SCI. Total environ.: almond is transformed into activated carbon with strong adsorption capacity for wastewater

With the rapid development of China's economy and urbanization, environmental pollution events emerge one after another, threatening people's life and health The most terrible is the invisible, colorless and ubiquitous heavy metal pollution! Heavy metal pollution refers to environmental pollution caused by heavy metals or their compounds It is mainly caused by mining, waste gas discharge, sewage irrigation and the use of heavy metal products Heavy metal pollution mainly includes lead, cadmium, nickel and other pollution The preparation of activated carbon from agricultural and forestry wastes is one of the hotspots in the research of clean conversion and utilization of biomass energy, which has a broad application prospect Compared with non biomass activated carbon, biomass activated carbon has many advantages First, biomass raw materials are abundant and most of them can be regenerated Secondly, the price of biomass raw materials is relatively low, non-toxic and harmless, which can reduce the cost of producing activated carbon to a certain extent, with considerable economic benefits Third, most of the raw materials of biomass activated carbon are waste, which are mostly disposed by landfill or incineration The reuse of waste effectively reduces environmental pollution, which conforms to the view of green chemical industry Therefore, biomass based activated carbon has become one of the hot spots in the field of activated carbon Almond is a by-product of fruit industry Some almonds can be processed into snacks for people to eat, and most of them will be discarded as waste products Almonds contain lignocellulose Maja Turk sekuli ć of Serbia studied the preparation and adsorption properties of almond based activated carbon Almond based activated carbon (aspha) has a good prospect in the field of heavy metal purification The researchers used discarded almonds (including shells) as raw materials Firstly, at room temperature (22.0 ± 1 ℃), 50% H3PO4 was used to soak the raw material for 24 hours Then, the mixed raw materials were carbonized under the conditions of heating rate of 10 ℃ · min - 1 and carbonization time of 45 min Then, the carbonized samples were further activated at a heating rate of 10 ℃ · min-1 and an activation time of 1 h Finally, wash the activated carbon sample with distilled water until the pH value of washing water reaches 5 The washed samples were dried at 110 ℃ for 3 hours, and then the almond based activated carbon (aspha) was obtained The BET specific surface area of amygdaloid based activated carbon (aspha) is up to 1099 M 2 · g-1, which has both microporous and mesoporous structure, and the microporous structure shows the high adsorption performance of the activated carbon At 20 ℃, the concentration of Pb 2 +, Cd 2 + and Ni 2 + decreased significantly 60 minutes after the adsorption of heavy metal ions by almond based activated carbon Batch studies were conducted by changing the initial pH (2-9), adsorbent dosage (0.2-10g / L), contact time (5-60min), temperature (22,32 and 42 ℃) and initial adsorbent concentration (5-500mg / L) Under the optimum conditions, the adsorption rate of heavy metals was over 95% (100 mg / L) Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were used to characterize and analyze the almond based activated carbon (APhA) and the adsorbed one respectively The results showed that the surface of the activated carbon was not smooth, with disordered pore structure, most of the pores were irregular slit, and the pore size was relatively uniform However, the pores of the activated carbon adsorbed heavy metal ions were almost filled, indicating that a large number of Pb2 +, Cd2 + and Ni2 + were adsorbed Figure a: SEM and EDX spectra of activated carbon before adsorption B: SEM and EDX spectra of activated carbon after adsorption of heavy metal ions (source: Science of the total environment) Finally, researchers used three adsorption models to describe the adsorption process The results show that the adsorption process of heavy metal ions can be described by quasi second-order kinetic model At all temperatures, the adsorption of heavy metal ions by almond based activated carbon is a spontaneous exothermic process Therefore, almond based activated carbon is a kind of low-cost activated carbon with good adsorption performance "The preparation of activated carbon from waste almonds" perfectly embodies "waste utilization, turning waste into treasure" Paper link: http://