Removal of Rhodamine B from Aqueous Solution on to Modified Jack Wood Sawdust:A Comparative Study

Among many environmental pollutants, dyes releasing from industries play a major role in contaminating the aquatic environment. Most of the dyes are non biodegradable, stable and carcinogenic due to their synthetic nature and aromatic structure. Therefore it is necessary to reduce the pollution load including decolourization of industrial effluents before disposal. Though the adsorption on to commercial activated carbon is a promising method, it is expensive. The present study was carried out to investigate the possibility of using a low cost adsorbent for the removal of carcinogenic dye, Rhodamine B in a more effective manner.Three different forms of sawdust, formaldehyde treated sawdust (SD), base treated sawdust (BTSD) and acid activated charred sawdust (AASD) were prepared and used for the removal of Rhodamine B from an aqueous solution. Batch experiments were carried out to investigate the potential efficiency of the three forms of sawdust to remove Rhodamine B from the aqueous solution as a function of the initial Rhodamine B concentration, Contact time and temperature. Equilibrium was found to be attained at about 30 min, 50 min and 60 min respectively for SD, BTSD and AASD. Based on Langmuir isotherms, the maximum adsorption capacity was found to be 319.5 mgg-1 at 60˚C for AASD among three different forms of sawdust.Various isotherms and kinetic models were fitted to describe the adsorption process and the activation parameters were evaluated in all three types of sawdust. Kinetic data of all three types of sawdust were well fitted for the second order rate model. Based on Langmuir, Frendlich and D-R isotherms, a better adsorption capacity was obtained for the AASD adsorbent compared to SD and BTSD. Thermodynamic parameters suggest that the adsorption of Rhodamine B onto all three type of adsorbent is spontaneous and the process is physisorption. SEM images revealed that AASD has more porous and irregularities in the surface which makes it a better adsorbent. IR spectral data reveal the disappearance of many functional groups in AASD adsorbent compared to SD and BTSD.Keywords: Rhodamine B, Kinetics, Equilibrium, Iisotherms, Modified jackwood sawdus

SUITABILITY OF ATTANAGALU OYA AS A DRINKING WATER SOURCE

Attanagalu oya basin is situated between the two major river basins Kelani and Maha Oya .It plays amajor role in national water supply since it contains major national water supply and drainage boardintakes. This study intends to study the quality of water of the Attanagalu Oya and its suitability fordrinking purpose. Because of its significance as a drinking water source it is important to maintain thequality of the water. Samples were collected from ten selected sampling locations along the main riverincluding one near the origin of the river, near the sea outfall, NWS&DB intakes from the main river.Other locations were selected so as to have the similar distance between sampling locations Samplingwas taken during both high and low flow rate conditions. Analysis was done on physical, chemicaland biological parameters.Results showed that records of COD, BOD, DO, pH, nutrient are low during the high flow rate whilethe levels of turbidity, metal iron total coliform and faecal coliform are high during the high flow rate

Hydrilla verticella as a carbon capturing plant

Global warming is a threatening problem to the entire world. As a proactive measure, scientists are developing new techniques to reduce CO2 emission to the atmosphere. Carbon capture and long time storage is a relatively new concept even though it is not economically feasible. Hence scientists have now focused on CO2 capture technology utilising salt water alga.In the present study, CO2 capturing rates of salt water algal plants Ulva fasciata, Caulerpa racemosa, Sargassum cervicone, Chaetomorpha spp, Padina spp, Corallina spp and Gracilaria spp. which are found in the ocean surrounding Sri Lanka were measured. However, it is very difficult to mimic the natural physical conditions inside the laboratory. Therefore an attempt was made to capture CO2 using an aquatic plant found in fresh water. Hydrilla verticella is an aquatic, invasive plant to Sri Lanka with a high growth rate. The CO2 capturing rate of Hydrilla verticella was compared with other salt water algal plants.When carrying out the experiment for salt water algae, the initial pH was reduced to 5 by pumping CO2 in to a fixed volume of salt water and then 30g of the specimen was placed and the variation of pH was measured with time. A Similar procedure was carried out with Hydrilla verticella by pumping CO2 in to distilled water. A control was kept under similar conditions without the specimen for each case. Ulva fasciata showed highest CO2 capture rate and Hydrilla verticella was second best. Hydrilla verticella was chosen as it is easy to manipulate for this study. The graph plotted between pH and time for Hydrilla verticella exhibited a typical photosynthetic pattern found in other plants.In this research, main parameters that have been investigated were on the salinity of the medium and the photoperiod to enhance the CO2 capture rate of Hydrilla verticella. Different salinity levels were obtained by adding different quantities of NaCl (10, 20, 30 ….70 g) in to one liter of distilled water. Results showed that this plant is adaptable to very different levels of salinity but the optimum salinity range is 10-20 gdm-3. Photoperiod was determined by exposing the samples to sun light over varying periods (0, 4, 8, 12 hrs) of time. Results showed that maximum activity was seen when exposed to 12 hrs of sunlight yet it is interesting to note that it can capture CO2 even under very low light intensities; even during night time when other plants respirate. CO2 capturing rate was the highest when the pH of the medium was in between 5-7.The concept of carbon credits came into existence as a result of increasing awareness of the need for controlling green house emissions. There are many companies that cell carbon credit to commercial and individual customer who are interested in lowering their carbon foot print on voluntary basis, hence above technique which is economically feasible can be implemented in order to mitigate global warming by reducing CO2 emission

Biodegradability Assessment of Bio-based Film Products (Lunch Sheets) in the Marine Environment

Plastic pollution is a current common problem and it causes a serious impact on the marine environment. Micro debris of plastics have accumulated in oceans and exhibit a natural tendency to interrelate with the ecosystem which can cause negative effects on both humans and animals. Polythene food wrappers are used worldwide as a packaging material. Considering the negative impact of polythene wrappers, biodegradable food wrappers have been produced in Sri Lanka following the Section 23 W of the National Environmental Act. The objective of the study was to determine the biodegradability of few bio-based film products (lunch sheets) available in the Sri Lankan market labeled as 100% biodegradable in the marine environment. The biodegradability of five different brands of biodegradable food wrappers were tested together with cellulose paper as the positive control and non-biodegradable food wrapper as the negative control in the marine environment. Laboratory models of three marine environments; inter tidal zone, pelagic zone and brackish water were selected and the biodegradability for a period of six months were tested using weight measurement and FT-IR analysis. Furthermore, several environmental parameters were tested for these three marine zones. Results indicated that the highest percentage weight loss was shown by brand 3 in all three marine environments. In the pelagic zone, percentage weight loss ranged from 8.60-48.92% while highest value of 48.92% was shown by brand 3. In the brackish water environment, brand 3 showed 73.51% of percentage weight loss and values ranged from 11.76-73.51%. The percentage weight loss, ranged from 68.29-89.99% in inter tidal zone and brand 3 showed the highest value as 89.99%. All the samples showed a considerable weight loss after six months duration in inter tidal zone compared to other zones and even the negative control has undergone physical disintegration. It is assumed that oxo-biodegradation leads to this disintegration in the food wrappers in this zone. The FT-IR results have shown that there is no significant degradation of the non-biodegradable food wrapper (negative control) while the cellulose paper (positive control) and the biodegradable food wrappers have undergone a considerable degradation. Keywords: Biodegradability, Food wrappers, Marine environmen