LDH Granular Filter for Surfactant Purification
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Solution Overview
Problem
Filters used for purifying water contaminated with surfactants, particularly those made of activated carbon or layered double hydroxides (LDH), tend to have short lifespans and premature breakthrough, requiring frequent intervention such as replacement or backwashing, which affects performance.
Innovation Solution
A composition of granules comprising 95-96% layered double hydroxide (LDH) with specific cation and anion combinations, 0.3-2% inorganic binder, and 0.2-1.5% organic binder, such as polyvinyl alcohol, which are calcined to enhance porosity and surface area, forming a packed-bed filter that prolongs breakthrough time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If activated carbon filters are used for purifying water contaminated with surfactants, then purification function is provided, but filter life is short and breakthrough occurs early
Solution Approach 1:
The patent changes the chemical composition parameters by using layered double hydroxides (LDH) with specific cation ratios (e.g., Mg/Al = 3/1) and interlayer anions (e.g., nitrate, sulfate) instead of conventional activated carbon. This compositional parameter change results in enhanced surfactant removal capacity and prolonged filter life, directly resolving the contradiction between providing purification function and extending breakthrough time.
Solution Approach 2:
The patent employs composite materials by combining layered double hydroxides with specific binders (e.g., polyvinyl alcohol, bentonite) to form granular filter media. This composite structure maintains the high surfactant removal efficiency of LDH while improving mechanical strength and hydro stability, thereby extending filter life and delaying breakthrough occurrence.
2Reliability
If layered double hydroxides are used for purification, then surfactant removal capacity is improved, but filter structural stability deteriorates
Solution Approach 1:
The patent introduces binders (e.g., polyvinyl alcohol, bentonite, cellulose) as intermediary materials that bridge the layered double hydroxide particles. These binders provide structural support and hydro stability to the filter media while preserving the high surfactant removal capacity of LDH, thus resolving the contradiction between removal capacity and structural stability.
Solution Approach 2:
By creating composite granules where LDH is combined with structurally stable binders in specific ratios (e.g., 90-99 wt% LDH and 1-10 wt% binder), the patent achieves both high surfactant removal efficiency and enhanced filter structural stability, preventing premature filter breakdown.
3Productivity
If granulated LDH is used without binder, then purification efficiency is maintained, but mechanical strength is insufficient leading to frequent intervention
Solution Approach 1:
The patent extracts only the minimum necessary amount of binder (1-10 wt%) required to provide mechanical strength, avoiding excessive binder that would reduce purification efficiency. This minimal binder approach maintains high surfactant removal capacity while providing sufficient structural integrity to reduce frequent filter intervention.
Solution Approach 2:
The patent optimizes the binder content parameter within a specific range (1-10 wt%) to achieve the balance between mechanical strength and purification efficiency. This parameter optimization ensures that the filter media has sufficient strength to prevent frequent breakdown while maintaining high surfactant removal efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The granular filter composition significantly extends breakthrough time, maintaining effectiveness and reducing the need for frequent intervention, with calcination and organic binder inclusion enhancing performance by up to an order of magnitude compared to commercial granulated activated carbon.
Implementation Method 1
filters made of activated carbon are used to purify such water
Implementation Method 2
granules made of just LDH are used for purification of water
Implementation Method 3
which are calcined to enhance porosity and surface area
Data Source
AI summary
Disclosed is a composition in the form of granules which comprise: (i) 95 to 98 % by weight layered double hydroxide (LDH) of molecular formula [Μ2+ 1-xΜ3+ x(ΟΗ)2]q+(Χn-)q/n.yΗ2O; where, M2+ is at least one of Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ or Zn2+; M3+ is at least one of Al3+, Fe3+, Cr3+, Ga3+ or V3+, X is an interlayer anion which is at least one of CI-, Br-, NO3 -, CO3 2-, SO4 2- or SeO4 2-; and "x" is the molar metal ratio from 0.1 to 0.33. (ii) 0.3 to 2 % by weight inorganic binder which is at least one of cement, white cement, gypsum, limestone, chalk, alumina silicate, fly ash, bentonite, bitumen, calcium aluminate, clay, hydrated lime or sodium silicate; and, 0.2 to 1.5 % by weight organic binder having molecular weight 1000 to 500,000 Daltons and decomposition temperature ≤ 400 °C, which is at least one of poly vinyl alcohol, polyethylene glycol, polyvinyl pyrollidone, polyacrylic acid, starch, cellulose, alginates, agar, gelatine or guar gum