Use Of Inorganic Chemicals Research Articles

Towards the Biobeneficiation of PGMs: Reviewing the Opportunities

Conventional beneficiation of the Platinum Group of Metals (PGMs) relies on the use of inorganic chemicals. With the depreciation of high grade deposits, these conventional processes are becoming less economically viable. Furthermore, the use of chemicals has serious negative impacts on the environment. To address the challenges of conventional PGM beneficiation, biobeneficiation has been proposed. In conventional flotation, the flotation behavior of the associated sulphides determines overall PGM recovery. The same principle may also be applied for the bio-beneficiation of PGMs. Therefore, this paper discusses the biobeneficiation behavior of sulphides closely associated with PGMs with the aim of postulating the bio-beneficiation behavior of PGMs associated with the same base metal sulphides. Conventional PGM processes are briefly discussed, as bio-beneficiation of PGMs is governed by similar underlying principles. Potential microorganisms for the biobeneficiation of PGMs are highlighted, as well as the corresponding conditions for their effectiveness. The use of both single cultures and mixed cultures is discussed. Depending on conditions, PGMs associated with pyrite and/or chalcopyrite were projected to be biofloatable with B. polymyxa, P. polymyxa, A. ferrooxidans, L. ferrooxidans, B. pumilus, B. subtilis, halophilic bacteria, Alicyclobacillus ferrooxidans, sulphate reducing bacteria, and mixed cultures of A. ferrooxidans, A. thiooxidans and L. ferrooxidans. Pyrite-associated PGMsare expected to be generally prone to biodepression, whereas chalcopyrite-associated PGMs are expected to be generally recovered as the floatable phase. Sulphate-reducing bacteria were reported to have a dual role on the bioflotation of sulphide ores (flotation and depression), depending on the conditions. Therefore, this type of microorganism may serve as both a depressant or a collector in the recovery of PGMs. Based on the bioflotation response of pyrrhotite to L. ferrooxidans, it is anticipated that pyrrhotite-associated PGMS can be biodepressed using L. ferrooxidans. In terms of bioflocculation, PGMs associated with chalcopyrite may be recovered using L. ferrooxidans, whereas A. ferrooxidans, A. thiooxidans, B. polyxyma and B. subtilis can be used in the bioflocculation of pyrite-associated PGMs. M. phlei can be employed in the reverse bioflocculation of pyrite-associated PGMs. Although no information was found on the biobeneficiation of pentlandite, postulations were made based on other sulphide minerals. It was postulated that biobeneficiation (biodepression and bioflotation) with pentlandite-associated PGMs should be possible using A. ferrooxidans. It is also projected that sulphate-reducing bacteria will be suitable for the bioflotation of PGMs associated with pentlandite. The removal of gangue species such as silicates and chromites associated with PGM concentrates was also discussed. A. ferrooxidans, P. polymyxa and B. mucilaginous are candidates for the removal of gangue species. Furthermore, the need to control process conditions was highlighted. The most suitable conditions for biobeneficiation of the various base metal sulphide minerals associated with PGMs are presented in the paper. Most of the challenges associated with biobeneficiation of PGMs are already common to conventional methods, and the means of circumventing them are already well established. Developments in genetic engineering and the advent of new data science techniques are tools that could make the biobeneficiation of PGMs a possibility.

Near‐term challenges for global agriculture: Herbicide‐resistant weeds

AbstractPrior to the 1950s, weeds were controlled by a wide variety of mechanical and cultural methods with limited use of inorganic chemicals at very high rates (100s kg ha–1). With the advent of selective carbon‐based herbicides in the 1950s, herbicide weed management became the norm throughout much of the world, using grams to a few kilograms of active ingredient per hectare. However, with the benefits, there are problems. A few resistant weeds were recognized in the 1970s, but in 2021, 521 unique cases of resistance have been documented throughout the world. It is imperative for farmers to rethink the herbicide paradigm and for researchers to explore and provide alternative weed management methods so that today's herbicides maintain efficacy and benefits into the future. Near‐term management strategies include going back to more integrated approaches, using mechanical techniques, and linking to new technologies to hit weeds with “many little hammers” rather than the “sledge hammer” of one or multiple herbicides.

A review on the use of plant seeds in water treatment

Global population, which has been estimated by United Nations to hit 9.8 Billion by the middle of this century and the corresponding demand for clean, affordable and portable water, which is not readily available, especially for developing countries and even developed ones, has become a course for concern. It is estimated that 1.2 billion people lack access to clean drinking water and about 2.2 million people die annually, mostly of children under five due to consumption of unsafe water. The use of inorganic chemicals in treating water is fast becoming problematic, as it is associated with different deteriorating human health condition and pollution of water bodies. Simple to complex methods are involved in this, but the general procedure involves, collection of plant seeds, drying, grinding/extraction of active compounds and its application in water sample.

Pertanian Organik sebagai Salah Satu Konsep Pertanian Berkelanjutan

Excessive use of inorganic chemicals results in adverse impacts on land and plants. In the midst of the community, there is anxiety about the high content of pesticide residues in agricultural products. There is a need to develop alternative farming systems that are able to produce quantities and quality of healthy products in a sustainable manner. One agricultural system that supports the concept is the organic farming system. The basic principles of organic farming are: (1) Keeping the ecosystem healthy, (2) Applying the principle of efficiency to the cultivation system, (3) Conducting production activities with the concept of sustainable agriculture, (4) Producing pesticide-free products, and (6) Maintaining environmental sustainability. Food Crop Production Study Program Lampung State Polytechnic makes Organic Agriculture as one of the leading competencies for its graduates. The establishment of the Organic Agriculture Business Unit on campus will increase student competencies, foster entrepreneurship, be a place for competency internships, and as an independent source of income.

Potential of native cold tolerant plant growth promoting bacilli to enhance nutrient use efficiency and yield of Amaranthus hypochondriacus

Background and aims Amaranth is an important underutilized crop with high nutritional value but due to acidic soils and low nutrient availability, its production is low in Uttarakhand hills. Use of inorganic chemicals is restricted as they may disturb the fragile Himalayan ecosystem. Therefore, native cold tolerant Bacillus spp. isolates were used to assess their effect on growth and yield enhancement in amaranth.

Life cycle environmental and economic assessment of ceramic tile production: A case study in China

Abstract Ceramic tiles are important building materials, but their production consumes large amounts of energy and raw materials and causes serious pollution. In this study, a cost combined life cycle assessment is conducted to quantify the environmental and economic impacts of ceramic tile production from cradle to gate and identify the key substances and processes to eliminate production issues. Results show that marine ecotoxicity, climate change, terrestrial ecotoxicity, human toxicity, and fossil depletion are the key environmental impact categories. Key substances include chlorine in soil, sulfur dioxide in air, and carbon dioxide in air. The total economic cost is $2.77/m2, and this cost mainly originates from raw materials. Inorganic chemicals used as raw materials account for general environmental (12.9%) and economic (39.6%) burdens. Application of alternative electricity generation types, such as hydropower as a replacement for coal power, can reduce the impacts on climate change and marine ecotoxicity by 98.4% and 96.4%, respectively, during the electricity generation stage. An environmental and economic win–win situation can be achieved by reducing the use of inorganic chemicals, coal, and electricity and optimizing the transport of raw materials.

The factors affecting chemical use in aquaculture in the Central Coast Region of Vietnam

AbstractUsing the econometric approach of Ordinary Least Squares, this study has identified the key factors affecting the use of inorganic chemicals in coastal aquaculture in South Central Vietnam. These factors included the amount of training and support policies for extensions and the level of participation by cooperative groups in aquaculture activities. The greatest impact factor to the use of inorganic chemicals in aquaculture was “Fishery Extension Support Policy Group” by −0.747. This value means that if the remaining variables do not change and this variable increased by one unit (meaning that an increasing in support including capital, machinery, the consultants, seed for aquaculture farmers), the use of chemicals in aquaculture sector will decrease 0.747 units. In contrast, the level of “participation in cooperative groups” in aquaculture in Vietnam was directly proportional, extended to the use of inorganic chemicals with a coefficient by 0.706. This result suggests that households participatin...

Monitoring of organochlorine pesticides in and around Keoladeo National Park, Bharatpur, Rajasthan, India

Keoladeo National Park (KNP) is an important wintering ground for thousands of birds that undertake a perilous journey over the Himalaya to make a seasonal home in a wetland ecosystem. However, this wetland is now getting polluted by various types of contaminants such as pesticides because of the agricultural practices in the catchment area from where the park receives water. Keeping this in mind, the present study has been undertaken to assess the organochlorine pesticide (OCP) residues in the sediments inside and around KNP. Samples were collected from the different blocks of the park. The concentrations of α-HCH, β-HCH, γ-HCH, δ-HCH, S-HCH, aldrin, dieldrin, heptachlor, hept.epoxide, endosulfan-I, endosulfan-II, endo.sulfate, S-endosulfan, endrin, 4,4'-DDE, 4,4'-DDD, and DDT were quantified using gas chromatography with electron capture detection. Analysis showed that the samples were contaminated with the above mentioned pesticides and that the concentration of total OCPs in the sediments varied from 0.1173 (dieldrin) to 5.558 ppm (γ HCH) in the samples collected from inside the park, whereas a range of pesticides varying in concentration from 0.1245 (4,4'-DDD) to 7.54 ppm (γ HCH) was found in samples from outside the park. Residues of S-HCH and S-endosulfan were not detected in any of the sediment samples. The occurrence of pesticides inside the park is a major threat to the park's biodiversity. Eco-friendly agriculture practices with minimal use of inorganic chemicals are suggested to minimize the pesticide residue levels in the park.

Sulphur and lead determination in petroleum products by raioisotope induced X‐ray fluorescence

AbstractA simple additive method, based on 55Fe and 109Cd source induced fluorescence in a helium environment, is presented for sulphur and lead determintion in petroleum products. Although the density of the matrix influences the X‐ray yields, the similarity of photon attenuation in water and petroleum products can be explotied. It is shown that routine system calibration can be achieved by the use of inorganic chemicals dissolved in water instead of organic additives in products. The low pressure helium flow suppresses the argon X‐rays, provides a good background region and increases the detection sensitivity for sulphur.