact time (30–240 min), settling time (30–240 min), pH of dye solution from pH 2 to 12 were studied. Optimum contact time and settling time for the maximum removal of MV were 2 and 1 h, respectively. Maximum MV removal was observed at its ambient pH. Elemental analysis and functional group characterization of the biosorbent were carried out using X-ray fluorescence and Fourier-transformed infrared spectroscopy, respectively. Surface morphology of Duckweed, before and after adsorption of MV, was characterized using scanning electron microscope, and ionic strengths and pre-treatment of biosorbent were also investigated. Six different isotherm models, namely Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Redlich–Peterson and Sips isotherms, were performed on the equilibrium adsorption isotherm of MV. Experimental data for adsorption of MV correlate well with both the Langmuir and Sips isotherm models. The maximum biosorption capacity (q max) at 298 K was 332.5 mg g−1 (Langmuir) and 307.3 mg g−1 (Sips) for MV, which is far superior to most biosorbents reported. Kinetics study followed the pseudo-second order.

This work reports the application of peat as cheap and effective adsorbent for the removal of rhodamine B dye (RhB) from aqueous solution. The effects of contact time, settling time and pH were studied to obtain the optimum conditions for adsorption studies. Optimum contact time was 4 h with 1 h settling time and ambient pH was used throughout the study. Adsorption isotherms, namely Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Redlich–Peterson and Sips, were employed in this study together with error functions to predict the most suitable isotherm model for the adsorption process. The Sips isotherm was found to be the best fit model. The maximum adsorption capacities (qmax) obtained for the adsorption at 298, 313, 324, 334 and 344 K are 162.87, 166.22, 172.45, 186.82 and 201.19 mg g−1, respectively. Thermodynamic parameters indicate that the adsorption was spontaneous, feasible and endothermic in nature. Pseudo second order kinetic model fitted well to the adsorption of RhB on peat. Regener...

Peat of Brunei Darussalam shows a great potential for the removal of methylene blue (MB) and malachite green (MG) dyes from aqueous solution. Carefully controlled batch experiments performed by changing one parameter at a time indicate that the optimum time periods of agitation and settling required for maximum removal of MB are 2.0 and 1.0 h, respectively, while these values for MG are 4.0 and 1.0 h, respectively. The optimum pH is determined to be the ambient value, and under the optimum conditions, 90 % removal of both dyes was determined under laboratory conditions. The equilibrium adsorption data analyzed for various isotherm models suggest that the Sips and Redlich–Peterson (R–P) models are valid for MB and MG, respectively. Further, thermodynamic studies show that the adsorption of both dyes on peat is spontaneous and endothermic. The adsorption capacities (q max) of MB and MG dyes on peat are 0.45 and 0.31 mmol g−1, respectively. Characterization of the surfaces of peat before and after treatment of dyes by SEM and FTIR provides conclusive evidence of adsorption of both dyes. Kinetics studies indicate that the adsorption of both MB and MG dyes is favored toward the pseudo-second-order model, with a little contribution of MG to the pseudo-first-order model. These results suggest that peat is a potential low-cost adsorbent for the removal of MB and MG dyes.

The flesh and seeds of ripened and unripened Artocarpus champeden and its ripened hybrid (Nanchem) were analyzed for their moisture, ash, crude fibre, crude protein, crude fat, total carbohydrate, energy and mineral content. Generally, unripened A. champeden which is always treated and cooked as a vegetable contains higher amounts of moisture, ash, crude fibre and crude protein for its flesh than ripened A. champeden and Nanchem. Ripened A. champeden and Nanchemhave higher total carbohydrates and energy content than the unripe fruit. Similarly, the unripened A. champeden seed has more nutritional components in terms of moisture, ash, crude fibre, crude protein, crude fat, total carbohydrate and energy compared to the ripened A. champeden and Nanchem seeds. Potassium and magnesium are the prevalent minerals in this fruit species. Nanchem has the characteristics of both jackfruit (A. heterophyllus) and A. champeden.

This work reports the potential use of peel of breadnut, Artocarpus camansi , as an effective low-cost biosorbent for the removal of methylene blue (MB). Oven dried A. camansi peel (ACP), which had a point of zero charge at pH = 4.8, showed maximum biosorption capacity which was far superior to most literature reported fruit biomasses, including samples that have been activated. Isotherm studies on biosorption of MB onto ACP gave a maximum biosorption capacity of 409 mg g −1 . The Langmuir model was found to give the best fit among various isotherm models investigated and error analyses performed. Kinetics studies were fast with 50% dye being removed in less than 8 min from a 50 mg L −1 dye solution and further, kinetics followed the pseudo second order. Thermodynamic studies indicated that the biosorption process was both spontaneous and exothermic. Fourier transform infrared (FT-IR) of ACP before and after MB adsorption was investigated. It can be concluded that oven dried breadnut peel is a highly promising low-cost biosorbent with great potential for the removal of MB.