Salt Solution pH Research Articles

Module Based on Metacognitive Strategies to Reduce Misconceptions on Salt Hydrolysis Material

The use of modules allows students to learn independently according to their abilities and interests, but it can also develop the ability to interact directly with the environment and other learning resources. This study aims to produce a module based on metacognitive strategies to reduce misconceptions on salt hydrolysis material. This research is a Research and Development by adapting the research and development stages modified by Sukmadinata with one group pretest-posttest design which is treated with a limited trial sample of 20 students of class XI MIPA at SMAN 1 Lamongan. The research instrument used was students' conception test sheets given before and after learning with the number of items, namely 5 reasoned multiple-choice questions accompanied by CRI (Certainty of Response Index). The results showed that in the concept of the hydrolysis reaction there was a change in misconception (MK) to know the concept (TK) by 74%, to not know the concept (TTK) by 0%, and still have a misconception (MK) by 26%. In the concept of salt solution pH there is a shift to TK, TTK, and MK respectively by 50%, 0%, and 50%. Thus, it can be concluded that modules based on metacognitive strategies can reduce misconceptions about the concept of hydrolysis reactions by 74% and about the concept of pH of salt solutions by 50%.

Experimental study on the effects of salt solution pH on the performance of reverse electrodialysis stack

Reverse electrodialysis (RED) is a promising way of harvesting salinity gradient energy (SGE). The seawater or industrial wastewater may have various pHs. Here the RED performance involving sodium salt solutions with different ion valence ratios including anions of Cl-, SO42-, and PO43- is experimentally investigated in symmetric and asymmetric pH configurations. In the symmetrical pH configuration, increasing the solution pH significantly weakens the energy conversion performance for the 1:1 and 1:3 salts; for the 1:2 salt, the power density and energy conversion efficiency increase and then decrease with increasing pH due to the coupling effects of OH- on the ion transportation through AEMs and CEMs. In the asymmetric pH configuration, increasing the pH of the low concentration solution decreases the power density and energy conversion efficiency. As the pH of the high concentration solution increases, the output power and energy conversion efficiency decrease and then increase for the 1:1 salt due to the coupling effects of the ion transmembrane concentration difference and OH- on the ion migration of IEMs; for the 1:2 salt, the output power and energy conversion efficiency increase and then decrease; for the 1:3 salt, OH- inhibits the hydrolysis of Na3PO4 and anion migration, leading to the lowered output power density and energy efficiency.

Development of module based introduction, connection, application, reflection, extention (icare) on ion balance and pH of salt solution class xi sma/ma

The development of a ICARE-based Module on the material of ion balance and pH of salt solution aims to develop a valid module and determine user responses in learning. The research method used is the research and development (R&D) method by applying a 4-D development model which includes Define, Design, Develop and Disseminate, pandemic conditions cause research to only be carried out until the Develop stage which was followed by one-on-one trials, teacher trials, and limited trials. The data collection tools used are validity sheets and user response questionnaires. The data analysis technique used is to calculate the results of the validation percentage score and user response. The results of the study explain that the ICARE-module developed has been categorized as "valid" according to 3 material validators and based on the feasibility of content, ICARE characteristics, language, graphics and respectively were 93.93%, 100%, 95.2%, 95% and 100%. The results of the user response test for three teacher and 20 students were categorized as “very good”. The percentage of user response scored based teacher and student response questionnaires were 93.33% and 90.12% respectively.

NEED ANALYSIS OF STUDENT WORKSHEET (LKS) OF IONIC EQUILIBRIUM AND pH OF THE SALT SOLUTION BASED ON PROBLEM SOLVING

Problem solving skills are one of the skills needed by students in the era of the industrial revolution 4.0, so it becomes a challenge for a teacher to design creative learning. One of the media that supports students' problem solving skills is to use worksheets. Meanwhile, the worksheets used so far are general in nature. Suitable worksheets are developed that support students in solving problems, namely problem solving-based worksheets. This study aims to analyze the need for problem solving-based student worksheets. This type of research is a qualitative descriptive study. This needs analysis is part of the research and development of the 4D model, specifically the Define stage. The subjects in this study were students of class XII in SMA Negeri 3 Cirebon City and chemistry teachers as informants. The results showed that students needed worksheets that were more attractive and easy to understand. The worksheets available are in accordance with KD, KI and the 2013 curriculum, but not yet according to student needs. Based on data obtained from several analyzes including analysis of student perceptions, teacher perceptions, student characteristics, curriculum, assignments, concepts and analysis of learning objectives. So it is necessary to develop problem solving worksheets, especially in the matter of ionic equilibrium and pH of salt solutions which can train students to solve problems and relate theory to facts in everyday life.

PENGEMBANGAN E-LKPD BERBASIS DISCOVERY LEARNING MENGGUNAKAN APLIKASI ADOBE ACROBAT 11 PRO EXTENDED PADA MATERI KESETIMBANGAN ION DAN pH LARUTAN GARAM UNTUK KELAS XI SMA/MA SEDERAJAT

This study aims to develop E-LKPD based on Discovery Learning using the Adobe Acrobat 11 Pro Extended application on the ion balance and pH of salt solution for class XI SMA / MA, to determine the validity of E-LKPD based on aspects of content feasibility, characteristics of Discovery Learning, linguistic aspects, presentation aspects, graphic aspects, size, cover design, content design and knowing the user's response to the developed E-LKPD. This development research is a type of Research and Development (R&D) with the Plomp development model. The data collection instruments are in the form of validation sheets given to two material validators and two media validators, as well as user response questionnaires for teachers and students. After two revisions, the validity results obtained by the material validator on the content feasibility aspect were 94.44%, the characteristic aspects of Discovery Learning were 95.83%, the presentation aspects were 90%, the linguistic aspects were 90.62% and the graphic aspects were 93.5% which each of these aspects is included in the valid criteria. Furthermore, the results of data analysis obtained validity by the media validator on the graphic aspect which included the E-LKPD size of 100%, the cover design was 90.63%, and the content design was 94.32%, each of which was categorized as valid. E-LKPD which has been declared valid by the validator is tested one by one on 3 students who have studied the ion balance and pH of the salt solution. Then ask for a response questionnaire to 3 chemistry teachers and 20 students. The results of the teacher's response were 95.55% including very high and practical criteria, the results of students' responses were 90.75% including interesting criteria. Based on the results of data analysis, it can be concluded that the E-LKPD based on Discovery Learning using the Adobe Acrobat 11 Pro Extended application produced was validated and can be used in high school chemistry subjects on ion balance and pH of salt solution.

Aqueous two-phase extraction of lead from contaminated aqueous solutions

Aqueous two-phase extraction is an ecologically safe method for heavy metal recovery and regeneration from contaminated aqueous solutions. Investigation has been carried out experimentally for the extraction of lead from aqueous solutions using Polyethylene Glycol 1500-Ammonium sulfate two-phase system. The extracting agent used is sodium chloride. Aqueous two-phase extraction experiments for Pb(II) have been performed in batch mode according to the central composite design under Response Surface Methodology. The effect of independent parameters as to the extractant concentration, initial salt solution pH, and initial salt phase metal concentration on the extraction efficiency has been studied experimentally. The results indicate that all the three independent parameters studied have significant effect on extraction efficiency. A second-order polynomial model has been used to fit the dependent variable in the experimental range of parameters. The maximum extraction efficiency obtained from the model is about 51% atinitial salt solution pH of 2.8, NaCl concentration of 49.9mmol/Land initial salt phaselead concentration of 9.8 mg/L. This is in agreement with the results obtained from the experiment conducted at optimum conditions.

Optimization studies on aqueous two-phase extraction of hexavalent chromium from contaminated aqueous solutions

Chromium has wide applications in industry and its resources are limited. The total chromium discharge to the environment needs to be monitoredand regulated. The extraction of chromium to PEG offers its reuse in pure form. The present study focuses on the optimization of hexavalent chromium extraction to PEG 1500 using ammonium salt. The effect of independent parameters as to the initial salt solution pH and initial salt phase metal concentration on the extraction efficiency has been studied experimentally. Second-order polynomial models have been used to fit the dependent variables in the experimental range of parameters.Central composite rotatable design in Minitabstatistical software version 16is used as the optimization tool. The maximum efficiency that is achieved through the optimization studies is 29.8%at an initialsalt solution pH of 6.5 and initial metal concentration 24.4 ppm. The corresponding distribution coefficient at the optimum conditionshas been found to be 1.14. The results of the optimization studies have been validated by conducting experiments at the optimum conditions.

Validitas dan Praktikalitas Modul Kesetimbangan Ion dan pH Larutan Garam Berbasis Inkuiri Terbimbing

This study aims to produce a module ion equilibrium and pH of salt solution and how to categorise module validity and practicality levels. As this is Research and Development study, we used Plomp model consisting three stages, preliminary research, prototyping stage and assessment phase. Guided inquiry is a learning model used in this study. This module is validated by 5 validators with a research instrument in validation and practicality sheet in the form of questionnaires. The validator’s evaluation of each statement was analysed using Kappa Cohen formula. The results show kappa moment value (κ) 0.85 with a very high category. The kappa moment value (κ) for practicality of module based on teacher’s response is 0.88, while student’s response is 0.81. The resulting module is very valid and practical to use.

PENERAPAN MODEL PEMBELAJARAN CORE UNTUK MENINGKATKAN PRESTASI BELAJAR PESERTA DIDIK PADA POKOK BAHASAN KESETIMBANGAN ION DAN pH LARUTAN GARAM

The research aims to improve student learning results on ion equilibrium and pH of salt solution in class XI IPA SMAN 6 Pekanbaru. This is an experimental study with a pretest-posttest design. The sample study was students of class XI IPA 2 as an experimental class and students in class XI IPA 1 as a control class. The experimental class is the class applied to the CORE learning model while the control class is not treated. The data analysis technique used is the t-test. Based on the results of the data analysis test, tcount> ttable is 9,03> 1.66, meaning that the application of CORE’s learning model can improve student learning achievement on the subject of ion equilibrium and pH of salt solution in class XI IPA 6 SMAN 6 Pekanbaru

PENERAPAN MODEL PEMBELAJARAN OSBORN UNTUK MENINGKATKAN PRESTASI BELAJAR PESERTA DIDIK PADA POKOK BAHASAN KESETIMBANGAN ION DAN PH LARUTAN GARAM DI KELAS XI IPA SMA NEGERI 14 PEKANBARU

The research aims to improve student learning achievement on the subject of ion equilibrium and pH of salt solution in class XI IPA SMAN 14 Pekanbaru. This type of research is an experimental study with a pretestposttest design. The research was conducted at SMAN 14 Pekanbaru. The sample from the study was students of class XI IPA 1 as an experimental class and students in class XI IPA 3 as a control class. The experimental class is the class applied to the Osborn learning model while the control class is not treated. The data analysis technique used is the t-test. Based on the results of the data analysis test, tcount> ttable is 7.25> 1.67, meaning that the application of Osborn's learning model can improve student learning achievement on the subject of ion equilibrium and pH of salt solution in class XI IPA 14 of SMA Negeri 14 with categories of achievement improvement learning in the experimental class based on Score (N-Gain) is high, which is 0.73.

GREEN CHEMISTRY EXTRACTION METHOD FOR RECOVERY OF GOLD IONS FROM CYANIDE WASTEWATERS

In this study, the possibility of Au(III) ions recovery from cyanide solution by extraction in aqueous two-phase systems formed from polyethylene glycol (PEG) and (NH4)2SO4 inorganic salt, in presence of chloride ions as extracting agent, was analyzed in batch systems. Due to the non-toxic character of the components of extraction system, the Au(III) ions extraction in aqueous two-phase systems can be included in the category of green chemistry methods. The Au(III) extraction efficiency was examined as a function of several experimental parameters, such as molecular weight of PEG, salt solution pH and chloride ions extractant concentration, in order to find the optimal conditions. The experimental results have shown that the maximum extraction of Au(III) ions (> 89%) is obtained in aqueous two-phase systems prepared by PEG-6000, salt solution with pH of 3.15 and chloride ions concentration higher than 0.1 mol.L-1. These conditions were then used in case of Au(III) extraction from cyanide wastewater, when the experimental data have indicated that the Au(III) ions extraction is more efficient in presence of 0.1 mol Cl-.L-1 (> 85%), than in their absence (< 17%). The obtained results indicate that the aqueous two-phase systems have potential for the recovery of Au(III) ions from cyanide wastewaters, both due to its extraction performances, and green chemistry characteristics.

Ảnh hưởng của ướp muối đến sự oxy hóa lipid và oxy hóa protein trong cơ thịt cá lóc (Channa striata) nuôi

The study was carried out to investigate lipid oxidation and protein oxidation of snakehead fish meat by changing the salt concentration (0, 4, 8, 12, 16, 20% NaCl, w/v) and pH adjustment (4, 5, 6, 7, 8 and 9) of soaking solution. The magnitude of oxidative changes was monitored by: (i) lipoxygenase enzyme activity (LOX), peroxide value (PV) and TBRAS (thiobarbituric acid reactive substances) value, (ii) protease activity, sulfhydryl index, and (iii) whiteness index, water holding capacity and drip loss (physicochemical properties). The results showed that salting process has limited the activity of lipoxygenase and protease enzymes, while improving the quality of fish meat. Salted fish in 12% NaCl (w/v) for 3 hours had significantly lower (p < 0.05) lipoxygenase and protease activity, PV and TBARS value and a higher sulfhydryl value when compared with control sample (no salt immersion) and salted fishes in lower salt concentration (4, 8% NaCl, w/v). In addition, lipid oxidation and protein oxidation of the snakehead fish meat was delayed at neutral pH of salt solution, which was most effective at pH 8. The quality of snakehead fish meat at this condition was also improved with whiteness index (WI) of 81.17, water holding capacity 72.39%, and drip loss 11.78%.

EXPLORATION OF THE FACTORS AFFECTING THE SOLUBLE PROTEIN EXTRACTION FROM CULTURED SNAKEHEAD FISH (Channa striata) MUSCLE

This study was conducted to identify the factors affecting the soluble protein extraction from cultured snakehead fish muscle, a protein having bioavailability and nutritional value. The study investigated the ratio of fish muscle to water (from 1:1 to 1:5 w/v) and salt (NaCl) concentration (from 0.05 M to 0.25 M) that are suitable for extracting soluble protein effectively. Research has applied a response surface methodology using a central composite design to optimize the effect of temperature and time extraction on soluble protein extraction efficiency. In addition, the study investigated the effect of pH of salt solution (pH 2 to pH 12) on the efficiency of soluble protein extraction from cultured snakehead fish muscle. As a result, the use of 0.15 M NaCl solution with 1:2 ratio of fish muscle to water gave high soluble protein extraction efficiency. The optimum extraction temperature and time were determined as 34.8 °C and 15.2 min respectively, and the appropriate pH value was also determined as pH 10. At the optimum extraction conditions, soluble protein recovery calculated by the amount of soluble protein extraction dividing total protein of fish muscle was 14.39 ± 0.18 %.

三種類の指示薬を用いて塩の pH を測る(デモ実験虎の巻)

三種類の指示薬を用いて塩の pH を測る(デモ実験虎の巻)

ANALISIS MODEL MENTAL SISWA DALAM PENERAPAN MODEL PEMBELAJARAN LEARNING CYCLE 8E PADA MATERI HIDROLISIS GARAM

This study aims to analyse the students’ mental model of students in SMA 42 Jakarta in the implementation of Learning Cycle 8E learning model on salt hydrolysis learning. This research was conducted in first semester of 2016/2017 academic year. There are 36 students of year XI in MIPA 5 was involved in the study. This qualitative research was conducted with the data collection of writing-drawing technique, in-depth interviews, classroom observation, student journal reflective. The Miles and Huberman data analysis was employed with quality standards of data reduction, display data, and verification. Class observation conducted before and after the learning Cycle 8E was implemented for understanding, the characteristics of students and classroom learning environment. The interview technique was conducted to have deep understanding the students’ mental model. The result showed that the students developed understanding on the concept of hydrolysis reaction process and pH of salt solution which were generated categories of understanding, not understanding, and misconception. The three categories are seen from the four stages of the learning Cycle 8E which are explore, elaborate, extend, and explain. students’ understanding and mental model development are influenced by the learning environment and prior knowledge. This model also has developed students’ soft skills of empathy communication, critical thinking and collaboration skills.&#x0D; Keyword: Chemistry Education, Mental Model, Salt Hydrolysis, Learning Cycle 8E

Application of polyethylene glycol based aqueous two-phase systems for extraction of heavy metals

Abstract In this work the partitioning behavior of Hg(II), Zn(II) and Co(II) was measured in a polyethylene glycol based aqueous two phase system (PEG–ATPS) containing Na 2 CO 3 as a phase forming salt. The experiments were performed by mixing equal weights of 30% ( w /w) PEG–6000 solution and 10% ( w /w) Na 2 CO 3 solution. The partitioning of ions was studied at various concentration of iodide as extracting agent, stock salt solution pH, temperature and initial metal ion concentration. The experimental results showed that extraction of metal ions mainly depends on concentration of iodide. In the other words the extraction of metal ions increases as the amount of iodide ions increases. It was observed that the extraction of mercury increases as pH increases, while in the case of zinc and cobalt it was insignificant meanwhile temperature has a minor effect on metal ions extraction. In this work the maximal extraction percentages of Hg(II), Zn(II) and Co(II) were obtained as 99.3%, 98.62% and 58.2%, respectively.

Fouling reduction and retention increment of polyethersulfone nanofiltration membranes embedded by amine-functionalized multi-walled carbon nanotubes

Flat sheet asymmetric amine-functionalized multiwalled carbon nanotubes (NH2-MWCNTs)/polyethersulfone (PES) nanocomposite nanofiltration membranes with different nanofiller contents were prepared by the phase inversion method. The characteristics of the mixed matrix membranes were analyzed by SEM, AFM, contact angle and zeta potential measurements. The performance of the membranes was evaluated in terms of pure water flux (PWF), static protein adsorption and bovine serum albumin (BSA) filtration. Results showed that the hydrophilicity and PWF of the nanocomposite membranes were enhanced with increase of NH2-MWCNTs dosages. Increasing the nanotube dosages from 0wt% to 0.045wt% led to increase of PWF from 13.6 to 23.7L/m2h. The SEM images illustrated that the fabricated membranes possessed a typical asymmetric finger-like structure. The salt rejection experiments and zeta potential measurements evidenced that the surface charge of the NH2-MWCNT embedded membranes was negative and the retention mechanism of the solutes was mainly the Donnan exclusion mechanism. The salt retention sequence for 0.045wt% NH2-MWCNT was Na2SO4 (65%)>MgSO4 (45%)>NaCl (20%) after 180min filtration. The increase of the salt solution pH caused more negative surface charge and higher retention. The addition of the modified MWCNTs, in BSA filtration analysis, led to significant improvement of the fouling recovery ratio (FRR) due to lower roughness, more negatively charged surface and higher hydrophilicity of the membrane surface.

Selective extraction of Hg(II), Cd(II) and Zn(II) ions from aqueous media by a green chemistry procedure using aqueous two-phase systems

A simple aqueous two-phase systems of polyethylene glycol (PEG)/sulphate salt (Na2SO4 or (NH4)2SO4) was proposed for the selective extraction of Hg(II), Cd(II) and Zn(II) ions from aqueous media, in presence of iodide as extracting agents. The extraction efficiency of metal ions from salt-rich phase to the polymer-rich phase was investigated as a function of the amount of added iodide extractant, nature of inorganic sulphate used as phase-forming salt, the volume ration between phases of aqueous two-phase system and the pH of salt solution. Maximum extraction efficiency of considered metal ions was obtained in the aqueous polyethylene glycol/ammonia sulphate two-phase system and a volume ration of the phases equal with 1.0. On the other hand, in mentioned experimental conditions, at iodide concentration higher than 0.06molL−1, the Hg(II) ions are quantitatively extracted (>99%) into polymer-rich phase, at all studied values of salt solution pH, while a quantitative extraction of Cd(II) ions was obtained only in strong acid media (salt solution pH lower than 3.0). The extraction efficiency of Zn(II) ions is insignificant (<15%) for all values of salt solution pH and iodide concentration added as extractant, they preferring to remain in the salt-rich phase of extraction system. Therefore, by adequate selection of the experimental conditions, and efficient and selective extraction of these metal ions could be obtained, and a separation procedure in two steps is proposed. The separation factors calculated for each case (SHg/Cd=(1.48±0.13)×103; SHg/Zn=(2.99±0.21)×103 and SCd/Zn=(3.16±0.17)×103, respectively) indicate that the proposed procedure is efficient and has a large viability for the selective extraction of Hg(II) and Cd(II) ions in presence of Zn(II) ions. In addition, this extraction procedure has the main advantage that is environmental safe.

Zeta Potentials of Suspended Humus in Multivalent Cationic Saline Solution and Its Effect on Electro-Osomosis Behavior

The surface electrical charge was measured for laboratory grade organic soil colloidal particles by varying pH between 2 and 11 and at 0.001, 0.01, 0.1, and 1.0 mol/L of cationic saline solution (CaCl2, Na2Sio3, Al2(SO4)3, MgCl2, and Na2CO3) concentrations. The zeta (ζ) potential values showed low sensitivity to pH in salt solutions. The ζ potential of pure organic soils varied from +7.5 mV at pH 2.8 to −28.5 mV at pH 11.3. The ζ potential calculation of humus particles in distilled water showed an increase in ζ potential value beyond pH > 3.3, which could be due to charge development at the humic substances by direct transfer of H+ from organic soil to water. The surface electrical charge was almost zero at pH 3.25. Colloidal charge reversal was observed at several stages according to the electrolyte concentrations and chemical reagents. It was also found that using high molarities of multivalent saline solution (e.g., CaCl2, Na2Sio3, Na2CO3, and MgCl2) as electrolytes led to very high ζ potential values and consequently high electro-osmotic conductivity (Ke). On the basis of the results of this research, it is recommended that the ζ potential of the soils be determined before any application of electrokinetic (EK) treatment.

Comparison Study of Zeta Potential Values of Bentonite in Salt Solutions

The electrokinetic mobility (EM) was measured and then zeta potential (ZP) was calculated for laboratory grade bentonite particles by varying pH between 4 and 10 and at 0.001, 0.01, and 0.1 M salt (NaCl, Na2SO4, LiCl, KCl, and CaCl2) concentrations. In all tests, bentonite particles displayed a negative zeta potential. No charge reversal was observed at any stage. The ZP values showed low sensitivity to pH in salt solutions. Zeta potential calculation of bentonite particles in distilled water showed an increase in ZP value beyond pH >8, which could be due to charge development at the edges by direct transfer of H+ from clay to water. For all salts, at a concentration of 0.1 M, and for all tested concentrations of CaCl2, bentonite particles showed a zero zeta potential. For NaCl and Na2SO4, at 75, 200, and 325 mg/L bentonite particle concentrations, increasing the salt concentration from 0.001 to 0.01 M did not affect the ZP value of the bentonite particles. For the same cation such as Na+, the presence of monovalent anions (Cl−) or divalent anions (SO4 −2) did not affect the zeta potential value of the clay for the tested conditions. In salt solutions containing common anions but different cations (LiCl, NaCl, and KCl), bentonite particles displayed a higher ZP value for NaCl than KCl, whereas no ZP difference was observed for bentonite particles in LiCl and NaCl at the experimental conditions.