Adsorption and coagulation in wastewater treatment – Review

Wastewater issues became a complex challenge in the world. There are several methods in wastewater treatment, such as chemical, physical, biological, and the combination of each method. However, each process has advantages and disadvantages. The physicochemical methods are common methods used in wastewater treatment, such as adsorption and coagulation. Adsorption and coagulation are excellent methods to remove pollutants. The adsorption process is greatly influenced by pH, adsorbent dose, temperature, and contact time. Coagulant dose, settling time, and pH are the main factors in the coagulation process. Chemical material as an adsorbent and coagulant has been studied in previous research, but recently, to substitution chemical materials is a challenging subject. Natural substances are potential new materials in wastewater treatment and became popular due to their efficiency and environment friendly characteristics. This review investigated the role of adsorption and coagulation in wastewater treatment and the utilization of natural materials as adsorbents and coagulants.

Pengembangan E-Modul Berbasis Inkuiri Terbimbing Terintegrasi Virtual Laboratory pada Materi Asam Basa Kelas XI SMA atau MA

Acid and base are a chemical material that contains facts, concepts, principles and procedures. This research aims to produce an e-module based on guided inquiry integrated virtual laboratory on acid-base material which is valid and practical. The development model used is the 4-D model. The validity test of the e-module was carried out by experts, namely 2 UNP chemistry lecturers, 1 UNP educational technology lecturer and 2 chemistry teachers, while the practicality test was carried out by 2 chemistry teachers and 18 students of SMAN 3 South Solok. The research instrument used was a validity questionnaire and a practicality questionnaire. The results of the validity and practicality test were analysed using the Aiken V formula, which obtained an average validity test with the high validity category, and the practicality test by teachers and students with high practicality categories. The result of the analysis of the answer to the e-module obtained an average the correct answer of 91,07 percent on the key questions, 92,38 percent on the worksheets and 91,9 percent on the evaluation sheets. Based on the research result, it can be concluded that the acid-base e-module is valid and practical.

Development of MISTION Software to Detect and Reduce Students' Misconception with Conceptual Change Text Strategy on Stoichiometry Materials

Misconceptions often occur, especially in chemical material like stoichiometry which are full of abstract concepts. The purpose of this study was to determine the feasibility of mistion software to detect and reduce misconceptions in stoichiometric material with conceptual change text strategy. This research was conducted using the Research and Development (R&D) method with 15 students of SMAN 1 Gedangan as research subjects. Software is developed using Adobe Flash CS 6 with action script 3.0. The software's feasibility is viewed from the validity practicality, and effectiveness. The data analysis results show that 1) the software is very valid with the average result of content validation is 93.52%, and the construct validation is 91.82%. 2) The software is very practical, with an average result of student response questionnaires is 95.28% and supported with the average result of student observations is 85%. 3) Software is effective with the average result of misconception shift for sub-concept basic chemical law is 77.27% with effective category, sub-concept of reaction equation is 85.05% with very effective category, and sub-concept of mole is 73,72% with effective category. Based on the result, we can conclude that mistion software is feasible to detect and reduce students' misconception.

Estimating mouthing exposure to chemicals in children’s products

Background Existing models for estimating children’s exposure to chemicals through mouthing currently depends on the availability of chemical- and material-specific experimental migration rates, only covering a few dozen chemicals. Objective This study objective is hence to develop a mouthing exposure model to predict migration into saliva, mouthing exposure, and related health risk from a wide range of chemical-material combinations in children’s products. Methods We collected experimental data on chemical migration from different products into saliva for multiple substance groups and materials, identifying chemical concentration and diffusion coefficient as main properties of influence. To predict migration rates into saliva, we adapted a previously developed migration model for chemicals in food packaging materials. We also developed a regression model based on identified chemical and material properties. Results Our migration predictions correlate well with experimental data (R2 = 0.85) and vary widely from 8 × 10−7 to 32.7 µg/10 cm2/min, with plasticizers in PVC showing the highest values. Related mouthing exposure doses vary across chemicals and materials from a median of 0.005 to 253 µg/kgBW/d. Finally, we combined exposure estimates with toxicity information to yield hazard quotients and identify chemicals of concern for average and upper bound mouthing behavior scenarios. Significance The proposed model can be applied for predicting migration rates for hundreds of chemical-material combinations to support high-throughput screening.

Environmental Method for Synthesizing Amorphous Silica Oxide Nanoparticles from a Natural Material

Numerous studies have been performed on the generation of several silicon-based engineering materials that often have used chemical materials that have high risks for health and the safety of the environment. Generally, in the synthesis of Nano-silica, tetramethoxysilane, tetraethoxysilane, and tetraethyl orthosilicate (TEOS) are used as precursor materials; however, these materials are toxic and expensive for the production of Nano-silica. This paper presents an environmentally friendly short method (EFSM) with high efficiency for the synthesis of amorphous silica oxide Nanoparticles by using agricultural waste called rice husks (RHs). Use of the EFSM method as an alternative to the chemical methods would have the advantages of fast and simple operation, controllability, great pureness of the Nanoparticles, and low manufacturing cost. A Nanoparticles (NPs) evaluation was conducted with energy-dispersive spectroscopy (EDS), field emission scanning electron microscope (FESEM) and X-ray fluorescence (XRF). By applying the EFSM method, non-toxic amorphous silica nanoparticles with a purity of 94.5% and particle size less than 100 nm was synthesized without using any chemical material.

Working and knowing in technology-mediated environments

Comprehensions of how technology-mediated environments work are marked by a lack of theoretical sophistication about how expertise emerges and develops. Using a practice-based approach to workplace learning and knowing, a case of telecardiological consultation is discussed, where a dedicated call center works by connecting general practitioners (GPs) with remote cardiologists. The service allows GPsto send electrocardiogram traces (ECGs) and discuss the needs of patients with a cardiologist. The role of materials (ECG traces, the recording machine, infrastructure), and communication (synchronous communication in the form of a phone call) are considered in the practical application of the service. It is argued that being an expert telecardiologist entails the ability to align heterogeneous elements, and co-construct, a reliable interpretation of the patient’s situation alongside a doctor. To do that when the situation is not immediately clear, necessitates both doctors discursively mobilize different bio-physiological, chemical, material, social and psychological aspects of a patient’s condition, in order to arrive at a reliable interpretation. Thanks to a practice-based sensitivity, I analyze the case study reading these interactions as competent material-discursive practices.