Environmental effects on the stable carbon and oxygen isotopic compositions and skeletal density banding pattern of Porites coral from Khang Khao Island, Thailand

The timing of band formation and linear skeletal growth rate based on environmental changes were investigated using alizarin red S (ARS) in Porites lutea coral at Khang Khao Island, the Gulf of Thailand from November 10, 1999 to March 15, 2001. The X-radiograph of the vertical section of the Porites coral skeleton was examined and three pairs of density bandings including intermediate bandings were observed in one year, suggesting that additional factors other than sea surface temperature (SST) were associated during the process of band formation. We assumed that variation of salinity variations, nutrition/sedimentation load and light intensity may control the process of density band formation which may be influenced by the river run-off due to heavy rainfall. The coral skeleton was analyzed and measured from top to a depth of 47 mm by mass spectrometry and three cyclic changes in both oxygen and carbon isotopic values which reveal the abrupt changes of aquatic environment was observed. By using isotopic compositions, X-radiography and analyzing ARS line, the average annual growth rate of the Porites coral was inferred at ~17.91 mm/year. Our results demonstrate that the density bands of coral and perhaps a useful proxy of extension rate could also be a potential indicator for reconstructing the past SSTs in rain-infested areas like the upper Gulf of Thailand.Keywords: Oxygen isotopes, carbon isotopes, Porites coral, density bands, skeletal growth, sea surface temperature, salinity, Khang Khao, Gulf of ThailandAfrican Journal of Biotechnology Vol. 9(33), pp. 5373-5382, 16 August, 201

Prospek Model Daur Belajar 5 Fase terhadap Keterampilan Proses Sains dan Kemampuan Berpikir Kritis Siswa pada Materi Termokimia

Materi termokimia mencakup konsep-konsep yang bersifat abstrak, algoritmik, dan saling berhubungan satu sama lain sehingga siswa mengalami kesulitan dalam memahaminya. Selain itu, proses pembelajaran kimia selama ini cenderung menggunakan model pembelajaran konvensional. Model pembelajaran ini lebih menekankan pada hasil belajar kognitif, namun tidak memperhatikan aktifitas keterampilan proses sains dan kurang melatih kemampuan berpikir kritis siswa. Dengan demikian, diperlukan model pembelajaran yang mampu meningkatkan keterampilan proses sains dan kemampuan berpikir kritis siswa yaitu menggunakan model daur belajar 5 fase. Kajian ini bersifat deskriptif dan berbasis literatur yang bertujuan untuk mengetahui prospek model daur belajar 5 fase terhadap keterampilan proses sains dan kemampuan berpikir kritis siswa

Characterization of Prigi South Coast Coral and Its Development as Adsorbent of Nickel Ions

The abundance of dead coral reefs or coral skeleton around the coast of Prigi Beach has the potential to be abundant and used as an adsorbent to reduce nickel content. Nickel in high concentrations can cause water pollution problems. It is urgently needed for the development of adsorbents at this time. This study aims to determine the characterization of coral adsorbents using XRF, SEM, and FT-IR and to then determine the optimization of the size and contact time of corals in the nickel ion adsorption process. The stages of this research consisted of taking coral samples at Prigi beach, production coral adsorbents using the pyrolysis method, coral activation process, characterization of corals with XRF, FTIR and SEM and application of coral adsorbents for nickel metal ion adsorption. The FT-IR results show the O-H vibration of the carboxylate group at a wave number of 3232.70 cm-1, aliphatic C-H bending vibration at a wave number of 2916.37 cm-1. Strain vibrations at wave number 1788.01 cm-1 are associated with C=O ketones and in the range 1247.94 cm-1 indicate C-O strain vibrations. SEM analysis found that corals had a rough morphology and the presence of micropores. The adsorption efficiency showed that the adsorbent at 200 mesh size was able to absorb the highest nickel ion of 84.52% with a contact time of 168 hours

The effect of silica and carbon as modified of calcium-alginate membrane for desalination

In order to improve the performance of the calcium alginate membrane, we modified it to add the silica and carbon as the potential to absorb NaCl as the desalination materials. The novelty of this study, the natural resources of coral skeletons, beach sand, and the mangrove leaves were utilized as the source of Ca, Si and C for membrane fabrication, respectively. The results indicate the calcium alginate-carbon membrane with its mangrove leaves as the activated carbon proved effective to reduce salt levels. FTIR analysis of this membrane revealed the presence of functional groups like -OH, C=O, and C-O as the evidence to absorb NaCl. The SEM analysis displayed a rugged membrane surface with an average particle diameter of 347.98 nm. This membrane was capable of adsorbing approximately 49.05%/20-minutes and 46.7%/30-minutes of Na+ and Clˉ ions with 0.05 grams of activated carbon, respectively. The calcium alginatesilica analysis also indicated the presence of functional groups (-OH, C=O, C-O, Si-O, and Si-OH) facilitating the NaCl binding process. Additionally, SEM analysis depicted a porous structural morphology with a particle size diameter of approximately 16192.78 nm. This membrane was capable of adsorbing approximately 55.04%/20-minutes and 49.4%/40-minutes of Na+ and Clˉ ions with 0.05 grams of activated carbon, respectively. The comparison between the two membranes revealed significant differences in their NaCl ion absorption capacities. The calcium alginate-silica membrane tended to exhibit slightly higher absorption capacity compared to the calcium alginate-carbon membrane under the specified optimal conditions

Learning, Teaching, and Demonstration of Unique Chemistry for the Indonesian Generation at Sanggar Bimbingan Mulia, Kuala Lumpur Malaysia

As a form of concern for the issues faced by the descendants of Indonesian nationals in Malaysia, especially for the Human Resources, we provide the unique theoretical and practical chemistry mentorship for future capability. Sanggar Bimbingan Sungai Mulia 5 is an organization that offers educational services for Indonesian descendants whose citizenship status is still unclear due to administrative reasons. Based on the Chemistry Department UM and Sanggar Bimbingan Mulia cooperation, It is important to enhance the nation's intellectual capacity, especially in ensuring the success of the mandatory 9-year education program. This community service aims to combat illiteracy, in still character education, and prepare students for higher education. The expected outcomes of this program is a unique chemistry Massive Open Online Course (MOOC), a service article published, a service report, and a poster. Our program successfully developed the interest of children to love a simple chemistry experiment and improved for reading and learning through various MOOC, books, and educational materials

Chemistry Study and Entrepreneurship Program for the younger generation at Sanggar Bimbingan Sentul, Kuala Lumpur Malaysia

Permasalahan yang dihadapi putra-putri Warga Negara Indonesia (WNI) di Malaysia adalah kesenjangan sosial, akses terhadap pendidikan, dan rasa keterlibatan masyarakat. Sanggar Bimbingan Sentul sebagai mitra menyediakan fasilitas belajar bagi anak-anak WNI untuk menyelesaikan tiga permasalahan utama tersebut. Kami menggagas penerapan program MAWIRAKI (Matahari Kewirausahan Kimia) dengan program studi kimia dan kewirausahaan melalui hibah Pengabdian Kemitraan Luar Negeri (PKLN) Universitas Negeri Malang (UM). Program ini terintegrasi dengan pelatihan komputer dengan program MS-Word dan Paint, eksperimen kimia kehidupan sehari-hari, dan seni kerajinan batik. Hasil proses pembelajaran anak-anak WNI menunjukkan bahwa 18 orang siswa menyukai program Paint dan 10 orang siswa menyukai program MS Word pada saat pelatihan komputer. Eksperimen "Di Mana Vitamin C" mendapat dukungan dari 17 siswa, yang menyoroti minat dalam studi kimia. Kegiatan tersebut melibatkan batik ecoprint dan jumput yang mendapat respon positif, 15 siswa menyukai batik jumputan dan 11 siswa memilih batik ecoprint. Data minat anak-anak WNI selama proses pembelajaran sebagai landasan dan semangat kami mengembangkan program untuk menggali potensi kewirausahaan dan kreativitas generasi muda

Surface Behavior of Rhodamin and Tartrazine on Silica-Cellulose Sol-Gel Surfaces by Thin Layer Elution

Physical and chemical interactions are the principles for different types of separation systems as the equillibrium dynamics on surface plays a key-role. Surface modification is a way for selective separation at interfaces. Moreover, synthesis of gel silica by a sol-gel method is preferred due to the homogeneity and surface feature easily controlled. Cellulose can be added in situ to modified the silica features during the process. Further application for to study interaction of rhodamin and tartrazine in its surface and their solubilities in mobile phase explains the possibility for their separation. This paper devoted to evaluate the surface behavior in term of adsorption and desorption of tartrazine and rhodamin on silica-cellulose thin layer in different mobile phase. Some carrier liquids applied such as methanol, acetone, n-hexane and chloroform. The result proves tartrazine and rhodamin is separated and have different behavior in different mobile phase. The retardation factors (Rf) of the mixtures suggest complexity behavior on silica-cellulose surface

Surface Behavior of Rhodamin and Tartrazine on Silica-Cellulose Sol-Gel Surfaces by Thin Layer Elution

Physical and chemical interactions are the principles for different types of separation systems as the equillibrium dynamics on surface plays a key-role. Surface modification is a way for selective separation at interfaces. Moreover, synthesis of gel silica by a sol-gel method is preferred due to the homogeneity and surface feature easily controlled. Cellulose can be added in situ to modified the silica features during the process. Further application for to study interaction of rhodamin and tartrazine in its surface and their solubilities in mobile phase explains the possibility for their separation. This paper devoted to evaluate the surface behavior in term of adsorption and desorption of tartrazine and rhodamin on silica-cellulose thin layer in different mobile phase. Some carrier liquids applied such as methanol, acetone, n-hexane and chloroform. The result proves tartrazine and rhodamin is separated and have different behavior in different mobile phase. The retardation factors (Rf) of the mixtures suggest complexity behavior on silica-cellulose surface

Optimasi pH dan Konsentrasi Elektrolit dalam Elektrokoagulasi Limbah Surfaktan

Surfactants are organic materials that act as active ingredients in detergents, soaps and shampoos which can reduce the surface tension of the water so that the particles attached to the materials being washed are released and float or dissolved in water thus polluting the environment. Therefor it is necessary to separate or change them into other harmless materials before being discharged into the environment. One of the methods used is electrocoagulation. The electrocoagulation method is an environmentally friendly method of treating liquid waste by combining the principles of coagulation, flotation and electrochemistry. In this study, the electrocoagulation method was carried out by varying pH and electrolyte concentrations in the simulated surfactant waste treatment. Surfactant levels were determined by spectrophotometer in methylene blue. The optimization of the method is done by determining the maximum absorption length, optimum pH, and the effect of adding electrolytes with different concentrations. The results showed that the maximum absorption at a wavelength of 659 nm. The electrocoagulation process runs optimally at pH 2 with the addition of 7mM Na2SO4 electrolyte resulting in a% removal of 65%