Varying Contact Time Research Articles

Effect of DVB on Adsorption of Methylene Blue using Coply(Eugenol-Strearyl acrylate-DVB)

This research aims to study the effect of divinylbenzene (DVB) on copoly(Eugenol-Stearyl Acrylate-Dvinylbenzene)/Copoly (Eg-SA-DVB) on the adsorption of methylene blue dyes. Variations of DVB ware added as much as 2%, 4% and 6% to the weight of eugenol. Adsorption was carried out by batch method in variations of acidity (pH), contact time and initial concentration of methylene blue. The results showed that the optimum pH of methylene blue dye adsorption ware pH 5.0 for copoly(Eg-DVB-SA) 2% and 6%; while for 4% was pH 3. The optimum adsorption contact time was 60 minutes for copoly(Eg-DVB-SA) 2% and 6%, while for 4% at 50 minutes. Study of adsorption kinetic presented the adsorption of methelene blue dyes using 2%, 4% and 6% copoly (Eg-DVB-SA) adsorbents followed the Largregen kinetic model, pseudo-first order. Study of isotherm revealed the adsorption of methylene blue dyes tends to follow the Langmuir isotherm. The maximum capacity of methylene dyes adsorption using copoly(Eg-DVB-SA) 2%, 4% and 6% were 31,2; 36,2 and 14,7 mg/g, with the adsorption energy 31.1; 33.6 and 31.3 KJ/mol respectively.

Investigation of the effect of surface crack on low-velocity impact response in hybrid laminated composite plates

Composite materials can be damaged in the environments in which they are used, due to the loads they are exposed to or due to different effects on the production processes. The formation processes of these damages generally develop as crack formation or progress of the existing crack. For this reason, it is very important to investigate the behavior of the crack that occurs after the dynamic loads to which the composite materials are exposed. In this study, the dynamic behaviors of hybrid laminated composites with different surface crack geometries were investigated. Surface cracks with different crack depth-to-thickness (a/t) and crack depth-to-crack width (a/c) ratios were machined upon hybrid composite laminates and subjected to low-velocity impact tests under 2 m/s, 2.5 m/s and 3 m/s impact velocities. The effect of different surface crack geometries upon variation of contact force versus time, variation of contact force versus displacement and variation of absorbed/rebound energy have been evaluated. The effect of surface crack geometry and impact velocity upon contact stiffness and bending stiffness was also evaluated. Damage formation during impact loading was examined by scanning electron microscopy and optical microscopy. After the evaluations, the damage behaviors caused by the dynamic loads depending on the initial surface crack geometry were examined in detail.

Synthesis and Characterization of Pectin Membrane as a Matrix for Curcumin Sustained-Release

This study aims to synthesize pectin membranes, characterization of pectin membranes use FTIR, XRD, SEM, and to see the loading of curcumin in pectin membranes as a drug delivery system by contact time variations. Pectin membrane synthesize by dissolved 0.5 gram of pectin powder in 25 ml of 2% acetic acid solution then stirred for 1 hour. The solution is molded in membrane mold then oven for 24 hours at 50°C. Pectin membranes were characterized by FTIR to determine functional groups, XRD test to determine crystallinity, and SEM test to determine the surface morphology. The loading of curcumin in pectin membrane are carried out by contacting the pectin membrane into 100 ppm curcumin at various times of 5 to 120 minutes. Determination of curcumin concentration contained in pectin membrane use UV-Vis spectrophotometer at λ 426 nm. The results showed that the produced of pectin membrane was thin, pellucid, and homogeneous sheets. The results of FTIR characterization showed OH group at wave number 3448.72 cm−1 and carbonyl group at wave number 1604.77 cm−1. XRD characterization result showed that the pectin membrane was amorf. SEM characterization results showed smooth and flat surface morphology. The optimum contact time in loading curcumin proses in pectin membrane was 60 minutes with a loading percentage of 10%.

Penyerapan Ion Logam Merkuri Menggunakan Arang Aktif Limbah Kulit Pisang Kepok (Musa paradisiaca Formatypica)

This research aimed to determine the percentage of mercury metal ion adsorbed in kapok banana peel’s activated carbon. It was done by applying Completely Randomized Design (CRD) with 6 variations of contact time, pH, and mercury concentration (i.e 10, 20, 30, 40, 50, 60 minutes; pH of 1, 2, 3, 4, 5, 6; and concentration of 10, 20, 30, 40, 50, 60 ppm, accordingly). The result showed that the equilibrium time was reached at 30 minutes, the maximum pH was reached at pH 5 and the maximum of adsorbed mercury ion at 40 ppm of mercury ion concentration. The adsorption percentages of those parameters were 61%, 98%, and 99%, respectively.
 Keywords: Kepok banana’s peel, charcoal, mercury metal ion.

KESETIMBANGAN PROSES DESORPSI AMONIA DARI ARANG AKTIF HASIL PIROLISIS LIMBAH BIOMASSA

Ammonia which is bound to the adsorbent can interfere adsorption process, so that release the compound can be done by desorption process. This research intends to know appropriate equilibrium models to determine maximum capacity of active carbon for desorption ammonia. The method which used in desorption process are Langmuir and Freundlich isotherm models. The research was performed with variation of active carbon mass and variation of contact time. The concentration of ammonia on the desorption process was determined using spectrophotometer at λ 420 nm. The experiment result showed that the more the active carbon dosage is used, the more the concentration of ammonia is increased. Optimum contact time during 7 hours with desorption percentage 94-96%. This research of ammonia desorption by active carbon followed the Langmuir equilibrium model R2 0.954 and Freundlich equilibrium model R2 0.952. The equilibrium equation is used Langmuir equation y = -0.015x + 3.185, maximum desorption capacity is 66.67 mg/g.

Managing an Environmentally-Friendly Coal Mining Wastewater Processing

Jambi is one of the provinces in Indonesia that has an abundance coal potential. One of the companies that holds the Mining-Business License (IUP) for Coal mining production and operations is PT. XYZ, which is chosen to be the source of samples for this research. One of the negative impacts caused by coal mining activities is the wastewater emerge from both mining and stockpile activities. Unprocessed wastewater can pollute the environment, particularly the surface water and ground water around the mining site. Materials utilized in managing coal mine wastewater in this research are bentonite (natural and activated) and limestone from clamshells. Bentonite is expected to be able to absorb TSS, Fe, Mn and Hg values, while clamshells to increase the pH value in coal mine wastewater. This research aims to determine the ability of clamshell bentonite and limestone in processing coal mine wastewater. The samples in this research are amounted to 19 consisting of 1 control sample and 18 treatment samples. The treatments are made in 6 mass variations and 3 variations of contact time. A combination of 1 gram of material is contacted with 250 ml of coal mine wastewater. The characteristics of coal mine wastewater from PT. XYZ based on the samples taken are as follows: pH 4,40, TSS 66 mg/l, Fe 0,998 mg/l, Mn 7,340 mg/l, dan Hg 0,00076 mg/l. The results of this research show that the compilation of bentonite and limestone from clamshells is able to reduce the parameters of coal mine wastewater. The absorption efficiency of the compilation of bentonite and limestone in decreasing the parameters of coal mine wastewater has varied values with the average of: pH 68,62%, TSS 90,91%, Fe 97,60%, Mn 26,71%, and Hg 96,05%. Mass variations and contact time influence the decrease in coal mine wastewater parameters. The treatment on variations of 0.75 grams of activated clamshell bentonite and 0.25 grams of clamshell limestone with 30 minutes contact time is the treatment that produces wastewater that meets the environmental quality standards, which are pH 7,16 from 6 – 9 of environmental quality standards value, TSS 6 mg/l from 400 mg/l of environmental quality standards value, Fe < 0,02 mg/l from 7 mg/l of environmental quality standards value, and Hg < 0,00003 mg/l from 0,002 mg/l of environmental quality standards value. With good management, it is expected that the impacts caused by waste water from coal mining can be minimized in order to achieve environmentally friendly mining activities

Biosorption of hexavalent chromium metal ions from an aqueous solution of leaves and bark of Cinnamomum verum via green route

In present research work Cinnamomum verum leaves (CL) and barks (CB) are exploited to encounter their effectiveness against the concentration of hexavalent chromium (Cr+6 metal ions) through biosorption process. To achieve this goal optimal conditions were set and broken into various parts such as; doses of adsorbents, concentrations of adsorbates, variations in contact and stirring time (5–100 min), temperatures (10 °C to 50 °C) and pHs from acidic to basic range (1 to 12). Thermodynamic parameters were also applied to validate the assay, which shows that the process is endothermic with positive ∆H° values, while negative values of ∆G° proved the spontaneous nature of sorption. Moreover, Lagergren’s kinetic equations were employed, which suggest that the observed reaction process followed the dynamics of pseudo-second order. Equilibrium adsorption isotherms namely Langmuir and Freundlich have been applied to study the adsorbate materials attraction towards Cr+6 metal ions. The determined adsorption capability, i.e. qe was found to be 11.33 and 26.85 mg/g acquired by CL and CB at 30 °C and 40 °C, respectively. FT-IR spectrums of loaded and unloaded metal ions were taken, which confirmed the participated functional groups of herbal plants in biosorption process. EDX analysis revealed the presence of Cr+6 metal ions after biosorption process. Furthermore, irregularities on surface of adsorbent material obtained from SEM images have provided more support to results for validation.

Removal of brilliant scarlet by MCM-48 materials

Wastewater resulted from textile dyeing is an enormous pollutant around the world. Therefore, the existence of dyes, such as brilliant scarlet (BS), in the water environment, has to be removed. Mesoporous silica (MCM-48) was used to remove BS through the adsorption process. MCM-48 was hydrothermally prepared using co-surfactant of CTAB and Triton X-100 as a template. After being synthesized, the material was washed once and twice with HCl-ethanol to remove surfactants used. Fourier Transform Infra-Red (FT-IR) and X-ray Diffraction (XRD) were methods utilized to characterize MCM-48 materials. We studied the ability of washed MCM-48 materials (washed once, MCM-48-W1 and washed twice, MCM-48-W2) to remove BS from aqueous media with a variation of contact time, pH, and concentration. A UV-Vis Spectrophotometer was an instrument used for measuring the concentration of BS after adsorption at a wavelength of 505 nm. The adsorption isotherms of BS by washed MCM-48 materials were studied using Langmuir and Freundlich models. The result showed that the optimum time of BS by MCM-48-W1 and MCM-48-W2 was 60 min. The optimum pH adsorption of the dye by MCM-48-W1 was 6, whereas those by MCM-48-W2 was 5. The adsorption of BS by MCM-48-W1 and MCM-48-W2 obeyed the Langmuir and Freundlich models. The adsorption capacity of the former was higher than that of the later. This result showed that mesoporous materials that still had some surfactants are promising to be used as adsorbent of dye.

Digestate residues analysis under elevated heat regime by using DNS method

The problems with unsorted municipal waste are always associated with disposal issues as it requires a large area for landfilling or high energy used for incineration. In recent years, an autoclaving technique has been considered a promising approach which could minimize the volume of organic waste from being directly disposed or incinerated. In this work, an attempt was done to study the saccharification potential of organic residues under elevated temperature Thermal treatment involving hot water bath was applied to treat the organic residue ranging from 60oC to 100oC for 30 and 60 minutes. The result obtained showed an increasing trend for the concentration of glucose and carbohydrate. However, the result for lignocellulose content which contains various component includes extractive, holocellulose, hemicellulose, cellulose and lignin show variation. Based on the thermal treatment carried out, the result indicated that the trend of glucose and carbohydrate content. The highest percentage of glucose that can be obtained 978.602 µg/ml which could be obtained at 90oC at 60 minutes. The carbohydrate also shows an increasing trend with 0.234 mg/ml as the highest peak achieved at 80oC for 30 minutes treatment. However, it was found that the lignocellulose content varies with temperature and time. The statistical analysis was carried out using two-ways ANOVA shows an interaction effect between the independent variables (temperature and contact time) and the saccharification effects on the food wastes. The result shows a variation in the significant effect of independent variables on the changes in the composition of food waste.

Batik Home Industry Wastewater Treatment Using UVC/Ozon Oxidation Method: Case Study in Cibelok Village, Pemalang, Indonesia

Batik is one of Indonesia’s cultural heritages that spread across various regions with their unique characteristics. One of the regions that have batik industries is Pemalang Regency. However, batik industries also contribute to liquid waste. Wastewater containing pollutants such as waxes, resins, dyes, and binders such as silicates produce high concentrations of Biochemical Oxygen Demand (BOD) and vibrant colors. There are still many batik enterprises that discard wastewater directly to the environment without being processed first. This study aims to degrade Remazol Black B and Biochemical Oxygen Demand (BOD) dyes in batik liquid waste to contact time variations 0, 15, 30, 45, 60 minutes with UVC-Ozone oxidation methods. The Ozone-UVC method is an alternative method for decolorization and degradation of BOD. The dye degradation test was carried out using Spectroquant UV/VIS Spectrophotometer, and the BOD degradation test was carried out using Dissolved Oxygen - DO Meter AZ-8403. The result shows that the BOD degradation at batik wastewater was from 190.17 – 96.83 mg/L. Visually, the increase in treatment time makes the sample look clearer (decolorization), evidenced by the sample image and decreased absorbance results.

Silica-cellulose material application as the immobilization matrix of Pseudomonas fluorescens

Waste management, including heavy metal removal through bioremediation, requires process optimization. One of the important processes in a modern method is bacterial immobilization intended to improve the performance of bioremediation. In this preliminary study, silica material from rice husk processed via sol-gel was used, and cellulose of Nata de Coco was incorporated in situ during gelling to give balanced surface properties of a porous matrix. The modified could hold bacteria such as Pseudomonas fluorescens to be immobilized for further use. Variation of contact time was done, while temperature and stirring speed were kept constant. Assessment of Pseudomonas fluorescens bioremediation activity was carried out in cadmium standard solution. The result showed that the optimum contact time of Pseudomonas fluorescens and silica matrices was achieved at 30 min contact time as 99.19% was embedded in the matrices. This system decreased 80% of heavy metal in solution. This result indicates the compatibility of silica-cellulose matrix in Pseudomonas fluorescens immobilization, as predicted for other types of bacteria as well.

The effect of mixing speed to adsorption heavy metal Cu2+ and color using kepok banana peel waste

Home industry of screen printing generally disposes wastewater directly into drainage without being processed first. Wastewater from screen printing industry has a high metal content exceeding the quality standards of Minister of Environment Regulation no. 5 of 2014 concerning Waste Water Quality Standards which are being problem for the environment. This study aims to analyze the effect of mixing speed on adsorption of heavy metal Cu2+ (Copper) using adsorbents from the utilization of kepok banana peel waste in batch reactors and mixed using the jartest tool. In the process of making the adsorbent, the kepok banana peel was dried for 2 days and carbonized by using furnace at 400°C for 2 hours to become powder. After the carbonization process, the size was uniformed into 100 mesh and activated using H2SO4 with an immersion process for 24 hours. The adsorbent powder was then used as much as 10 grams in 250 mL of screen printing wastewater with variations in mixing speed (rpm): 100,150,200 and variations in contact time (minutes): 30,60,90. The result showed that the optimum mixing speed is 100 rpm with a time of 60 minutes. The initial concentration of heavy metals Cu2+ of 3.52 mg/L and after the adsorption process it becomes 0.0716 mg/L, that meet the quality standards of 0.8 mg/L.

Adsorption of Pb(II), Cu(II) and Ni(II) ions from aqueous solutions by functionalised henna powder (Lawsonia Inermis); isotherm, kinetic and thermodynamic studies

ABSTRACT In this study, the functionalised henna powder was tested for the adsorption of the lead, copper, and nickel. The method of making this adsorbent is very easy, as it can be prepared with the materials available in the kitchen. Three metals with equal concentration are used as multi-metals adsorption. The experiment was conducted at varying contact time(30–180), adsorbent dose(0.05–0.25 g), adsorbate concentration(10-50 mg/l), temperature(15, 25, 40 and 60ºс), and pH(2–8). Most of the significant changes were observed at 30 min, 0.25 g, 20 mg/l and 5 for the contact time, adsorbent dosage, adsorbate concentration, and pH, respectively. At pH 5, the lead, copper, and nickel removal percentage were 99.96%, 97.90%, and 86.2%, respectively. In this condition, the total surface coating is less than 40% in henna, meaning that over 60% of the adsorption sites have been left unsaturated and free, so more metal ions can be adsorbed with the increase in the initial concentrations of the metal solutions. From the results, it can be concluded that the best adsorption isotherm model and correlation coefficient (R2) were followed for Pb (Langmuir, 0.997), Cu(Langmuir, 0.992) and Ni(Freundlich, 0.965). Of four kinetic models, the highest values of correlation coefficient (R2) were obtained in the Pseudo-second-order model for adsorption of Pb(1), Cu(1) and Ni(0.999). At all temperature ranges, ΔG is negative (spontaneous reaction) for lead and copper, it is positive(non-spontaneous reaction) for nickel(except at 25°C). The ΔG becomes more negative with increasing temperature for copper and this means that increasing temperature effects copper adsorption. The results are shown that thermodynamic properties such as ΔH and ΔS are for lead(−58.4, 0.151), copper(15.4, −0.07), and nickel(2.44, −0.006), respectively. The negative ΔH and ΔS are indicated that exothermic reaction(lead) and the regular arrangement of the adsorbed molecules on the adsorbent(copper and nickel), respectively.

Karakterisasi Karbon Baggase Teraktivasi dan Aplikasinya untuk Adsorpsi Logam Tembaga

Bagasse is waste produced from the process of milking or extracting sugarcane stems. Baggase can be optimized in terms of use value and its function as an alternative technology, namely as an active carbon manufacturing material that can be used as a copper (Cu) adsorbent. This study discusses the functional baggase activated carbon group of phosphoric acid and nitric acid using Fourier Transform Infra Red (FTIR) and its application as a copper metal adsorbent in silver craft waste in Ungga Village, Praya, Central Lombok. The production of activated bagasse carbon consists of three stages, namely first dehydration by burning bagasse until it turns into carbon, the second carbonation is heating at 500ºC, carbon results are 100-200 mesh and third, activation by soaking 50 grams of carbon in 500 mL of 20% phosphoric acid and 20% nitric acid for 12 hours. After that the carbon is dried at 110ºC and finally heated at 500ºC for 1 hour. The bagasse carbon that has been made is put into 25 mL of waste water sample with a mass of 2 grams of adsorbent. Samples were then stirred at 30, 60, 90, 120 and 150 minutes contact time variations at a speed of 180 rpm using a batch system. The optimum contact time that is used to calculate the efficiency of copper metal content reduction is by calculating the difference in the metal content of copper metal before it is adsorbed and after it is adsorbed using activated carbon baggase. Concentrations of all copper metals were analyzed using Atomic Absorption Spectrophotometer (AAS). Identification using FTIR spectrophotometer shows that carbon baggase in this study contains functional groups C = O, C = C, C-C, N = O, C = N, C-OH, CH2 and C-H. From the research it was found that the copper metal content in the sample was 14.5710 ppm. The optimum contact time on copper metal adsorption is at 120 minutes contact time which results in optimum adsorption efficiency on copper metal that is 84.88%. Activated carbon baggase is an effective adsorbent to reduce levels of copper metal in silver craft waste.

Adsorption Studies of Silica Adsorbent Using Rice Husk as a Base Material for Metal Ions Removal from Aqueous Solution

This study was carried out to evaluate the efficiency of metal ions removal from aqueous solution using silica adsorbent. Silica was extracted from rice husk using sol-gel method. The silica was modified with 1.0 M of nitric acid. Using batch adsorption technique, the effects of temperature, pH, contact time and adsorbent dosage on adsorption process of Cu (II), Zn (II), Mn (II) and Pb (II) ions were studied using standard solutions of their salts. Percentage removal of the metals ions studied decreased as the temperature was varied between 28°C and 43°C. Percentage removal of metal ions studied showed an increase at different pH varying from 4 to 8 and decreased after the pH 8. The variation of contact time between 2 and 8 hours showed a sharp increase in metals removal from 2 to 6 hours but a slow increase after 6 hours. The percentage removal of metal ions increase as the adsorbent dosage increased between 0.5 g and 2.0 g. The maximum percentage removal of metal ions was found to be 99.48%. The general observed trend of efficiency being Cu>Pb>Zn>Mn. The experimental data was also tested using adsorption isotherm models of Langmuir and Freundlich and Langmuir model was found to be the best fit for the data.

Adsorptive, kinetics and regeneration studies of fluoride removal from water using zirconium-based metal organic frameworks.

Fluoride contamination has been recognised as one of the major problems worldwide, imposing a serious threat to human health and affecting the safety of drinking water. Adsorption is one of the widely considered appropriate technologies for water defluorination. The present study describes the preparation of a zirconium-based metal organic framework (MOF-801) adsorbent using a solvothermal method and its adsorption efficiency for removal of fluoride ions from water. The morphology of MOF-801 was characterized by PXRD, FESEM and XPS, and the pore structure and surface area were calculated according to BET. It was found that the synthesized MOF-801 showed the distinguishable octahedral shape particle with a lattice spacing of 0.304 nm, indicative of (011) planes of ZrO2. Adsorption studies were carried out to study the defluorination effectiveness by varying contact time (30–150 min), adsorbent dose (0.3–1.5 g L−1), adsorbate concentration (5–25 mg L−1), as well as kinetics and isotherms. The maximum removal efficiency for fluoride using MOF-801 at equilibrium was found to be 92.3%. Moreover, the adsorption kinetic studies indicate that the overall fluoride adsorption process was best described by pseudo-second-order kinetics. The adsorption data were well-fitted with the Langmuir isotherm model (R2 = 0.9925) with maximum adsorption capacity of 19.42 mg g−1. The synthesized MOF-801 had good reusability and was used in up to four cycles for fluoride removal attaining around 79% removal efficiency after the fourth cycle. All the results suggested that the synthesized MOF-801 has potential to be an excellent adsorbent for wastewater defluorination treatment.

PEMANFAATAN LIMBAH DAUN NANAS (ANANAS COSMOSUS) SEBAGAI ADSORBEN LOGAM BERAT Cu

Pineapple leaf waste (Ananas cosmosus) contains a constituent component in the form of cellulose and lignin. Cellulose, hemicellulose, and lignin bind to each other to form lignocellulose. The high cellulose content can be used as an adsorbent through the process of delignification or removal of lignin. This study aims to determine the characteristics and ability of pineapple leaf cellulose to remover heavy Cu metals. Applied pineapple leaves to be used are equalized to 60 mesh then delignified for 70 and 90 minutes by mixing pineapple powder using 9% NaOH with a ratio of 1:30 (w/v). Pineapple leaves are characterized by chesson, SEM, and XRD analysis. The results of Chesson analysis showed that pineapple leaf cellulose had a cellulose content of 25.33% and the delignification time of 70 minutes resulted in the highest cellulose content of 59.12%. The XRD diffractogram showed pineapple leaf cellulose including type I cellulose. The highest degree of crystallinity was obtained by pineapple leaf cellulose with a delignification time of 90 minutes which was equal to 65.98%. The adsorption process was observed with variations in contact time 30, 60, 90, and 120 minutes. The highest Cu metal adsorption was pineapple leaves with a delignification process of 70 minutes with a contact time of 90 minutes.

Reducing the ammonia content of hospital liquid waste by active carbon plastic ore adsorption

Considerable visits from patients increases the content of ammonia within the liquid waste of the hospital which, in turn, results in water pollution. Adsorption of active carbon is an alternative technology in reducing the ammonia level of liquid waste. This research aims at revealing the contact time of active carbon plastic ore towards the degression of ammonia level of liquid waste. This research was an experiment designed by Pretest-Postest design with control. The population of the research was all the liquid waste taken from the influent of RSUD Al Ihsan Bandung, while the sample of the research was taken from the population by time combining collection technique. The collected data was then analysed using ANOVA. The results of the research show that the average of the degression percentage for contact time of sixty minutes is 1,840%, 90 minutes 35.07% and 120 minutes 48.77%. The value of t acquired from ANOVA testing is 0.001, smaller than 0.05 (α 5%). There is significant influence of the variations of contact time of active carbon plastic ore on the degression of ammonia level of liquid waste. The results of the research could be utilised by the hospital to manage its liquid waste.

UPAYA PENINGKATAN SENSITIVITAS NANOPARTIKEL PERAK UNTUK ANALISIS ION MERKURI(II) SECARA CITRA DIGITAL DENGAN PENAMBAHAN NaCl

The very small concentration of mercury (Hg) in the environment is difficult to detect, so an accurate and sensitive method is needed in order to detect the concentration. Therefore, the purpose of this study was to develop an accurate and sensitive method based on the use of digital imaging methods and silver nanoparticles (AgNPs) as colorimetric sensors for mercury(II) ions (Hg2+) analysis. The process of making AgNPS is done by a bottom up method involving a reduction reaction. The precursor used is 1 mM AgNO3 solution and as bioreductor is an antioxidant compound present in extract of chili pepper (Capsicum frutescens L) with ratio 1: 9. Contact time variation 15, 30, 45, 60 min and 1, 2, 7 days. Addition of NaCl 0.5 and 1 M NaCl were used to increase the sensitivity of AgNPs as colorimetric sensors of Hg2+ ions. Digital Image Method is used to analyze Hg2+ ions at ppb concentration level. The results of the most optimum silver nanoparticles synthesized at the time of solar heating is 60 minutes. The addition of NaCl 0.5 M and 1 M into AgNPs is able to increase the sensitivity of AgNPs. Limit of Detection (LoD) of AgNPs added NaCl 0.5 M and 1 M was able to detect Hg2 + ions by 3.02 ppb and 2.46ppb.

Pengaruh Waktu Kontak Karbon Aktif dari Kulit Durian terhadap Kadar COD, BOD, dan TSS pada Limbah Cair Industri Tahu

The disposal of tofu industrial wastewater into the environment without treatment can cause pollution. The purpose of this study was to utilize durian peel as activated carbon which is used to treat the tofu industrial wastewater through adsorption process. In addition, to determine the effect of variation in contact time on the adsorption process. Carbon from durian peel with chemical activation using KOH 25% containing 10.15% water, 6.14% ash, and iod adsorption of 1194.83 mg/g. Activated carbon from durian peel was tested by FTIR obtained by functional groups of –OH, C−H, and C=C aromatic. Porosity analysis of activated carbon using SAA with BET method obtained surface area of 471.6 m 2 /g, pore volume of 0.5698 cc/g, and average pore diameter of 24 A classified as mesoporous. Adsorption process between activated carbon and tofu industrial wastewater variations in contact time during 30, 60, 90, and 120 minutes. Based on the study, the optimum contact time was 90 minutes. At that time, activated carbon from durian peel can reduce COD levels to 57%, BOD to 59%, and TSS to 72% from the initial levels of tofu industrial wastewater.