Varying Contact Time Research Articles

The Catalytic Function of Phosphorus Enriched on the Surface of Vanadium‐based Catalysts in Selective Oxidations

AbstractVanadium phosphates are established as the benchmark system for the selective oxidation of n‐butane towards maleic anhydride. By varying the phosphorus content on the surface of three V‐based catalysts with diverse performance, this study experimentally elaborates on the catalytic function of phosphorus. Contact time variation and cofeed studies revealed, that surface phosphates, deposited in sub‐monolayers via atomic layer deposition, significantly contribute to an increased product selectivity. Furthermore, our results suggest that the phosphorus particularly suppresses the consecutive combustion of the (re‐)adsorbed product. The recently introduced solid solution catalyst V1‐xNbxOPO4 with medium maleic anhydride selectivity could be tuned by the surface enrichment with phosphorus towards product selectivities of up to SMAN=60 %, under optimized alkane‐rich feed conditions. Therefore, POx‐V0.3Nb0.7OPO4 is introduced as promising catalyst, which is not based on vanadyl(IV) pyrophosphate, to access significantly higher MAN formation rates at increased alkane partial pressures of cn‐butane>10 %vol in n‐butane oxidation.

The use of activated charcoal from corn cobs as adsorbent of heavy metals from groundwater

Iron (Fe) and manganese (Mn) are heavy metals which are found in high concentration in highly weathered soils, especially in the tropics, resulting in high content of them in groundwater. These metals cause a distinctive odor, reddish brown, yellowish color, and high sediment. This condition could cause health problems when it is used as a source of drinking water. This study was aimed to evaluate the efficiency of activated carbon from corn cobs in reducing the concentrations of Fe and Mn from groundwater adsorption. The adsorption process was performed by applying activated carbon with varying doses of 0.1 g, 0.2 g, 0.3 g, 0.4 g, 0.5 g, 1 g, 1.5 g and 2 g into 100 ml groundwater. Variations of pH were pH 2, pH 3, pH 4, pH 5, pH 6, pH 7 and pH 8, and variations in contact time of 10, 30, 45, 60, 90 and 120 minutes. The results showed that the optimum doses to reduce Fe and Mn concentration from groundwater were 1 g and 0.5 g with the adsorption efficiency of 70.14% and 41.60% respectively. The optimum pH for both Fe and Mn was pH 4 with an adsorption efficiency of 75.44% and 56.52% respectively, while the optimum contact times were 60 and 30 minutes with an adsorption efficiency of 75.44 dan 59.29% respectively.

Pemanfaatan Karbon Aktif Kulit Kacang Tanah untuk Menurunkan Kadar Ion logam Ca2+ dan Mg2+ dalam Air

Peanut shell has a high cellulose content as a carbon source which can be used as a basic ingredient for making activated charcoal. Research on peanut shells used as activated charcoal aims to determine the effect of contact time and pH on reducing levels of metal ions Ca2+ and Mg2+ in water. The research was conducted using contact time variables (30, 60, 90, 120, and 150 minutes) and pH (4, 5, 6, 7, and 8). Measurement of adsorbed metal levels was determined by using an Atomic Absorption Spectrophotometer (AAS). The research results obtained showed that variations in contact time could reduce Ca2+ levels by 77.46% -84.89% and Mg2+ by 86.88%-88.91%. Adsorbents with variations in pH can reduce Ca2+ levels by 63.48%-88.74% and Mg2+ by 90.35%-94.49%. The best conditions for the absorption of Ca2+ and Mg2+ ions were a contact time of 60 minutes and pH 4. The adsorbent was applied to reduce Ca2+ and Mg2+ levels in water with different hardness levels. The results of the analysis of water samples from two different locations had Ca2+ levels of 94.180 mg/L and 210.20 mg/L, while Mg2+ levels were 13.536 mg/L and 17.420 mg/L. The percentages of Ca2+ adsorption for the two samples were 96.19% and 77.08%, and the percentages of Mg2+ adsorption for the two samples were 21.16% and 10.63%. Carbon from peanut shells activated with sodium acetate has the potential to be used to reduce hardness in water.

Activated Charcoal from Coffee Dregs Waste as an Alternative Biosorbent of Cu(II) and Ag(I)

This study examines the use of coffee dregs waste as biosorbents of Cu(II) and Ag(I). Coffee dregs waste still contains a high level of carbon and cellulose for biosorbents production. The production process was started with charcoal activation using H3PO4. The batch method was applied by variations of contact time, the mass of the biosorbent, and the initial concentration of metal ions. The results showed that Cu(II) and Ag(I) were optimally adsorbed at pH 6 and 4, respectively. The amount of adsorbed metal ions increased with adsorption contact time. The adsorption process of both metal ions reaches stability within 60 min and the optimum biosorbent mass is 1 g. Isothermal adsorption studies show that Cu(II) adsorption tends to follow Langmuir isotherm with an adsorption energy of 31.42 kJ/mol and Ag(I) adsorption follows Freundlich isotherms with an adsorption energy of 27.74 kJ/mol. Based on the results, the interaction between metal ions and adsorbents is a chemical adsorption process and coffee dregs charcoal has the potential to adsorb Cu(II) and Ag(I) metal ions.

Adsorptive removal of Cr (VI) from aqueous solution using laboratory prepared ZnO nanoparticles

Nano sized zinc oxide (ZnO) been successfully prepared in laboratory by precipitation technique. As prepared ZnO materials were characterized by XRD and SEM analyses. The XRD pattern showed the crystallinity of the material and average crystallite size was found to be 16.61 nm. The SEM images of ZnO nanoparticle revealed that it was flakes like structure having smooth texture. Batch adsorption experiments were performed to investigate the percentage removal of Cr (VI) from aqueous solution. The effects of Cr (VI) concentration, pH of solution, adsorbent dose and contact time variations were studied in order to have adsorptive efficiency of as prepared ZnO nanoparticles. The optimum contact time for maximum adsorption was found to be 90 minutes. The optimum pH was found to be 2.0 at an initial concentration of 20 mg/L. Similarly, the optimum dose of ZnO for the adsorption of Cr (VI) was found to be 0.4 g. The adsorption properties of ZnO were then evaluated by using Langmuir, Freundlich and Temkin isotherm models. The maximum adsorption capacity (Qm) was found to be 3.43 mg/g which is in good agreement with literature value. The correlation value showed that Langmuir isotherm model was found to be more favorable than Freundlich and Temkin adsorption isotherm model, indicating the presence of homogeneous equivalent active sites in ZnO with monolayer adsorption.

Adsorption Properties of Fe (II) from Activated Carbon Composite of Empty Palm Oil Bunches with Metal Organic Frameworks Cu-TAC

This study aims to determine the adsorption capacity, study the kinetics and adsorption equilibrium of activated carbon/AC and composite carbon/AC-Cu(TAC) in the adsorption process of Fe metal. Oil palm empty fruit bunches (EFB) were used as activated carbon and modified with MOFs Cu(TAC) composite. The concentration of Fe(II) ions adsorbed during the adsorption process was analyzed using AAS. The variations used to determine the optimum conditions for absorption of Fe(II) ions are the mass variation of the adsorbent, the variation of the adsorbate concentration and the contact time between the adsorbent and the adsorbate. Through variations in concentration, the adsorption isotherm characteristics were determined and through variations in contact time, the adsorption kinetics model was determined. The results of AC characterization showed a sharp absorption in the presence of OH, CH and CO groups which indicated the presence of cellulose. AC is amorphous and AC-Cu(TAC) is crystalline and the pore size is mesoporous. The optimum condition for AC is the mass variation of 1 g with an absorption capacity of 0.1816 mg/g, a variation of the concentration of 60 ppm with an absorption capacity of 3.49 mg/g and a contact time of 75 minutes with an absorption capacity of 3.82 mg/g. The optimum condition for ACCu(TAC) was the mass variation of 1 g with an absorption capacity of 0.7275 mg/g, a variation of the concentration of 180 ppm with an absorption capacity of 10.52 mg/g and a contact time of 15 minutes with an absorption capacity of 10.85 mg/g. AC-Cu(TAC) has a better adsorption ability in adsorbing Fe(II) ions. For AC and AC-Cu(TAC) the suitable adsorption isotherm is Freundlich isotherm and the suitable adsorption kinetics model is pseudo second order

Contact time has limited impact on the efficacy of disinfectant towelettes when tested under conditions reflective of realistic use

BackgroundDisinfectant towelettes are increasingly being used as a means to prevent transmission of clinically important pathogens which could lead to healthcare-associated infections (HAIs). However, the efficacy of disinfectant towelette products when tested under realistic use conditions is understudied. A test model was designed to replicate realistic wiping conditions. The objective of this study was to determine the impact of varied contact time on disinfectant towelette efficacy under these conditions.MethodsFive product types were tested against Staphylococcus aureus (ATCC 6538) and Pseudomonas aeruginosa (ATCC 15,442) at five contact times (30 s, one min, two min, three min, and 10 min) on hard, non-porous laminate templates to determine the impact of contact time on disinfectant towelette efficacy when tested under realistic use.ResultsProduct type had a significant impact on the efficacy of disinfectant towelettes when tested under conditions reflective of realistic use. The effect of contact time was limited and no differences in efficacy were seen at a contact time of one min compared with the other contact times tested. Only one disinfectant towelette product achieved a mean 5-log reduction under the tested conditions.ConclusionEfficacy of disinfectant towelettes was primarily impacted by product type when applied in a model designed to replicate realistic use in which only a limited effect of contact time was observed. There is a need for further investigation into which factors have the greatest impact on disinfectant towelette efficacy when applied in clinical settings.

Palm oil mill effluent (POME) precipitation using ammonium-intercalated clay coagulant

Clay intercalation has been completed to improve coagulation ability using ammonium ions intercalant via multi-step intercalation. The intercalated clay was confirmed by Scanning Electron Microscope-Energy Dispersive Spectroscopy analysis of expanded lamellar and reduction impurities. Fourier Transform Infra-Red analysis confirmed the sharp and strong peak adsorption at 1448 cm-1 as ammonium (NH4+) bendingvibration, and X-Ray Diffraction analysis confirmed the peak shifting to smaller 2? at 10.08° as increasing basal spacing because of ammonium ion intercalated. The Palm Oil Mill Effluent (POME) coagulation was carried out using contact time and coagulant dose variations to determine the optimum conditions, reaching 45 minutes of coagulation and 0.4 g coagulant was used. Furthermore, the turbidity, free fatty acid, and total suspended solids were measured to reach the reduction values of 93%, 49.7%, and 73.7%, respectively. The reusable study of ammoniumintercalated clay confirmed the stability of the three cycles of coagulation used.

Adsorptive Elimination of Methyl Orange Dye over the Activated Carbon Derived from Bitter Almond Shells. An Isothermal, Thermodynamic, and Kinetic Study

Abstract: Bitter almond shells (BAS) were inspected as a low-cost precursor in producing activated carbon (AC) through the optimized ZnCl2 activation route. The raw BAS were impregnated with ZnCl2 at multiple ratios (1:1 - 3:1 ZnCl2:BAS), followed by carbonization at various temperatures (400 – 800 °C) for different durations (30 – 120 minutes) in a tubular reactor. The typical AC sample was prepared using a 1:1 ZnCl2:BAS impregnation ratio and activated at 500 °C for 60 minutes. The AC yield under those conditions was 23.46%. The BET surface area (SABET), Boehm titration method, point of zero charge (pHPZC), Field Emission-Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), and Energy Dispersive X-ray (EDX) of the optimal AC sample were determined. The identification outcomes disclosed that this AC sample is mesoporous with SABET, iodine number, total pore volume, and average pore width of 1221.60 m2/g, 1444.23 mg/g,1.50 cm3/g, and 4.98 nm, respectively. The adsorptive removal of methyl orange (MO) dye from its aqueous phase by this AC was accomplished at various solution pH (2–10), different amounts of the AC (0.05-0.4 g), multiple initial concentrations (50–400 mg/L), variable temperature (10-50 °C) and varied contact time (0–420 min) in a batch- mode operation. The maximum monolayer adsorption capacity of 224.71 mg/g was obtained at 323 K, pH= 2.0, initial (MO) concentration of 400 mg/L, 0.25 g AC dose, and 420 minutes contact time. The kinetic outcomes best fitted to the pseudo-2nd -order kinetics model, while the MO equilibrium capacity obeyed the Langmuir model rather than other models. Thermodynamic studies of the MO adsorption by the BAS-derived AC disclosed that the adsorption was spontaneous and endothermic. The adsorption mechanism of MO by the declared AC mostly involved electrostatic attractions and hydrogen bonding interaction. This work demonstrates that BAS is an advantageous raw material for producing low-cost and effectual mesoporous AC carbon with substantive surface area.

Adsorption of heavy metals (lead and chromium) by Calliandra surinamensis chaff

Adsorption is one of the most effective ways of removing heavy metals such as Cu, Zn, Pb etc from media. This research work investigated the adsorption efficiency of Calliandra surinamensis pod chaff (Powder Puff flower) for the removal of heavy metals from their aqueous solutions using its chaff as the absorbent. C. surinamensis chaff was activated using ZnCl2 solution in water. The activated carbon obtained was characterized in terms of functional groups present in the carbon using FTIR which gave the infrared spectra of the activated carbon of the sample material. The impact of varying adsorption parameters such as pH of the solution, adsorbent dosage, particle size of the adsorbent and contact time on the amounts of lead and chromium removed from their solutions were evaluated to determine the maximum amounts of the metals adsorbed by changing the initial concentrations of the metals from 10 to 50 mg/l in solution. Analysis of variance was also done to determine the effects of varying process variables on the amounts of metals adsorbed. Increase in the process variables considered, pH, adsorbent dosage, particle size and contact time led to a corresponding increase in the amounts of lead and chromium adsorbed according to the order 10<20<30<40<50 mg/l. However, chromium was more adsorbed than lead as pH, adsorbent dosage and contact time increased while lead was more adsorbed with increasing particle size. Analysis of variance showed a p-value > 0.05 for pH and >0.10 for contact time showed that the variation in pH and contact time were not significant on the amounts of lead adsorbed by the adsorbent. While the p-value <0.005 for pH and adsorbent dosage and <0.05 for particle size showed that variations in adsorbent dosage and particle size are significant on the amounts of lead adsorbed. Also, for chromium, a p-value of 0.0145, 0.0001 and 0.0034 for pH, adsorbent dosage and particle size respectively showed that variations in pH, adsorbent dosage and particle size were significant on the amounts of chromium adsorbed by the adsorbent, while a p-value of 0.1679 for contact time showed that variation in contact time has no significant effect on the amount of chromium adsorbed by the adsorbent. In conclusion, C. surinamensis activated carbon is a promising and environmental friendly adsorbent for the treatment of aqueous solutions laden with heavy metals of lead and chromium.

Ability of Moringa Ore (Moringa Oleifera) As Biosorbent in Used Cooking Oil Processing

The results of this study stated that the use of activated moringa ore biosorbents had a great influence on the quality of cooking oil both physically and chemically. The results of data analysis based on variations in contact time and dose variations can show that free fatty acid levels have decreased but are not in accordance with the stipulated SNI, namely 0.17%. Activation of Moringa ore using Sodium Hydroxide (NaOH) can reduce the levels of free fatty acids in used cooking oil. Variation of biosorbent contact time can affect the decrease in fatty acid levels, which occurs at the optimum contact time of 90 minutes, the free fatty acid percentage of 0.17% is not in accordance with SNI. Variations in biosorbent doses can also affect the increase in free fatty acid levels, namely the optimum dose of 1.00-gram percentage of free fatty acids decreased by 0.17% not according to SNI. Variations in contact time and variations in optimum doses of biosorbents can also affect color organoleptic tests and the smell of used cooking oil. Where the results of each respondent's statement that 95% of the refined oil using Moringa ore biosorbent are similar to new cooking oil, namely with a bright yellow color. The method used in this study is a quantitative method by conducting experiments on the subjects to be studied and used as a reference for finding and obtaining data directly through observation or experimentation

Hierarchical mesoporous spherical Zn(4-hzba) MOF for efficient adsorption of Strontium and Caesium ions from aqueous solution

This paper describes the synthesis of mesoporous spherical Zn(4-hzba) MOF with the formula of {[Zn(μ-4-hzba)2]2}n utilizing 4-hydrazinyl benzoic acid (4-hzba) linker by solvothermal method. And investigates its adsorptive efficiency towards strontium (Sr2+) and caesium (Cs+) by varying contact time, pH, and feed solution concentration. 10 mg of Zn(4-hzba) MOF show maximum adsorption capacity of 275.2 mg/g for Sr2+ and 335.05 for Cs+ at pH 4 from a 100 mg/L sample solution within 100 min at room temperature. Among the Langmuir, Freundlich and Temkin adsorption isotherms studies, the Langmuir isotherm was well fitted for Sr2+ and Cs+ adsorption onto MOF, demonstrating the monolayer adsorption. Experimental data and pseudo-second-order kinetic studies showed that chemisorption is the dominant process. High adsorption efficiency was demonstrated by electrostatic interaction between positively charged Sr2+/Cs+ and the negatively charged surface of the MOF at pH 4 was proved by zeta potential analysis. IR, SEM, XPS analysis and Langmuir adsorption studies support the monolayer surface complexation mechanism. While the ion exchange mechanism followed by surface complexation of Sr2+/ Cs+ with replacement of hydrogen in H2NNH- of the MOF. In order to acquire a good picture of the ion exchange mechanism, and Sr2+/Cs+ exchanged MOF were optimized, and the binding energies of Sr2+ (2.19 kJ/mol) and MOF Cs+ (2.06 kJ/mol) were calculated by DFT method using Gaussian 16. Recycle studies of Zn(4-hzba) MOF show 80% recovery of Sr2+ and Cs+ even after seven cycles. The adsorption of Sr2+ and Cs+ was influenced by dosage, initial concentration of metal ions, pH solution, contact time, and coexisting ions of Na, K, Ca, and Mg. Adsorption efficiency of Sr2+ and Cs+ ions in simulated seawater was 92.3% and 96.7%, respectively.

The Isotherm Studies of Cu (II) Adsorption in Kolong Bangka’s Water onto NaOH-Deacetylated Shrimp Shells Waste Chitin

Isotherm models of Cu (II) adsorption in Kolong Bangka’s water onto NaOH-deacetylated shrimp shells waste chitin was studied. The extraction of chitin was carried out through three steps: deproteinization, demineralization and decolorization. The deacetylated shrimp shells waste chitin (DA-SW chitin) were prepared by the reaction of DA-SW chitin with NaOH at varying concentrations of 20, 40 and 60% (%W) with stirring for 1 hour at room suhue where the degree of deacetylation for varying NaOH concentrations were 65.72, 67.44 and 88.98%, respectively based on our previous research. Increasing the NaOH concentration causes the diffusion rate of OH- increase thus realizing the effectiveness of OH- attack on the carbonyl carbon group in chitin acetamide increasing so that the chitin deacetylation process becomes more effective. In order to study adsorbent equilibrium behaviour, Freundlich and Langmuir isotherm models were used based on Cu (II) adsorption data with variations in contact time 5, 10, 15, 20, 25, and 30 minutes. The results showed that the concentration of Cu (II) decreased with the increase of the degree of deacetylation and contact time. The optimum condition for the percentage of Cu (II) adsorption was achieved in DA-SW chitin with NaOH 60% (where the degree of deacetylation was 88.98%) during 30 minutes was 97.19%. The Cu (II) adsorption isotherm model in Kolong Bangka water onto DA-SW chitin is represented by the Freundlich isotherm model where the Cu (II) adsorption mechanism onto DA-SW chitin causes the formation of multilayer surface which may due to Van der Waals force.

Synthesis and Characterization of TiO2-Chitosan Beads and Its Application as A Degradation Agent of Methylene Blue

Dye waste is an environmental problem that has a negative impact on the ecosystem. One way to overcome this is by chemically degrading dyes using photocatalyst materials. TiO2 is one of the photocatalysts that can be synthesized by utilizing microwave radiation which is transferred directly to the material. This method takes a short amount of time so it can be completed in a very short time. TiO2 powder has the disadvantage that it is difficult to separate from the waste solution. TiO2 can be modified into beads by utilizing chitosan to produce TiO2-chitosan beads (TCB). In this research, the synthesis of TiO2 was carried out using microwave, followed by modification with chitosan to produce TCB and then its application in the degradation of methylene blue dye waste at various pH, concentration and contact time variations. Material characterization was carried out by determining the surface area of the material using Brunauer-Emmet-Teller (BET), band gap energy with UV-Vis Diffuse Reflectance Spectrocopy (UV-Vis DRS), crystal phase with X-Ray Diffraction (XRD), and surface morphology with Scanning Electron Microscope (SEM). The results showed that the synthesized TiO2 has anatase crystalline phase with an average crystal size of 18.85 nm and a bandgap energy of 3.16 eV. The TCB surface morphology indicated the successful impregnation of TiO2 on the chitosan. This study showed that the optimum performance of TCB was at pH 11 within 5 min and kinetic analysis results follows 2nd order. HIGHLIGHTS Methylene blue dye waste pollutes the aquatic environment TiO2 as a photocatalyst can degrade methylene blue Chitosan is an abundant natural polymer which has high adsorption ability TiO2-chitosan beads material was synthesized to facilitate the separation of the material from the liquid after photodegradation process GRAPHICAL ABSTRACT

Lignosulfonate-Based Ionic Liquids as Asphaltene Dispersants.

Asphaltenes are recognized as being troublesome from upstream to downstream in the oil industry due to their tendency to precipitate and self-associate. Their extraction from asphaltenic crude oil for a cost-effective refining process is a crucial and critical challenge in the oil and gas sector. Lignosulfonate (LS), as a by-product of the wood pulping process in the papermaking industry, is a highly available and underutilized feedstock. This study aimed to synthesize novel LS-based ionic liquids (ILs) by reacting lignosulfonate acid sodium salt [Na]2[LS] with different alkyl chains of piperidinium chloride for asphaltene dispersion. The synthesized ILs, 1-hexyl-1-methyl-piperidinium lignosulfonate [C6C1Pip]2[LS], 1-octyl-1-methyl-piperidinium lignosulfonate [C8C1Pip]2[LS], 1-dodecyl-1-methyl-piperidinium lignosulfonate [C12C1Pip]2[LS] and 1-hexadecyl-1-methyl-piperidinium lignosulfonate [C16C1Pip]2[LS] were characterized using FTIR-ATR and 1H NMR for functional groups and structural confirmation. The ILs depicted high thermal stability because of the presence of a long side alkyl chain and piperidinium cation following thermogravimetric analysis (TGA). Asphaltene dispersion indices (%) of ILs were tested by varying contact time, temperature and ILs concentration. The obtained indices were high for all ILs, with a dispersion index of more than 91.2% [C16C1Pip]2[LS], representing the highest dispersion at 50,000 ppm. It was able to lower asphaltene particle size diameter from 51 nm to 11 nm. The kinetic data of [C16C1Pip]2[LS] were consistent with the pseudo-second-order kinetic model. The dispersion index (%), asphaltene particle growth and the kinetic model agreed with the molecular modeling studies of the HOMO-LUMO energy of IL holds.

Analysis of Fe metal adsorption in industrial wastewater using adsorbents from betel nut skin

This study aims to determine the adsorption ability of betel nut skin-activated carbon on Fe metal in industrial wastewater. Betel nut skin carbon is activated using H2SO4 and HNO3. To identify the quality of adsorption using betel nut skin adsorbents, carbon and activated carbon are characterized using XRD and BET analysis. To determine the concentration of Fe metal adsorbed in the adsorption process, it was analyzed using AAS by determining the optimum conditions for the adsorption of Fe metal from the adsorbent using mass and contact time variations. The XRD characterization results show that betel nut skin carbon activated with sulfuric acid has a higher degree of crystallinity (41.03%) than that activated with nitric acid (20.61%). Betel nut skin activated carbon has a larger pore size of 3.2110 nm than the pore size of betel nut skin carbon of 2.2644 nm. The optimum condition of activated carbon on the adsorption of Fe metal was obtained at a mass of 1 gram with an optimum contact time of 45 minutes. The adsorption capacity of betel nut skin-activated carbon obtained was 1.4174 mg/g and the adsorption efficiency of betel nut skin-activated carbon was 99.84%. The initial concentration of Fe metal obtained was 25.86 ppm, after adding activated carbon from betel nut skin is decreased the concentration of Fe metal obtained was 3.72 ppm. So, the ability of betel nut skin adsorbent to adsorb Fe metal in industrial wastewater was 22.14 ppm. Keywords: Activated carbon; Adsorption; Amorphous; Betel nut skin; Wastewater

PEMANFAATAN BIOCHAR BERBAHAN DASAR AMPAS TEBU (Saccharum Officinarum Linn) SEBAGAI BAHAN PEMBENAH TANAH PADA LAHAN BEKAS TAMBANG BATUBARA

Mining activities in South Kalimantan are carried out openly which have an impact on changes in soil structure due to excavation of top soil to reach deeper layers of mining material. The soil in the mining area is infertile with a high acidity level with very low nutrients, water retention, unstructured, and the content of elements is toxic. Therefore, it is necessary to carry out treatment through remediation of mining land to restore the carrying capacity of the soil. One alternative that can be used is biochar made from bagasse. This study aims to determine the characteristics of bagasse biochar and see the effect of using bagasse biochar with variations in dosage and contact time on the soil improvement process in stabilizing pH and eliminating soil Fe levels. The soil remediation process was carried out on a laboratory scale with various doses of biochar (0 g, 7.5 g, 15 g and 30 g) and contact time (15 days, 30 days, and 45 days). The results showed that bagasse biochar has characteristics that meet the requirements as a soil enhancer based on pH, C/N ratio, organic C, total N, CEC, total P, total K, ash content and water content. The results of remediation carried out for 45 days showed that bagasse biochar was able to neutralize the initial pH from 4.9 to 6.9 and was able to reduce Fe levels by 8158.1 mg/kg.Keyworld: Biochar, Sugarcane Bagasse Mining Land, Heavy Metal (Fe), pH

Estrogen adsorption from an aqueous solution on the chitosan nanoparticles

In this research, chitosan nanoparticles as an efficient and reusable adsorbent with adsorption capacity of 5.79 mg/g, surface area of 62 m2/g and pHpzc of 8.07 were applied to remove the ethinylestradiol (as a sample of estrogen) from an aqueous wastewater. The chitosan nanoparticles were characterized by SEM, XRD and FT-IR analyses. Four independent variables involving contact time, adsorbent dosage, pH, and initial concentration of estrogen were applied to design the experiments by Design Expert software (CCD under RSM). In fact, number of experiments was minimized and the operating conditions were optimized for the maximum estrogen removal. The results indicated that three independent variables (contact time, adsorbent dosage, and pH) increment increased the estrogen removal while the estrogen initial concentration enhancement decreased the removal due to the concentration polarization phenomenon. The optimum conditions for the estrogen removal (92.50 %) on the chitosan nanoparticles were found at contact time of 220 min, adsorbent dosage of 1.45 g/l, pH of 7.3 and estrogen initial concentration of 5.7 mg/l. Moreover, the Langmuir isotherm and pseudo-second order models could properly legitimize estrogen adsorption process on the chitosan nanoparticles.

Efektivitas Fly Ash Sebagai Adsorben Dalam Menurunkan Chemical Oxygen Demand (COD) pada Air Limbah Pulp and Paper

This study aims to determine the characteristics of fly ash as an adsorbent that has been activated and to determine the optimum conditions of fly ash adsorbent to reduce the COD value of pulp and paper wastewater. The characteristics of water content, ash and iodine number were tested. The quality of fly ash adsorbent is done by determining the optimum pH, mass and time. The variations of pH 4,5,6,7,8,9 and 10, mass 0.5 g, 1 g, 1.5 g, and 2 g and contact time variations are 5 minutes, 15 minutes, 30 minutes, 45 minutes and 60 minutes. This research method uses experimental method with Complete Randomized Design analysis by conducting Anova test and Duncan's further test. The results showed that the test results of the characteristics of water content, ash and iodine number have met SNI 06-3730-1995 regarding technical activated charcoal. The optimum conditions obtained during adsorption consisting of optimum pH was found at pH 4 with % Removal COD as much as 18.1%, the optimum mass obtained was 1 gram with % Removal COD as much as 24.8%, while the optimum time obtained was 15 minutes with % Removal COD as much as 20.38%. The adsorption results show that the decrease in COD of pulp and paper wastewater is still not effective in accordance with PermenLH No. 5 of 2014.

Synthesis of mesoporous silica and chitosan-coated magnetite nanoparticles for heavy metal adsorption from wastewater

The use of magnetic nano-sized adsorbents for the removal of heavy metals from water possesses significant potential in water remediation sector. The goal of this study was to develop economically feasible magnetite nanoparticles with an appropriate surface functionalization that will simultaneously provide adsorption efficiency, hydrophilicity, and recyclability without compromising magnetic properties. Magnetite nanoparticles (MNPs) were produced via the thermal decomposition process of iron oleate precursor due to monodispersity provided by this method. The particles were coated with mesoporous silica layers by utilizing cetyltrimethylammonium bromide (CTAB) as the surfactant. The coated particles were subjected to chitosan coating by stirring in chitosan solution. The success of the coating process was confirmed by performing Fourier-transform infrared spectroscopy (FTIR) analysis between each step. The particles were used as an adsorbent in heavy metal salts solutions of known concentrations. The adsorption study was conducted with varying contact time and initial concentration and the data was analyzed for fitting to pseudo 1st order and pseudo 2nd order kinetic models, and the Langmuir and Freundlich isotherm models to determine the adsorption characteristics. The kinetic model and isotherm fitting indicted that the adsorption occurred by monolayer chemical adsorption. The developed adsorbent exhibited a satisfactory adsorption capacity of 150.33 mg/g and 126.26 mg/g for Pb2+ and Cd2+ respectively which is a good indication for further exploration and analysis.