Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium(Cd) from spiked high-hardness groundwater(GW). Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by1 H NMR spectroscopy. Pullulan succinate(Pull-Suc) was converted into the sodium salt(Pull-Suc-Na). The effect of contact time(5–200 min) and p H(2–8) on Cd-uptake by the sorbent(Pull-Suc-Na) was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water(DW) and GW solution,respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents suggested its high efficiency(DW 476.2 mg/g and GW 454.5 mg/g) and selectivity for the removal of Cd by an ion exchange mechanism, which is further supported by the negative Gibbs free energy values calculated from Langmuir isotherms. A Langmuir isotherm kinetic model provided the best fit for the sorption of Cd using Pull-Suc-Na. The sorbent showed a negligible decrease in Cd-uptake over three regeneration cycles. The thermal stability testing of the sorbents indicated that Pull-Suc-Na(sorbent) is more stable than Pull-Suc.
A pot culture experiment was carried out to investigate the accumulation properties of mercury(Hg) in rice grain and cabbage grown in seven soil types(Udic Ferrisols, Mollisol, Periudic Argosols, Latosol, Ustic Cambosols, Calcaric Regosols, and Stagnic Anthrosols) spiked with different concentrations of Hg(CK, 0.25, 0.50, 1.00, 2.00, and 4.00 mg/kg). The results of this study showed that Hg accumulation of plants was significantly affected by soil types. Hg concentration in both rice grain and cabbage increased with soil Hg concentrations, but this increase differed among the seven soils. The stepwise multiple regression analysis showed that pH, Mn(II), particle size distribution, and cation exchange capacity have a close relationship with Hg accumulation in plants, which suggested that physicochemical characteristics of soils can affect the Hg accumulation in rice grain and cabbage. Critical Hg concentrations in seven soils were identified for rice grain and cabbage based on the maximum safe level for daily intake of Hg, dietary habits of the population, and Hg accumulation in plants grown in different soil types. Soil Hg limits for rice grain in Udic Ferrisols, Mollisol, Periudic Argosols, Latosol, Ustic Cambosols, Calcaric Regosols, and Stagnic Anthrosols were 1.10, 2.00, 2.60, 2.78, 1.53, 0.63, and 2.17 mg/kg, respectively, and critical soil Hg levels for cabbage are 0.27, 1.35, 1.80, 1.70, 0.69, 1.68, and 2.60 mg/kg, respectively.
The mesoporous carbon coated monoliths (MCCM) were developed by dipcoating method using furfuryl alcohol (FA) as a carbon precursor and poly(ethylene glycol) (PEG) as a poreformer. The effect of molecular weight of PEG, carbonization temperature and PEG composition on the synthesis of MCCM were studied. The maximum specific surface area and mesopore area obtained were 61.13 m2/g and 49.39 m2/g. The pore size distribution of the carbon coated monolith exhibited two main peaks. One peak was located at 2.0 nm and the other at 3.6 nm. The pore size distribution curve indicated that the porous carbon was bimodally distributed. The MCCM was utilized as an adsorbent for adsorption of β-carotene from isopropyl alcohol (IPA) and n-hexane miscellas. The effect of temperature on the adsorption was investigated by batch adsorption experiments. The adsorption quantity increased with increasing temperature. The maximum adsorption capacity of β-carotene obtained was 62.118 mg/g for IPA at 50 °C. The experimental results were fitted using the Langmuir and Freundlich isotherms. The Langmuir described the adsorption process better. The negative values of Gibbs free energy change suggested that the adsorption was a spontaneous process. The positive values of heat of enthalpy and entropy change confirmed the endothermic nature of the adsorption. The adsorption kinetics of β-carotene onto mesoporous carbon coated monolith in isopropyl alcohol (IPA) and n-hexane solution was investigated, as functions of temperature and β-carotene initial concentration. Adsorption capacity increased as initial β-carotene concentration and temperature increased. In addition, the solvents also play an important role in the adsorption of β-carotene; adsorption kinetic of β-carotene by using IPA is higher than n-hexane. Two kinetic models, namely the pseudo-first-order and pseudo-second-order, were used to predict the adsorption kinetics. The rate parameters of the intraparticle diffusion model for adsorption were also evaluated to identify the adsorption mechanisms. The results clearly showed that the adsorption of carotene onto MCCM followed the pseudo-first-order model for IPA, and pseudo-second-order model for n-hexane solvent. The energy activation parameters were 11.45 and 9.41 kJ/mol for IPA and n-hexane, respectively. Sorption kinetics of β-carotene in IPA solution was analyzed at different temperatures and initial concentrations by using the linear driving force (LDF) model. The software MATLAB® was used to solve the LDF model simultaneously with the adsorption equilibrium isotherm at liquid/solid interface. The linear driving force mass transfer coefficient (kLDF) obtained was increased with increasing temperature. However, the LDF model did not describe experimental results satisfactorily at high initial concentrations. The equilibrium and kinetics of desorption process of β-carotene from MCCM were investigated in a batch system. The MCCM was first saturated with β-carotene from IPA solution. The β-carotene was then desorbed by using n-hexane solution. The data of desorption were evaluated by two models i.e. linear isotherm and Freundlich isotherm. The desorption was satisfactorily fitted with the Freundlich model. The desorption kinetic was analyzed using a first-order two-compartment three-parameter model. The activation energy obtained was 7.88 and 44.47 kJ/mol for rapid and slow desorption, respectively.
ABSTRACT A carbon-based honeycomb monolith was prepared using dip-coating method. The carbon-based monolith was then used to remove a cationic dye (methylene blue [MB]) from aqueous solution. Surface chemistry studies demonstrated that acidic functionality (0.567 mmol g−1) dominated as compared to basic functionality (0.019 mmol g−1). N2 adsorption/desorption revealed a mesoporous structure. The Brunauer-Emmett-Teller surface area was approximately 352 m2 g−1 and the mesoporous volume devoted about 67% the total pore volume. The effects of different parameters (such as initial pH, initial dye concentration, temperature, and contact time) on MB removal were investigated in batch mode. The maximum adsorption capacity is around 121.3 mg g−1 at optimum pH = 10. An increase in adsorption capacity was observed via increasing MB concentration, with equilibration time ranged between 3,200 and 4,000 min. Both the Langmuir and the Redlich-Peterson models were found to describe well the equilibrium data. Kinetic studies showed better fitting for the pseudo-second-order model. The intraparticle diffusion model showed multilinearity, indicating two or more steps were involved to describe the adsorption process. Regeneration studies showed that the adsorption capacity of the adsorbent was reduced by about 20% after six cycles.
CV. X yang merupakan suatu perusahaan pembuatan aneka macam mebel seperti pintu, jendela, kusen, meja, dan kursi. CV. X ini bertempat di Jl. Medan-Banda Aceh, Blang Panyang, Lhokseumawe.Penelitian ini dilakukan pada setiap stasiun kerja pembuatan pintu karena dari permasalahan tersebut berdampak pada efesiensi dan efektifitas pekerjaan.Pada stasiun kerja ini masih terdapatnya gerakan-gerakan yang tidak diperlukan yang dilakukan oleh operator pada saat melakukan pekerjaannya.Sehingga ada waktu yang terbuang untuk hal yang tidak diperlukan yang menyebabkan adanya pemborosan waktu yang menyebabkan tidak efektifnya suatu pekerjaan.Penelitian ini bertujuan untuk perbaikan gerakan-gerakan yang kurang efektif dalam melakukan suatu pekerjaan. Dilakukan pengamatan selama proses perakitan berlangsung, Pada kondisi kerja awal, waktu standar awal mencapai 10.908,45 detik atau 181,8 menit, sedangkan pada kondisi kerja usulan mencapai 9.610 detik atau 160,2 menit, Sehingga dengan mengurangi gerakan yang kurang efektif dapat menghemat waktu selama 1.296 detik atau 21,6 menit dalam satu pintu.
Wilsonomyces carpophilus is the major fungus that produces shot hole disease (SHD) in apricots, which results in significant economic losses. This problem can be addressed through the monitoring of the diseases and spotlighting the risks connected with them. This study employed descriptive and geostatistical mapping techniques to track the spatial distribution and risk of SHD in apricot orchards in five apricot-growing valleys. The results showed a spatial distribution of the disease within the study area even varying within the valleys and orchards. A moderate spatial dependence of SHD prevalence (0.524), incidence (0.363), and severity index (0.313) were observed. GIS maps and trend analysis graphs also showed the spatial distribution of the disease from east-west and south-north directions. Climate and cultural practices favor the perpetuation of pathogens and the spread of SHD. This information will help apricot growers regarding disease management and improve sustainable profitability.
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